AN EVALUATION OF THE MOLTEN SALT BREEDER REACTOR
I. INTRODUCTION
The Division of Reactor Development and Technology, USAEC, was assigned the responsibility of assessing the status of the technology of the Molten Salt Breeder Reactor (MSBR) as part of the Federal Council of Science and Technology Research and Development Goals Study. In conducting this review, the attractive features and problem areas associated with the concept have been examined; but more importantly, the assessment has been directed to provide a view of the technology and engineering development efforts and the associated government and industrial commitments which would be required to develop the MSBR into a safe, reliable and economic power source for central station application.
The MSBR concept, currently under study at the Oak Ridge National Laboratory (ORNL), is based on use of a circulating fluid fuel reactor coupled with on-line continuous fuel processing. As presently envisioned, it would operate as a thermal spectrum reactor system utilizing a thorium-uranium fuel cycle. Thus, the concept would offer the potential for broadened utilization of the nation's natural resources through operation of a breeder system employing another fertile material (thorium instead of uranium).
The long-term objective of any new reactor concept and the incentive for the government to support its development are to help provide a self-sustaining, competitive industrial capability for producing economical power in a reliable and safe manner. A basic part of achievement of this objective is to gain public acceptance of a new form of power production. Success in such an endeavor is required to permit the utilities and others to consider the concept as a viable option for generating electrical power in the future and to consider making the heavy, long-term commitments of resources in funds, facilities and personnel needed to provide the transition from the early experimental facilities and demonstration plants to full-scale commercial reactor power plant systems.
Consistent with the policy established for all power reactor development programs, the MSBR would require the successful accomplishment of three basic research and development phases:
- An initial research and development phase in which the basic technical aspects of the MSBR concept are confirmed, involving exploratory development, laboratory experiment, and conceptual engineering.
- A second phase in which the engineering and manufacturing capabilities are developed. This includes the conduct of in-depth engineering and proof testing of first-of-a-kind components, equipment and systems. These would then be incorporated into experimental installations and supporting test facilities to assure adequate understanding of design and performance characteristics, as well as to gain overall experience associated with major operational, economic and environmental parameters. As these research and development efforts progress, the technological uncertainties would need to be resolved and decision points reached that would permit development to proceed with necessary confidence. When the technology is sufficiently developed and confidence in the system was attained, the next stage would be the construction of large demonstration plants.
- A third phase in which the utilities make large-scale commitments to electric generating plants by developing the capability to manage the design, construction, test and operation of these power plants in a safe, reliable, economic, and environmentally acceptable manner.
[This paragraph reflects Milton Shaw's views, but Shaw clearly over-estimated the relative maturity of the reactor technologies referred to by the paragraph. Developmental problems with light water reactor reactor technology were to cost reactor owners tens of billions of dollars during the next two decades. Reactor scientists had told Shaw about the problems, but Shaw discounted the warnings. Again Shaw's belief that the LMFBR had reached an advanced stage of development was far from reality in 1972, and remains questionable in 2008. Shaw's demonstrably mistaken beliefs thus appear to lie at the heart of the WASH-1222 assessment of the potential of MSR technology.
It should be pointed out that the AEC initially endorsed the development of the Molten Salt Reactor upon the recommendation of the Fluid Fuel Reactor Task Force. The Report found that the Molten Salt reactor was the most likely to be successful of the three reactor types evaluated. The report had found that there were significant developmental tasks before a MiThe subsequent history of MSR. In no respect had the subsequent 13 years of MSR development at ORNL disappointed the expectations of the Task Force evaluators. During the 14 year period from the task force evaluation the Molten Salt Reactor Experiment had been devised and successfully conducted. The MSRE had been considered entirely successful, and that success had been acknowledged by WASH-1222. By the beginning of 1972 there was considerable commercial interest in the development of large (1000 MWe) Molten Salt Breeder Reactors for electric power generation and 15 companies including 9 utilities and Ebasco Services Inc. (a utility Industries consultant group), together with five industrial companies. These companies had organized a Molten Salt Reactor task force under the supervision of Ebasco, and the task force had initiated planning for the construction of a 1000 MWe power generation MSR. Despite this industrial interest, the AEC and in particular Milton Shaw had decided to withdraw support from ORNL and from Molten Salt Reactor. The withdrawal of funds from ORNL was devastating, and during the late 1960's and early 1970's as many as 1700 ORNL staff positions were eliminated. Whole ORNL divisions, long associated with the MSR project were dissolved, and if no work could be found for their scientists and engineers in the greatly diminished ORNL establishment, they were terminated from ORNL employment. Once this background is understood, the irony of the next sentence of WASH-1222 becomes apparent.]
It should also be kept in mind that the large backlog of commitments and the shortage of qualified engineering and technical management personnel and proof-test facilities in the government, in industry and in the utilities make it even more necessary that all the reactor systems be thoroughly designed and tested before additional significant commitment to and construction of, commercial power plants are initiated.
It should also be kept in mind that the large backlog of commitments and the shortage of qualified engineering and technical management personnel and proof-test facilities in the government, in industry and in the utilities make it even more necessary that all the reactor systems be thoroughly designed and tested before additional significant commitment to and construction of, commercial power plants are initiated.
[As we have seen "the shortage of qualified engineering and technical management personnel and proof-test facilities" was a problem which Milton Shaw himself had created. Thus as we shall see, not only does WASH-1222 commit egregious errors in logic, as well as misstatement of facts, it covers up the fact that Shaw himself had destroyed the resources that were required to complete the development of the MSR. Statements like this must be counted as duplicitous. - CB]
With regard to the MSBR, preliminary reactor designs were evaluated in WASH-1097 (“The Use of Thorium in Nuclear Power Reactors”) based upon the information supplied by ORNL. Two reactor design concepts were considered—a two-fluid reactor in which the fissile and fertile salts were separated by graphite and a single fluid concept in which the fissile and fertile salts were completely mixed. This evaluation identified problem areas requiring resolution through conduct of an intensive research and development program.
With regard to the MSBR, preliminary reactor designs were evaluated in WASH-1097 (“The Use of Thorium in Nuclear Power Reactors”) based upon the information supplied by ORNL. Two reactor design concepts were considered—a two-fluid reactor in which the fissile and fertile salts were separated by graphite and a single fluid concept in which the fissile and fertile salts were completely mixed. This evaluation identified problem areas requiring resolution through conduct of an intensive research and development program.
[The two fluid MSR was an auto breeder. That meant it was intended to produced at least enough U233 to keep working until it ran out of thorium to breed. As long as a reactor produces as much fuel as it consumes, it is a successful breeder. Thus WASH-1222 should have considered the advantages of 2 fluid MSRs. - CB]
Since the publication of WASH-1097, all efforts related to the two-fluid system have been discontinued because of mechanical design problems and the development of processes which would, if developed into engineering systems, permit the on-line reprocessing of fuel from single fluid reactors. At present, the MSBR concept is essentially in the initial research and development phase, with emphasis on the development of basic MSBR technology. The technology program is centered at ORNL where essentially all research and development on molten salt reactors has been performed to date. The program is currently funded at a level of $5 million per year. Expenditures to date on molten salt reactor technology both for military and civilian power applications have amounted to approximately $150 million of which approximately $70 million has been in support of central station power plants. These efforts date back to the 1940's.
[ORNL chose a one fluid approach, for technical reasons, however there were advantages to a two fluid approach, and ORNL scientists like my father believed that the problems of the two fluid approach were not serious, while the single fluid approach created its own set of difficulties. These sums of $150 million and $70 million seem quite paltry by the standards of 2010. Even when inflation is factored in, we are talking about an investment of no more than 1 billion 2010 dollars, far less than the United States was to spend on Shaw's preferred but ultimately unsuccessful breeder project, the Clinch River Breeder Reactor. Thus even if dollars from the 1950’s and 1960’s are translated into 2010 terms, the amount spent seems trivial in comparison to say the cost of military weapons systems. In retrospect we can say that ORNL provided a whole lot of information about a promising technology very inexpensively. - CB]
In considering the MSBR for central station power plant application, it is noted that this concept has several unique and desirable features; at the same time, it is characterized by both complex technological and practical engineering problems which are specific to fluid-fueled reactors and for which solutions have not been developed. Thus, this concept introduced major concerns that are different in kind and magnitude from those commonly associated with solid fuel breeder reactors. The development of satisfactory experimental units and further consideration of this concept for use as a commercial power plant will require resolution of these as well as other problems which are common to all reactor concepts.
[This paragraph shifts from obvious facts, to unwarranted conclusions. The facts involve “complex technological,” and “practical engineering problems” for which “solutions have not been developed.” In fact ORNL scientists and engineers had developed solutions to most of the complex problems by 1972 - they had to do so in order for the MSRE to be successful - but if solutions for all of the complex problems had already been developed, then there would be no need or purpose for the MSBR development program which has been proposed. The next statement does not follow from the stated issues. “Thus, this concept introduced major concerns that are different in kind and magnitude from those commonly associated with solid fuel breeder reactors.” Why are concerns about the developmental problems of the MSR different in kind and magnitude?” WASH-1222 had not shown that the development problems associated with Molten Salt Breeder Reactors were not different "in kind and magnitude" from those associated with the Light Water Reactor. Further, the developmental difficulties associated with the LMFBR differed in kind and magnitude from those of the Light Water Reactor and the Molten Salt Nreeder Reactor. Given what we know today, the AEC had not only underestimated the problems associated with the development of the LMFBR, they had seriously underestimated the developmental problems associated with the LWR, a technology which Shaw and the AEC in 1972 incorrectly believed to be mature. - CB]
As part of the AEC's Systems Analysis Task Force (AEC report WASH-1098) and the "Cost-Benefit Analysis of the U.S. Breeder Reactor Program" (AEC reports WASH-1126 and WASH-1184), studies were conducted on the cost and benefit of developing another breeder system, "parallel" to the LMFBR. The consistent conclusion reached in these studies is that sufficient information is available to indicate that the projected benefits from the LMFBR program can support a parallel breeder program. However, these results are highly sensitive to the assumptions on plant capital costs with the recognition, even among concepts in which ample experience exists, that capital costs and especially small estimated differences in costs are highly speculative for plants to be built 15 or 20 years from now. Therefore, it is questionable whether analyses based upon such costs should constitute a major basis for making decisions relative to the desirability of a parallel breeder effort. Experience in reactor development programs in this country and abroad has demonstrated that different organizations, in evaluating the projected costs of introducing a reactor development program and carrying it forward to the point of large-scale commercial utilization, would arrive at different estimates of the methods, scope of development and engineering efforts, and the costs and time required to bring that program to a stage of successful large scale application and public acceptance.
[The statement of risk considerations in the proceeding paragraph is sound. Future cost estimates for projects in developmental stages represent risky conjectures. This would seem to be an argument for rather than against parallel programs. Given the cost uncertainties attendant to taking a single line approach to a technological development, it is always wise to have an alternative solution at hand, in case costs start to run away. Developmental costs for the LMFRB “Clinch River Breeder Reactor” project did run away in the 1970’s and early 1980’s. Since all of the contentions about cost risk apply equally to both the LMFBR and the MSR, the argument in the last paragraph is incoherent. That is, it supports contradictory conclusions. We are being set up by this paragraph for an attempt to block further development of the MSR on the basis of cost. WASH-1222 has already made the judgment that development of the LMFBR would proceed. It appears to have assessed that the AEC’s 1970’s LMFB project could fail, as it did. The possibility of project failure is a risk. Any comparative cost/benefits study, should assess relative risks of failure. - CB]
Based upon the AEC's experience with other complex reactor development programs, it is estimated that a total government investment up to about 2 billion dollars in undiscounted direct costs could be required to bring the molten salt breeder or any parallel breeder to fruition as a viable, commercial power reactor. A magnitude of funding up to this level could be needed to establish the necessary technology and engineering bases, obtain the required industrial capability, and advance through a series of test facilities, reactor experiments, and demonstration plants to a commercial MSBR, safe and suitable to serve as a major energy option for central station power generation in the utility environment.
[Looking at this statement today with the benefit of hindsight, I would have to say that a development cost of $2 billion 1972 dollars was trivial. The Apollo Moon program cost $25.4 Billion 1969 dollars, arguably the nation would have been far better off if 10% of that money had been diverted to MSR development. In 1984 the GAO reviewed the Clinch River Breeder Reactor project, which was the sucessor of the AEC’s LMFBR project. In 1971 the AEC had estimated that the project would cost $400 million, of which $257 was to have come from private sources. By 1972, when WASH-1222 was written the cost estimate had risen to $700 million. By 1981 after $1 billion had been spent, the estimated cost of completion was 3 to 3.2 Billion more, with an estimated further project cost of $1 billion for a plutonium processing facility. By 1984 project cost had risen to $8 billion. And this was only a proof of concept reactor. Other LMFBR proof of concept reactors have had a very mixed history. Even today, a case can be made that LMFBT technology has not been proven either safe, reliable or cost effective. -
Introduction: I have, in three posts on Nuclear Green discussed the effects that Milton Shaw's beliefs, managerial style, and policies had both on nuclear research at some and probably all National Laboratories. Shaw's ruthless methods of imposing his views even led to the firing of Alvin Weinberg over disagreements about nuclear safety. In my last post, on the introduction to WASH-1222, I suggested that not only did Shaw have mistaken beliefs about the maturity of Liquid Metal Fast Breeder Reactor and Light Water Reactor technology, but that these beliefs cost Light Water Reactor owners tens of billions of dollars. I may elaborate on this at a further time. I also argued that Shaw's mistakes about technology extended to breeder reactors, He held the mistaken belief that the maturity of LMFBR's had reached a level of maturity similar to that of LWRs.
In my Earlier comments, I began a review of a WASH-1222, a document prepared under Shaw's direction. In the introduction to the document I found evidence that Shaw's mistaken beliefs, coupled with the consequences of his own bureaucratic decisions, decisions for which he failed to acknowledge responsibility, and shocking errors in logic, led Shaw to discount a promising new reactor technology, the Molten Salt Reactor. At the same time, Shaw was implicitly pushing other technologies, even though they shared many of the problems of Molten Salt Reactor technology, while for other problems with technology Shaw favored, were solved by using the molten salt approach. Shaw claimed that unanticipated costs might be incurred during the course of development.
AN EVALUATION OF THE MOLTEN SALT BREEDER REACTOR
II. SUMMARY
The MSBR concept is a thermal spectrum, fluid-fuel reactor which operates on the thorium-uranium fuel cycle and when coupled with on-line fuel processing, has the potential for breeding at a meaningful level. The marked differences in the concept as compared to solid-fueled reactors make the MSBR a distinctive alternate. Although the concept has attractive features, there are a number of difficult development problems that must be resolved; many of these are unique to the MSBR while others are pertinent to any complex reactor system.
The technical effort accomplished since the publication of WASH-1097 and WASH-1098 has identified and further defined the problem areas; however, this work has not advanced the program beyond the initial phase of research and development. Although progress has been made in several areas (e.g., reprocessing and improved graphite), new problems not addressed in WASH-1097 have arisen which could affect the practicality of designing and operating a MSBR. Examples of major uncertainties relate to materials of construction, methods for control of tritium, and the design of components and systems along with their special handling, inspection and maintenance equipment. Considerable research and development efforts are required in order to obtain the data necessary to resolve the uncertainties.
Assuming that practical solutions to these problems can be found, a further assessment would have to be made as to the advisability of proceeding to the next stage of the development program. In advancing to the next phase, it would be necessary to develop a greatly expanded industrial and utility participation and commitment along with a substantial increase in government support. Such broadened involvement would require an evaluation of the MSBR in terms of already existing commitments to other nuclear power and high priority energy development efforts.
III. RESOURCE UTILIZATION
It has long been recognized that the importance of nuclear fuels for power production depends initially on the utilization of the naturally occurring fissile 235U; but it is the more abundant fertile materials, 238U and 232Th, which will be the major source of nuclear power generated in the future. The basic physics characteristics of fissile plutonium produced from 238U offer the potential for high breeding gains in fast reactors, and the potential to expand greatly the utilization of uranium resources by making feasible the utilization of additional vast quantities of otherwise uneconomic low grade ore. In a similar manner, the basic physics characteristics of the thorium cycle will permit full utilization of the nation's thorium resources while at the same time offering the potential for breeding in thermal reactors.
The estimated thorium reserves are sufficient to supply the world's electric energy needs for many hundreds of years if the thorium is used in a high-gain breeder reactor. It is projected that if this quantity of thorium were used in a breeder reactor, approximately 1,000,000 quad (1 quad = 1 quadrillion Btu) would be realized from this fertile material. It is estimated that the uranium reserves would also supply 1,000,000 quads of energy if the uranium were used in LMFBRs. In contrast, only 20,000 quads would be available if thorium were used as the fertile material in an advanced converter reactor because the reactor would be dependent upon 235U availability for fissile inventory make-up. (Note: a conservative estimate is that between 20,000 and 30,000 quads will be used for electric power generation between now and the year 2100.)
IV. HISTORICAL DEVELOPMENT OF MOLTEN SALT REACTORS
The investigation of molten salt reactors began in the late 1940's as part of the U.S. Aircraft Nuclear Propulsion (ANP) Program. Subsequently, the Aircraft Reactor Experiment (ARE) was built at Oak Ridge and in 1954 it was operated successfully for nine days at power levels up to 2.5 MWt and fuel outlet temperatures up to 1580ºF (1133 K). The ARE fuel was a mixture of NaF, ZrF4, and UF4. The moderator was beryllium oxide and the piping and vessel were constructed of Inconel.
In 1956, ORNL began to study molten salt reactors for application as central station converters and breeders. These studies concluded that graphite moderated, thermal spectrum reactors operating on a thorium-uranium cycle were most attractive for economic power production. Based on the technology at that time, it was thought that a two-fluid reactor in which the fertile and fissile salts were kept separate was required in order to have a breeder system. The single-fluid reactor, while not a breeder, appeared simpler in design and also seemed to have the potential for low power costs.
Over the next few years, ORNL continued to study both the two-fluid and single-fluid concepts, and in 1960 the design of the single-fluid 8 MWt Molten Salt Reactor Experiment (MSRE) was begun. The MSRE was completed in 1965 and operated successfully during the period 1965-1969. The MSRE experience is treated in more detail in a later section.
Concurrent with the construction of the MSRE, ORNL performed research and development on means for processing molten salt fuels. In 1967 new discoveries were made which suggested that a single-fluid reactor could be combined with continuous on-line fuel processing to become a breeder system. Because of the mechanical design problems of the two-fluid concept and the laboratory-scale development of processes which would permit on-line reprocessing, it was determined that a shift in emphasis to the single-fluid breeder concept should be made; this system is being studied at the present.
[I have pointed to evidence that Milton Shaw's mistaken beliefs about the maturity and developmental costs of solid core nuclear reactor technology, coupled with the consequences of his own bureaucratic decisions for which he failed to acknowledge responsibility, and errors in logic, led Shaw to discount a promising new reactor technology, the Molten Salt Reactor. At the same time, Shaw was pushing the development of other technologies, even though they shared many of the problems he alleged that Molten Salt Reactor technology suffered from.]
AN EVALUATION OF THE MOLTEN SALT BREEDER REACTOR
I. SUMMARY
The MSBR concept is a thermal spectrum, fluid-fuel reactor which operates on the thorium-uranium fuel cycle and when coupled with on-line fuel processing, has the potential for breeding at a meaningful level. The marked differences in the concept as compared to solid-fueled reactors make the MSBR a distinctive alternate. Although the concept has attractive features, there are a number of difficult development problems that must be resolved; many of these are unique to the MSBR while others are pertinent to any complex reactor system.
The technical effort accomplished since the publication of WASH-1097 and WASH-1098 has identified and further defined the problem areas; however, this work has not advanced the program beyond the initial phase of research and development. Although progress has been made in several areas (e.g., reprocessing and improved graphite), new problems not addressed in WASH-1097 have arisen which could affect the practicality of designing and operating a MSBR. Examples of major uncertainties relate to materials of construction, methods for control of tritium, and the design of components and systems along with their special handling, inspection and maintenance equipment. Considerable research and development efforts are required in order to obtain the data necessary to resolve the uncertainties.
Assuming that practical solutions to these problems can be found, a further assessment would have to be made as to the advisability of proceeding to the next stage of the development program. In advancing to the next phase, it would be necessary to develop a greatly expanded industrial and utility participation and commitment along with a substantial increase in government support. Such broadened involvement would require an evaluation of the MSBR in terms of already existing commitments to other nuclear power and high priority energy development efforts.
III. RESOURCE UTILIZATION
It has long been recognized that the importance of nuclear fuels for power production depends initially on the utilization of the naturally occurring fissile 235U; but it is the more abundant fertile materials, 238U and 232Th, which will be the major source of nuclear power generated in the future. The basic physics characteristics of fissile plutonium produced from 238U offer the potential for high breeding gains in fast reactors, and the potential to expand greatly the utilization of uranium resources by making feasible the utilization of additional vast quantities of otherwise uneconomic low grade ore. In a similar manner, the basic physics characteristics of the thorium cycle will permit full utilization of the nation's thorium resources while at the same time offering the potential for breeding in thermal reactors.
The estimated thorium reserves are sufficient to supply the world's electric energy needs for many hundreds of years if the thorium is used in a high-gain breeder reactor. It is projected that if this quantity of thorium were used in a breeder reactor, approximately 1,000,000 quad (1 quad = 1 quadrillion Btu) would be realized from this fertile material. It is estimated that the uranium reserves would also supply 1,000,000 quads of energy if the uranium were used in LMFBRs. In contrast, only 20,000 quads would be available if thorium were used as the fertile material in an advanced converter reactor because the reactor would be dependent upon 235U availability for fissile inventory make-up. (Note: a conservative estimate is that between 20,000 and 30,000 quads will be used for electric power generation between now and the year 2100.)
IV. HISTORICAL DEVELOPMENT OF MOLTEN SALT REACTORS
The investigation of molten salt reactors began in the late 1940's as part of the U.S. Aircraft Nuclear Propulsion (ANP) Program. Subsequently, the Aircraft Reactor Experiment (ARE) was built at Oak Ridge and in 1954 it was operated successfully for nine days at power levels up to 2.5 MWt and fuel outlet temperatures up to 1580ºF (1133 K). The ARE fuel was a mixture of NaF, ZrF4, and UF4. The moderator was beryllium oxide and the piping and vessel were constructed of Inconel.
In 1956, ORNL began to study molten salt reactors for application as central station converters and breeders. These studies concluded that graphite moderated, thermal spectrum reactors operating on a thorium-uranium cycle were most attractive for economic power production. Based on the technology at that time, it was thought that a two-fluid reactor in which the fertile and fissile salts were kept separate was required in order to have a breeder system. The single-fluid reactor, while not a breeder, appeared simpler in design and also seemed to have the potential for low power costs.
Over the next few years, ORNL continued to study both the two-fluid and single-fluid concepts, and in 1960 the design of the single-fluid 8 MWt Molten Salt Reactor Experiment (MSRE) was begun. The MSRE was completed in 1965 and operated successfully during the period 1965-1969. The MSRE experience is treated in more detail in a later section.
Concurrent with the construction of the MSRE, ORNL performed research and development on means for processing molten salt fuels. In 1967 new discoveries were made which suggested that a single-fluid reactor could be combined with continuous on-line fuel processing to become a breeder system. Because of the mechanical design problems of the two-fluid concept and the laboratory-scale development of processes which would permit on-line reprocessing, it was determined that a shift in emphasis to the single-fluid breeder concept should be made; this system is being studied at the present.
[The above statements are factually accurate and for the most part can be passed over without further comment, however, it should be noted that ORNL scientists had proposed solutions to the problem of the two fluid approach, and that there were significant problems with the one fluid approach. Current evaluations of MSR technology, have still not settled on which is the more desirable approach.]
Part III
Introduction: In the first section of my exploration of WASH-1222, I pointed to what might be considered errors in logic or reasoning, in which argument went from true assumptions to false conclusions. But in the WASH-1222 discussion of the actual state of Molten Salt Reactor technology, we clearly encounter repeated and dishonest statements of facts. I will presently demonstrate the depth of this dishonesty.
V. MOLTEN SALT BREEDER REACTOR CONCEPT DESCRIPTION
The breeding reactions of the thorium cycle are:
232Th +n --> 233Th --> 233 Pa --> 233U
Because of the number of neutrons produced perneutron absorbed and the small fast-fission bonus associated with 233U and 232Th in the thermal spectrum, a breeding ratio only slightly greater than unity is achievable. In order to realize breeding with the thorium cycle it is necessary to remove the bred 233Pa and the various nuclear poisons produced by the fission process from the high-flux region as quickly as possible. The Molten-Salt Breeder Reactor concept permits rapid removal of 233Pa and the nuclear poisons (e.g. 135Xe and the rare earth elements). The reactor is a fluid-fueled system containing UF4 and ThF4 dissolved in LiF - BeF2. The molten fuel salt flows through a graphite moderator where the nuclear reactions take place. A side stream is continuously processed to remove the Pa and rare earth elements, thereby permitting the achievement of a calculated breeding ratio of about 1.06.
The MSBR is attractive because of the following:
- Use of a fluid fuel and on-site processing would eliminate the problems of solid fuel fabrication and the handling and shipping and reprocessing of spent fuel elements which are associated with all other reactor types under active consideration.
- MSBR operation on the thorium-uranium fuel cycle would help conserve uranium and thorium resources by utilizing thorium reserves with high efficiency.
- The MSBR is projected to have attractive fuel cycle costs. The major uncertainty in the fuel cycle cost is associated with the continuous fuel processing plant which has not been developed.
- The safety issues associated with the MSBR are generally different from those of solid fuel reactors. Thus, there might be safety advantages for the MSBR when considering major accidents. An accurate assessment of MSBR safety is not possible today because of the early state of development.
- Like other advanced reactor systems such as the LMFBR and HTGR, the MSBR would employ modem steam technology for power generation with high thermal efficiencies. This would reduce the amount of waste heat to be discharged to the environment.
To give an idea of the extent to which Statement 4 subverts the truth I will compare it with Eric H. Ottewitte's sometime later listing of the safety advantages of the MSR:
1. Already being a molten fuel, further "meltdown" cannot occur
2. Fluid fuel has inherently a strong negative temperature coefficient of reactivity due to expansion, greatly inhibiting boiling
3. Elimination of pressurized and pressure-evolving components inside the containment
4. Elimination of the possibility of gas and vapor evolution, especially the release of free hydrogen and attendant fire hazard
5. Reduced risk of radioactivity release outside the containment due to
a. reduced risk of failure of the containment, and
b. two orders of magnitude reduction in the FP decay heat source relative to
conventional solid-fuel reactors, due to continuous on-site chemical processing
6. Reduced FP inventory improves the capability for emergency heat removal by natural
convection, thereby greatly reducing the designated evacuation area
7. Fluidity facilitates removal from the reactor to ever-safe containers
8. High heat capacity of fuel restricts temperature rise on loss of normal cooling
9. Low salt vapor pressure minimizes the effect of any temperature rise
Ottewitte's list would have been based on knowledge that the writers of WASH-1222 in 1972. The list should not be regarded as comprehensive. Thus WASH-1222 appears to be deliberately minimizing the numerous and well-established safety advantages of the MSR.
- CB]
Selected conceptual design data for a large MSBR, based primarily on design studies performed at ORNL, are given in Table I.
There are, however, problem areas associated with the MSBR which must be overcome before the potential of the concept could be attained. These include development of continuous fuel processing, reactor and processing structural materials, tritium control methods, reactor equipment and systems, maintenance techniques, safety technology, and MSBR codes and standards. Each of these problem areas will now be evaluated in some detail, using as a reference point the technology which was demonstrated by the Molten Salt Reactor Experiment (MSRE) during its design, construction and operation at Oak Ridge and the conceptual design parameters presented in Table I and in Appendix A. A conceptual flowsheet for this system is shown in Figure 1.
[I will comment on the problems alluded to in this paragraph as WASH-1222 discusses them in greater detail. - CB]
[Assessments of technologies under development are problematic. At best they are like a snapshot of where the technology is, coupled with some educated guesses about where it might be headed. It is the educated guess, that create the biggest problems. Overly optimistic assessments of the potential for progress, may be based on unrealistic expectations for program progress. This was most certainly the case with the AEC's assessment of LMFBR technology in the late 1960's and early 1970's. Milton Shaw and other members of the AEC establishment including Glenn T Seaborg, and Congressman Chet Holifield, as well as the AEC staff had greatly underestimated the degree of difficulty involved in the development of a commercial LMFBR. Conversely, bureaucratic manipulators like Shaw, could use the assessments to kill promising technologies that competed with pet projects.
It should be understood that the purpose of any technological research and development program is to identify and fix problems related to the implementation of a new technology. Considering the radical and daring nature of the Molten Salt Reactor concept, and the extreme conditions the reactor was expected to operate under, developmental problems were to be expected. The point of the 1965 to 1969 Molten Salt Reactor experiment was to explore potential problems and fixes for them before the MSR went into development for commercial use. – CB]
Appendix I, The AEC case for the Fast Breeder
WASH-1184 COST-BENEFIT ANALYSIS OF THE U.S. BREEDER REACTOR PROGRAM. Updated (1970) played an important role in supporting the decision by the Nixon administration to support the Liquid Metal Fast Breeder Reactor development, while abandoning the alternative Molten Salt Breeder Reactor concept developed by Oak Ridge National Laboratory. WASH-1184 was a revision of WASH-1126 which in turn was a product of cost-benefit analyses of the long term nuclear power options which the AEC believed were available to the United States in the late 1960's. These cost-benefit assessments would have been conducted under the supervision of Milton Shaw who was the Director of the AECs’ Division of Reactor Development and Technology. The text of WASH-1184 strongly suggested that the Molten Salt Breeder Reactor had not been included in the USAEC's on-going breeder cost benefit analysis despite a vigorous championing of that technology by ORNL Director and famed reactor scientist, Alvin Weinberg, who had invented the Light Water Reactor, and had suggested his invention to Hyman Rickover as a means of powering Navy submarines. Shaw, and Rickover had himself been trained in reactor technology at Oak Ridge in a program that Weinberg had supervised.
Weinberg's contentions about the MSBR were supported by a large body of research which indicated that the MSBR was viable, and likely to be a safe and cost-effective source of future electricity. Thus Shaw appears to have chosen to ignore questions about the cost-effectiveness of the MSBR in AEC breeder cost-effectiveness studies which he directed. This choice has never been fully explained.
It appears likely that Milton Shaw was pushing LMFBR development, perhaps, it was alleged at the time, even to the extent of diverting money meant for Light Water Reactor safety research, to LMFBR development.
A study of AEC/DoE LMFBR cost assessments made between the late 1960's and mid-1970's found steadily rising estimated costs for the LMFBR. It would appear that the late 1960's LMFBR cost estimate, which would have been referenced by the Nixon administration in its choice to support LMFB technology involved a direct cost of $2.2 billion. The total breeder program development cost of was estimated to run to $4.4 billion. WASH-1184 estimated direct costs for a LMFBR development program to run to $2.5 billion with total breeder development costs dropping to $3.8 billion. This drop was largely due to a drop in support of alternative breeder technology from $0.8 billion to $100 million. This accounting ploy allowed WASH-1184 to claim an overall program cost drop at a time when LMFBR cost estimates were rising.
In the WASH-1535, DRAFT EIS (1973-74) LMFBR cost estimates had risen to $4.0 billion, while in WASH-1535, PFEIS, LMFBR cost estimates had risen to $6.5 billion.
The 1975 Natural Resources Defense Council, paper Bypassing the Breeder, reported that the initial estimate for the Clinch River Breeder Reactor was around $400 million,
The LMFBR made an easy target for nuclear critics like the Natural Resources Defense Council. All they had to do was lay out the facts. President Nixon had admitted,
Selected conceptual design data for a large MSBR, based primarily on design studies performed at ORNL, are given in Table I.
There are, however, problem areas associated with the MSBR which must be overcome before the potential of the concept could be attained. These include development of continuous fuel processing, reactor and processing structural materials, tritium control methods, reactor equipment and systems, maintenance techniques, safety technology, and MSBR codes and standards. Each of these problem areas will now be evaluated in some detail, using as a reference point the technology which was demonstrated by the Molten Salt Reactor Experiment (MSRE) during its design, construction and operation at Oak Ridge and the conceptual design parameters presented in Table I and in Appendix A. A conceptual flowsheet for this system is shown in Figure 1.
[I will comment on the problems alluded to in this paragraph as WASH-1222 discusses them in greater detail. - CB]
[Assessments of technologies under development are problematic. At best they are like a snapshot of where the technology is, coupled with some educated guesses about where it might be headed. It is the educated guess, that create the biggest problems. Overly optimistic assessments of the potential for progress, may be based on unrealistic expectations for program progress. This was most certainly the case with the AEC's assessment of LMFBR technology in the late 1960's and early 1970's. Milton Shaw and other members of the AEC establishment including Glenn T Seaborg, and Congressman Chet Holifield, as well as the AEC staff had greatly underestimated the degree of difficulty involved in the development of a commercial LMFBR. Conversely, bureaucratic manipulators like Shaw, could use the assessments to kill promising technologies that competed with pet projects.
It should be understood that the purpose of any technological research and development program is to identify and fix problems related to the implementation of a new technology. Considering the radical and daring nature of the Molten Salt Reactor concept, and the extreme conditions the reactor was expected to operate under, developmental problems were to be expected. The point of the 1965 to 1969 Molten Salt Reactor experiment was to explore potential problems and fixes for them before the MSR went into development for commercial use. – CB]
AN EVALUATION OF THE MOLTEN SALT BREEDER REACTOR
VI. STATUS OF MSBR TECHNOLOGY
A. MSRE - The Reference Point for Current Technology
The Molten Salt Reactor Experiment (MSRE) was begun in 1960 at ORNL as part of the Civilian Nuclear Power Program. The purpose of the experiment was to demonstrate the basic feasibility of molten salt power reactors. All objectives of the experiment were achieved during its successful operation from June 1965 to December 1969. These included the distinction of becoming the first reactor in the world to operate solely on 233U. Some of the more significant dates and statistics pertinent to the MSRE are given in Table II.
In spite of the success of the MSRE, there are many areas of molten salt technology which must be expanded and developed in order to proceed from this small non-breeding experiment to a safe, reliable, and economic 1000 MWe MSBR with a 30-year life. To illustrate this point, some of the most important differences in basic design and performance characteristics between the MSRE and a conceptual 1000 MWe MSBR are given in Table III. Scale-up would logically be accomplished through development of reactor plants of increasing size. Examination of Table III provides an appreciation of the scale-up requirements in going from the MSRE to a large MSBR. Some problems associated with progressing from a small experiment to a commercial, high performance power plant are not adequately represented by the comparison presented in the Table. Therefore it is useful to examine additional facets of MSBR technology in more detail.
[This statement says nothing more than that the MSR is under development, and that problems have been identified and steps to identify and implement solutions are underway. – CB]
B. Continuous Fuel Processing: The Key to Breeding
In order to achieve nuclear breeding in the single-fluid MSBR it is necessary to have an on-line continuous fuel processing system. This would accomplish the following:
VI. STATUS OF MSBR TECHNOLOGY
A. MSRE - The Reference Point for Current Technology
The Molten Salt Reactor Experiment (MSRE) was begun in 1960 at ORNL as part of the Civilian Nuclear Power Program. The purpose of the experiment was to demonstrate the basic feasibility of molten salt power reactors. All objectives of the experiment were achieved during its successful operation from June 1965 to December 1969. These included the distinction of becoming the first reactor in the world to operate solely on 233U. Some of the more significant dates and statistics pertinent to the MSRE are given in Table II.
In spite of the success of the MSRE, there are many areas of molten salt technology which must be expanded and developed in order to proceed from this small non-breeding experiment to a safe, reliable, and economic 1000 MWe MSBR with a 30-year life. To illustrate this point, some of the most important differences in basic design and performance characteristics between the MSRE and a conceptual 1000 MWe MSBR are given in Table III. Scale-up would logically be accomplished through development of reactor plants of increasing size. Examination of Table III provides an appreciation of the scale-up requirements in going from the MSRE to a large MSBR. Some problems associated with progressing from a small experiment to a commercial, high performance power plant are not adequately represented by the comparison presented in the Table. Therefore it is useful to examine additional facets of MSBR technology in more detail.
[This statement says nothing more than that the MSR is under development, and that problems have been identified and steps to identify and implement solutions are underway. – CB]
B. Continuous Fuel Processing: The Key to Breeding
In order to achieve nuclear breeding in the single-fluid MSBR it is necessary to have an on-line continuous fuel processing system. This would accomplish the following:
- Isolate protactinium-233 from the reactor environment so it can decay into the fissile fuel isotope uranium-233 before being transmuted into other isotopes by neutron irradiation.
- Remove undesirable neutron poisons from the fuel salt and thus improve the neutron economy and breeding performance of the system.
- Control the fuel chemistry and remove excess uranium-233 which is to be exported from the breeder system.
1. Chemical Process Development
The Oak Ridge National Laboratory has proposed a fuel processing scheme to accomplish breeding in the MSBR, and the flowsheet processes involve:
At this time, the basic chemistry involved in the MSBR processing scheme has been demonstrated in laboratory-scale experiments. Current efforts at Oak Ridge are being directed toward development of subsystems incorporating many of the required processing steps. Ultimately a complete breeder processing experiment would be required to demonstrate the system with all the chemical conditions and operational requirements which would be encountered with any MSBR.
Not shown on the flowsheet is a separate processing system which would require injecting helium bubbles into the fuel salt, allowing them to circulate in the reactor system until they collect fission product xenon, and then removing the bubbles and xenon from the reactor system. Xenon is a highly undesirable neutron poison which will hamper breeding performance by capturing neutrons which would otherwise breed new fuel. This concept for xenon stripping was demonstrated in principle by the MSRE, although more efficient and controllable stripping systems will be desirable for the MSBR. The xenon poisoning in the MSRE was reduced by a factor of six by xenon stripping; the goal for the MSBR is a factor of ten reduction.
[Xenon is the Achilles' heel of reactor physics. Xenon-135, both a direct and indirect (through I-135 decay) fission product, is a noble radioactive gas. It has a high neutron cross section, which means that it captures neutrons which could better be used in promoting chain reactions, or in breeding new fuel. In solid fuel reactors, Xenon remains inside fuel capsules where it poisoned the nuclear process. The presence of Xenon inside solid fueled reactors created control issues, and attempts to compensate for Xenon poisoning, could make reactors unstable and potentially dangerous. However in fluid fueled reactors, Xenon can be removed or stripped. The ability to strip Xenon from reactor fuel was a major accomplishment of ORNL, and clearly demonstrated the importance of the MSR concept. – CB]
2. Fuel Processing Structural Materials
Aside from the chemical processes themselves, there are also development requirements associated with containment materials for the fuel processing systems. In particular, liquid bismuth presents difficult compatibility problems with most structural metals, and present efforts are concentrated on using molybdenum and graphite for containing bismuth. Unfortunately, both molybdenum and graphite are difficult to use for such engineering applications. Thus, it will be necessary to develop improved techniques for fabrication and joining before their use is possible in the reprocessing system.
[This is simply a development issue, but one which does not appear to pose exceptional challenges. The liquid bismuth problem is one of the reasons why many ORNL scientists continued to favor the two fluid approach.- CB]
A second materials problem of the current fuel processing system is the containment for the fluorination step in which uranium is volatilized from the fuel salt. The fluorine and fluoride salt mixture is corrosive to most structural materials, including graphite, and present ORNL flowsheets show a “frozen wall” fluorinator which operates with a protective layer of frozen fuel salt covering a Hastelloy-N vessel wall. This component would require considerable engineering development before it is truly practical for use in on-line, full processing systems.
[Considering the extreme conditions that the fuel processing system operated under, engineering challenges were to be expected. By 1972, ORNL scientists and engineers had made considerable progress in overcoming these challenges, and there were reasons to be optimistic about further progress. – CB]
C. Molten Salt Reactor Design - Materials Requirements
In concept, the molten salt reactor core is a comparatively uncomplicated type of heat source. The MSRE reactor core, for example, consisted of a prismatic structure of unclad graphite moderator through which fuel salt flowed to be heated by the self-sustaining chain reaction which took place as long as the salt was in the graphite. The entire reactor internals and fuel salt were contained in vessels and piping made of Hastelloy-N, a high-strength nickel-base alloy which was developed under the Aircraft Nuclear Propulsion Program. Over the four-year lifetime of the MSRE, the reactor structural materials performed satisfactorily for the purposes of the experiments although operation of the MSRE revealed possible problems with long term use of Hastelloy-N in contact with fuel salts containing fission products.
The MSBR application is more demanding in many respects than the MSRE, and additional development work would be required in several areas of materials technology before suitable materials could become available.
1. Fuel and Coolant Salts
The MSRE fuel salt was a mixture of 7LiF–BeF2–ZrF4–UF4 in proportions of 65.0-29.1-5.0-0.9 mole %, respectively. Zirconium fluoride was included as protection against UO2 precipitation should inadvertent oxide contamination of the system occur. MSRE operation indicated that control of oxides was not a major problem and thus it is not considered necessary to include zirconium in future molten salt reactor fuels. It should also be noted that the MSRE fuel contained no thorium whereas the proposed MSBR fuels would include thorium as the fertile material for breeding. With the possible exception of incompatibilities with Hastelloy-N, the MSRE fuel salt performed satisfactorily throughout the life of the reactor.
The MSBR fuel salt, as currently proposed by ORNL, would be a mixture of 7LiF–BeF2–ThF4–UF4 in proportions of 71.7–16–12–0.3 mole %, respectively. This salt has a melting point of about 930°F (772 K) and a vapor pressure of less then 0.1 mm Hg (13 Pa) at the mean operating temperature of 1150°F (895 K). It also has about 3.3 times the density and 10 times the viscosity of water. Its thermal conductivity and volumetric heat capacity are comparable to water.
The high melting temperature is an obvious limitation for a system using this salt, and the MSBR is limited to high temperature operation. In addition, the lithium component must be enriched in 7Li in order to allow nuclear breeding, since naturally occurring lithium contains about 7.5% 6Li. 6Li is undesirable in the MSBR because of its tendency to capture neutrons, thus penalizing breeding performance.
[The statement about the high melting temperature of salt, is exceedingly strange. One of the disadvantages of water as a reactor coolant is its low boiling point and the high pressure created by heating steam above the boiling point of water. Steam pressure causes major safety problems for light water reactors. In contrast molten salts have extremely high boiling points and vapor pressure is no problem in MSRs. Hence a major safety problem of LWRs is eliminated by using hot molten salt as a coolant. The two MSR prototypes had demonstrated that the high melting temperature of liquid salts was not a serious problem for MSR operations. This comment is thus a sort of Swift-Boating: an attempt to point to major strength and argue that it is really a weakness. – CB]
The chemical and physical characteristics of the proposed MSBR fuel mixture have been and are being investigated, and they are reasonably well known for unirradiated salts. The major unknowns are associated with the reactor fuel after it has been irradiated. For example, not enough is known about the behavior of fission products. The ability to predict fission product behavior is important to plant safety, operation, and maintenance. While the MSRE provided much useful information, there is still a need for more information, particularly with regard to the fate of the so-called "noble-metal" fission products such as molybdenum, niobium and others which are generated in substantial quantities and whose behavior in the system is not well understood.
[Here we have more of the same. The MSRE explored numerous issues including the effects of radiation on molten salts, and the behavior of fission products in the circulating reactor salt fuel mixture. ORNL scientist wanted to know more. The desirability of conducting more research is regarded as a liability by WASH-1222. – CB]
A more complete understanding of the physical/chemical characteristics of the irradiated fuel salt is also needed. As an illustration of this point, anomalous power pulses were observed during early operation of the MSRE with 233U fuel which were attributed to unusual behavior of helium gas bubbles as they circulated through the reactor. This behavior is believed to have been due to some physical and/or chemical characteristics of the fuel salt which were never fully understood. Out-of-reactor work on molten fuel salt fission product chemistry is currently under way. Eventually, the behavior of the fuel salt would need to be confirmed in an operating reactor.
[This statement asserts, "Research is being conducted, but some answers will only come by trying the idea out." - CB]
The coolant salt in the secondary system of the MSRE was of molar composition 66% 7LiF - 34% BeF2. While this coolant performed satisfactorily (no detectable corrosion or reaction could be observed in the secondary svstem), the salt has a high melting temperature (850°F / 728 K) and is relatively expensive. Thus, it may not be the appropriate choice for power reactors for two reasons: (1) larger volumes of coolant salt will be used to generate steam in the MSBR, and (2) salt temperatures in the steam generator should be low enough, if possible, to utilize conventional steam system technology with feedwater temperatures up to about 550°F. The operation of MSRE was less affected by the coolant salt melting temperature since it dumped the 8 MWt of heat via an air-cooled radiator. The high melting temperatures of potential coolant salts remain a problem. The current choice is a eutectic mixture of sodium fluoride and sodium fluoroborate with a molar composition of 8% NaF - 92% NaBF4; this salt melts at 725°F (658 K). It is comparatively inexpensive and has satisfactory heat transfer properties.
However, the effects of heat exchanger leaks between the coolant and fuel salts, and between the coolant salt and steam systems, must be shown to be tolerable. The fluoroborate salt is currently being studied with respect to both its chemistry and compatibility with Hastelloy-N.
[Heat exchange leaks have been a major problem with all liquid cooled reactors. Given the endemic problem, molten salt has several advantages over other coolants. MSRs operate under low pressure. High pressure will increase the likelihood of leaks. The molten salts used in the reactor do not interact chemically with some metals. Electro-chemical interactions can be controlled. Finally Hastelloy-N had by 1972, a considerable history of use in molten salt reactors. It was known to perform well under the very hot conditions found in heat exchangers. – CB]
2. Reactor Fuel Containment Materials
A prerequisite to success for the MSBR would be the ability to assure reliable and safe containment and handling of molten fuel salts at all times during the life of the reactor. It would be necessary, therefore, to develop suitable containment materials for MSBR application before plants could be constructed.
A serious question concerning compatibility of Hastelloy-N with the constituents of irradiated fuel salt was raised by the post-operation examination of the MSRE in 1971. Although the MSRE materials performed satisfactorily for that system during its operation, subsequent examination of metal which was exposed to MSRE fuel salt revealed that the alloy had experienced intergranular attack to depths of about 0.007 inch (0.2 mm). The attack was not obvious until metal specimens were tensile-tested, at which time cracks opened up as the metal was strained. Further examination revealed that several fission products, including tellurium, had penetrated the metal to depths comparable to those of the cracks. At the present time, it is thought that the intergranular attack was due to the presence of tellurium. Subsequent laboratory tests have verified that tellurium can produce, under certain conditions, intergranular cracking in Hastelloy-N.
Although the limited penetration of cracks presented no problems for the MSRE, concern now exists with respect to the chemical compatibility of Hastelloy-N and MSBR fuel salts when subjected to the more stringent MSBR requirements of higher power density and 30-year life. If the observed intergranular attack was indeed due to fission product attack of the Hastelloy-N, then this material may not be suitable for either the piping or the vessels which would be exposed to much higher fission product concentrations for longer periods of time. Efforts are under way to understand and explain the cracking problem, and to determine whether alternate reactor containment materials should be actively considered.
In addition to the intergranular corrosion problem, the standard Hastelloy-N used in the MSRE is not suitable for use in the MSBR because its mechanical properties deteriorate to an unacceptable level when subjected to the higher neutron doses which would occur in the higher power density, longer-life MSBR. The problem is thought to be due mainly to impurities in the metal which are transmuted to helium when exposed to thermal neutrons. The helium is believed to cause a deterioration of mechanical properties by its presence at grain boundaries within the alloy. It would be necessary to develop a modified Hastelloy-N with improved irradiation resistance for the MSBR, and some progress is being made in that direction. It appears at this time that small additions of certain elements, such as titanium, improve the irradiation performance of Hastelloy-N substantially. Development work on modified alloys with improved irradiation resistance is currently under way.
[Some problems with Hastelloy-N were identified during the course of the MSRE. Their sources were identified, and work on fixing the problem is underway. – The problems would be routine for R&D, and fixing them posed no significant challenge. Indeed two potential solutions were found by ORNL researchers shortly after WASH-1222 was written. – CB]
3 Graphite
Additional developmental effort on two problems is required to produce graphites suitable for MSBR application. The first is associated with irradiation damage to graphite structures which results from fast neutrons. Under high neutron doses, of the order of 10^22 neutrons/cm2, most graphites tend to become dimensionally unstable and gross swelling of the material occurs.
Based on tests of small graphite samples at ORNL, the best commercially available graphites at this time may be usable to about 3 x 10^21 neutrons/cm2, before the core graphite would have to be replaced. This corresponds to roughly a four-year graphite lifetime for the ORNL reference design. While this might be acceptable, there are still uncertainties about the fabrication and performance of large graphite pieces, and additional work would be required before a four-year life could be assured at the higher MSBR power densities now being. considered. In any event, there would be an obvious economic incentive to develop longer-lived graphites for MSBR application since a four-year life for graphite is estimated to represent a fuel cycle cost penalty of about 0.2 mills/kW-hr relative to a system with 30-year graphite life.
The second major problem associated with graphites for MSBR application is the development of a sealing technique which will keep xenon, an undesirable neutron poison, from diffusing into the core graphite where it can capture neutrons to the detriment of breeding performance. While graphite sealing may not be necessary to achieve nuclear breeding in the MSBR, the use of sealed graphite would certainly enhance breeding performance. The economic incentives or penalties of graphite sealing cannot be assessed until a suitable sealing process is developed.
Sealing methods which have been investigated to date include pyrolytic carbon coating and carbon impregnation. Thus far, however, no sealed graphite that has been tested remained sufficiently impermeable to gas at MSBR design irradiation doses, and research and development in this area is continuing.
[Graphite is a form of carbon used in pencils. It has many other uses and can serve as a reactor moderator, as well as a core structural material. Most molten salt concepts envision the use of graphite in cores. However, there are some drawbacks to graphite. Under the high radiation conditions found inside the MSR, graphite is expected to deteriorate. Readers of the discussion forum of Kirk Sorensen’s blog will find extensive discussions of the advantages and disadvantages of graphite, and proposed methods of solving the graphite problem. The use of graphite as a moderator and structural material inside MSRs is not strictly speaking absolutely required, and other approaches have been explored. It is possible to use heavy water as a moderator, and even unmoderated designs are possible. One approach would be to avoid structural uses of graphite, but moderate the reactor with small graphite pebbles that float in the fuel salts. The graphite balls could be floated out of the reactor as they aged, and replaced with new pebbles. The graphite related issues are perhaps the most difficult material concerns, but since it is possible to forgo using graphite entirely, the graphite problems are hardly fatal for molten salt reactor technology. - CB]
4. Other Structural Materials
In addition to the structural materials requirements for the reactor and fuel processing systems proper, there are other components and systems which have special materials requirements. Such components as the primary heat exchangers and steam generators must function while in contact with two, different working fluids.
At the present time, Hastelloy-N is considered to be the most promising material for use in all salt containment systems, including the secondary piping and components. Research to date indicates that sodium fluoroborate and Hastelloy-N are compatible as long as the water content of the fluoroborate is kept low; otherwise, accelerated corrosion can occur. Additional testing would be needed and is underway.
Hastelloy-N has not been adequately evaluated for service under a range of steam conditions and whether it will be a suitable material for use in steam generators is still not known.
[Here WASH-1222 does not point to significant problems, but to a need for more research and testing. That would be normal for a research & development projects. - CB]
AN EVALUATION OF THE MOLTEN SALT BREEDER REACTOR
VI. STATUS OF MSBR TECHNOLOGY
H. Codes, Standards, and High Temperature Design Methods
Codes and standards for MSBR equipment and systems must be developed in conjunction with other research and development before large MSBR's can be built. In particular, the materials of construction which are currently being developed and tested would have to be certified for use in nuclear power plant applications.
The need for high-temperature design technology is a problem for the MSBR as well as for other high temperature systems. The AEC currently has under way a program in support of the LMFBR which is providing materials data and structural analysis methods for design of systems employing various steel alloys at temperatures up to 1200ºF (920 K). This program would need to be broadened to include MSBR structural materials such as Hastelloy-N and to include temperatures as high as 1400ºF (1030 K) to provide the design technology applicable to high-temperature, long-term operating conditions which would be expected for MSBR vessels, components, and core structures.
[No comment. – CB]
VII. INDUSTRIAL PARTICIPATION IN THE MSBR PROGRAM
Privately funded conceptual design studies and evaluations of MSBR technology were performed in 1970 by the Molten Salt Breeder Reactor Associates (MSBRA), a study group headed by the engineering firm of Black & Veatch and including five midwest utilities. The MSBRA concluded that the economic potential of the MSBR is attractive relative to light-water reactors, but they recognized a number of problems which must be resolved in order to realize this potential. Since that time the MSBRA has been relatively inactive.
A second privately funded organization, the Molten Salt Group, is headed by Ebasco Services, Incorporated and includes five other industrial firms and fifteen utilities. In 1971 the Group completed an evaluation of the MSBR concept and technology and concluded that existing technology is sufficient to justify construction of an MSBR demonstration plant although the performance characteristics could not be predicted with confidence. Additional support for further studies has recently been committed by the members of this group.
In addition to these studies, manufacturers of graphite and Hastelloy-N have been cooperating with ORNL to develop improved materials.
There has been little other industrial participation in the MSBR Program aside from ORNL subcontractors. At the present time, there are two ORNL subcontracts in effect. Ebasco Services, Inc., utilizing the industrial firms who are participants in the Molten Salt Group is performing a design and evaluation study. Foster-Wheeler Corporation is currently performing design studies on steam generators for MSBR application.
[Another disingenuous argument. We are pointed to evidence of industrial interest in the MSR concept. Then we are told that there is little industrial participation in MSR beyond ORNL contractors. In fact, interested industries in the early 1970's included, Babcock & Wilcox, Byron Jackson, Cabot Corp., Continental Oil, and Union Carbide. Other industries had approached ORNL informally. Because the viability of the MSR concept had not been established prior to the MSRE, industrial interest was premature prior to the late 1960’s. The MSRE had changed that. The Black & Veatch study had demonstrated that the MSR was potentially economically attractive to utilities relative to light-water reactors. There is little doubt that Shaw would have regarded this as a threat to his intention to direct US nuclear development towards the light water reactor. The LMFBR would have complimented the LWR, while the MSR had the potential of competing successfully against it. – CB]
A number of factors can be identified which tend to limit further industrial involvement at this time, namely:
1. The existing major industrial and utility commitments to the LWR, HTGR, and LMFBR.
2. The lack of incentive attractive relative to light-water reactors, for industrial investment in supplying fuel cycle services such as those required for solid-fuel reactors.
3. The overwhelming manufacturing and operating experience with solid-fuel reactors in contrast with the very limited involvement with fluid-fueled reactors.
4. The less advanced state of MSBR technology and the lack of demonstrated solutions to the major technical problems associated with the MSBR concept.
[This argument rests on assumptions by the Shaw and other members of the AEC staff, that are at least in retrospective mistaken. First is the issue of cost containment. During the next decade the cost of LWRs was to rise dramatically. Eventually this reactor cost inflation was to put an end to the first nuclear era. The MSR had the potential to better control power reactor inflation, and thus offered a potential cost advantage over LWRs. Secondly, LWRs offered the same high temperature advantage as gas cooled reactors, but were more compact, and thus potentially lower costs. Gas cooled reactors were never attractive to the American electrical utility industries. The point about the relative experience of manufacturers in building LWRs and MSRs is strange and probably silly. Manufactures never have experience with the manufacture of new technologies when they are introduced, but that has not prevented the repeated introduction of new technologies in the market. The formula of industrial involvement is used to object to the MSR project. Here the term refers to manufacturer involvement. No one is yet interested in building a commercial MSR. Yet the AEC has not encouraged manufactures to do so, indeed as WASH-1222 demonstrates, quite the opposite was the case. Because the AEC was in effect discouraging manufacturer interest in the MSR, manufactures were largely withholding interest. The lack of manufacture interest was then used to justify the AEC’s attempt to suppress MSR technology.
Yet if there was customer interest in MSR technology, as an earlier paragraph of this section reports, there was potentially manufacturer interest.
The second point of this argument at first seem to be obvious. The MSR, by using fuel far more efficiently would seem to create disincentives for industrial investment in supplying fuel cycle services. But this could be a case of Jevons’ paradox. By greatly increasing the efficiency of nuclear fuel use, the MSR might actually create as situation in which more rather than less fuel was in demand. Thus the objection is short-sighted, and assumes shortsightedness on the part of suppliers as well.
The third objection could be raised against any new technology. In 1952 manufacturers had had very limited involvement Light Water Reactors. Demand had led them to explore the new technology.
The fourth objection is circular. In effect, “the less advanced state of MSBR technology and the lack of demonstrated solutions to the major technical problems associated with the MSBR concept,” is used as an argument against advancing the state of MSBR technology, and finding solutions to the major technical problems. – CB]
It should be noted that these factors are also relevant considerations in establishing the level of governmental support for the MSBR program which in turn, to some extent, affects the interest of the manufacturing and utility industries.
[False premises lead to false conclusions. This is the money statement as far as Milton Shaw was concerned. Given the weakness and contradictions of the arguments WASH-1222 offered against “industrial interest” in the development of MSR technology, the case most certainly had not been made against continuing government support of research directed at the development of MSR technology. Milton Shaw had thus erected his case in favor of discontinuing development of MSR technology of the most insubstantial grounds. – CB]
VIII. CONCLUSIONS
The Molten Salt Breeder Reactor, if successfully developed and marketed, could provide a useful supplement to the currently developing uranium-plutonium reactor economy. This concept offers the potential for:
H. G. MacPherson listed the advantages of the MSR as:
Eric Ottewitte listed some salient advantages of an unusual type of MSR, the Molten Chloride Fast Reactor (MCFR) as:
1. Simplicity: no control rods, fuel handling mechanisms, fuel elements or associated structures. Very uncluttered: should maximize test space and facilitate access thereto. Fluid fuel can be transferred remotely by pumping through pipes connecting storage and reactor.
2. MSRs don't refuel or reprocess, just add fuel and process out wastes. Continuous processing and refueling would minimize reactor downtime. Can usefully consume all fuel forms, simplifying fuel supply while simultaneously solving other people's problems.
3. MSR is the safest concept of all due to very strong negative temperature coefficient. No gaseous hydrogen can possibly evolve from fuel or primary coolant. Fuel already molten and handled by system. Simple design technique makes boiling impossible. Continuous removal of fission products reduces their heat source by two orders of magnitude; consequently, natural circulation suffices for emergency cooling, thereby greatly reducing the designated evacuation area. Also, under any off-normal conditions, the liquid fuel can be channeled to a continuously cooled drain tank, in a short time.
4. Very fast neutron spectrum in an annular core engenders high neutron fluxes, driving inner and outer thermal neutron flux traps, each variable in size and neutron energy spectrum by means of molten salt composition. Elimination of fuel cladding and structural material significantly improves the neutron economy of the reactor: more neutrons are available for applications.
5. Elimination of pressurized and pressure-evolving components inside the containment, reducing risk of containment failure.
6. Potential additional missions for an MCFR BATR could include
A. Sr and Cs waste transmutation because of very high neutron flux
B. Useful consumption of fissile fuel from dismantled weapons because of the flexibility in fuel form
C. Process heat R&D due to high temperature capability
D. A 6LiD or 6LiOD shell for generation of a 14 MeV fusion neutron trap.
Ottewitte also notes some disadvantages of MSRs and MCFRs. - CB]
Notwithstanding these attractive features, this assessment has reconfirmed the existence of major technological and engineering problems affecting feasibility of the concept as a reliable and economic breeder for the utility industry. The principal concerns include uncertainties with materials, with methods of controlling tritium, and with the design of components and systems along with their special handling, inspection and maintenance equipment. Many of these problems are compounded by the use of a fluid fuel in which fission products and delayed neutrons are distributed throughout the primary reactor and reprocessing systems.
[Here we have Shaw's attempt to nail the lid on the coffin of the MSR. The claim that "this assessment has reconfirmed the existence of major technological and engineering problems affecting feasibility of the concept as a reliable and economic breeder for the utility industry" is simply untrue. The assessment had not established anything other than MSR technology requires further development before it can be commercialized. WASH-1222 does not established that MSR developmental problems are unusually difficult and certainly has not established that developmental problems are in any way insurmountable. Some of the so called principal concerns were close to resolution when WASH-1222 was written, as the author must have known. The final sentence provides us with yet another example of Swift-boating, turning the MSR's primary strength—its fluid core, into a weakness. - CB]
The resolution of the problems of the MSBR will require the conduct of an intensive research and development program. Included among the major efforts that would have to be accomplished are:
But not all of the premises to the argument are stated, and unstated premises are false. WASH-1222 has already told us that other nuclear technologies, including the LWR and the LMFBR, are so mature that they were beyond the research and development stage requirements which are outlined above. In 1972 this was disputed by scientists at AEC Labs, who correctly argued that LWR safety issues had not been adequately addressed. Many scientists at AEC facilities had well-founded doubts about the maturity of LMFBR technology. In addition, in 1972 there was growing public concern about both the problems of “nuclear waste,” and “nuclear proliferation.” Both of these issues were unresolved problems for LWR technology. “Nuclear proliferation,” was and is a significant issue for LMFNR technology. In contrast, the MSR offers attractive solutions to both the “nuclear waste,” and “nuclear proliferation” issues. Thus the hidden premises of the conclusions reached by WASH-1222 were basically false. False assumptions lead to false conclusions, and this was most certainly the case with WASH-1222. – CB]
The major problems associated with the MSBR are rather difficult in nature and many are unique to this concept. Continuing support of the research and development effort will be required to obtain satisfactory solutions to the problems. When significant evidence is available that demonstrates realistic solutions are practical, a further assessment could then be made as to the advisability of advancing into the detailed design and engineering phase of the development process including that of industrial involvement. Proceeding with this next step would also be contingent upon obtaining a firm demonstration of interest and commitment to the concept by the power industry and the utilities and reasonable assurances that large-scale government and industrial resources can be made available on a continuing basis to this program in light of other commitments to the commercial nuclear power program and higher priority energy development efforts.
[This last paragraph requires very careful examination:
IX. REFERENCES
1. US Atomic Energy Commission, “The 1967 Supplement to the 1962 Report to the President on Civilian Nuclear Power” USAEC Report, February 1967.
2. US Atomic Energy Commission, “The Use of Thorium in Nuclear Power Reactors” USAEC Report WASH-1097, 1969.
3. US Atomic Energy Commission, “Potential Nuclear Power Growth Patterns,” USAEC Report WASH-1098, December 1970.
4. US Atomic Energy Commission, “Cost-Benefit Analysis of the US Breeder Reactor Program,” USAEC Report WASH-1126, 1969.
5. US Atomic Energy Commission, “Updated (1970) Cost-Benefit Analysis of the US Breeder Reactor Program,” USAEC Report WASH-1184, January 1972.
6. Edison Electric Institute, “Report on the EEI Reactor Assessment Panel,” EEI Publication No. 70-30, 1970.
7. Annual Hearings on Reactor Development Program, US Atomic Energy Commission FY 1972 Authorizing Legislation, Hearings before the Joint Committee on Atomic Energy, Congress of the United States p. 820-830, US Government Printing Office
8. Nuclear Applications and Technology, Volume 8, February 1970.
9. Robertson, R. D. (ed) “Conceptual Design Study of a Single-Fluid Molten Salt Breeder Reactor,” ORNL-4541, June 1971.
10. Rosenthal, M. W., et al.; “Advances in the Development of Molten-Salt Breeder Reactors,” A/CONF-49/P-048, Fourth United Nations International Conference on the Peaceful Uses of Atomic Energy, Geneva, September 6 - 16, 1971.
11. Trinko, J. R. (ed.), “Molten-Salt Reactor Technology,” Technical Report of the Molten-Salt Group, Part I, December 1971.
12. Trinko, J. R. (ed), “Evaluation of a 1000 MWe Molten-Salt Breeder Reactor," Technical Report of the Molten Salt Group, Part II, November 1971.
13. Ebasco Services Inc., “1000 MWe Molten-Salt Breeder Reactor Conceptual Design Study,” Final Report Task I, Prepared under ORNL subcontract 3560, February 1972.
14. “Project for Investigation of Molten-Salt Breeder Reactor,” Final Report, Phase I Study for Molten Salt Breeder Reactor Associates, September 1970.
15. Cardwell, D. W. and Haubenreich, P. N., “Indexed Abstracts of Selected References on Molten-Salt Reactor Technology,” ORNL-TM-3595, December 1971.
16. Kasten, P. R., Bettis, E. S. and Robertson, R. C., “Design Studies of 1000 MWe Molten-Salt Breeder Reactors,” ORNL-3996, August 1966.
17. Molten Salt Reactor Program Semiannual Reports beginning in February 1962.
The Oak Ridge National Laboratory has proposed a fuel processing scheme to accomplish breeding in the MSBR, and the flowsheet processes involve:
- Fluorination of the fuel salt to remove uranium as UF6.
- Reductive extraction of protactinium by contacting the salt with a mixture of lithium and bismuth.
- Metal transfer processing to preferentially remove the rare earth fission product poisons which would otherwise hinder breeding performance.
At this time, the basic chemistry involved in the MSBR processing scheme has been demonstrated in laboratory-scale experiments. Current efforts at Oak Ridge are being directed toward development of subsystems incorporating many of the required processing steps. Ultimately a complete breeder processing experiment would be required to demonstrate the system with all the chemical conditions and operational requirements which would be encountered with any MSBR.
Not shown on the flowsheet is a separate processing system which would require injecting helium bubbles into the fuel salt, allowing them to circulate in the reactor system until they collect fission product xenon, and then removing the bubbles and xenon from the reactor system. Xenon is a highly undesirable neutron poison which will hamper breeding performance by capturing neutrons which would otherwise breed new fuel. This concept for xenon stripping was demonstrated in principle by the MSRE, although more efficient and controllable stripping systems will be desirable for the MSBR. The xenon poisoning in the MSRE was reduced by a factor of six by xenon stripping; the goal for the MSBR is a factor of ten reduction.
[Xenon is the Achilles' heel of reactor physics. Xenon-135, both a direct and indirect (through I-135 decay) fission product, is a noble radioactive gas. It has a high neutron cross section, which means that it captures neutrons which could better be used in promoting chain reactions, or in breeding new fuel. In solid fuel reactors, Xenon remains inside fuel capsules where it poisoned the nuclear process. The presence of Xenon inside solid fueled reactors created control issues, and attempts to compensate for Xenon poisoning, could make reactors unstable and potentially dangerous. However in fluid fueled reactors, Xenon can be removed or stripped. The ability to strip Xenon from reactor fuel was a major accomplishment of ORNL, and clearly demonstrated the importance of the MSR concept. – CB]
2. Fuel Processing Structural Materials
Aside from the chemical processes themselves, there are also development requirements associated with containment materials for the fuel processing systems. In particular, liquid bismuth presents difficult compatibility problems with most structural metals, and present efforts are concentrated on using molybdenum and graphite for containing bismuth. Unfortunately, both molybdenum and graphite are difficult to use for such engineering applications. Thus, it will be necessary to develop improved techniques for fabrication and joining before their use is possible in the reprocessing system.
[This is simply a development issue, but one which does not appear to pose exceptional challenges. The liquid bismuth problem is one of the reasons why many ORNL scientists continued to favor the two fluid approach.- CB]
A second materials problem of the current fuel processing system is the containment for the fluorination step in which uranium is volatilized from the fuel salt. The fluorine and fluoride salt mixture is corrosive to most structural materials, including graphite, and present ORNL flowsheets show a “frozen wall” fluorinator which operates with a protective layer of frozen fuel salt covering a Hastelloy-N vessel wall. This component would require considerable engineering development before it is truly practical for use in on-line, full processing systems.
[Considering the extreme conditions that the fuel processing system operated under, engineering challenges were to be expected. By 1972, ORNL scientists and engineers had made considerable progress in overcoming these challenges, and there were reasons to be optimistic about further progress. – CB]
C. Molten Salt Reactor Design - Materials Requirements
In concept, the molten salt reactor core is a comparatively uncomplicated type of heat source. The MSRE reactor core, for example, consisted of a prismatic structure of unclad graphite moderator through which fuel salt flowed to be heated by the self-sustaining chain reaction which took place as long as the salt was in the graphite. The entire reactor internals and fuel salt were contained in vessels and piping made of Hastelloy-N, a high-strength nickel-base alloy which was developed under the Aircraft Nuclear Propulsion Program. Over the four-year lifetime of the MSRE, the reactor structural materials performed satisfactorily for the purposes of the experiments although operation of the MSRE revealed possible problems with long term use of Hastelloy-N in contact with fuel salts containing fission products.
The MSBR application is more demanding in many respects than the MSRE, and additional development work would be required in several areas of materials technology before suitable materials could become available.
1. Fuel and Coolant Salts
The MSRE fuel salt was a mixture of 7LiF–BeF2–ZrF4–UF4 in proportions of 65.0-29.1-5.0-0.9 mole %, respectively. Zirconium fluoride was included as protection against UO2 precipitation should inadvertent oxide contamination of the system occur. MSRE operation indicated that control of oxides was not a major problem and thus it is not considered necessary to include zirconium in future molten salt reactor fuels. It should also be noted that the MSRE fuel contained no thorium whereas the proposed MSBR fuels would include thorium as the fertile material for breeding. With the possible exception of incompatibilities with Hastelloy-N, the MSRE fuel salt performed satisfactorily throughout the life of the reactor.
The MSBR fuel salt, as currently proposed by ORNL, would be a mixture of 7LiF–BeF2–ThF4–UF4 in proportions of 71.7–16–12–0.3 mole %, respectively. This salt has a melting point of about 930°F (772 K) and a vapor pressure of less then 0.1 mm Hg (13 Pa) at the mean operating temperature of 1150°F (895 K). It also has about 3.3 times the density and 10 times the viscosity of water. Its thermal conductivity and volumetric heat capacity are comparable to water.
The high melting temperature is an obvious limitation for a system using this salt, and the MSBR is limited to high temperature operation. In addition, the lithium component must be enriched in 7Li in order to allow nuclear breeding, since naturally occurring lithium contains about 7.5% 6Li. 6Li is undesirable in the MSBR because of its tendency to capture neutrons, thus penalizing breeding performance.
[The statement about the high melting temperature of salt, is exceedingly strange. One of the disadvantages of water as a reactor coolant is its low boiling point and the high pressure created by heating steam above the boiling point of water. Steam pressure causes major safety problems for light water reactors. In contrast molten salts have extremely high boiling points and vapor pressure is no problem in MSRs. Hence a major safety problem of LWRs is eliminated by using hot molten salt as a coolant. The two MSR prototypes had demonstrated that the high melting temperature of liquid salts was not a serious problem for MSR operations. This comment is thus a sort of Swift-Boating: an attempt to point to major strength and argue that it is really a weakness. – CB]
The chemical and physical characteristics of the proposed MSBR fuel mixture have been and are being investigated, and they are reasonably well known for unirradiated salts. The major unknowns are associated with the reactor fuel after it has been irradiated. For example, not enough is known about the behavior of fission products. The ability to predict fission product behavior is important to plant safety, operation, and maintenance. While the MSRE provided much useful information, there is still a need for more information, particularly with regard to the fate of the so-called "noble-metal" fission products such as molybdenum, niobium and others which are generated in substantial quantities and whose behavior in the system is not well understood.
[Here we have more of the same. The MSRE explored numerous issues including the effects of radiation on molten salts, and the behavior of fission products in the circulating reactor salt fuel mixture. ORNL scientist wanted to know more. The desirability of conducting more research is regarded as a liability by WASH-1222. – CB]
A more complete understanding of the physical/chemical characteristics of the irradiated fuel salt is also needed. As an illustration of this point, anomalous power pulses were observed during early operation of the MSRE with 233U fuel which were attributed to unusual behavior of helium gas bubbles as they circulated through the reactor. This behavior is believed to have been due to some physical and/or chemical characteristics of the fuel salt which were never fully understood. Out-of-reactor work on molten fuel salt fission product chemistry is currently under way. Eventually, the behavior of the fuel salt would need to be confirmed in an operating reactor.
[This statement asserts, "Research is being conducted, but some answers will only come by trying the idea out." - CB]
The coolant salt in the secondary system of the MSRE was of molar composition 66% 7LiF - 34% BeF2. While this coolant performed satisfactorily (no detectable corrosion or reaction could be observed in the secondary svstem), the salt has a high melting temperature (850°F / 728 K) and is relatively expensive. Thus, it may not be the appropriate choice for power reactors for two reasons: (1) larger volumes of coolant salt will be used to generate steam in the MSBR, and (2) salt temperatures in the steam generator should be low enough, if possible, to utilize conventional steam system technology with feedwater temperatures up to about 550°F. The operation of MSRE was less affected by the coolant salt melting temperature since it dumped the 8 MWt of heat via an air-cooled radiator. The high melting temperatures of potential coolant salts remain a problem. The current choice is a eutectic mixture of sodium fluoride and sodium fluoroborate with a molar composition of 8% NaF - 92% NaBF4; this salt melts at 725°F (658 K). It is comparatively inexpensive and has satisfactory heat transfer properties.
However, the effects of heat exchanger leaks between the coolant and fuel salts, and between the coolant salt and steam systems, must be shown to be tolerable. The fluoroborate salt is currently being studied with respect to both its chemistry and compatibility with Hastelloy-N.
[Heat exchange leaks have been a major problem with all liquid cooled reactors. Given the endemic problem, molten salt has several advantages over other coolants. MSRs operate under low pressure. High pressure will increase the likelihood of leaks. The molten salts used in the reactor do not interact chemically with some metals. Electro-chemical interactions can be controlled. Finally Hastelloy-N had by 1972, a considerable history of use in molten salt reactors. It was known to perform well under the very hot conditions found in heat exchangers. – CB]
2. Reactor Fuel Containment Materials
A prerequisite to success for the MSBR would be the ability to assure reliable and safe containment and handling of molten fuel salts at all times during the life of the reactor. It would be necessary, therefore, to develop suitable containment materials for MSBR application before plants could be constructed.
A serious question concerning compatibility of Hastelloy-N with the constituents of irradiated fuel salt was raised by the post-operation examination of the MSRE in 1971. Although the MSRE materials performed satisfactorily for that system during its operation, subsequent examination of metal which was exposed to MSRE fuel salt revealed that the alloy had experienced intergranular attack to depths of about 0.007 inch (0.2 mm). The attack was not obvious until metal specimens were tensile-tested, at which time cracks opened up as the metal was strained. Further examination revealed that several fission products, including tellurium, had penetrated the metal to depths comparable to those of the cracks. At the present time, it is thought that the intergranular attack was due to the presence of tellurium. Subsequent laboratory tests have verified that tellurium can produce, under certain conditions, intergranular cracking in Hastelloy-N.
Although the limited penetration of cracks presented no problems for the MSRE, concern now exists with respect to the chemical compatibility of Hastelloy-N and MSBR fuel salts when subjected to the more stringent MSBR requirements of higher power density and 30-year life. If the observed intergranular attack was indeed due to fission product attack of the Hastelloy-N, then this material may not be suitable for either the piping or the vessels which would be exposed to much higher fission product concentrations for longer periods of time. Efforts are under way to understand and explain the cracking problem, and to determine whether alternate reactor containment materials should be actively considered.
In addition to the intergranular corrosion problem, the standard Hastelloy-N used in the MSRE is not suitable for use in the MSBR because its mechanical properties deteriorate to an unacceptable level when subjected to the higher neutron doses which would occur in the higher power density, longer-life MSBR. The problem is thought to be due mainly to impurities in the metal which are transmuted to helium when exposed to thermal neutrons. The helium is believed to cause a deterioration of mechanical properties by its presence at grain boundaries within the alloy. It would be necessary to develop a modified Hastelloy-N with improved irradiation resistance for the MSBR, and some progress is being made in that direction. It appears at this time that small additions of certain elements, such as titanium, improve the irradiation performance of Hastelloy-N substantially. Development work on modified alloys with improved irradiation resistance is currently under way.
[Some problems with Hastelloy-N were identified during the course of the MSRE. Their sources were identified, and work on fixing the problem is underway. – The problems would be routine for R&D, and fixing them posed no significant challenge. Indeed two potential solutions were found by ORNL researchers shortly after WASH-1222 was written. – CB]
3 Graphite
Additional developmental effort on two problems is required to produce graphites suitable for MSBR application. The first is associated with irradiation damage to graphite structures which results from fast neutrons. Under high neutron doses, of the order of 10^22 neutrons/cm2, most graphites tend to become dimensionally unstable and gross swelling of the material occurs.
Based on tests of small graphite samples at ORNL, the best commercially available graphites at this time may be usable to about 3 x 10^21 neutrons/cm2, before the core graphite would have to be replaced. This corresponds to roughly a four-year graphite lifetime for the ORNL reference design. While this might be acceptable, there are still uncertainties about the fabrication and performance of large graphite pieces, and additional work would be required before a four-year life could be assured at the higher MSBR power densities now being. considered. In any event, there would be an obvious economic incentive to develop longer-lived graphites for MSBR application since a four-year life for graphite is estimated to represent a fuel cycle cost penalty of about 0.2 mills/kW-hr relative to a system with 30-year graphite life.
The second major problem associated with graphites for MSBR application is the development of a sealing technique which will keep xenon, an undesirable neutron poison, from diffusing into the core graphite where it can capture neutrons to the detriment of breeding performance. While graphite sealing may not be necessary to achieve nuclear breeding in the MSBR, the use of sealed graphite would certainly enhance breeding performance. The economic incentives or penalties of graphite sealing cannot be assessed until a suitable sealing process is developed.
Sealing methods which have been investigated to date include pyrolytic carbon coating and carbon impregnation. Thus far, however, no sealed graphite that has been tested remained sufficiently impermeable to gas at MSBR design irradiation doses, and research and development in this area is continuing.
[Graphite is a form of carbon used in pencils. It has many other uses and can serve as a reactor moderator, as well as a core structural material. Most molten salt concepts envision the use of graphite in cores. However, there are some drawbacks to graphite. Under the high radiation conditions found inside the MSR, graphite is expected to deteriorate. Readers of the discussion forum of Kirk Sorensen’s blog will find extensive discussions of the advantages and disadvantages of graphite, and proposed methods of solving the graphite problem. The use of graphite as a moderator and structural material inside MSRs is not strictly speaking absolutely required, and other approaches have been explored. It is possible to use heavy water as a moderator, and even unmoderated designs are possible. One approach would be to avoid structural uses of graphite, but moderate the reactor with small graphite pebbles that float in the fuel salts. The graphite balls could be floated out of the reactor as they aged, and replaced with new pebbles. The graphite related issues are perhaps the most difficult material concerns, but since it is possible to forgo using graphite entirely, the graphite problems are hardly fatal for molten salt reactor technology. - CB]
4. Other Structural Materials
In addition to the structural materials requirements for the reactor and fuel processing systems proper, there are other components and systems which have special materials requirements. Such components as the primary heat exchangers and steam generators must function while in contact with two, different working fluids.
At the present time, Hastelloy-N is considered to be the most promising material for use in all salt containment systems, including the secondary piping and components. Research to date indicates that sodium fluoroborate and Hastelloy-N are compatible as long as the water content of the fluoroborate is kept low; otherwise, accelerated corrosion can occur. Additional testing would be needed and is underway.
Hastelloy-N has not been adequately evaluated for service under a range of steam conditions and whether it will be a suitable material for use in steam generators is still not known.
[Here WASH-1222 does not point to significant problems, but to a need for more research and testing. That would be normal for a research & development projects. - CB]
AN EVALUATION OF THE MOLTEN SALT BREEDER REACTOR
VI. STATUS OF MSBR TECHNOLOGY
H. Codes, Standards, and High Temperature Design Methods
Codes and standards for MSBR equipment and systems must be developed in conjunction with other research and development before large MSBR's can be built. In particular, the materials of construction which are currently being developed and tested would have to be certified for use in nuclear power plant applications.
The need for high-temperature design technology is a problem for the MSBR as well as for other high temperature systems. The AEC currently has under way a program in support of the LMFBR which is providing materials data and structural analysis methods for design of systems employing various steel alloys at temperatures up to 1200ºF (920 K). This program would need to be broadened to include MSBR structural materials such as Hastelloy-N and to include temperatures as high as 1400ºF (1030 K) to provide the design technology applicable to high-temperature, long-term operating conditions which would be expected for MSBR vessels, components, and core structures.
[No comment. – CB]
VII. INDUSTRIAL PARTICIPATION IN THE MSBR PROGRAM
Privately funded conceptual design studies and evaluations of MSBR technology were performed in 1970 by the Molten Salt Breeder Reactor Associates (MSBRA), a study group headed by the engineering firm of Black & Veatch and including five midwest utilities. The MSBRA concluded that the economic potential of the MSBR is attractive relative to light-water reactors, but they recognized a number of problems which must be resolved in order to realize this potential. Since that time the MSBRA has been relatively inactive.
A second privately funded organization, the Molten Salt Group, is headed by Ebasco Services, Incorporated and includes five other industrial firms and fifteen utilities. In 1971 the Group completed an evaluation of the MSBR concept and technology and concluded that existing technology is sufficient to justify construction of an MSBR demonstration plant although the performance characteristics could not be predicted with confidence. Additional support for further studies has recently been committed by the members of this group.
In addition to these studies, manufacturers of graphite and Hastelloy-N have been cooperating with ORNL to develop improved materials.
There has been little other industrial participation in the MSBR Program aside from ORNL subcontractors. At the present time, there are two ORNL subcontracts in effect. Ebasco Services, Inc., utilizing the industrial firms who are participants in the Molten Salt Group is performing a design and evaluation study. Foster-Wheeler Corporation is currently performing design studies on steam generators for MSBR application.
[Another disingenuous argument. We are pointed to evidence of industrial interest in the MSR concept. Then we are told that there is little industrial participation in MSR beyond ORNL contractors. In fact, interested industries in the early 1970's included, Babcock & Wilcox, Byron Jackson, Cabot Corp., Continental Oil, and Union Carbide. Other industries had approached ORNL informally. Because the viability of the MSR concept had not been established prior to the MSRE, industrial interest was premature prior to the late 1960’s. The MSRE had changed that. The Black & Veatch study had demonstrated that the MSR was potentially economically attractive to utilities relative to light-water reactors. There is little doubt that Shaw would have regarded this as a threat to his intention to direct US nuclear development towards the light water reactor. The LMFBR would have complimented the LWR, while the MSR had the potential of competing successfully against it. – CB]
A number of factors can be identified which tend to limit further industrial involvement at this time, namely:
1. The existing major industrial and utility commitments to the LWR, HTGR, and LMFBR.
2. The lack of incentive attractive relative to light-water reactors, for industrial investment in supplying fuel cycle services such as those required for solid-fuel reactors.
3. The overwhelming manufacturing and operating experience with solid-fuel reactors in contrast with the very limited involvement with fluid-fueled reactors.
4. The less advanced state of MSBR technology and the lack of demonstrated solutions to the major technical problems associated with the MSBR concept.
[This argument rests on assumptions by the Shaw and other members of the AEC staff, that are at least in retrospective mistaken. First is the issue of cost containment. During the next decade the cost of LWRs was to rise dramatically. Eventually this reactor cost inflation was to put an end to the first nuclear era. The MSR had the potential to better control power reactor inflation, and thus offered a potential cost advantage over LWRs. Secondly, LWRs offered the same high temperature advantage as gas cooled reactors, but were more compact, and thus potentially lower costs. Gas cooled reactors were never attractive to the American electrical utility industries. The point about the relative experience of manufacturers in building LWRs and MSRs is strange and probably silly. Manufactures never have experience with the manufacture of new technologies when they are introduced, but that has not prevented the repeated introduction of new technologies in the market. The formula of industrial involvement is used to object to the MSR project. Here the term refers to manufacturer involvement. No one is yet interested in building a commercial MSR. Yet the AEC has not encouraged manufactures to do so, indeed as WASH-1222 demonstrates, quite the opposite was the case. Because the AEC was in effect discouraging manufacturer interest in the MSR, manufactures were largely withholding interest. The lack of manufacture interest was then used to justify the AEC’s attempt to suppress MSR technology.
Yet if there was customer interest in MSR technology, as an earlier paragraph of this section reports, there was potentially manufacturer interest.
The second point of this argument at first seem to be obvious. The MSR, by using fuel far more efficiently would seem to create disincentives for industrial investment in supplying fuel cycle services. But this could be a case of Jevons’ paradox. By greatly increasing the efficiency of nuclear fuel use, the MSR might actually create as situation in which more rather than less fuel was in demand. Thus the objection is short-sighted, and assumes shortsightedness on the part of suppliers as well.
The third objection could be raised against any new technology. In 1952 manufacturers had had very limited involvement Light Water Reactors. Demand had led them to explore the new technology.
The fourth objection is circular. In effect, “the less advanced state of MSBR technology and the lack of demonstrated solutions to the major technical problems associated with the MSBR concept,” is used as an argument against advancing the state of MSBR technology, and finding solutions to the major technical problems. – CB]
It should be noted that these factors are also relevant considerations in establishing the level of governmental support for the MSBR program which in turn, to some extent, affects the interest of the manufacturing and utility industries.
[False premises lead to false conclusions. This is the money statement as far as Milton Shaw was concerned. Given the weakness and contradictions of the arguments WASH-1222 offered against “industrial interest” in the development of MSR technology, the case most certainly had not been made against continuing government support of research directed at the development of MSR technology. Milton Shaw had thus erected his case in favor of discontinuing development of MSR technology of the most insubstantial grounds. – CB]
VIII. CONCLUSIONS
The Molten Salt Breeder Reactor, if successfully developed and marketed, could provide a useful supplement to the currently developing uranium-plutonium reactor economy. This concept offers the potential for:
- Breeding in a thermal spectrum reactor;
- Efficient use of thorium as a fertile material;
- Elimination of fuel fabrication and spent fuel shipping;
- High thermal efficiencies.
H. G. MacPherson listed the advantages of the MSR as:
- The fuel handling system will be much simpler.
- The molten salts have a much higher heat capacity per unit volume than sodium, so that the physical size of pumps and piping will be smaller.
- There is no threat of a "core disruptive accident" with the MSCR, so that safety-related equipment can be simpler.
- The molten salts have a much lower thermal conductivity than sodium, so that sudden coolant temperature changes will provide less thermal shock to system components.
- The coolant is more compatible with water than is sodium, so that there should be fewer problems in the design and maintenance of steam generators.
Eric Ottewitte listed some salient advantages of an unusual type of MSR, the Molten Chloride Fast Reactor (MCFR) as:
1. Simplicity: no control rods, fuel handling mechanisms, fuel elements or associated structures. Very uncluttered: should maximize test space and facilitate access thereto. Fluid fuel can be transferred remotely by pumping through pipes connecting storage and reactor.
2. MSRs don't refuel or reprocess, just add fuel and process out wastes. Continuous processing and refueling would minimize reactor downtime. Can usefully consume all fuel forms, simplifying fuel supply while simultaneously solving other people's problems.
3. MSR is the safest concept of all due to very strong negative temperature coefficient. No gaseous hydrogen can possibly evolve from fuel or primary coolant. Fuel already molten and handled by system. Simple design technique makes boiling impossible. Continuous removal of fission products reduces their heat source by two orders of magnitude; consequently, natural circulation suffices for emergency cooling, thereby greatly reducing the designated evacuation area. Also, under any off-normal conditions, the liquid fuel can be channeled to a continuously cooled drain tank, in a short time.
4. Very fast neutron spectrum in an annular core engenders high neutron fluxes, driving inner and outer thermal neutron flux traps, each variable in size and neutron energy spectrum by means of molten salt composition. Elimination of fuel cladding and structural material significantly improves the neutron economy of the reactor: more neutrons are available for applications.
5. Elimination of pressurized and pressure-evolving components inside the containment, reducing risk of containment failure.
6. Potential additional missions for an MCFR BATR could include
A. Sr and Cs waste transmutation because of very high neutron flux
B. Useful consumption of fissile fuel from dismantled weapons because of the flexibility in fuel form
C. Process heat R&D due to high temperature capability
D. A 6LiD or 6LiOD shell for generation of a 14 MeV fusion neutron trap.
Ottewitte also notes some disadvantages of MSRs and MCFRs. - CB]
Notwithstanding these attractive features, this assessment has reconfirmed the existence of major technological and engineering problems affecting feasibility of the concept as a reliable and economic breeder for the utility industry. The principal concerns include uncertainties with materials, with methods of controlling tritium, and with the design of components and systems along with their special handling, inspection and maintenance equipment. Many of these problems are compounded by the use of a fluid fuel in which fission products and delayed neutrons are distributed throughout the primary reactor and reprocessing systems.
[Here we have Shaw's attempt to nail the lid on the coffin of the MSR. The claim that "this assessment has reconfirmed the existence of major technological and engineering problems affecting feasibility of the concept as a reliable and economic breeder for the utility industry" is simply untrue. The assessment had not established anything other than MSR technology requires further development before it can be commercialized. WASH-1222 does not established that MSR developmental problems are unusually difficult and certainly has not established that developmental problems are in any way insurmountable. Some of the so called principal concerns were close to resolution when WASH-1222 was written, as the author must have known. The final sentence provides us with yet another example of Swift-boating, turning the MSR's primary strength—its fluid core, into a weakness. - CB]
The resolution of the problems of the MSBR will require the conduct of an intensive research and development program. Included among the major efforts that would have to be accomplished are:
- Proof testing of an integrated reprocessing system;
- Development of a suitable containment material;
- Development of a satisfactory method for the control and retention of tritium;
- Attainment of a thorough understanding of the behavior of fission products in a molten-salt system;
- Development of long-life moderator graphite, suitable for breeder application;
- Conceptual definition of the engineering features of the many components and systems;
- Development of adequate methods and equipment for remote inspection, handling, and maintenance of the plant.
But not all of the premises to the argument are stated, and unstated premises are false. WASH-1222 has already told us that other nuclear technologies, including the LWR and the LMFBR, are so mature that they were beyond the research and development stage requirements which are outlined above. In 1972 this was disputed by scientists at AEC Labs, who correctly argued that LWR safety issues had not been adequately addressed. Many scientists at AEC facilities had well-founded doubts about the maturity of LMFBR technology. In addition, in 1972 there was growing public concern about both the problems of “nuclear waste,” and “nuclear proliferation.” Both of these issues were unresolved problems for LWR technology. “Nuclear proliferation,” was and is a significant issue for LMFNR technology. In contrast, the MSR offers attractive solutions to both the “nuclear waste,” and “nuclear proliferation” issues. Thus the hidden premises of the conclusions reached by WASH-1222 were basically false. False assumptions lead to false conclusions, and this was most certainly the case with WASH-1222. – CB]
The major problems associated with the MSBR are rather difficult in nature and many are unique to this concept. Continuing support of the research and development effort will be required to obtain satisfactory solutions to the problems. When significant evidence is available that demonstrates realistic solutions are practical, a further assessment could then be made as to the advisability of advancing into the detailed design and engineering phase of the development process including that of industrial involvement. Proceeding with this next step would also be contingent upon obtaining a firm demonstration of interest and commitment to the concept by the power industry and the utilities and reasonable assurances that large-scale government and industrial resources can be made available on a continuing basis to this program in light of other commitments to the commercial nuclear power program and higher priority energy development efforts.
[This last paragraph requires very careful examination:
- “The major problems associated with the MSBR are rather difficult in nature and many are unique to this concept.” In fact WASH-1222 has not shown that there were exceptional difficulties involved in the development of MSR technology.
- “Continuing support of the research and development effort will be required to obtain satisfactory solutions to the problems.” This is to state the obvious.
- “When significant evidence is available that demonstrates realistic solutions are practical, a further assessment could then be made as to the advisability of advancing into the detailed design and engineering phase of the development process including that of industrial involvement.” Which would have been the case had not WASH-1222 not been used to justify curtailing of MSR research.
- “Proceeding with this next step would also be contingent upon obtaining a firm demonstration of interest and commitment to the concept by the power industry and the utilities and reasonable assurances that large-scale government and industrial resources can be made available on a continuing basis to this program in light of other commitments to the commercial nuclear power program and higher priority energy development efforts.”
IX. REFERENCES
1. US Atomic Energy Commission, “The 1967 Supplement to the 1962 Report to the President on Civilian Nuclear Power” USAEC Report, February 1967.
2. US Atomic Energy Commission, “The Use of Thorium in Nuclear Power Reactors” USAEC Report WASH-1097, 1969.
3. US Atomic Energy Commission, “Potential Nuclear Power Growth Patterns,” USAEC Report WASH-1098, December 1970.
4. US Atomic Energy Commission, “Cost-Benefit Analysis of the US Breeder Reactor Program,” USAEC Report WASH-1126, 1969.
5. US Atomic Energy Commission, “Updated (1970) Cost-Benefit Analysis of the US Breeder Reactor Program,” USAEC Report WASH-1184, January 1972.
6. Edison Electric Institute, “Report on the EEI Reactor Assessment Panel,” EEI Publication No. 70-30, 1970.
7. Annual Hearings on Reactor Development Program, US Atomic Energy Commission FY 1972 Authorizing Legislation, Hearings before the Joint Committee on Atomic Energy, Congress of the United States p. 820-830, US Government Printing Office
8. Nuclear Applications and Technology, Volume 8, February 1970.
9. Robertson, R. D. (ed) “Conceptual Design Study of a Single-Fluid Molten Salt Breeder Reactor,” ORNL-4541, June 1971.
10. Rosenthal, M. W., et al.; “Advances in the Development of Molten-Salt Breeder Reactors,” A/CONF-49/P-048, Fourth United Nations International Conference on the Peaceful Uses of Atomic Energy, Geneva, September 6 - 16, 1971.
11. Trinko, J. R. (ed.), “Molten-Salt Reactor Technology,” Technical Report of the Molten-Salt Group, Part I, December 1971.
12. Trinko, J. R. (ed), “Evaluation of a 1000 MWe Molten-Salt Breeder Reactor," Technical Report of the Molten Salt Group, Part II, November 1971.
13. Ebasco Services Inc., “1000 MWe Molten-Salt Breeder Reactor Conceptual Design Study,” Final Report Task I, Prepared under ORNL subcontract 3560, February 1972.
14. “Project for Investigation of Molten-Salt Breeder Reactor,” Final Report, Phase I Study for Molten Salt Breeder Reactor Associates, September 1970.
15. Cardwell, D. W. and Haubenreich, P. N., “Indexed Abstracts of Selected References on Molten-Salt Reactor Technology,” ORNL-TM-3595, December 1971.
16. Kasten, P. R., Bettis, E. S. and Robertson, R. C., “Design Studies of 1000 MWe Molten-Salt Breeder Reactors,” ORNL-3996, August 1966.
17. Molten Salt Reactor Program Semiannual Reports beginning in February 1962.
Concluding Remarks about WASH-1222
I have argued that WASH-1222 was a bureaucratic hatchet job. It was designed as part of Milton's Shaw's concerted program to kill off the Molten Salt Reactor. I would also like to note that WASH-1222 should be read in light of a closely-related event, the firing of Alvin Weinberg as Director of ORNL. I believe that the WASH-1222 and the firing of Weinberg were part of a single bureaucratic move by Shaw and a few associates to gain control of the American nuclear establishment, and to control the future direction of nuclear technology and of the nuclear industry in the United States. Indeed I believe that despite his 1973 forced departure from the AEC by Dixie Lee Ray, Shaw largely achieved his objectives. The United States Nuclear Industry still largely carries Milton Shaw's imprint. Unfortunately the legacy of problems left by Shaw's fundamentally flawed vision is still with us. The mistrust of nuclear safety and of the governmental regulation of the nuclear industry is still widespread in American society, and represents a significant handicap in the fight against global warming.
The 1970 Bureau of Mines Mineral Yearbook reported:
"[The] AEC also requested proposals for a design study of a 1,000-megawatt molten-salt
breeder reactor (MSBR). There was also a significant increase in private efforts involving this concept. The Molten Salt Breeder Reactor Associates, an association of five electric utility companies and a consulting engineering firm, completed Phase I of their study of the MSBR. In addition, 15 utility companies and six major industrial companies formed the Molten Salt Group, which will jointly study MSBR technology, including the feasibility of thorium as a fuel.12"
The footnote cited "Wall Street Journal. V. 176, No. 29, Aug. 10, 1970, p. 17."
Contrary to WASH-1222 there was by 1970 considerable industrial interest in MSR technology.
Among the reports on the MSR by private industrial groups and their consultants were:
Molten-Salt Breeder Reactor Associates Staff, Final Report, Phase I Study—Project for
Investigation of Molten-Salt Breeder Reactor, Black & Veatch Consulting Engineers,
Kansas City, Mo. (1970).
Evaluation of a 1000-MWe Molten-Salt Breeder Reactor, Technical Report of the
Molten-Salt Group, Part II, Ebasco Services, Inc., October 1971.
Molten-Salt Reactor Technology, Technical Report of the Molten-Salt Group, Part I,
Ebasco Services, Inc., December 1971.
1000-MW(e) Molten-Salt Breeder Reactor Conceptual Design Study, Final Report—
Task I, Ebasco Services, Inc., New York, February 1972.
Shaw had managed to abort an important industrial development and his destructive action had profoundly negative implications for the energy future of the United States.
Shaw's vision was also flawed by his failure to recognize that problems like "nuclear waste" and "nuclear proliferation" could and should be solved by a radical change in reactor design. The MSR possessed the potential to resolve these issues. Failure to move forward on MSR technology meant that the best chance to address major public concerns about nuclear technology was ignored.
In 2008 MSR technology remains potentially the best single tool for responding to the challenge posed by anthropogenic global warming, and peak fossil fuel energy. Yet the Molten Salt Reactor is today little known and almost entirely ignored by decision makers. This should not be its fate, considering the potential that it brings.
The 1970 Bureau of Mines Mineral Yearbook reported:
"[The] AEC also requested proposals for a design study of a 1,000-megawatt molten-salt
breeder reactor (MSBR). There was also a significant increase in private efforts involving this concept. The Molten Salt Breeder Reactor Associates, an association of five electric utility companies and a consulting engineering firm, completed Phase I of their study of the MSBR. In addition, 15 utility companies and six major industrial companies formed the Molten Salt Group, which will jointly study MSBR technology, including the feasibility of thorium as a fuel.12"
The footnote cited "Wall Street Journal. V. 176, No. 29, Aug. 10, 1970, p. 17."
Contrary to WASH-1222 there was by 1970 considerable industrial interest in MSR technology.
Among the reports on the MSR by private industrial groups and their consultants were:
Molten-Salt Breeder Reactor Associates Staff, Final Report, Phase I Study—Project for
Investigation of Molten-Salt Breeder Reactor, Black & Veatch Consulting Engineers,
Kansas City, Mo. (1970).
Evaluation of a 1000-MWe Molten-Salt Breeder Reactor, Technical Report of the
Molten-Salt Group, Part II, Ebasco Services, Inc., October 1971.
Molten-Salt Reactor Technology, Technical Report of the Molten-Salt Group, Part I,
Ebasco Services, Inc., December 1971.
1000-MW(e) Molten-Salt Breeder Reactor Conceptual Design Study, Final Report—
Task I, Ebasco Services, Inc., New York, February 1972.
Shaw had managed to abort an important industrial development and his destructive action had profoundly negative implications for the energy future of the United States.
Shaw's vision was also flawed by his failure to recognize that problems like "nuclear waste" and "nuclear proliferation" could and should be solved by a radical change in reactor design. The MSR possessed the potential to resolve these issues. Failure to move forward on MSR technology meant that the best chance to address major public concerns about nuclear technology was ignored.
In 2008 MSR technology remains potentially the best single tool for responding to the challenge posed by anthropogenic global warming, and peak fossil fuel energy. Yet the Molten Salt Reactor is today little known and almost entirely ignored by decision makers. This should not be its fate, considering the potential that it brings.
WASH-1184 COST-BENEFIT ANALYSIS OF THE U.S. BREEDER REACTOR PROGRAM. Updated (1970) played an important role in supporting the decision by the Nixon administration to support the Liquid Metal Fast Breeder Reactor development, while abandoning the alternative Molten Salt Breeder Reactor concept developed by Oak Ridge National Laboratory. WASH-1184 was a revision of WASH-1126 which in turn was a product of cost-benefit analyses of the long term nuclear power options which the AEC believed were available to the United States in the late 1960's. These cost-benefit assessments would have been conducted under the supervision of Milton Shaw who was the Director of the AECs’ Division of Reactor Development and Technology. The text of WASH-1184 strongly suggested that the Molten Salt Breeder Reactor had not been included in the USAEC's on-going breeder cost benefit analysis despite a vigorous championing of that technology by ORNL Director and famed reactor scientist, Alvin Weinberg, who had invented the Light Water Reactor, and had suggested his invention to Hyman Rickover as a means of powering Navy submarines. Shaw, and Rickover had himself been trained in reactor technology at Oak Ridge in a program that Weinberg had supervised.
Weinberg's contentions about the MSBR were supported by a large body of research which indicated that the MSBR was viable, and likely to be a safe and cost-effective source of future electricity. Thus Shaw appears to have chosen to ignore questions about the cost-effectiveness of the MSBR in AEC breeder cost-effectiveness studies which he directed. This choice has never been fully explained.
It appears likely that Milton Shaw was pushing LMFBR development, perhaps, it was alleged at the time, even to the extent of diverting money meant for Light Water Reactor safety research, to LMFBR development.
A study of AEC/DoE LMFBR cost assessments made between the late 1960's and mid-1970's found steadily rising estimated costs for the LMFBR. It would appear that the late 1960's LMFBR cost estimate, which would have been referenced by the Nixon administration in its choice to support LMFB technology involved a direct cost of $2.2 billion. The total breeder program development cost of was estimated to run to $4.4 billion. WASH-1184 estimated direct costs for a LMFBR development program to run to $2.5 billion with total breeder development costs dropping to $3.8 billion. This drop was largely due to a drop in support of alternative breeder technology from $0.8 billion to $100 million. This accounting ploy allowed WASH-1184 to claim an overall program cost drop at a time when LMFBR cost estimates were rising.
In the WASH-1535, DRAFT EIS (1973-74) LMFBR cost estimates had risen to $4.0 billion, while in WASH-1535, PFEIS, LMFBR cost estimates had risen to $6.5 billion.
The 1975 Natural Resources Defense Council, paper Bypassing the Breeder, reported that the initial estimate for the Clinch River Breeder Reactor was around $400 million,
In a 1972 Memorandum of Understanding its cost was estimated at $700 million, two-thirds coming from the AEC and with the AEC (now ERDA) assuming an open-ended risk (i.e., all the cost overruns). This estimate was $150 ao $200 million higher than an AEC estimate only six months previous. In March 1974, it was reported that CRBR project officials are "focusing on some major steps that they hope will hold the total costs for the plant will be under 1.0 billion".In 1983, shortly before the plug on the Clinch River Breeder was pulled by Congress, the GAO estimated its cost at $8.0 billion.
In July (1974) it was reported that the CRBR project would cost $1.6 - $2.0 billion,-- and in September it was pegged at $1.736 billion.
The LMFBR made an easy target for nuclear critics like the Natural Resources Defense Council. All they had to do was lay out the facts. President Nixon had admitted,
all this business about breeder reactors and nuclear energy is over my headBypassing the Breeder stated,
the LMFBR has been oversold by its proponents to the point that it is now one of the great white elephants of the day.Indeed it was. Part of that overselling was of course the invidious comparison of the of the MSBR to the LMFBR found in WASH-1222, which states,
Significant experience with the Light Water Reactor (LWR), the High Temperature Gas-cooled Reactor (HTGR)and the Liquid Metal-cooled Fast Breeder Reactor (LMFBR) has been gained over the past two decades pertaining to the efforts that are required to develop and advance nuclear reactors to the point of public and commercial acceptance.In light of the subsequent history of the LMFBR Milton Shaw's WASH-1184 laid out claims that were to not prove true:
The substantial benefits to be realized from the breeder were clearly brought out in a 1968 AEC Study entitled "Cost-Benefit Analysis of the U.S. Breeder Program" subsequently published as WASH 1126. This Study indicated that the readily quantifiable benefits of a successful commercial breeder in the form of reduced cost of electrical energy, reductions in uranium ore requirements and separative work demand, increased Plutonium production, and use of the depleted uranium byproduct from the diffusion plants would exceed the development costs of the breeder by a significant amount. Other benefits, quantifiable and non-quantifiable, such as those associated with reductions in air pollution and enhanced social values through the availability of low-cost electricity were noted. It is apparent that the results of this Study in combination with other important national studies on alternative energy production systems contributed in a major way to achieving the consensus of support which this developed for the breeder program.WASH-1184 certainly did not demonstrate what it claimed: that it was possible, by use of LMFBR reactors, to lower electrical costs. Indeed even recent Indian FBR developments have shown that LMFBRs are not capable of producing electricity at a lower cost than PHWRs. Shaw's preposterous overselling of LMFBR technology is further illustrated by this statement:
Recognizing the rapidly changing nature of the U.S. energy program, it was decided to update the 1968 Study. The updating, started in 1970, which is reported in this document, indicates that the anticipated benefits are about twice as large as reported in the 1968 Study. This is attributable primarily to the greater electrical energy demands that are now being projected, the increase in the cost of fossil fuels since performing the last study, and the increased cost of uranium separative work which tends to improve the competitive position of the breeder over light water reactors.It is quite clear that the AEC's late 1960's early to mid 1970's attempt to establish a case for the LMFBR was very poorly executed. In addition the AEC, under the direction of reactor research czar Milton Shaw, made a deliberate attempt to exclude the potentially far more viable MSBR from serious consideration as a future American breeder reactor. Even worse is the role that these early assessments have played in creating the continuing illusion that liquid sodium cooled breeder reactors such as the Integral Fast Reactor have some sort of inside track as a future low cost energy source. The world and the American people clearly need other less-problematic long-term nuclear choices.
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1 comment:
Charles, this description of alternative nuclear technologies is appreciated, and so is your site in general. Your blog does a good job of keeping people with some knowledge of nuclear technology, or the interest in acquiring that knowledge,abreast of developments in the LFTR and other nuclear technologies that could provide safer, more economical nuclear power for much longer into the future than those now in use.
However, most policy makers and citizens don't have enough knowledge of the science involved to be able to understand many of these articles, and I wonder if you can refer to an article you or someone else has written that can tell people just how close to being commercially viable these technologies are, how many regulatory obstacles remain to their approval, and how much money would be required to get plants up and running that would produce 1Gw or more power... and what timeframe we would be looking at if we started the process today?
I realize that you have supplied all of the above information in many articles you have published on your site throughout the past couple of years, and that the information is available elsewhere as well, for I have found it in many different places.
However, your typical legislator or bureaucrat has no patience with anything that takes more than about 3 minutes to read or requires more technical understanding than the instruction manual for a dishwasher- for anything more complex than that, he has to call on his 12-year-old grandkid. The politician moreover has a lot of calls on his time and attention.
I believe that the principal reason so many of our policy makers and citizens at large are hostile to nuclear power, or at least don't believe that it constitutes a real advancement on what we have, is because they do not begin to understand it. Most people out here have no idea of the more advanced and economical technologies, and if they discover your site by accident, they are not likely to linger long because your articles assume a higher level of intelligence and technical knowledge than the typical policy maker, or citizen, is likely to have.
Therefore, an article that simplifies this subject for the people we need most to influence, would be greatly appreciated.
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