Dr. Robert Hargraves is a very bright fellow. He thought of some of my best ideas before I did. I did not steal Dr. Hargraves ideas, but I may have borrowed a few. I think that I actually developed my ideas for a factory build, small LFTR before I read Dr. Hargraves Blog. There are actually a few variations between Dr. Hargraves visions and mine, but that is beside the point. Both of us think along similar lines about the advantages of small reactors and how to build them quickly, in expensively and in large numbers. Our thinking is directed to slightly different technologies. Dr. Harvraves offers us some interesting insights into technological advances since the 1970's that can contribute of PBR and for that matter LFTR technology. Anyone who is interested in Reactor safety, ought to read Dr. Hargraves discussion of PBR passive safety.

Of course not all of the ideas Dr. Hargraves presents are original with him. Some of them come from a little school called MIT. The MIT Pebble Bed Reactor web site is well worth the time the nuclear curious might spend poking around it. Clearly the MIT work on industrial production of PBRs is a starting point for anyone who wants to design a system of large scale LFTR production.

Looking at the MIT site raised some issues. For example, MIT cost studies based on 1992 data found that a 1100 MWs modular PBR generating facility would cost $2296 1992 dollars over night costs. This was not the sort of savings I would hope for. However, MIT did not engage in the sort of full court press model of reactor cost savings I advocate. Jim Holm proposed reusing old coal fired stem plants as sites for new nuclear facilities. MIT did not consider the economic advantages of Holm plan. Old power plant sites would be well suited to a modular approach, and would enable power production to closely approximate local grid capacity.. One way LFTRs would lower nuclear costs would be the very reduced need for nuclear waste handling and storage facilities. The 100 fold reduction of the nuclear waste problem with LFTR in one of the most significant advantages of that technology over the PBR approach, PBR waste would not only be far more expensive to store, but also far more expensive to reprocess, than LFTR waste would. But then one of the reasons why ORNL chose to examine the liquid fuel approach was the lower cost of fuel reprocessing that a liquid fuel would facilitate.

MIT researchers acknowledged the capital cost advantages of adding more reactors to a modular facility as demand increases, rather than building over capacity, in order to achieve economies of scale in a reactor. Hence an owner might buy 5 100 MWe PRR or LFTR units, thus lowering initial costs. Each unit can be in place ands producing electricity far sooner than a large reactor would be. Thus interest carrying costs would be substantially reduced.

Lowering the cost of electrical generating technology is going to be a major future concern. Research should be directed to lowering nuclear cost. Unfortunately the conventional method for lowering reactor costs is the economies of scale approach. This approach makes far less efficient use of labor that the factory production or factory produced modules approach. Even with reactors like the AP-1000, a conventional reactor designed to be built using factory produced modules, the rate of module production would be far lower, thus the savings entailed by serial production of modules will be far from fully realized. Clearly much more research on lowering nuclear cost should be conducted. Research needs to be directed to developing cost lowering stratigies, and to the potential for cost saving with Generation 4 technology.

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If there is to be a major LFTR effort, where should it take place? I would argue that ORNL would be the ideal place, because of its tradition of Liquid core reactors, even though ORNL stopped MSR research over a generation ago. Were INL to take responsibility for LFTR research, it would require new facilities and a new staff. INL has entirely devoted itself to solid core reactors, thus would have no advantage over ORNL as far as institutional memory is concerned. In fact INL long term commitment to solid core reactors would serve as a disadvantage as Lab staff struggled to understand the challenges of liquid core reactors.

The old K-25 site outside Oak Ridge could serve as the location of a LFTR factory. Ready access to Milton Hill Lake would allow whole reactor assemblies to be moved to destinations by barge.

Rod Adams comments and I respond on nuclear waste

There are no dumb nuclear bloggers, and in fact I have a very high respect for the brain power of my peers. So when one of them comments on one of my posts, I look at the comment carefully. Rod Adams looked over my "Keys"which I had cross posted on "Energy from Thorium". Rod liked most of what I had said, but he had some disagreements with my comments on nuclear waste. Rod would have to disagree with me, because it is my view that Rod's favorite reactor, the Pebble Bed Reactor, leaves a mess behind it, after it burns nuclear fuel. At reason for the mess is simple, the Uranium-plutonium fuel cycle is wasteful in the use of nuclear fuel and potential nuclear fuel in both the LWR and the PBR. The Thorium-Uranium fuel cycle used in the LFTR, by contrast makes highly efficient use of nuclear fuel.

Adams stated:

"I do not think that anything that we do will "solve the problem of nuclear waste" since it is not really a problem in the first place.

There are plenty of people in the world with an interest in making it an unsolvable problem; those people will never be satisfied no matter how tightly we wind up the technical details.

My solution is to accept the fact that there is opposition and to try to help the rest of the people understand that the opposition is a body of people with financial interests in slowing nuclear power. That way, the opposition does not disappear, but they become far less effective in changing the way that we need to do business."

My response:
One major advantages of having an up to 98% burn up rate plus FP recycling is that very little of site construction has to be devoted to post reactor by product storage. The facilities to handle LWR post reactor fuel, are not inconsiderable part of current reactor construction expenses. The fluoride salts FP extraction technology researched and developed at ORNL during the 1950's to 1970's demonstrate that low cost extraction of FPs from nuclear fuel is possible. By separating FPs we change them from "waste" into by products, which have real and/or potential uses in the economy.

I am in complete agreement with the very idea that there is no such a thing as "nuclear waste" in the conventional meaning of the term. Where I differ with Rod is in our evaluation of a once through fuel cycle, which I regard as very inefficient and "wasteful" because it fails to extract more than a small fraction of the potential energy from nuclear fuel. I do see a waste of fuel potential by the once through Uranium fuel cycle.

I discussed the fundamental problem of the uranium fuel cycle in a March post on Nuclear Green. My discussion of the relative merits of the uranium fuel and thorium cycles, rests on the discussion of those cycles in WASH-1097 which makes the issues wonderfully clear.

"The relevant characteristics of the important fissile and fertile isotopes in thermal and fast-spectrum reactors are summarized as follows:

(1) Thermal absorption in U-233 produces more neutrons per neutron absorbed** than does
corresponding absorption in either Pu-239 or U-235.
(2) The neutron production for U-233 is relatively insensitive to change in temperature, but for U-235 and Pu-239 eta decreases as the temperature increases. Thus, the advantage of U-233 over U-235 and Pu-239 is more pronounced in a hard (higher energy) thermal spectrum than in a soft (lower energy) thermal spectrum.
(3) From a nuclear standpoint, the use of U-233 in a thermal reactor makes it possible to achieve
higher fuel conversion ratios and longer fuel burnups than is practical with either U-235 or Pu-239 (Section 2.2).
(4) The higher conversion ratios which can be obtained in thermal-spectrum reactors when using U-233 instead of Pu-239 can result in a significantly better utilization of natural uranium fuel resources with thorium-fueled reactors than with the low-enrichment, light-water cooled uranium-fueled reactors (Section 2.3).
(5) A higher breeding ratio can be obtained with Pu-239 than with U-233 in a very high-energy, fast-neutron spectrum reactor. On the other hand, in a degraded (10 to 100 keV) fast spectrum, U-233 would probably be as good as, or better than, Pu-239. Also, the variation of U-233 and Pu-239 cross sections with energy are such that improved reactivity coefficients would be obtained with the use of U-233 in a large sodium-cooled FBR. This leads to improved nuclear safety characteristics.
(6) The energy dependence of the fast-fission cross sections of Th-232 and U-238 is such that the use of Th-232 would produce an improved reactivity coefficient in a liquid-metal-cooled FBR. The fast fission cross-section of Th-232 is much lower than that of U-238 so that use of the latter leads to much larger conversion ratios in fast-spectrum reactors."

The inference is clear, even in fast neutron spectrum reactors, the Thorium fuel cycle is more efficient and thus less wasteful than the Uranium fuel cycle. My disagreement with Rod is not about these facts, but about their implications for reactor and especially PBR construction costs. If i am right, the prize for lowest overall reactor construction should be given to the reactor that uses fuel most efficiently, all other things being equal. There is little doubt that if the price of fuel reprocessing is factored into the price of reactor construction the LFTR would be lss expensive than the PBR.   If you do not pay the price of reprocessing, cost are related to the cost of storing and handling of unprocessed post reactor fuel.  

My other disagreement with Rod has to do with the best approach to dealing with opposition to nuclear power.  I believe that the problems of post reactor nuclear fuel, and the problems of reactor safety are real issues that the nuclear community needs to solve.  The best answer to opponents questions about "nuclear safety," and "nuclear waste," is not simply a public education, being able to say, "our reactors are safe and do no produce nuclear waste," is really what, in my view, is required to answer nuclear critics.  

I must add that I have very high regard for Rod's intelligence, integrity and abilities. Rod isan amazingly talented man, and I am very happy that we have him in our camp.