Saturday, October 2, 2010

Arjun Makhijani and the Modular Small Reactor null-hypothesis

Arjun Makhijani (with Michele Boyd) has recently published a fact sheet on Small Modular Reactors which in effect advertises itself as the null-hypothesis to the case I an others have been making for some time on the advantages of small reactors. Small Modular ReactorsNo Solution for the Cost, Safety, and Waste Problems of Nuclear Power, Makhijani's title proclaims. But what is the evidence that backs Makhijani's case up. As it turns out Makhijani offers no empirical data to back up his assertion, so as an example of scientific reasoning, Makhijani's fact sheet rates an F.

Arjun Makhijani is one of the more intelligent and better informed of the anti-nuclear activists. He usually puts the anti-nuclear arguments in the best possible light. Although the arguments Makhijani makes is answerable, answering him can be challenging. However, in a recent fact sheet titled Small Modular Reactors, Makhijani offers what can be described at best as weak arguments. For example he claims,
Some proponents of nuclear power are advocating for the development of small modular reactors (SMRs) as the solution to the problems facing large reactors, particularly soaring costs, safety, and radioactive waste. Unfortunately, small-scale reactors can’t solve these problems, and would likely exacerbate them.
This is a classic straw man argument, Makhijani attributes to some unnamed proponents of nuclear power a view which he can easily show to be false. But nowhere does he say who might hold these views. He does not say, for example, that Rod Adams and Charles Barton say that simply by diminishing reactor size, we can solve problems such as nuclear waste and nuclear safety. Or that by building any small modular reactor we can lower nuclear cost. Nuclear proponents, who have looked at the case for small reactors, have made far more complex and well thought out arguments. Were Dr. Makhijani to respond appropriately to our analysis, his would be forced to leave the black and white universe, in which he and other anti-nuclear spokesperson live, and enter a world that is characterized by shades of gray.

It is undoubredly the case that there are good and bad small reactor designs. In the history of nuclear power, some small reactor designs have proven unsafe, while others have operated for thousands of hours without a problem. Some small reactor designs include unusual and highly ingenious safety features, which Makhijani tends to ignore. Thus when Makhijani states
Some designs (such as the PBMR) propose no secondary containment, but this would increase safety risks
he does not explain why secondary containment might be considered unnecessary with the PBMR designs. This would of course lead back to a discussion of why secondary containment is considered necessicary with conventional NPPs, and the difference between the accident potential and safety features of various reactor designs. This would involve Makhijani in providing his readers far too much information, information that might lead them to conclude that the world of nuclear power is not a world of nuclear black verses the anti-nuclear white.

Thus we find Makhijani making sweeping generalizations on nuclear safety, without offering a justification for his claims. A second major flaw in Makhijani's safety arguments is his failure to place events in historical context. Like every technology, nuclear technology has evolved, and part of that evolution most definitely has been the development of safer designs, and better safety related practices. One of the ways that that development has occurred has been through a series of accidents which reactor designers have studied for clues about safer reactor design. It has been the good fortune of the nuclear industry that its safety problems have been grotesquely exaggerated. In the United States no one has ever been killed as a result of an reactor accident in a civilian nuclear power plant. Thus in the United States Power reactors have proven highly safe.

If we judge safety be fatality producing accidents, we should note that NPP reactor accidents have yet to produce even a single human casualty. This is not he case with natural gas. As recently as last February, 6 workers were killed as the result of a natural gas explosion at a natural gas fired power plant in Middletown, Connecticut. In August 2007 a wind generation tower in Oregon, collapsed and a worker was killed. This was hardly the only wind generator fatality within the boundaries of the United States. Thus the safety record of the Nuclear Industry is an outstanding accomplishment, and compared to energy solutions which anti-nuclear proponents like Makhijani offer, the operation of nuclear power in the United States is remarkably safe.

Do small reactors deviate from this record? Not at all! During the last 56 years, the United States Navy has operated hundreds of small reactors, and has accumulated thousands of years of experience doing so. Yet as Rod Adams will point out the Navy has never suffered a major reactor accident, let alone a casualty producing accident in its small reactors. This fact does not mean that small reactors are inevitably safe, rather with some diligence, safe design and operation practices are possible with small reactors. In contrast to the Navy experience,there was a casualty producing accident in a small experimental Army reactor, one which most experts who have studied its design agree had serious safety flaws. But that accident does not probe that all small reactors are unsafe, only that it is possible through carelessness to design and build a small reactor that poses a danger to its operators.

Makhijani raises questions about the safety of mass produced reactors,
Mass manufacturing raises a host of new safety, quality, and licensing concerns that the NRC has yet to address. For instance, the NRC may have to devise and test new licensing and inspection procedures for the manufacturing facilities, including inspections of welds and the like. There may have to be a process for recalls in case of major defects in mass-manufactured reactors, as there is with other mass-manufactured products from cars to hamburger meat. It is unclear how recalls would work, especially if transportation offsite and prolonged work at a repair facility were required.
At this point it should be recalled that the aircraft industry engages in large scale manufacture of passenger aircraft, with acceptable safety records. This safety record has been accomplished despite the fact that the inherent risks of passenger aircraft operations are far greater than the inherent risks of reactor operations. Reactors used by the United States Navy, reactors which as I have noted have a sterling record for safety, are factory built. Thus the notion that factory manufacture will lead to unsafe small reactors finds reactors, finds not the slightest evidence from small reactor manufacturing experience.

Thus Arjun Makhijani offers not the slightest amount of evidence to back up his assertion that small reactors are unsafe, and his null-hypothese can be asserted to have no supporting evidence. This does not mean, however, that the door should be shut on small reactor safety. In fact quite the opposite is the case. All small reactor designs should be carefully investigated for possible safety issues before they are licensed for manufacture. It simply should not be assumed that there is something inherently dangerous about small reactors as Makhijani seems too.

What about nuclear waste? First no one has ver claimed that small size reactors offer any solution to the problem of nuclear waste. Some proposed small reactor designs do belong to classes of reactors that could contribute to solving the nuclear waste problem. Thus at least a partial solution to the nuclear waste problem might be possible if some potential small reactor designs are successfully implemented. This is as far as I know it, the extent of claims that have been offered by small reactor proponents. Makhijani creates a straw man by creating claims that no one has voiced about the capacity of small reactors to solve the nuclear waste problem, and demonstrating that this argument is false. Straw man arguments are rhetorical rackets in which easily refuted arguments are attributed to the other side and then shown to be false. We need not look for evidence in the case of a straw man argument, and thus the nuclear waste argument carries no weight.

For those who are interested, the Liquid Fluoride Thorium Reactors, and the Denatured Molten Salt Reactor produce at worse very little nuclear waste, and could be operated to dispose of nuclear the nuclear waste from other reactors. But at the moment no priority has been given to the low waste producing reactors or to waste disposal reactors. It should be presumed if society thought low waste production or waste disposal capacity were considered desirable reactor characteristics, and should characteristics could be mandated, and small reactors could be built that would accomplish these goals.

Finally, we should consider Makhijani assertions about small reactor costs. First he claims,
SMR proponents claim that small size will en- able mass manufacture in a factory, enabling considerable savings relative to field construc- tion and assembly that is typical of large reactors. In other words, modular reactors will
be cheaper because they will be more like as-sembly line cars than handmade Lamborghi- nis. In the case of reactors, however, several offsetting factors will tend to neutralize this advantage and make the costs per kilowatt
of small reactors higher than large reactors.

Makujani claims
in contrast to cars or smart phones or similar widgets, the materials cost per kilowatt of a reactor goes up as the size goes down. This is because the surface area per kilowatt of capacity, which dominates materi-als cost, goes up as reactor size is decreased.
Material costs do effect the cost of other industrial produced products including cars, and manufacturers take several approaches to that problem, including careful redesign of components to eliminate part of the expensive material, or the substitution of low cost materials for high cost materials. Makujani does not believe that this is possible, but for example it is possible to eliminate some of the cement and steel in the massive reactor containment dome by housing the reactor in an underground chamber. Thus high cost concrete and steel are replaced by low cost earth and rock, Reactors with compact cores, require less manufacturing material, and smaller housing facilities. Thus the choice of a compact core nuclear technology might offer considerable savings in materials costs. Thus the small reactor manufacturer may have several options to lower materials costs.

Makhijani claims that other costs might be inversely proportional to reactor size,
Similarly, the cost per kilowatt of secondary containment, as well as independent systems for control, instrumentation, and emergency management, increases as size decreases.
Yet as I have already noted there are things that manufacturers can do about containment costs. Control rooms are not huge parts of overall reactor costs, and there are undoubtedly things which reactor manufacturers could do to lower control room building costs. For example whole control room modules can be factory fabricated and moved to the reactor housing site where they could be house underground or in preexisting recycled structures. Similar solutions could be found for the emergency management housing issues.
Finally Makhijani tells us
Cost per kilowatt also increases if each reactor has dedicated and independent systems for control, instrumentation, and emergency management.
Yet smaller reactors will require fewer sensors. reactor control and emergency management and with the very large number of instruments required by mass produced factory manufactured reactors, the cost of instrument manufacture and indeed whole instrument room manufacture will fall significantly. Small reactors require smaller, less costly control and emergency management systems, and the the cost benefits of serial manufacturing will effect the costs of these systems as well. Finally it should be noted that Makhijani fails to mention the clear cut cost lowering benifits of factory manufactured reactors. For example, Labor costs are significantly lowered in several ways. Factory assembly offers superior labor organization and thus the same tasks take less time in the factory. Secondly workers can live close to factory sites, thus do not require high wages to induce them into the transient lifestyle of construction workers. Thirdly, in a factory in which several reactors are being constructed at any one time, individual workers will require fewer skills. The less skilled workers will command lower wages. Taken together significant labor savings are possible through factory manufacture. Labor is by no means the only source of savings. A further source of savings would come from the serial manufacture of parts. It is well known that are the number of a part built increases, the cost of manufacturing that part falls. Thus serial production tends to lower unit costs. In addition serial production introduces cost lowering learning. As knowledge of a manufacturing process rises, awareness of cost lowering possibilities also increase. This is called the learning curve. It ia reasonable to anticipate a learning curve based saving for serial produced small reactors. Thus cost savings will be available to the manufacturers of small factory built reactors.

We lack cost the cost date that we need to judge the extent to which small factory manufactured reactors will lower nuclear costs. Arguments for the nuclear cost lowering benefits of economies of scale are not nearly strong as Makhijani believes them to be, while the evidence of a cost lowering effect of serial reactor manufacturer is stronger. Thus Makhijani has chosen to reject the stronger evidence will upholding the case for which the evidence appears to be so weak as to offer no support.

We can conclude then, that Arjun Makhijani has not established reasonable grounds in support of his assertion that Small Modular Reactors offer no solution for the cost, safety, and waste problems of nuclear power. Thus to the extent that this assertion can be viewed as a null-hypothesis to the claim that Small Modular Reactors offer an valuable attractive alternative to large conventional power plants, the hypothesis must be still be viewed as unfalsified by the available evidence. Further evidence could still change this picture, but for the moment advocates of small reactors have plausible grounds for their case.


Martin Burkle said...

I would like to see a comparative labor analysis for the operations of an AP1000 verses a small nuclear reactor. Some reports say that an AP1000 will require 800 people for operations, That's a lot of people, but what is the break down? Are there 3 nuclear engineers and 10 operators and 100 maintenance and 100 in security? The task would be to look at the labor by category and then think about how many would be needed for a smaller reactor.
For example, the number of security people required. If the external threat is the same then would the same number of people for security be required?

Anonymous said...

Charles, this would be a DK entry.


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