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Critique of MIT Nuclear Fuel Cycle Report

EDITOR’S NOTE: Dan Yurman has clarified that this report was not authored solely by Tom Blees, but rather came out of a working group.

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Fast reactors were given short notice. Technology choices are available.

Guest Blog Post by: Tom Blees, Science Council for Global Initiatives
Email Contact: tomsciencecouncil@gmail.com

Introduction

MIT (energy initiative) recently released a controversial and well-publicized report on the future of the nuclear fuel cycle. The authors argue that there is sufficient uranium to allow ongoing deployment of water-cooled reactors for many decades. They recommend that no far-reaching decision be made yet on the ultimate disposal of the ‘spent’ nuclear fuel so produced and suggest that research on technical solutions can be ongoing over this period, with no particular urgency.

Below, on behalf of the members of the Science Council for Global Initiatives, I present a critique of this report which focuses on its core arguments — and their inherent weaknesses. A printable 6-page PDF version of the critique can be downloaded here.

1. The Study recommendations on actions to deal with spent nuclear fuel and waste do not recognize the importance of the technological options to reduce the radiological toxicity, which could have great impact on waste management.

One of the main Study recommendations is:

Planning for long term interim storage of spent fuel – on the scale of a century – should be an integral part of nuclear fuel cycle design.

This recommendation is based on an implicit assumption that spent nuclear fuel is a de-facto waste form destined for ultimate disposal, and that it would take a long time to develop repositories. The Study ponders whether the spent nuclear fuel is a resource or a waste.

Since the Study speculates on a large supply of low-price uranium that will continue to meet rising demand for many decades, the value of spent fuel as a resource is diminished.

However, there is another dimension to this equation. The actinides contained in the spent fuel are potentially a valuable resource. They are also a long-term radiological risk, and thus must be managed accordingly.

The radiological toxicity of the LWR spent fuel constituents is presented in Figure 1 below.

Figure 1. Radiological toxicity of LWR spent fuel constituents as a function of time

Radiological toxicity here is a relative measure of the cancer risk if ingested or inhaled, which we have normalized to that of the original natural uranium ore. As mined, the ore contains uranium along with decay products that have accumulated by its (very slow) decay over millennia.

Normalization to the natural uranium ore from which the spent fuel originated is a useful but somewhat arbitrary relative standard. If the radiological toxicity drops below the natural uranium ore level we would be disposing of nuclear wastes that had no greater hazard than the uranium found naturally. The point at which the radiological toxicity curve crosses the natural uranium line then can be defined (at least loosely) as an effective lifetime of the waste components.

For all practical purposes, the radiological toxicity due to the fission product portion of the waste decays with (approximately) a 30 year half-life, due to the dominance of strontium and cesium isotopes. It drops below the natural uranium ore level in about 300 years, and becomes harmless in well under 1,000 years.

On the other hand, the radiotoxicity level associated with the actinide portion stays far above that of natural uranium ore for a very long time, and remains at least three orders of magnitude higher than that for the fission products for hundreds of thousands of years.

This is why following the National Academy of Sciences Committee recommendation, the EPA standards and NRC regulations for the Yucca Mountain repository extended the regulatory timeframe from the original 10,000 years to one million years.

The important point is this: if 99.9% of actinides could be removed from the waste form, then the radiological toxicity of the remaining 0.1% actinides would stay below the level of natural uranium ore at all times and the effective lifetime of the waste would be dictated by the fission products.

If the actinides were mostly removed from the waste stream, the EPA standards and the NRC regulations [whether they cover 10,000 years or millions of years] can be met on an a priori basis. Needless to say, this is an extraordinarily important fact, and the MIT Study ignored it.

2. The role of fast reactors in the analysis of future fuel cycle options is misrepresented and therefore its impact is grossly underestimated.

A system analysis of future fuel cycle options performed by the MIT Study reached the following conclusion:

A key finding of this analysis is that reactors with conversion ratios much higher than one are not materially advantageous for a sustainable fuel cycle – a conversion ratio near unity is acceptable and has multiple advantages.

In assessing the impact of fast reactors on the uranium resource requirements, the above conclusion was reached because of a combination of several incorrect assumptions regarding fast reactor characteristics:

The analysis used Advanced Liquid Metal Reactor (PRISM Mod B) as the representative fast breeder reactor design, with a specific inventory (kg fissile material per megawatt electric) about a factor of two too high. The specific actinide inventory is presented here in Figure 2 as a function of the reactor size.

Figure 2. Specific Inventory vs. Reactor Size (MWe)

A breeding gain of 0.23 was assumed, which is too low by a factor of two or three. The breeding ratio potential for what we’ll call “advanced” fast reactors is presented in Figure 3 for various fuel types.

Here, breeding ratio is the net gain in fissile material over some period of time, compared to the fissile loss from power generation. The metal fuel developed during the Integral Fast Reactor (IFR) program has become the reference fuel in the U.S. It has a breeding ratio potential in the range of 1.50–1.65.

In the early years of deployment, the high breeding gain is not needed, but it is there from the start, and it can be used by simply deploying more U-238 “blankets” — reflector regions actually — to capture a higher fraction of the neutrons leaving the core.

If you don’t need the plutonium early in fast reactor deployment, you would not load full blankets. A key advantage of the fast reactor design is that the plutonium production rate can be easily tailored to plutonium demand.

Figure 3. Range of Breeding Ratios

The Study states that breeders require a higher fissile inventory than fast burners, to compensate for a higher neutron absorption rate in the blanket. This statement is flatly wrong, indicative of inadequate knowledge of fast reactors.

When there is a sufficient fissile inventory coming from LWRs, the initial fast reactors do not need to breed, and the blankets can be replaced with reflectors.

As the demand for breeding plutonium grows over time, the “burner reactors” can be converted back to breeders. However, continuing to build burners when the fast reactor introduction is constrained by fissile availability is not a viable strategy, which was the focus of the Study.

The Study assumes that “All spent fuel is cooled for 5 years before it is reprocessed and recycled as fuel.” That is perhaps realistic for LWR fuel, but pyroprocessing of fast-reactor fuel can be done while the fuel is still hot, typically after one year cooling for handling purposes. Application of five-year cooling to fast reactors results in a serious overestimate of the ex-core fissile requirement, with a consequent underestimate of the fast reactor’s potential market penetration.

In the Study, fast reactors are deployed in large numbers only after ~2065 and hence have limited influence on the uranium consumption through 2100. In this case, the uranium requirements are dominated by the large number of LWRs built continuously through this century. If the time horizon is extended, the difference between with and without breeder reactors becomes much more pronounced.

Figure 4. Example scenario for worldwide nuclear energy growth


An example of nuclear fuel cycle system analysis more properly done is illustrated in Figures 4 and 5. These figures depict a scenario for world-wide nuclear energy growth, and the impact of fast reactors on the cumulative uranium requirement is very clear. The introduction of breeders can cap the LWR capacity (Figure 4) and hence also cap the ultimate uranium requirements (Figure 5).

The divergence of the cumulative uranium requirements (Figure 5) will continue to widen if the plot is extended beyond 2100.

Figure 5. Uranium resource requirements and availability
or nuclear growth scenarios with and without fast reactors

 

3. Fast reactors are critically needed for both limitless energy supply and for waste management.

The public views adequate nuclear waste management as a critical linchpin in further development of nuclear energy. The technical community, therefore, needs to provide a practical approach to deal with the waste issue.

The Fukushima accidents call attention to the importance of managing spent fuel safely. It appears the best technical approach is extracting the actinides from spent fuel, which reduces the effective lifetime of nuclear wastes from ~300,000 years to ~300 years.

Extracting actinides (and using them to generate power) is by far the best technical approach to dealing with nuclear wastes. The MIT Study fails to mention this important possibility. If actinide extraction is chosen as a pathway for waste “disposal,” the recovered actinides still must be transmuted to fissile material or fissioned directly. This can be done only in fast reactors.

Actinides can be burned in fast reactors, generating energy and at the same time creating more fissile material for the future. A key advantage of fast reactors is that they can be utilized as “burners” when excess plutonium inventories exist, and then converted to “breeders” whenever needed. Only fast reactors can satisfy the waste-disposal mission simply and effectively while extending utilization of the uranium resources by more than two orders of magnitude.

Thermal reactors—such as LWRs and high-temperature gas-cooled reactors—utilize less than 1% of uranium resources, even with recycling of plutonium and some of the uranium. Thermal-spectrum reactors, even optimized, can extend the resource utilization only marginally, and they cannot burn actinides effectively. Actinide recycling also requires an efficient processing technology, with improved economics and nonproliferation characteristics.

The pyroprocessing technique based on electrorefining, developed in the IFR program, has the potential to recover the actinides from LWR spent fuel as well as to fully recycle fuel in fast reactors. The fundamentals of pyroprocessing have already been demonstrated – this is not new science.

The technology is now ready for pilot-scale demonstration, and it should be given the highest priority. We do not need decades of R&D to pursue all esoteric ideas. We already have in our hands the most advanced technology, technology that no other countries possess.

The MIT Study also talks about the inter-generational equity considerations. We believe that our generation should demonstrate the technologies that will solve the energy supply and waste management problems, rather than proposing a century-long interim storage of the spent nuclear fuel.

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Idaho Samizdat would like to thank Barry Brook at Brave New Climate for facilitating the publication of the critique here. Minor format changes were made to the original to accommodate the transition from a WordPress to Blogpost template.

Dan Yurman's picture

Thank Dan for the Post!

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Discussions

Charles Barton's picture
Charles Barton on June 1, 2011

This contents of this post amounts to an unsubstantuated protest by the IFR crowd against a well researched document by MIT.  I posted a response on Barry’s excelent blog, Brave New Climate:

“Unfortunately this Critique does not document its claims. I am not going to say that these claims are false, but simply that I am unfamiliar with sources that support these claims. Thermal thorium breeders are capable of operating at a one to one conversion ratio with small fissile inventories. In fact such small fissile inventories that higher breeding ratios are not required to produce sustainable large scale nuclear power for tens of thousands of years. The one to one conversion ratio is very advantageous, as far as proliferation control is concerned. This is the primary reason why the MIT fuel cycle study concluded:

“A key finding of this analysis is that reactors with conversion ratios much higher than one are not materially advantageous for a sustainable fuel cycle – a conversion ratio near unity is acceptable and has multiple advantages.”

“Not only are high breeding ratio IFRs not needed, but it is far from clear what research backsup the claim that they are capable a breeding ratio potential in the range of 1.50–1.65. I would like to see studies which support this claim, and further which would demonstrate that there are no serious safety or proliferation related problems associated with such a high breeding ratio. I would also like to see detailed reports that lay out a development program intended to bring a high breeding ratio IFR to a prototype stage together with estimated costs of that program.

Finally, I would like to see a rational for developing high breeding ratio IFRs, as opposed to one to one thorium converters. Would the high breeding ratio IFRs have cost advantages compared to one to one thorium thermal converters?”

So far neither Tom nor Barry has posted a responce, although Barry has indicated that he intends too.  A number of other comments were also critical of Tom’s post, including comments by David LeBlanc,

http://bravenewclimate.com/2011/05/31/critique-mit-fnfc-2011/#comment-12...

David also supports one of my complaints, “Trying to find actual IFR data is like pulling teeth sometimes, I’ve dug through countless documents to pull out numbers I can reference,”

http://bravenewclimate.com/2011/05/31/critique-mit-fnfc-2011/#comment-12...

One of the more Ironic moments in the discussion came when the moderator – I assume Barry – commented, MODERATOR:
“Alan has been reminded of BNC Comments Policy and the need to substantiate opinion with refs.”

I must add that I have a lot of respect for both Tom and Barry, but I do not always agree with them. 

 

David Lewis's picture
David Lewis on June 2, 2011

 

One key to understanding MIT is that they have a great concern if at any point in a fuel cycle “weapons usable” material is created, no matter what the safeguards are.  On this and other points, your critique of MIT’s report reads as if you haven’t read it.
You say MIT ignored what you call an “extraordinarily important fact”, i.e. that according to you there would be no long term nuclear waste problem if everyone followed your plan.  They didn’t ignore your idea.  They disagree.  They say no matter what plan is followed, “all fuel cycles generate long-lived radioactive wastes that can not be practically destroyed;  thus, all fuel cycles require a geological repository to support the disposal of radioactive wastes”.  You say they don’t know what they are talking about.  We’re supposed to believe MIT doesn’t know and you do?
What seems more likely is that you don’t understand their report.  It will be interesting to see if your claim stands up. Why not publish, with references, in a peer reviewed journal where, if you convince enough of the nuclear scientific community, MIT will be forced to respond?  
Perhaps what you miss is that the MIT report often offers as their conclusion an opinion about what other people will do in a market based system with a form of democracy, i.e. in the reality that is the US today, as opposed to what people might do in a system that was more rational from your point of view.  They don’t think everyone is going to follow your plan, if they ever do, for quite a while, in part because they believe one or more of many other possibilities than the one you’ve latched on to might succeed in the marketplace.  It is a completely different thing than what you say MIT did, i.e. ignore your plan, and misunderstand nuclear technology. 
 
MIT offers scenarios based on their perception of what the nuclear industry will do.  Ernie Moniz, one of the study co-chairs, has said elsewhere that the nuclear industry is “deeply conservative”.  Obviously, you are not.  
Your critique ends with a statement we do not need to look further than your choice of technology, because it is “the most advanced”.  “It should be given the highest priority”.  MIT directly addresses you and others like you with this:  
“Too much has changed to assume that the traditional fuel cycle futures chosen in the 1970s based on what was known at that time are appropriate for today.  There is a window of time, if used wisely with a focused effort, to develop better fuel cycle options before major decisions to deploy advanced fuel cycles are made.”  p14
MIT calls for “rebuilding” US nuclear research capability by sustained large expenditure over many years. 
Basically they conclude that the <b>capital cost </b>of anything new has to be lower than LWRs if utility execs are to be convinced they should invest in them.  This isn’t MIT’s opinion, its their opinion of what the “deeply conservative” nuclear industry will do.  “If a new reactor type is demonstrated to be more economic than an LWR, it may drive many fuel cycle decisions” – p. 22  Note “may”.  MIT is just guessing at what the utilities will do.  Would you invest billions knowing some 1 in a 1000 year tsunami at Fukushima might cause a government to bankrupt your operation that is nowhere near the sea?  If you had the choice, would you build the first fast breeder, or would you prefer to go with what made a lot of money for you in the past?  
How is the nuclear industry supposed to view its future as a solution to climate change when by far the majority of climate activists want the entire industry shut down no matter what implications there are for climate?  And there is one other teensy issue:  the industry itself appears deeply committed to the idea that climate science is bogus. They just don’t believe it.   
MIT isn’t with the US nuclear industry on this one.  They remind readers that the prime focus of their 2003 “The Future of Nuclear Power” report was the role nuclear power might have in avoiding greenhouse gas emissions.  The emphasize that their “primary recommendation” at that time was for the US government to use loan guarantees to attempt to eliminate the “risk premium” charged by Wall Street on new nukes which by itself makes nuclear power uncompetitive with fossil power.  They point out that “the urgency to address climate change has increased”, and they call in this report for that loan guarantee program to be accelerated. The designs that are licensed and ready to go are LWRs.  If the industry itself and society at large can’t see the climate problem and can’t even start to build some reactors for any other reason such as the national energy security why do you expect MIT to suddenly start in backing your plan as an emergency climate measure?  
They appear to have their own plan, given the circumstances they see.  They make repeated references to “hard spectrum (modified) LWRs”, i.e. fast reactors with a conversion ratio of 1, that can be started with “low enriched non-weapons usable (enrichment below 20%) uranium”, which could “enable full utilization of uranium and thorium resource”, a concept which they say originated with “recent work at MIT” – page 25.  They have a great concern if at any point in a fuel cycle “weapons usable” material is created, no matter what the safeguards are. 

One key to understanding MIT is that they have a great concern if at any point in a fuel cycle “weapons usable” material is created, no matter what the safeguards are.  On this and other points, the Blees critique of MIT’s report reads as if he hasn’t read it.

Blees says MIT “ignored” what he calls an “extraordinarily important fact”, i.e. that according to him there would be no long term nuclear waste problem if everyone followed his plan.  They didn’t ignore Blees’ idea.  They disagree.    

They say no matter what plan is followed, “all fuel cycles generate long-lived radioactive wastes that can not be practically destroyed;  thus, all fuel cycles require a geological repository to support the disposal of radioactive wastes”.  Blees then says MIT don’t know what they are talking about.  We’re supposed to believe MIT doesn’t know and Blees does?  

What seems more likely is that Blees didn’t understand the MIT report.  It will be interesting to see if his claim stands up, i.e. that he knows more about nuclear waste and fast breeders than MIT. He should publish, with references, in a peer reviewed journal where, if he can convince enough of the nuclear scientific community, MIT will be forced to respond.

Perhaps what Blees misses is that the MIT report often offers as their conclusion an opinion about what other people will do in a market based system with a form of democracy, i.e. in the reality that is the US today, as opposed to what people might do in a system that was more rational from his point of view.  MIT don’t think everyone is going to follow the Blees plan, if they ever do, for quite a while, in part because they believe one or more of many other possibilities than the one he’s latched on to might succeed in the marketplace.

MIT offers scenarios based on their perception of what the nuclear industry will do.  Ernie Moniz, one of the study co-chairs, has said elsewhere that the nuclear industry is “deeply conservative” which is why he feels they are most likely to build LWRs almost no matter what. 

The Blees critique ends with a statement we do not need to look further than his choice of technology, because it is “the most advanced”.  “It should be given the highest priority”.  

MIT directly addresses Blees and others who think like him with this:  

“Too much has changed to assume that the traditional fuel cycle futures chosen in the 1970s based on what was known at that time are appropriate for today.  There is a window of time, if used wisely with a focused effort, to develop better fuel cycle options before major decisions to deploy advanced fuel cycles are made.”  p14  

MIT calls for “rebuilding” US nuclear research capability by sustained large expenditure over many years. 

Basically they conclude that the capital cost of anything new has to be lower than LWRs if there is to be any chance utility execs will be convinced they should invest in them.  This isn’t MIT’s opinion, its their opinion of what the “deeply conservative” nuclear industry will do.  “If a new reactor type is demonstrated to be more economic than an LWR, it may drive many fuel cycle decisions” – p. 22  Note “may”.  MIT is just guessing at what the utilities will do.  Would you invest billions knowing some 1 in a 1000 year tsunami at Fukushima might cause a government to bankrupt your operation that is nowhere near the sea?  If you had the choice, would you build the first fast breeder, or would you prefer to go with what made a lot of money for you in the past?  

How is the nuclear industry supposed to view its future as a solution to climate change when by far the majority of climate activists want the entire industry shut down no matter what implications there are for climate?  And there is one other teensy issue:  the industry itself appears deeply committed to the idea that climate science is bogus. They just don’t believe it.   
MIT isn’t with the US nuclear industry on that one.  They remind readers that the prime focus of their 2003 “The Future of Nuclear Power” report was the role nuclear power might have in avoiding greenhouse gas emissions.  The emphasize that their “primary recommendation” at that time was for the US government to use loan guarantees to attempt to eliminate the “risk premium” charged by Wall Street on new nukes which by itself makes nuclear power uncompetitive with fossil power.  

They point out that “the urgency to address climate change has increased”, and they call in this report for that loan guarantee program to be accelerated. The designs that are licensed and ready to go are LWRs.  If the industry itself and society at large can’t see the climate problem and can’t even start to build some reactors for any other reason such as national energy security why does Blees expect MIT to suddenly start in backing his plan as an emergency climate measure?  

MIT appears to have and favor their own fast breeder plan, given the circumstances they see.  They make repeated references to “hard spectrum (modified) LWRs”, i.e. fast reactors with a conversion ratio of 1, that can be started with “low enriched non-weapons usable (enrichment below 20%) uranium”, which could “enable full utilization of uranium and thorium resources”, a concept which they say originated with “recent work at MIT” – page 25.  Blees should critique that.  

 

 

David Lewis's picture
David Lewis on June 3, 2011

Tom Blees didn’t write your “guest post” by the way.  

When I wrote a critique of this as if the author of the study was Blees and posted it as a comment over at BraveNewClimate, Barry seemed to get quite upset.  Apparently the S.C.G.I. group actually wrote this, and Tom’s name appears only as a contact.  

Dan Yurman's picture
Dan Yurman on June 3, 2011

It turns out Lewis is right. 

In an exchange of emails today (June 3, 2011), Barry Brook advised me that while Blees participated in the writing, he’s not the sole author of the guest post which appeared on my blog.

The history here is that I posted the article on my blog from which TEC posted it here. I’ve asked TEC to post a clarification.

 

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