PROLIFERATION AND THE IFR The dialog below is based on an email exchange related to the proposed commercialization of the Integral Fast Reactor. Background: The Integral Fast Reactor (IFR) completely closes the nuclear fuel cycle, extracting virtually all of the energy in its fuel. To accomplish that, the fuel must be periodically processed to extract the fission products and reconstitute the fuel, with the addition of a small amount of depleted uranium for makeup fuel. In some quarters, there is worry that recycling the fuel will lead to the segregation of bomb-usable plutonium. In response to an appeal for signatures on a paper (the “Holdren letter”) advocating completion of IFR development, one thoughtful recipient (referred to below as XYZ), who had been advised not to sign, asked for clarification of a couple of proliferation-related issues. The request was passed along to George S. Stanford, a retired reactor physicist. Here, somewhat edited, is the gist of the ensuing exchange of emails. GSS to XYZ, M.D. John Shanahan has asked me to respond to your thoughtful request. You said, I would like to know if there is a way to reprocess fuel without generating the kinds of risks that those in the non-proliferation community oppose. Your question cannot be answered with a simple yes or a no. With your indulgence, I will rephrase it: "How can the risks of nuclear-weapons proliferation be minimized, given the reality of the accelerating global growth of nuclear power?" In response to that one, here are some of the considerations: (a) The path to plutonium for nuclear weapons has always been special-purpose production reactors, where the uranium is only irradiated for a very short period before being processed to extract Pu of good isotopic quality. (b) The easiest way for a non-weapons state to get an A-bomb is by enriching uranium -- no reactors needed. If the only reactors were IFRs, there would be no call for enrichment at all, and therefore no civilian excuse for a nation to have an enrichment capability. (c) Any reactor type at all can be diverted to the production of Pu-239 for weapons (and thorium reactors can be adapted, as well, to the production of pure U-233). (A possible exception would be the case of a low-power “nuclear battery” that is in a transportable, sealed containment.) (c) Plutonium for a weapon cannot be obtained without an aqueous, PUREX-type processing capability, regardless of how many reactors, of any type, that a nation has. Pyroprocessing by itself is unable to separate pure plutonium from used reactor fuel, so a supplementary separation capability would be needed -- even if the plutonium had an acceptable isotopic mix, which it normally does not.
(d) Nevertheless, for optimum proliferation prevention, all fuel-processing facilities should be confined to nations that already have all the weapons-Pu capability that they want, with ironclad, international guarantees that any nation with civilian reactors can get the fuel they need. Here is a relevant link (from the Bulletin of the Atomic Scientists): < http://www.sustainablenuclear.org/PADs/pad0611marsh.pdf>. (e) A vital point to understand is this: Fast reactors are being worked on in India, China, Japan, Russia, France, South Korea, etc. They require the fuel to be recycled. The U.S. can either join the game and try to keep it manageable -- or we can continue to let the technology develop uncoordinated. That last point is what baffles me about your advisor's opposition to "reprocessing"â&#x20AC;&#x201D;he seems to assume that the global evolution of nuclear power will proceed more safely without U.S. leadership than with it. For some of the more technical aspects of recycling and proliferation, consider something that Yoon Chang, former director of the IFR project at Argonne, has written: Electrorefining cannot separate out pure plutonium product. [There are] three key factors affecting direct weapons usability: (1) high decay heat melts explosives surrounding the plutonium, (2) high spontaneous neutron source reduces the weapons yield significantly, and (3) high gamma radiation makes hands-on assembly extremely difficult. However, the gamma radiation coming from rare earth fission product contamination decays in time. But these intrinsic properties do not make pyroprocessing proliferation free. The materials can be diverted for further processing, etc. Pyroprocessing may also make the entire safeguards system more robust because of a straightforward physical security (hot cell with very limited access) and simpler materials accountability. My point here is not that the main justification of the IFR/pyroprocessing is proliferation-resistance, but these characteristics are highly desirable regardless. The world would be far better off if pyroprocessing replaced aqueous reprocessing. Of course, the main justification for IFR/pyroprocessing is its huge energy potential in the long-term and solving the LWR spent fuel dilemma in the near-term, potentially with huge economic benefits compared to aqueous reprocessing. The only down side is that it has not been fully demonstrated. I hope this has been a help. If you'd like further information, please say so. With best wishes, -- George Stanford
Dr. XYZ to GSS Thanks, George I had a conversation with one of my colleagues here, who explained reprocessing to me. According to him, the byproducts of reactor fuel are: fission products (cesium, etc), uranium, and plutonium. Reprocessing separates these three components apart which is what they have problems with because the plutonium can then be handled safely and apparently only 15 kg is needed to make a weapon. By leaving it unprocessed, it's too hazardous to touch the stuff. Regardless of whether it's reprocessed or not, the fission products need to be stored somewhere-preferably underground, and who wants the stuff in their backyard? It's not clear if there is any place where it's safe to store it. Anyway, it's clear to me that there are passionate opinions on both sides of the coin. I can see both sides of the argument, but since this isn't my main area of research (I focus on epidemics) for the sake of my peaceful co-existence with my colleagues here, I'd prefer not to support one side or the other. I hope you understand. Sincerely, -- XYZ
GSS to Dr. XYZ Thanks for another thoughtful reply. At the risk of sending you more than you want, I'll comment briefly on some of the points you raise -- not to pester you for your signature, but to give you something more to think about. Here's your paragraph, with comments interspersed. I had a conversation with one of my colleagues here . . . who explained reprocessing to me. According to him, the byproducts of reactor fuel are: fission products (cesium, etc), uranium, and plutonium. Those are indeed three of the components of used reactor fuel. A fourth component is the collection of "minor actinides" -- mainly americium and curium -- which, along with the various plutonium isotopes, constitute about 1.2% of spent LWR fuel and account for the concern about the safety of Yucca Mountain 10,000+ years down the road. Reprocessing separates these three components . . . That is true only for the aqueous PUREX process, which is what is now used to a minor extent (not in the U.S.) to cycle some of the plutonium back into thermal reactors. It is not true of the "dry" pyrometallurgical processing that would be used to recycle the metallic fuel used in IFRs. As emphasized in the material from Yoon Chang that I sent, pyroprocessing is incapable of separating, from used reactor fuel, plutonium with the chemical purity needed for weapons. For that you would need a supplemental PUREX-type facility (PUREX is inherited from the
weapons program). Oversimplified, the three processing-output streams involved in treating LWR used fuel for use in IFRs are (a) the bulk of the uranium, to be stored for later use, (b) fission products (the waste), and (c) the plutonium and higher actinides mixed with some of the uranium and some of the fission products; this third stream constitutes the fuel for IFRs. . . . which is what they have problems with because the plutonium can then be handled safely and apparently only 15 kg is needed to make a weapon. That is only true of special uranium fuel elements that (a) have been irradiated only briefly, to get plutonium that is isotopically pure enough for weapons use, and (b) that have been processed by aqueous chemistry to obtain plutonium with the needed chemical purity. Any group with the desire for a weapon and the expertise to make one would be able to find a number of routes to fissile material that are much easier than starting with plutonium from IFRs (or even from thermal reactors with normal fuel cycles). Reactors are neither necessary nor sufficient for a weapons program. By leaving it unprocessed, it's too hazardous to touch the stuff. The used LWR fuel can of course be left unprocessed until it is needed for starting up new IFRs. Once in a IFR plant, the plutonium is securely contained in a fiercely radioactive enclosure, where everything is done by remote control. With IFRs, eventually virtually all existing plutonium can be sequestered like that. Regardless of whether it's reprocessed or not, the fission products need to be stored somewhereâ&#x20AC;&#x201D;preferably underground, and who wants the stuff in their back yard? It's not clear if there is any place where it's safe to store it. One safe place would be Yucca Mountain, which can be counted on to be secure for at least 500 years, by which time the activity is well below any level of reasonable concern. Additional thought, August 2013: Another safe disposal method would be vitrify any unwanted fission products and drop the capsules into the silt in deep oceanic trenches. (Glass is in sea water is known to be stable for millennia, but even if it dissolved much sooner, the activity would be so diluted that it would constitute a completely negligible increment to the natural radioactivity already in the water.) Unfortunately, though, this disposal method is so cheap that thereâ&#x20AC;&#x2122;s no special interest with a financial motivation to lobby for it. *
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However, the above discussion looks at the trees instead of the forest. Even if all those problems were real, what are the policy implications? Your friend's implicit assumption seems to be that if only the U.S. forgoes recycling, the rest of the world will followâ&#x20AC;&#x201D;which is manifestly and hopelessly unrealistic. The rest of the world is forging ahead, with us or without us. Do you think it might be best for us to abandon any hope of achieving some sort of international oversight that could safely manage capabilities for enriching uranium and processing fuel?
Summary It seems clear that uranium supply is not a near-term problem, even for thermal reactors. But there are other reasons for the United States to move ahead with IFRs. Here are some of them: 1. Eighty years of waste from 1000 thermal reactors (1-GWe) with a once-through fuel cycle would leave enough used fuel for ten or twenty Yucca Mountains. 2. The environmental effects of accelerated uranium mining will impinge increasingly on the public's consciousness. Resistance to uranium mining is already growing. 3. The accumulating plutonium inventory will, rightly or wrongly, be seen as an ever-increasing proliferation risk, 4. The multiplying need for uranium enrichment means the spread of centrifugeâ&#x20AC;&#x201D;or perhaps the even cheaper laser-separationâ&#x20AC;&#x201D;technology, and loss of international control of enrichment technology has serious proliferation implications. 5. Since China, India, Russia, et al. are forging ahead with their fast-reactor programs, technological leadership will continue to move in that direction. 6. The concomitant spread of fuel-processing technology will mean loss of international control of that technology, with further serious proliferation worries. 7. No nation can make nuclear weapons without either enrichment or reprocessing facilities, regardless of how many reactors it has. The loss of U.S. technological leadership will mean the loss of ability to bring order to the global development and deployment of nuclear technology, with the consequent uninhibited spread of proliferation potential. 8. The institutional knowledge of the U.S.-developed IFR technology is rapidly dying off, accelerating the North American descent to second-class technological status. With best regards, -- George
Dr. XYZ to GSS Thanks for the info, George. -- XYZ