THE REVISED PLUTONIUM DISPOSITION STRATEGY:
Edwin S. Lyman
The revised U.S. strategy to dispose of 34 metric tons (MT) of weapons-grade plutonium in accordance with a September 2000 U.S.-Russian agreement, announced by DOE/NNSA in January, was billed as a significant improvement to the original program that would lead to an acceleration of the plutonium disposition mission. In the revised program, DOE/NNSA cancelled plans to build a plant to immobilize 8.4 metric tons (MT) of weapon-grade plutonium (as well as several MT of non-weapon-grade plutonium), and decided to dispose of all 34 MT by incorporating it into mixed-oxide reactor fuel (MOX) and irradiating it in commercial nuclear reactors. This announcement immediately raised questions, because DOE/NNSA had not indicated how the MOX program could actually absorb an additional 8.4 metric tons (MT) of plutonium that was originally supposed to have been immobilized, yet be completed in less time than the original program for disposing of 25.6 MT of plutonium as MOX. Nonetheless, DOE/NNSA asserted that the revised program had less technical risk than the original program.
With the issuance of a February 15 report to Congress, it is now known how DOE/NNSA hopes to accelerate the rate of plutonium disposition. According to the report, which proposes increasing the rate of disposition via MOX from 2 MT to 3.5 MT per year, successful implementation requires obtaining two additional commercial reactors to participate in the program and expanding the rate of plutonium disposition in Russia. However, the report does not provide any details about how it plans to accomplish these highly speculative objectives and still maintain the aggressive schedule put forward in the report.
Moreover, DOE/NNSAs estimate of the number of new reactors needed is incorrect. At the currently planned maximum core loading of 40% MOX --- a maximum rooted in technical limits of operating light-water reactors --- a large pressurized-water reactor (1150 MWe) operating on a standard 1.5-year refueling cycle can only accommodate at most 0.5 MT of plutonium per year. Under the old plutonium disposition strategy, which relied on the four reactors currently in the program (Duke Powers Catawba and McGuire ice condenser plants), only 2 MT per year could have been absorbed. Thus a minimum of three new reactors --- and probably four --- would be needed to accommodate another 1.5 MT of plutonium per year without exceeding the current maximum core loading.
Before Dominion Resources removed its North Anna 1&2 reactors from the plutonium disposition program in April 2000, the maximum estimated throughput for all six reactors was about 2.9 MT per year, and 13 years would required to irradiate 34 MT, beginning in 2007 and ending in 2020, according to a 2000 report. Under the new program, batch delivery of fuel to reactors is scheduled to begin in Fall 2008, and the program is slated for completion in 2019 (11 years duration). Thus at least seven reactors --- three more than the number currently under contract --- would be required to dispose of 34 MT over the shorter time period. More realistically, the start of the program will be further delayed as a result of the changes to the MOX fabrication plant design that are necessary to purify the plutonium feedstock that was originally slated for immobilization, so completion by 2019 would likely require yet another reactor.
The details of how DOE/NNSA intends to carry out the amazing feat of locating three or even two additional reactors for the MOX program without causing any delays to the existing schedule --- and reducing the overall cost of MOX irradiation by several hundred million dollars to boot --- were not discussed in the Report to Congress. As mentioned above, the North Anna plant in Virginia was originally part of the plutonium disposition program, but its owner, Dominion Resources, dropped out in April 2000, in what was described as a business decision. Part of the reason for this was the fact that North Anna would have required additional control rods or modification of the existing control rods to accommodate a 40% MOX loading, which would have been costly. It is highly unlikely that Dominion could be persuaded to participate again in the controversial MOX program without significant economic incentives.
The prospect of finding other reactors to participate in the MOX program is even more unlikely. In the current electricity marketplace, the additional NRC scrutiny, technical risk and public opposition associated with adopting a novel fuel material is not likely to be an appealing prospect to utility executives, even with the possibility of a reduction in fuel costs as a result of government subsidy of MOX fabrication. In any event, the multi-year process of identifying potential interest in the program among U.S. utilities would have to be repeated.
In contrast to the uncertainties in cost and schedule associated with the all-MOX revised program, the Report to Congress acknowledges that immobilization of plutonium achieves full disposition of 34 MT of U.S . plutonium inventory with the lowest cost. While the report claims that immobilization of all U.S. plutonium would have been unacceptable to Russia because immobilization does not degrade the isotopic content of the plutonium, the fact remains that Russia had agreed (in the September 2000 U.S.-Russian Agreement) to allow the U.S. to dispose of 8.4 MT of non-pit, weapons-grade plutonium through immobilization without degradation of the isotopic content. The fact that this material is less chemically pure than the nuclear weapon pits that have always been destined for MOX is irrelevant, since the end product of immobilization would be the same whether the initial feedstock were pure or impure. Moreover, Russia is insisting on loading a portion of its excess plutonium in a test plutonium fast-breeder reactor, the BN-600, which would barely change the isotopics of the plutonium from weapons-grade. Thus this alleged Russian position is logically inconsistent.
In short, the purported advantages of DOE/NNSAs revised plutonium disposition strategy are entirely based on a speculative foundation --- a house of cards --- that is highly unlikely to succeed without major additional costs and delays to the program, and will significantly increase environmental and public health risks by requiring the use of MOX fuel in at least three additional reactors. The number of cancer deaths anticipated to result from a severe accident at a reactor with a 40% core of weapons-grade MOX fuel has been calculated to be about 25% higher than the number that would result from the same accident if only low-enriched uranium fuel had been present.
For these reasons, it is crucial that DOE/NNSA issue a draft Supplemental Environmental Impact Statement to accurately document the additional risks associated with the revision of the plutonium disposition strategy originally outlined in its Record of Decision in January 2000. There are indications that DOE/NNSA simply plans to amend the Record of Decision, attempting to bypass all statutory requirements required under the National Environmental Policy Act (NEPA) for public comment on proposed Federal actions that have undergone substantial changes.
 Richard Clark, David Dziadosz and Steven Nesbit, MOX Fuel Irradiation Program for Disposition of Surplus United States Plutonium, Proceedings of the Embedded Topical Meeting on DOE Spent Nuclear Fuel and Fissile Material Management (sponsored by the American Nuclear Society), San Diego, CA, June 4-8, 2000, p. 417.
 Edwin S. Lyman, Public Health Risks of Substituting Mixed-Oxide for Uranium Fuel in Pressurized-Water Reactors, Science and Global Security 9 (2001) 33.