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Executive Summary Under the first and second Strategic Arms Reduction Treaties (START I and II) and unilateral pledges made by Presidents Bush, Gorbachev, and Yeltsin, many thousands of U.S. and Russian nuclear weapons are slated to be retired within the next decade. As a result, 50 or more metric tons of plutonium on each side are expected to become surplus to military needs, along with hun- dreds of tons of highly enriched uranium (HEU). These two materials are the essential ingredients of nuclear weapons, and limits on access to them are the primary technical barrier to acquisition of nuclear weapons capability in the world today. Several kilograms of plutonium, or several times that amount of HEU, are sufficient to make a nuclear weapon. The existence of this surplus material constitutes a clear and present dan- ger to national and international security. None of the options yet identified for managing this material can eliminate this danger; all they can do is to reduce the risks. Moreover, none of the options for long-term disposition of excess weapons plutonium can be expected to substantially reduce the inventories of excess plutonium from nuclear weapons for at least a decade. PRINCIPAL RECOMMENDATIONS Our study of this problem leads us to the following four principal recom- mendations: 1. A New Weapons and Fissile Materials Regime. We recommend that the United States work to reach agreement with Russia on a new, reciprocal regime that would include: (a) declarations of stockpiles of nuclear weapons and all fissile materials (b) cooperative measures to clarify and confirm those declarations;

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2 EXECUTIVE SUMMARY (c) an agreed halt to the production of fissile materials for weapons; and (d) agreed, monitored net reductions from these stockpiles. Monitoring of warhead dismantlement and commitment of excess fissile mate- rials to non-weapons use or disposal, initially under bilateral and later under international safeguards, would be integral parts of this regime, as would some form of monitoring of whatever warhead assembly continues. 2. Safeguarded Storage. We recommend that the United States and Russia pur- sue a reciprocal regime of secure, internationally monitored storage of fissile material, with the aim of ensuring that the inventory in storage can be with- drawn only for non-weapons purposes. 3. Long-Term Plutonium Disposition. We recommend that the United States and Russia pursue long-term plutonium disposition options that: (a) minimize the time during which the plutonium is stored in forms readily usable for nuclear weapons; (b) preserve material safeguards and security during the disposition process, seeking to maintain the same high standards of security and accounting applied to stored nuclear weapons; (c) result in a form from which the plutonium would be as difficult to recover for weapons use as the larger and growing quantity of plutonium in com- mercial spent fuel; and (d) meet high standards of protection for public and worker health and for the environment. The two most promising alternatives for achieving these aims are: fabrication and use as fuel, without reprocessing, in existing or modified nuclear reactors; or vitrification in combination with high-level radioactive waste. A third option, burial of the excess plutonium in deep boreholes, has until now been less thoroughly studied than have the first two options, but could turn out to be comparably attractive. 4. All Fissile Material. We recommend that the United States pursue new international arrangements to improve safeguards and physical security over all forms of plutonium and HEU worldwide. In particular, new cooperative efforts to improve security and accounting for all fissile materials in the former Soviet Union should be an urgent priority. _ . . . Because plutonium In spent fuel or glass logs incorporating high-level wastes still entails a risk of weapons use, and because the barrier to such use diminishes with time as the radioactivity decays, consideration of further steps to reduce the long-term proliferation risks of such materials is required, regard- less of what option is chosen for disposition of weapons plutonium. This global effort should include continued consideration of more proliferation-resistant , _ .

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EXECUTIVE SUMMARY 3 nuclear fuel cycles, including concepts that might offer a long-term option for nearly complete elimination of the world's plutonium stocks. On September 27, 1993, the Clinton administration announced a non-pro- liferation initiative that included some first steps in the directions recom- mended above, among them a proposal for a global convention banning production of fissile materials for weapons; a voluntary offer to put U.S. excess fissile materials under International Atomic Energy Agency (IAEA) safe- guards; and a recognition that plutonium disposition is an important non-pro- liferation problem requiring renewed interagency, and ultimately international, attention. This is a much needed and timely start; more, however, remains to be done. CRITERIA AND CONTEXT The steps we recommend are designed to meet three key security objectives: 1. to minimize the risk that either weapons or fissile materials could be obtained by unauthorized parties; 2. to minimize the risk that weapons or fissile materials could be reintroduced into the arsenals from which they came, thereby halting or reversing the arms reduction process; and 3. to strengthen the national and international arms control mechanisms and incentives designed to ensure continued arms reductions and prevent the spread of nuclear weapons. Other key criteria include protecting worker and public health and the environment; being acceptable to the public and the institutions whose approval is needed; and, to the extent consistent with other criteria, minimizing costs and delays. We note that the expenditures implied by all our recommendations com- bined would total at most several billion dollars, spread over a period of a dec- ade or decades. Since the primary objective is the reduction of major security risks, these expenditures should be considered in the context of the far larger sums being spent every year to provide national and international security. Thus, although the costs of alternate approaches are important and are dis- cussed in the report, cost is not the primary criterion in choosing among com- peting options. Moreover, exploiting the energy value of plutonium should not be a central criterion for decision making, both because the cost of fabricating and safeguarding plutonium fuels makes them currently uncompetitive with cheap and widely available low-enriched uranium fuels, and because whatever economic value this plutonium might represent now or in the future is small by comparison to the security stakes.

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4 EXECUTIVE SUMMARY World Stocks of Fissile Materials The problem of management and disposition of excess weapons plutonium must be considered in the context of the large world stocks of fissile materials. While all but a small fraction of the world's HEU is in military use, civilian stocks of plutonium are several times larger than military stocks and are grow- ing much faster, by some 60 to 70 tons each year. Most of these civilian stocks, however, are in the form of radioactive spent fuel from the world's power reac- tors, from which the plutonium is difficult to extract. The difficulty of extract- ing this plutonium declines substantially as the radioactivity of the fuel decays over the decades after it leaves the reactor. Roughly 130 tons of plutonium have been separated from spent fuel for reuse as reactor fuel, of which some 80 to 90 tons remains in storage in separated form. Plutonium customarily used in nuclear weapons (weapons-grade pluto- nium) and plutonium separated from spent reactor fuel (reactor-grade pluto- nium) have different isotopic compositions. Plutonium of virtually any isotopic composition, however, can be used to make nuclear weapons. Using reactor- grade rather than weapons-grade plutonium would present some complications. But even with relatively simple designs such as that used in the Nagasaki weapon- which are within the capabilities of many nations and possibly some subnational groups nuclear explosives could be constructed that would be assured of having yields of at least 1 or 2 kilotons. Using more sophisticated designs, reactor-grade plutonium could be used for weapons having considera- bly higher minimum yields. Thus, the difference in proliferation risk posed by separated weapons-grade plutonium and separated reactor-grade plutonium is small in comparison to the difference between separated plutonium of any grade and unseparated material in spent fuel. While plutonium and HEU can both be used to make nuclear weapons, there are two important differences between them. The first is that HEU can be diluted with other, more abundant, naturally occurring isotopes of uranium to make low-enriched uranium (LEU), which cannot sustain the fast-neutron chain reaction needed for a nuclear explosion. LEU is the fuel for most of the world's nuclear power reactors. In contrast, plutonium cannot be diluted with other isotopes of plutonium to make it unusable for weapons. "Re-enriching" LEU to the enrichment needed for weapons requires complex enrichment tech- nology to which most potential proliferators do not have access, while separat- ing plutonium from other elements with which it might be mixed in fresh reactor fuel requires only straightforward chemical processing. Thus, the management of plutonium in any form requires greater security than does the management of LEU. Second, as noted earlier, in the current nuclear fuel market, the use of plu- tonium fuels is generally more expensive than the use of widely available LEU fuels-even if the plutonium itself is "free" because of the high fabrication costs resulting from plutonium's radiological toxicity and from the security

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EXECUTIVE SUMMARY 5 precautions required when handling it. As a result, while most of the world's roughly 400 nuclear reactors could in principle burn plutonium in fuel contain- ing a mixture of uranium and plutonium (mixed-oxide or MOX fuel), few and none in the United States- are currently licensed to do so. The United States has agreed to buy 500 tons of surplus Russian HEU, blended to LEU, for $11.9 billion over the next 20 years, provided certain con- ditions are met. The United States will later resell the material to fulfill the demand for nuclear fuel on the domestic and world markets. While the pur- chase of Russian plutonium could, similarly, be justified on security grounds, both the security aspects and the economics of using plutonium as reactor fuel would be less attractive than in the case of LEU. Because of the more difficult technical and policy issues involved, this report focuses primarily on the disposition of plutonium rather than HEU. The International Environment The management and disposition of plutonium from dismantled nuclear weapons will take place within a complex international context that includes the arms reduction and nonproliferation regimes of which this problem is an element, the continuing crisis in the former Soviet Union, worldwide plans for civilian nuclear energy (particularly the use of separated plutonium), and exist- ing approaches to safeguards and security for nuclear materials. Recent nuclear arms reduction agreements and pledges, along with national decisions concerning what stocks of plutonium are to be declared "excess," will largely set the parameters of how much plutonium will require disposition and when it will become available. The reductions agreements entail a complex and uneven schedule of reductions in deployed launchers be- tween now and 2003. As yet, no agreement exists to govern the dismantlement of the surplus nuclear weapons, or the modes of storage and eventual disposi- tion of the fissile materials, although discussions of some aspects of the prob- lem are under way. Mutually agreed, monitored provisions for the disposition of fissile materials could help enhance political support for implementation of START II and for agreement on deeper reductions. The current crisis in the former Soviet Union creates a variety of risks with respect to the management and disposition of nuclear weapons and fissile materials. We categorize these as dangers of: "breakup," meaning the emergence of multiple nuclear-armed states where . previously there was only one; "breakdown," meaning erosion of government control over nuclear weapons and materials within a particular state; and "breakout," meaning repudiation of arms reduction agreements and pledges, and reconstruction of a larger nuclear arsenal.

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6 EXECUTIVE SUMMARY Breakup is the most immediate threat, mainly because of uncertainty over whether Ukraine will carry out its denuclearization pledges. Security concerns may well be the driving factors in Ukraine's ultimate decision, but that decision could be affected by measures that ensure that weapons and fissile materials transferred to Russia will not be reused for military purposes, and that provide compensation for these materials. Breakdown of the elaborate system of control of nuclear weapons and fis- sile materials in the former Soviet Union remains a possibility, despite Russian efforts to maintain the former Soviet systems for this purpose. The thefts of conventional weapons and nuclear materials other than plutonium and HEU that have already occurred are disturbing. Enhanced assistance in improving security and accounting for fissile materials in the former Soviet Union is a potentially high-leverage area deserving urgent attention. The broad regime of accounting we recommend could provide an important basis for additional steps to improve security of these materials. Breakout seems unlikely in the near term. The significant nuclear arsenals that each side will retain under START II will further reduce any motivation that a future Russian government might have for taking such a step. Ratifica- tion and implementation of START I and START II are not yet assured, how- ever. The steps that we outline would reduce the potential for breakout, and provide a foundation for deeper reductions and for the inclusion of additional parties in the future. The foundation of the nuclear nonproliferation regime is the Non-Prolif- eration Treaty (NPT), which is up for extension in 1995. Agreements for se- cure, safeguarded management and disposition of fissile materials from surplus nuclear weapons could help make clear that the nuclear powers are fulfilling their disarmament obligations under Article VI of the NPT. Moreover, accep- tance by the major nuclear powers of safeguards and constraints on substantial portions of their nuclear programs would help to reduce the inherently dis- criminatory nature of the nonproliferation regime. These steps, while probably not dissuading all nations that might be attempting to acquire nuclear weapons, would help build global political support for indefinite extension of the NPT and strengthening the regime, which are major U.S. policy goals. International efforts to reduce the proliferation risks posed by the existence of civilian plutonium and enriched uranium rest on safeguards, which are na- tional and international measures designed to detect diversion of materials and enable a timely response, and security, which consists of (currently national) measures designed to prevent theft of materials through the use of barriers, guards, and the like. Standards for both vary widely. Those applied to civilian materials, even separated plutonium and HEU, are less stringent than those applied to nuclear weapons and fissile material in military stocks. Varying and lower standards may be justified in the case of spent fuel for the first decades outside the reactor, when its high radioactivity makes it difficult to steal or di- vert, but they are not justified in the case of separated civilian plutonium or

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EXECUTIVE SUMMARY 7 HEU. New steps toward improved and consistent international standards should be pursued. Choices regarding the fissile materials from dismantled weapons may also affect and be affected by civilian nuclear power programs, a topic that depends on economic, political, and technical factors outside the scope of this study. In some countries, nuclear power programs already include the use of plutonium in the fuel loaded into reactors. But the amount of weapons plutonium likely to be surplus is small on the scale of global nuclear power use the equivalent of only a few months of fuel for existing reactors-and it is not essential to the future of civilian nuclear power. There is thus no reason that disposition of this weapons plutonium should drive decisions on the broader questions surround- ing the future of nuclear power. The production of tritium was not part of our charge, and we have not ex- amined alternatives for this purpose in detail. We believe, however, that there is no essential reason why plutonium disposition and tritium production need be linked, and there appear to be good arguments why they should not be. Techni- cally, the scale of the plutonium disposition task is very much larger than any tritium production requirement. From a policy perspective, producing weapons materials in the same facility that was destroying other weapons materials would raise political and safeguards issues. THE PROPOSED WEAPONS AND FISSILE MATERIALS REGIME We recommend a broad transparency regime for nuclear weapons and fis- sile materials, as outlined above. This regime could be approached step-by-step, with each step adding to security while posing little risk. The regime we envi- sion would include a variety of measures applying to each phase of the life cycle of military fissile materials: production and separation of the materials; fabrication of fissile material weapons components; assembly, deployment, re- tirement, and disassembly of nuclear weapons; and storage and eventual dispo- sition of fissile materials. These measures should be mutually reinforcing, to build confidence that the information exchanged is accurate and that the goals of the regime are being met. There is likely to be some resistance to a regime of full accounting and monitoring of total weapons and fissile material stocks and facilities, but such a regime meets objectives shared by the United States and Russia (and, for that matter, by many other countries). Moreover, extensive data exchanges and verification measures have already been agreed for deployed strategic nuclear forces and other military systems. Declarations of total stocks of weapons and fissile materials, with their locations, coupled with exchanges of operating records and inspections of material production sites, would reduce the large uncertainty in present esti- mates of these stocks. Fissile material production facilities and their operating

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8 EXECUTIVE SUMMARY records can be examined to confirm consistency with reported production fig- ures, and stocks of fissile materials and weapons at declared sites can be con- firmed through routine and occasional challenge inspections. The commitment of the Russian and U.S. governments to such declarations and the progressive opening of Russian society should make it less likely that a stockpile or pro- duction facility of any significant size could be hidden. Dismantlement should also be monitored. The United States is dismantling its nuclear weapons at a rate of somewhat less than 2,000 per year, with a goal of increasing that rate to 2,000 the maximum rate permitted by available fa- cilities; personnel; and environment, safety, and health (ES&H) considerations. The plutonium components ("pits") are being placed intact into containers and put in intermediate storage at the Pantex disassembly site near Amarillo, Texas. The HEU components are being shipped to the Y-12 plant at Oak Ridge, Tennessee, for storage and eventual use as naval or civilian reactor fuel. Rus- sian spokesmen have declared that Russia is dismantling nuclear weapons at four sites, at a rate comparable to the U.S. rate, and is storing the materials at . . . severe existing sites. Neither the United States nor Russia plans to monitor the other's disman- tlement, although limited Ukrainian monitoring is reported to be in place in Russia. Means exist or could be developed to monitor dismantlement without undue interference or costs, while protecting sensitive information. As with other parts of the regime, some declassification would be necessary to permit effective monitoring. The basic approach would be a variant of the perimeter- portal monitoring system now in place to verify that missiles banned by the Intermediate-Range Nuclear Forces treaty are not being produced; war-heads entering and leaving the facility would be counted, and amounts of fissile ma- terial measured. Such monitoring could be applied without undue interference with necessary maintenance and modification of the remaining military stockpile. A cutoff of production of weapons materials would require monitoring of enrichment and reprocessing facilities. Still greater confidence could be achieved if all fuel cycle facilities were monitored. These tasks could be carried out by bilateral or international monitors (or both), using means that have met international acceptance in nonproliferation verification. Continued production of HEU for naval reactors and tritium for nuclear stockpile maintenance would introduce some complications, but these could readily be addressed through careful design of the agreement and the monitoring system. The United States is no longer producing plutonium or HFU for weapons. Russia has also ceased production of HEU for weapons, but is still operating plutonium production reactors and separating the resulting weapons-grade plu- tonium. The Russian government asserts that these reactors provide necessary heat and power to surrounding areas, and that the fuel must be reprocessed for safety reasons. The United States has begun discussions with Russia about as- sistance in converting these reactors so that separated weapons plutonium is not

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EXECUTIVE SUMMARY 9 generated, or in providing alternate power sources, but these discussions remain embryonic. Internationalizing the Regime The security goals outlined above would be best served if the standards set by this regime for managing U.S. and Russian excess weapons and fissile materials were extended worldwide. In particular, new agreements should be pursued to: 1. create consistent, stringent international standards of accounting and secu rity for fissile materials; 2. end all production of fissile materials for nuclear weapons, worldwide; 3. create an international system of declarations and inspections covering declared nuclear weapons arsenals, including reserves, and fissile material stocks (complementing the declarations and inspections already required of non-nuclear-weapon-state parties to the Non-Proliferation Treaty); and 4. create an international safeguarded storage regime under which all civilian fissile materials not in immediate use would be placed in agreed safeguarded storage sites, with agreed levels of physical security. The IAEA secretariat and organizations in several countries are now working on concepts for such universal reporting and safeguarding of civilian fissile materials. These steps, and others that we recommend, would require increased resources for the IAEA, as well as organizational improvements. In some cases resources could be provided specifically for a new task. But the agency also urgently needs more resources overall. INTERMEDIATE STORAGE Present and Planned Arrangements It will be necessary to provide secure intermediate storage of surplus weap- ons plutonium for decades, since long-term disposition will take years to start and possibly decades to complete. In both the United States and Russia, fissile materials from dismantled weapons are currently stored in the form of weapons components, some at the dismantlement site and some elsewhere. Neither coun- try has yet decided how much will be held in reserve. No monitoring or trans- parency measures relating to storage of these fissile materials are yet in place, although the Clinton administration has announced that U.S. excess fissile materials will be placed under international safeguards, and Russia has ex- pressed willingness to do the same. Russia and the United States also have tens of tons of weapons-grade plutonium not incorporated in weapons that are stored in various forms at several sites in their weapons complexes.

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10 EXECUTIVE SUMMARY In the United States, plutonium from weapons is being stored temporarily in simple "igloos" at Pantex, the dismantlement site. This arrangement pro- vides high security and generally adequate standards of protection for environ- ment, safety, and health. Given the stability of both the pits and the facilities at the site, there is no technical or economic reason why this arrangement could not be continued for a considerable time, but the public and the authorities in the area surrounding the site have been assured that interim storage there will not be extended beyond a decade. To meet that pledge, and to provide improved storage for plutonium in other forms now stored at several widely dispersed sites, the Department of Energy proposes to invest in a new, consolidated facility for long-term storage at a site to be selected. No full analysis of the advantages and disadvantages of this approach compared to upgrading existing storage facilities has been completed. We therefore do not offer a recommen- dation, though we recognize the safeguards and security advantages that a new consolidated facility might offer. Less is known about Russian storage arrangements. Russia has requested, and the United States has agreed to provide, assistance in constructing a storage facility for excess fissile materials from weapons. We support construction of a facility designed to consolidate all these excess weapons materials, as this would facilitate security and international monitoring. There is considerable debate concerning the optimum physical form in which to store plutonium. We recommend that, for the time being, plutonium continue to be stored in the form of intact weapons components. Decades of experience have demonstrated that pits are relatively safe and stable, and stor- age in this form would postpone the costs and ES&H issues of conversion to other forms. Although the design of pits is sensitive, international monitors could externally assay the amount of plutonium in a canister containing a pit without, in most cases, revealing sensitive design information. Intact pits can more easily be reused for weapons by the state that produced them than pluto- nium in other forms, but they probably do not pose substantially greater prolif- eration risks than storage as deformed pits or metal ingots. Deformation of pits and perhaps other steps to reduce the rearmament risk should be given serious consideration, and should be undertaken if they can be accomplished at rela- tively low cost and ES&H risk. One cannot be confident, however, that plutonium in pits can be stored without degradation for more than a few decades. When a definite decision regarding long-term disposition has been made, the pits should be converted into the forms required for that disposition option, under agreed safeguards and security.

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EXECUTIVE SUMMARY 11 A New Storage Regime The following measures constitute a regime for intermediate storage of surplus fissile materials that serves the objectives noted earlier with minimum disruption to the process of dismantlement and storage: 1. Commitment to Non-Weapons Use. The United States and Russia should commit a large fraction of the fissile materials from dismantled weapons to non-weapons use. They should agree on the specific amounts. 2. Safeguarded Storage and Disposition. The preceding commitment should be verified by monitoring of the present and future sites where fissile materials are stored, and continued monitoring of the material after it leaves these sites for long-term disposition. 3. IAEA Involvement. Although such monitoring might begin bilaterally, the IAEA should be brought into the process expeditiously, in an expansion and strengthening of its nonproliferation role. The IAEA would monitor the amount of material in the storage site and safeguard any material removed from the site to ensure its use for peaceful purposes. Such safeguards would be an extension of the existing safeguards system. Bilateral monitoring would probably continue as well. Financial or other incentives could be provided to Russia for putting the material into storage. Management, control, or outright ownership of the stores and the material in them might be transferred to other parties, such as an inter- national consortium formed for that purpose. The material might even be physically relocated to some other country, possibly in return for cash, as in the case of the HEU deal. Such incentives would not obviate the need for, and are secondary to, prompt agreement on a storage regime along the lines recom- mended here. LONG-TERM DISPOSITION Categories, Criteria, and Standards The technical options for long-term disposition of excess weapons pluto nium can be divided into three categories: indefinite storage, in which the storage arrangements outlined in the previ- ous section would be extended indefinitely; minimized accessibility, in which physical, chemical, or radiological barriers would be created to reduce the plutonium's accessibility for use in weapons (either by potential proliferators or by the state from whose weapons it came), for example, by irradiating the plutonium in reactors or mixing it with high-level wastes; and elimination, in which the plutonium would be made essentially completely -inaccessible, for example, by burning it in reactors so completely that only a

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12 EXECUTIVE SUMMARY few grams would remain in a truckload of spent fuel, or by launching it into deep space. In both the "minimized accessibility" and the "elimination" categories, some of the options use the plutonium to generate electricity, while others dispose of the plutonium without using its energy content. Both classes of op- tions would involve net economic costs. The electricity generation options would produce revenues, but the costs of using plutonium to produce this elec- tricity would be higher than the costs of generating it using enriched uranium. The current Russian government nonetheless sees weapons plutonium as a valuable asset and therefore strongly prefers options that use the plutonium. Risks of Storage. Although intermediate storage is an inevitable step pre- ceding all disposition options, it should not be extended longer than necessary. Maintaining this material in a readily weapons-usable form over the long term would send negative political signals for nonproliferation and arms reduction, and the security offered by indefinite storage against the risks of breakout and theft is entirely dependent on the durability of the political arrangements. In- deed, one of the key criteria by which disposition options should be judged is the speed with which they can be accomplished, and thus how rapidly they cur- tail these risks of storage. Risks of Handling-The "Stored Weapons Standard." Although options in the "minimized accessibility" and "elimination" classes decrease the long-term accessibility of the material for weapons use, they could increase the short-term risks of theft or diversion because of the required processing and transport steps. In order to ensure that the overall process reduces net security risks, an agreed and stringent standard of security and accounting must be maintained throughout the disposition process, approximating as closely as practicable the security and accounting applied to intact nuclear weapons. We call this the "stored weapons standard." These risks of handling are a second key criterion for judging disposition options. Risks of Recover~The "Spent Fuel Standard." A third key security crite- rion for judging disposition options is the risk of recovery of the plutonium after disposition. We believe that options for the long-term disposition of weap- ons plutonium should seek to meet a "spent fuel standard"-that is, to make this plutonium roughly as inaccessible for weapons use as the much larger and growing quantity of plutonium that exists in spent fuel from commercial reac- tors. Options that left the plutonium more accessible than these existing stocks would mean that this material would continue to pose a unique safeguards problem indefinitely. Conversely, the costs, complexities, risks, and delays of going beyond the spent fuel standard to eliminate the excess weapons pluto- nium completely, or nearly so, would not be justified unless the same approach were to be taken with the global stock of civilian plutonium. Over the long term, however, steps beyond the spent fuel standard will be necessary-for both the weapons plutonium and the larger civilian stock as described below.

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EXECUTIVE SUMMARY 13 In addition, policymakers will have to take into account the political im- pact that the use of excess weapons plutonium in reactors, or the disposal of that plutonium, would have on nuclear fuel cycle debates abroad. Whatever choice it makes, the United States will have to explain how that choice fits into the broader context of its nonproliferation and fuel cycle policies. The Preferred Approaches The best means of plutonium disposition may well differ in the United States and Russia, given that the two countries have different economies, reac- tor and waste infrastructures, and plutonium fuel policies, and given that very different safeguards and security risks currently pertain. As noted above, there are two options that hold especially strong promise of being able to meet the criteria just outlined: the use of plutonium as fuel in existing or modified reactors without reprocessing, and vitrification together with high-level wastes. A third option, burial in deep boreholes, might prove on further study to be on a par with the first two. We now describe each of these options in turn. The Spent Fuel Option Excess weapons plutonium could be used as fuel in reactors, transforming it into intensely radioactive spent fuel similar in most respects to the spent fuel produced in commercial reactors today. This use could probably begin within approximately 10 years (paced by obtaining the necessary fuel fabrication ca- pability and the needed approvals and licenses) and be completed within 20 to 40 years thereafter (paced by the number of reactors used, the fraction of the reactor core using plutonium fuel, the percentage of plutonium that this fuel contains, and the amount of time that the fuel remains in the reactor). Exam- ples include: U.S. Light-Water Reactors. The predominant commercial reactors in the world today are light-water reactors (LWRs). Without major modifications, typical LWRs could burn a fuel consisting of mixed oxides of plutonium and uranium (MOX) in one-third of their reactor cores. Four existing LWRs in the United States (three operational at Palo Verde in Arizona, and one 75 percent complete in Washington State) were designed to use MOX in 100 percent of their reactor cores; a single such reactor, using fuel containing somewhat more plutonium than would be used if energy production alone were the aim, could transform 50 tons of weapons plutonium into spent fuel in 30 years. Alterna- tively, other operating or partly completed reactors could also be modified to use full MOX cores, or a new full-MOX reactor might be built on a government site, with costs partly offset by later sales of electricity.

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14 EXECUTIVE SUMMARY Although the United States has no operating MOX fuel fabrication capabil- ity, there is an unfinished facility at the Hanford site that could be completed and modified for this purpose; alternatively, a new MOX facility could be built in roughly a decade, at significantly higher cost. This option is technically demonstrated, as LWRs in several countries are burning MOX fuels today. Environmental, health, and safety risks can be minimized with the application of money and good management, although some of the specifics of how best to do so require further study. Use of MOX fuels, however, would be controversial in the United States, where such fuels are not now used, and gaining licenses and public approval could raise difficul- ties. The subsidy required to transform 50 tons of plutonium into spent fuel in this way (compared to the cost of producing the same electricity by the means with which it would otherwise be produced) would probably fall in the range from a few hundred million to a few billion dollars, depending on assumptions and on the specific approach chosen. Russian Light-Water Reactors. Similarly, Russian plutonium could be used as MOX in Russian VVER-1000 reactors (the only existing reactors in Russia likely to be safe enough and long-lived enough for this mission). VVER- 1000s that are not yet operational, but that the Russian government plans to complete for electricity production, could be modified to handle full MOX cores, or such modifications could be incorporated in operating reactors during the shutdowns for safety improvements that are now planned. Because of the current political and social upheaval in Russia, safeguards and security risks would be substantial. The current Russian government's preference for storing plutonium until it can be used in the next generation of Russian liquid-metal fast reactors is not attractive because of the indefinite time before disposition could begin, the security liabilities of prolonged storage, and the high cost of these reactors. CAND Us. Existing Canadian deuterium-uranium (CANDU) reactors are a technically attractive possibility for this mission, because the reactor design allows them inherently to handle full-MOX cores, with less change from the usual physics of the reactor than in the case of LWRs. The cost of this option is difficult to estimate, as no one has yet attempted to fabricate MOX fuel for CANDU reactors on any significant scale. We do not know whether the oppor- tunity for Canada to participate in an important disarmament process, com- bined with possible U.S. subsidies for the project, would be attractive enough to cause that country to reverse its long-standing policy against the use of fuels other than natural uranium in its power reactors. Substitution for Civilian Plutonium. Utilities in Europe and Japan cur- rently plan to use more than 100 tons of reactor-grade plutonium in MOX fuels over the next decade. If excess weapons plutonium from Russia or the United States were substituted for this material-with an associated delay in separation

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EXECUTIVE SUMMARY 15 of plutonium from civilian spent fuel, so that additional excess stocks of civil- ian plutonium did not build up as a result-disposition of 50 or even 100 tons of plutonium could be accomplished relatively rapidly (since the facilities re- quired are already built and licensed, or scheduled to be) and with compara- tively small net additional safeguards risks (since after the initial transport, all the facilities handling plutonium would have done so in any case). However, the agreements required to implement this option would be complex and probably difficult to reach. Substantial changes in a variety of existing contracts and programs would have to be made, and transport of weapons plutonium to these countries would be controversial. New Reactors for the Plutonium Mission. Given the high costs and long times required for the construction of new reactors, building such reactors for the mission of transfo~n~ing weapons plutonium into spent fuel would be justi- fiable only if problems of licensing and public acceptance made currently oper- ating or partly completed reactors unavailable (and only, of course, if the reac- tor-MOX option were deemed preferable to the vitrification and deep-borehole approaches). If that proves to be the case, the new reactors should be built on a government-owned site and should be of sufficiently well-proven design so as not to create additional technical and licensing uncertainties. Reactors we have examined of more advanced design do not offer sufficient advantages for this mission to offset the extra costs and delays that their use would entail. In par- ticular, the use of advanced reactors and fuels to achieve high plutonium con- sumption without reprocessing is not worthwhile, because the consumption fractions that can be achieved-between 50 and 80 percent-are not sufficient to greatly alter the security risks posed by the material remaining in the spent fuel. Development of advanced reactors and fuel types is of interest for the fu- ture of nuclear electricity generation, including the minimization of safety and security risks, but the timing and scope of such development need not and should not be governed by the current weapons plutonium problem. The Vitrification Option An alternative means of creating similar radioactive and chemical barriers to weapons use of this material would be to mix it with radioactive high-level waste (HLW) left from the separation of plutonium from weapons and other defense activities. Under current plans, HOW will be mixed with molten glass (vitrified) to produce large glass logs. These logs, like spent reactor fuel, will be stored for an interim period and then placed in a geologic repository. The logs would pose radiological barriers to handling and processing similar to those of spent LWR fuel a few decades old. Incorporating plutonium into these logs appears feasible, although technical questions remain. These technical issues are more substantial than those facing the MOX options, but licensing and public approval appear easier to obtain in the vitrification case, at least in the

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16 EXECUTIVE SUMMARY United States. Vitrification raises fewer security risks in handling than the MOX option, because the process of mixing plutonium with HLW would be easier to safeguard than the more complex process of fabricating MOX. This might be of particular importance in the current Russian context. Russian vitri- fication efforts have so far focused on a phosphate glass that is less appropriate for this mission than the borosilicate glass used in the United States and else- where because it is less durable and offers less protection against the possibility of an unplanned nuclear chain reaction once plutonium is embedded in it. New technologies for comparatively small melters could be transferred to Russia for this purpose. So far, however, the Russian officials responsible for these issues have rejected disposal options such as vitrification. The Deep-Borehole Option Disposal in deep boreholes has been examined in several countries as an approach to spent fuel and HLW management, and is still being examined in Sweden. Because of the very great depth of the holes, there are good reasons to believe that the materials emplaced would remain isolated from the environ- ment for periods comparable to or possibly longer than those expected for the geologic repository case, but significant uncertainties must be resolved. Pluto- nium in such boreholes would be extremely inaccessible to potential prolifera- tors, but would be recoverable by the state in control of the borehole site. The method would be relatively inexpensive to implement, but developing sufficient confidence to permit licensing could be costly and time-consuming; the United States has expended decades and billions of dollars in preparation for such licensing in the case of geological repositories for spent fuel and HLW. All three of these options have the potential to be satisfactory next steps beyond interim storage in the disposition of excess weapons plutonium. None of them, however, could be confidently selected until currently open questions, described in Chapter 6 of this report, are answered. Other Approaches A variety of other reactors have been proposed for this mission, such as high-temperature gas-cooled reactors, fast-neutron reactors, or various existing research or plutonium production reactors. Existing reactors other than the LWRs and CANDUs described above should be rejected on grounds of the un- certain availability and safety of those reactors with sufficient capacity. The advanced reactors, as noted above, are not competitive for this mission because of the cost and delay of their development, licensing, and construction. A variety of exotic disposal options have also been proposed, including sub-seabed disposal, detonation in underground nuclear explosions, launching into deep space, and dilution in the ocean, among others. This report rejects all

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EXECUTIVE SUMMARY 17 of these on grounds of retrievability, cost, delay, environmental concerns, or conflict with existing policies and international agreements. Beyond the Spent Fuel Standard Long-term steps will be needed to reduce the proliferation risks posed by the entire global stock of plutonium, particularly as the radioactivity of spent fuel decays. Options for reducing these risks could include placement of spent fuel in geologic repositories, or pursuit of fission options that would burn exist- ing plutonium stocks nearly completely. A variety of reprocessing-oriented re- actor options have been proposed for this mission, ranging from the use of standard LWRs to challenging concepts such as accelerator-based conversion. The costs of these approaches would be in the tens or hundreds of billions of dollars, and the time scales would be many decades or centuries, depending on the choice of options. These technologies can only be realistically considered in the broader context of managing the future of nuclear power to provide energy while minimizing the risk of nuclear proliferation, an important task that is beyond the scope of this committee. To further refine these concepts, research on fission options for near-total elimination of plutonium should continue at the conceptual level. Although all the plausible disposition options will take many years to im- plement, it is important to begin now to build consensus on a road map for de- cision. Such a road map would provide guidelines for the necessary national and international debate to come, focus further efforts on those options most likely to minimize future risks, and provide plausible end points for the process that the near-term steps will set in motion. Research and development should be undertaken immediately to resolve the outstanding uncertainties facing each of the options. THE INSTITUTIONAL FRAMEWORK The institutional and political issues involved in managing weapons dis- mantlement, intermediate storage of fissile materials, and long-term disposition may be more complex and difficult to resolve than the technical ones. Because disposition options will require decades to carry out, it is critical that decisions throughout be made in a way that can muster a sustainable consensus. The en- tire process must be carefully managed to provide adequate safeguards, secu- rity, and transparency; to obtain public and institutional approval, including licenses; and to allow adequate participation in the decision making by all af- fected parties, including the U.S. and Russian publics and the international community. Adequate information must be made available to give substance to the public's participation. These issues cover a broad institutional and technical spectrum. Establish- ing fully developed arrangements for managing these tasks will require an un

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18 EXECUTIVE SUMMARY usually demanding integration of policy under conditions of dispersed authority and intense political sensitivity. In the United States, jurisdiction over fissile material and fabricated weapons is divided between the Department of Energy (DOE) and the Department of Defense (DOD) in different phases of the de- ployment cycle. Each department has many subordinate divisions involved. Related diplomacy is handled by the State Department and the Arms Control and Disarmament Agency, with input from DOE and DOD. Numerous other agencies perform supporting functions. The relevant installations are author- ized and financed by Congress, regulated by independent agencies and com- missions, constrained by state laws, and increasingly affected by public opinion in their surrounding communities. Policy debates too often focus on specific options, such as particular reactor types, rather than the comprehensive view required to make choices for this complex problem. The consequences of this fragmentation are illustrated in a related area by the fact that technical assess- ment of the U.S. high-level waste repository at Yucca Mountain is incomplete after two decades of work and billions of dollars of expenditure, and final licensing is not projected for another two decades. These challenges to compre- hensive policymaking are at least as great in Russia, where they must be sur- mounted in the midst of continuing political and economic upheaval. None of the governments involved have previously faced the problem of handling excess plutonium in the quantities now contemplated, and none ap- pear to have developed policies and procedures likely to be adequate to the task. Yet decisions are urgent, since without new approaches even the near-term tasks of dismantlement and storage are not likely to meet all of the required . . security criteria. In these areas, the United States bears a special burden of policy leader- ship. If demanding technical assessments are to be completed, if consensus is to be forged, and if implementation is to be accomplished in reasonable time, major advances in the formulation and integration of policy and in institutional coordination will be needed. The president should establish a more systematic process of interagency coordination to deal with the areas addressed in this re- port, with sustained top-level leadership. The new interagency examination of plutonium disposition options envisioned in President Clinton's September 27, 1993, nonproliferation initiative is a first step in that direction, but much more remains to be done.