NUCLEAR PROLIFERATION ISSUES
Scope and Organization
The purpose of this appendix is to provide background information and supplementary detail to support the evaluation in Chapter 6, Proliferation Issues section, concerning nuclear proliferation issues raised by the possible deployment of a separations and transmutation (S&T) system. That evaluation uses the light-water reactor (LWR) once-through fuel cycle as the baseline, taking into account the U.S. policies for nonproliferation, the disposition of plutonium, and nuclear energy. This section provides a brief introduction to the nonproliferation policy context and summarizes how the LWR once-through cycle fits into that context, in particular, the relation to the safeguards system of the International Atomic Energy Agency (IAEA).
The following section, Nonproliferation Policy and International Safeguards, reviews the IAEA safeguards system and the U.S. nonproliferation policies that affect the use of S&T technologies and facilities. The review emphasizes the period since 1970 and highlights major nonproliferation successes and failures that had an impact on U.S. policies for nonproliferation and energy. At present, the credibility of the IAEA safeguards system and of the agency itself are being severely tested by two situations: (1) the discovery in 1991 of a covert nuclear weapons program in Iraq as a result of the special inspections conducted there by the IAEA from 1991 to the present under U.N. Security Council mandate and (2) the current difficulties in achieving a satisfactory safeguards implementation with North Korea, amid concerns that it may have a clandestine nuclear weapon effort. The section discusses the impact of the two situations on nonproliferation policy and reviews suggestions for strengthening IAEA safeguards.
The final section of the appendix, Assessment of Proliferation Issues for S&T Systems, provides detail on the nuclear proliferation issues that are raised by S&T systems, emphasizing the ways in which an S&T deployment could either increase or minimize the risk of nuclear weapon proliferation compared with the once-through LWR fuel cycle, assuming both are implemented under safeguards. The section treats reprocessing, enrichment, and reactor facilities and technologies generically and also assesses four specific S&T proposals.
The LWR Once-Through Fuel Cycle as the Nonproliferation Baseline
The general objective of U.S. nonproliferation policy is to prevent the misuse of civil nuclear facilities and materials for military purposes and to discourage dedicated nuclear
weapons programs.1 This and more specific objectives are implemented through a web of formal and informal arrangements—treaties, agreements, laws, voluntary guidelines, understandings, and working relationships—that have grown over half a century and involve a variety of multinational and international institutions, governmental organizations, and private groups.
The key international organization for nonproliferation is the IAEA, which was chartered at the United Nations in 1957 in the wake of the U.S. "Atoms for Peace" initiative. The agency has dual responsibilities to promote the peaceful uses of nuclear energy and to guard against the diversion of the products of its use for military purposes.2 As discussed in the next section, the IAEA instituted a system of safeguards that feature inspections of civil nuclear facilities in IAEA member nations.
Efforts to limit the spread of nuclear weapons were greatly strengthened in 1970 with the establishment of the Nuclear Nonproliferation Treaty (NPT).3 Over 140 nations are parties to the NPT as nonnuclear-weapon nations, which agree not to acquire nuclear weapons or the means to produce them and to place all nuclear facilities and stores of fissionable materials under IAEA safeguards. Parties as nuclear weapon nations agree to share the technology for peaceful uses of nuclear energy and to refrain from helping nonnuclear-weapon nations to acquire nuclear weapons.
Nonproliferation efforts have focused on controlling fissionable weapon materials—either plutonium or highly enriched uranium (HEU). Obtaining such materials in sufficient quantity and purity is recognized as the most challenging task in the development of a nuclear weapon. The task has three types of requirements: (1) technical—attaining the knowledge and know-how to enrich uranium or operate a reactor and reprocess the spent fuel to recover the plutonium; (2) practical —acquiring trained manpower and equipment to build and operate the medium-to large-scale facilities needed to produce fissionable weapon materials in sufficient quantity and purity; and (3) political—controlling the national political and military apparatus and maintaining secrecy or suitable international relations long enough to obtain the required materials and assemble (and perhaps test) the explosive devices. In effect, the three types of requirements, in addition to economic costs, pose barriers to nuclear weapon proliferation.
The LWR proved to be an efficient first-generation nuclear system for electrical power production. Moreover, the fresh LWR fuel contains low enriched uranium (LEU) that presents
a high barrier to nuclear proliferation. The fresh fuel contains only 3-4% of the fissile isotope 235U diluted with nonfissile238U, which is a much lower enrichment than the HEU used for nuclear weapons, and which is generally greater than 90% 235U. The dominant technologies for isotopic enrichment, in particular the gaseous diffusion and gas centrifuge methods, require specialized materials and other high technologies that are not generally available (see Assessment of Proliferation Issues for S&T Systems below). A few developing nations—Argentina, Brazil, Pakistan, and South Africa—finally acquired the knowledge and know-how for uranium enrichment during the 1970s (see the following section). However, constructing and operating the large, complex enrichment plants poses a practical barrier to producing HEU, a barrier that was overcome by the five declared nuclear weapon nations but by no other nations until the 1980s.
The plutonium in the LWR spent fuel presents a dilemma. While 239Pu is the best isotope by far for a weapon, all the plutonium isotopes are fissionable by fast neutrons in a nuclear weapon (Mark, 1990) or a "fast" reactor having a high energy neutron spectrum (see Chapter 4). Isotopic dilution, an effective strategy with uranium, is not an effective means to prevent plutonium from being used as nuclear weapon material. The technical proliferation barrier is not nearly so high for plutonium as for 235U, because only chemical separation is needed. However, 239Pu is also an excellent nuclear fuel in reactors. In the 1960s, the major nuclear supplier nations were planning to reprocess their civil-reactor spent fuel to separate the plutonium for recycle in civil power reactors (see Chapter 4). These nations demonstrated plutonium recycle to their LWRs, but anticipated plutonium recycle to fast breeder reactors when such reactors became commercialized in the future.
Normally, the spent fuel rods would be stored in water pools for several years to cool thermally and radioactively. This intense radioactivity presents a formidable hazard but does not prevent chemical separation. The technical knowledge for such separation became generally available during the 1950s. Yet the practical proliferation barrier for medium-to large-scale plutonium reprocessing was (and still is) substantial (see Chapter 3). When the LWR was being introduced commercially, spent-fuel reprocessing was confined to the nuclear weapon nations. In the late 1950s and the 1960s, however, many nations began small research and development programs on reprocessing technology, ostensibly to explore the future use of the recovered plutonium in their civil power reactors. Several of these programs proved to be proliferation seeds, as discussed in the next section.
To minimize the proliferation risk posed by the LWR spent fuel, the fuel might be disposed of permanently in a once-through cycle—isolation of high-level waste (HLW) in geologic repositories had been proposed in 1957. Yet, this would preclude plans at that time for the future civil use of the fissionable resources contained in the spent fuel. As an alternative, the spent fuel could remain in storage pools for an extended period and the disposition (reprocessing or disposal) deferred, provided nations could be assured that the spent fuel would not be diverted and used to obtain plutonium for nuclear weapons. That concern was met successfully by the development of IAEA safeguards, which act as a political/technical barrier, as discussed in the next section.
It is useful to compare the LWR with two other contenders for a first-generation nuclear power standard—namely a heavy-water reactor (HWR) and a liquid-cooled graphite-moderated
reactor (LGR). Both have better neutron moderators than a LWR in terms of neutron economy; in fact, a HWR can be operated on natural uranium. However, both can be refueled on-line (i.e., replacing fuel rods while the reactor is still operating; see Assessment of Proliferation Issues for S&T Systems below). This makes them attractive for producing weapons-grade plutonium; indeed, HWRs and LGRs were used for that purpose by the nuclear weapon nations. In comparison, the characteristics of a LWR require refueling in a batch mode (i.e., shut-down, typically for an annual change of a third of the reactor core).
A commercial HWR for electrical power production, the CANDU, was developed by Canada and exported to several nations, including India and Argentina. However, its excellent properties for plutonium production raised serious questions about the wisdom of HWR export. Indeed, India used its CANDU to make plutonium for a nuclear explosive device (see the following section). Following that incident, Canada worked with the IAEA to develop a system of safeguards for the CANDU (see the last section of this appendix) which are required by Canada as a condition of sale. The batch refueling characteristics of the LWR, on the other hand, accommodated well to a control regime including the IAEA safeguards being established during the early to mid-1960s. This opened the way for LWR exports to many nations for electrical power production, while maintaining high nuclear proliferation barriers. It was not until the mid-1970s, however, that the LWR once-through cycle with geologic isolation of the spent fuel was adopted by the United States and many other nations.
NONPROLIFERATION POLICY AND INTERNATIONAL SAFEGUARDS
Overview of Safeguards Concepts
This subsection provides an overview of IAEA safeguards concepts that would apply to a S&T system. Although the IAEA predates the NPT by some 13 years, the treaty had a profound effect on the agency and its safeguards system. The following subsection discusses the comprehensive safeguards basis for NPT nonnuclear-weapon nations as defined in the IAEA Information Circular 153 (INFCIRC 153). It is compared with the varied and much less comprehensive safeguards basis under Information Circular 66, which was developed in the 1960s and applies to IAEA member nations that are not yet NPT signatories.
The objective of the IAEA safeguards system is "… the timely detection of diversion of significant quantities of nuclear material from peaceful nuclear activities to the manufacture of nuclear weapons … and deterrence of such diversion by the risk of timely detection."4 A related political objective is to provide assurance to the international community that nations are complying with their nonproliferation agreements and that any significant diversion would be detected in a timely manner. The nations enter into safeguards agreements voluntarily; the
IAEA has no authority to apply safeguards unless a nation so requests, as NPT signatories are obligated to do.
To meet the objective, the IAEA safeguards system emphasizes materials accountancy augmented by containment and surveillance as the key verification measures. The materials accountancy concept, historically the primary emphasis of IAEA safeguards, focuses on the quantification of any material unaccounted for. Materials accountancy uses random sampling techniques and special technologies (e.g., secure identification tags and seals, instruments to assay nuclear materials). These are implemented with inspections at regular and random intervals, together with extensive maintenance and checking of records to compare expected quantities of nuclear materials with measured quantities (Fischer and Szasz, 1985).
Containment and surveillance technologies and techniques have historically been used by the IAEA to augment the primary materials-accountancy practices, especially where conversion time might be short or material quantities are large. Recently, with the advent of more advanced surveillance equipment and secure communications, such techniques are being considered for a more prominent safeguards role in applications with large facilities for enrichment or for reprocessing and refabricating nuclear fuels, as would occur in S&T applications (Scheinman, 1992a).
The frequency of inspections and the design of random sampling are geared to the quantity and form of the nuclear material under safeguards and to country-specific factors, particularly to the estimated time for a nation to obtain sufficient quantity in such a form that the manufacture of a nuclear explosive device cannot be excluded. For example, spent fuel rods containing plutonium or HEU pose a qualitatively different safeguards problem than the same quantities of nuclear materials in separated bulk form. Using statistical methods, the IAEA aims at a 90-95% probability level for detection of a diversion, with a false alarm rate of less than 5%.
The concepts of timely detection and deterrence by the risk of early detection are central to understanding the system and evaluating its effectiveness (see Scheinman, 1987:165–166). The expected result of applying IAEA safeguards is to confirm that no diversion has taken place. Were the IAEA to discover a possible diversion, the agency cannot by itself take direct corrective action but, rather, is obligated to report the situation immediately to its board of governors and, thus, to the international community. The IAEA member nations would take the appropriate action. Therefore, the likelihood of detection must be certain enough, and the time scale for detection and report of any suspected diversion short enough, that a high risk of early detection affords deterrence.
The goals and criteria for materials accountancy are geared to the detection of quantities of safeguard significance of special nuclear materials for building a single nuclear explosive device, which the IAEA takes to be 8 kg for plutonium and, for uranium of greater than 20% enrichment, an amount containing 25 kg of 235U. These amounts reflect an estimate of how much is likely to be required for a straightforward device design that might be produced by a nation. The publicly available literature on nuclear weapons suggests significantly lower mass
requirements for both materials.5 The mass estimates per nuclear device of 5 kg of plutonium and 15 kg of HEU are used in the next section to assess the proliferation issues raised by various types of nuclear facilities.
Safeguards Under the NPT
Article III of the NPT specifies the key safeguards and inspection provisions of the treaty, which apply to all nuclear materials and facilities used for peaceful purposes in nonnuclear-weapon nations, and which all nonnuclear-weapon signatories are obliged to accept. The broad nature of Article III and the experience with pre-NPT safeguards under Information Circular 66 stimulated demands by several nations with advanced nuclear capabilities, including Germany and Japan, that IAEA safeguards be reviewed and strengthened. The resulting IAEA safeguards basis was codified under Information Circular 153 and the related subsidiary agreements and facilities agreements.6
The Information Circular 153 implementation is better defined and more uniformly applied than in earlier bilateral safeguards agreements under Information Circular 66 that are still in effect with non-NPT nations, such as India, Israel, and Pakistan. In particular, the safeguards agreements under Information Circular 153 have strengthened and unified provisions for recordkeeping and reporting requirements and for implementing materials accountancy and containment and surveillance technologies and practices. In contrast, safeguards agreements under Information Circular 66 apply only to certain facilities agreed on by the nation and the IAEA and sometimes are limited to nuclear materials that are imported.
Another key improvement of NPT-type safeguards was the adoption of the concept of diversion for purposes unknown, which put the burden of responsibility on the nation in question (rather than on the IAEA) to prove that any unaccounted material of significance has not been diverted to military purposes. Inspections were codified to include random as well as regularly scheduled inspections at facilities declared by a nation to contain stores of special nuclear materials or to be capable of their production. Under NPT, Article II, nonnuclear-weapon
signatories are obliged to declare all such facilities on their territory. IAEA also has authority to make "special inspections" of suspected undeclared facilities, activities, and nuclear materials under Information Circular 153 and, in principle, under the charter, within any IAEA member nation (Blix, 1992; Bunn, 1992; Scheinman, 1992a). Before the 1991 inspections in Iraq, however, neither the NPT nor bilateral safeguards agreements were used by the IAEA to authorize special inspections.7 The nations did not exchange the intelligence information with the IAEA that might have lead to requests for such inspections.
The NPT, with IAEA safeguards, is the cornerstone of the international nonproliferation effort, which has enjoyed remarkable success. NPT members Germany, Japan, and South Korea are notable examples of nonnuclear-weapon nations with large civil nuclear programs. The NPT nations include most states of Eastern and Western Europe, several of the latter with nuclear programs covered by Euratom safeguards. Moreover, numerous developing nations decided that the NPT would provide a suitable political framework for their small nuclear power programs. However, several nations with sizable nuclear programs remain outside the NPT framework, although all of them agreed to IAEA safeguards for some of their facilities as a price for the ability to import nuclear technology and systems from the major nuclear suppliers. Such facilities that have not been included in the IAEA safeguards regime have been the basis for several nations to attain de facto but undeclared nuclear weapon capability, as discussed below.
Creeping Proliferation and the Effect on Nuclear Policies
The major nuclear nations differ at present on reprocessing and the use of plutonium in civil reactors. In the 1960s, as noted earlier, the United States and a few other nations engaged in the limited reprocessing of LWR spent fuel and the recycle of the recovered plutonium to commercial LWRs and other thermal reactors, looking ahead to breeder reactor deployment. However, many nations were forced to reexamine their policies and plans when India detonated a "peaceful nuclear explosion" in 1974. The event became all the more vexing for Canada and the United States when the public learned that India produced the plutonium for the device using a Canadian-built reactor and fuel of U.S. origin, which had been sold to India without IAEA safeguards (see Spector, 1988).
In the mid-1970s, the United States cancelled its breeder deployment plans and discontinued reprocessing and thermal recycle of plutonium, for both economic and nonproliferation reasons.8 The United States adopted the LWR once-through fuel cycle with geologic disposal of the spent fuel and encouraged other nations to do the same. Moreover, Congress passed the Nuclear Nonproliferation Treaty of 1978, which restricted the reprocessing of nuclear fuel of U.S. origin. Congress also enacted the Glenn-Symington Amendment to the
Foreign Assistance Act of 1979, which provided for the cutoff of economic assistance to any nation considered by the Carter administration to be importing a capability for uranium enrichment.
From 1976 to 1979, the nuclear nations, large and small, took part in an International Fuel Cycle Evaluation (INFCE), which reexamined all aspects of the nuclear fuel cycle. The Foreign Assistance Act of 1979, which provided for the cutoff of economic assistance to any nation considered by the Carter administration to be importing a capability for uranium enrichment participants agreed that the once-through fuel cycle with geologic disposal of LWR spent fuel could be a safe practice and that the time scale, if not the desirability, of a cost-effective breeder economy was very uncertain (INFCE, 1980). The European nuclear suppliers suspended their plans to export reprocessing facilities and technology to several developing states. However, France, the United Kingdom, the former Soviet Union, and Japan continued their policies to reprocess civil-reactor spent fuel and store the separated plutonium not needed for breeder reactor research and development.
By the early 1980s, several factors combined to take the heat out of the debate about reprocessing versus once-through for LWR spent fuel: (1) the discoveries of large uranium ore reserves in Australia and Canada; (2) reduced uranium ore requirements due to less deployment of LWRs in the United States and several other nations than had been projected earlier; (3) high costs and continuing technical difficulties of breeder reactors; and (4) agreement that the once-through fuel cycle could, in principle, resolve the issues attending the steadily growing amount of spent fuel in pool storage around the world. In 1982, the Reagan administration relaxed the ban against reprocessing in the United States. However, the change had little practical effect, since reprocessing of LWR spent fuel for recycle was uneconomic for the reasons cited above. Moreover, the restrictions in the 1978 Nuclear Nonproliferation Treaty still applied.
Stability proved to be elusive as a series of public exposures during the 1980s revealed that three additional non-NPT nations—Israel, Pakistan, and South Africa—had attained de facto but undeclared nuclear weapon capability (Spector, 1988). Like India, the three nations used nuclear facilities not under IAEA safeguards and drew heavily on their civil nuclear programs to attain such capability (Spector and Smith, 1990). Also, two other nations, Argentina and Brazil, disclosed their ability to produce enriched uranium. The particulars of the above are summarized as follows:
In the case of India, the facilities and trained manpower from the nation's civil nuclear program, including a purchased CANDU reactor, played a direct part in the plutonium production for the nuclear device test in 1974 (Spector, 1988:80-119). India subsequently constructed several large reactors and a large reprocessing complex that operate outside IAEA safeguards and is reported to have material for several hundred nuclear weapons (Albright and Zamora, 1989).
Israel conducted plutonium reprocessing at Dimona from the late 1960s and reportedly has accumulated material for a hundred or more nuclear weapons (Spector, 1988:164-193). The publicly available information from a 1986 expose in the Sunday Times of London includes cut-away pictures of sophisticated nuclear devices.
Pakistan began uranium enrichment in the mid-1980s using the centrifuge method reportedly based on stolen European design information. The facility at Kahuta may have
produced a material stockpile sufficient for tens of nuclear weapons (Albright and Zamora, 1989). In October 1990, the Bush administration was no longer able to certify to Congress that Pakistan did not possess nuclear weapons, which resulted in a cutoff of economic and military assistance to Pakistan under the 1985 Pressler Amendment to the Foreign Assistance Act.
South Africa indigenously developed the capability for uranium enrichment (Spector, 1988). In 1990, South Africa disclosed that it had constructed six gun-type uranium nuclear weapons in the 1980s, which were destroyed when the nuclear weapon program was abandoned (Albright, 1993b; de Villiers et al., 1993). South Africa recently joined the NPT, accepting full-scope IAEA safeguards.
Argentina and Brazil, which are not NPT members, also developed the technology and facilities capable of "dual-purpose" uranium enrichment—Argentina using gaseous diffusion and Brazil using the centrifuge approach (Albright, 1989, 1990; Donnelly, 1990). In the late 1980s, however, the two nations ended their long-standing nuclear rivalry and entered into a stringent bilateral nuclear safeguards regime backed up by full-scope IAEA safeguards that have provisions for regular, random, and special inspections (Albright, 1990; Redick, 1990; Krasno, 1992).
Yet, because of the growing number of NPT signatories, this series of exposures did not seriously impugn the credibility of the IAEA safeguard system.9 Indeed, Argentina and Brazil, and to a lesser extent South Africa, could be regarded as nonproliferation success stories. Moreover, the progressive improvement in safeguards technologies, developed through cooperative programs between the IAEA and various nuclear powers and gradually deployed in nonnuclear-weapon nations, further encouraged the perception that safeguards in NPT nations were adequate. By the mid-1980s, however, U.S. nonproliferation policy began to emphasize coping with rogue nations concomitantly, with less emphasis on the earlier priority of limiting the spread of reprocessing and enrichment capability beyond the European nuclear suppliers, the former Soviet Union, and Japan. The shift of emphasis was accentuated by the recent events in Iraq and North Korea, discussed below.
The Crisis in Safeguards Credibility
THE COVERT IRAQI NUCLEAR WEAPONS PROGRAM
After the Persian Gulf War, the IAEA conducted a series of special inspections of facilities and records in Iraq, a NPT signatory since the 1970s. Acting under a U.N. Security Council mandate and benefiting from intelligence information, the IAEA inspection team discovered a covert effort to develop nuclear weapons—in violation of Iraqi treaty obligations (Fainberg, 1993; Davis and Kay, 1992; Thorne, 1992; Donohue and Zeisler, 1992; UN/IAEA,
1991). The effort centered on a uranium enrichment capability that was based primarily on the inefficient but technologically straightforward method of electromagnetic isotope separation. The extensive facilities near Al-Tarmiya and Ash-Sharkat, under construction but not yet in operation, were undetected in regular IAEA inspections prior to the war (see Pilat, 1992).
Iraq was perhaps 3 to 5 years from having a source of HEU sufficient to be able to manufacture about one nuclear weapon a year (Fainberg, 1993). A smaller, longer-range research and development effort on centrifuge separation of uranium, involving technology obtained from Germany, might eventually have enabled Iraq to achieve a much higher rate of weapon production than is possible with electromagnetic isotope separation (UN/IAEA, 1991). Estimates of the overall budget for the Iraqi program are at least $1 billion annually (Fainberg, 1993). The evidence collected by the IAEA appears to implicate most of the Western nuclear supplier nations in supplying equipment for the Iraqi effort (Muller, 1993; UN/IAEA, 1991).
THE CURRENT SAFEGUARDS STALEMATE IN NORTH KOREA
An ambiguous nuclear proliferation episode is currently unfolding with North Korea. That nation joined the NPT in 1985 but delayed entering into a safeguards agreement with the IAEA. North and South Korea signed a mutual nonaggression pact in December 1991, agreeing to a nuclear-free Korean peninsula and pledging economic cooperation. North Korea finally signed the safeguards agreement in January 1992, which cleared the way, in May 1992, for the IAEA to make inspections and emplace safeguards equipment at the Yongbyon and other nuclear facilities.
However, a serious dispute arose in February 1993, when the IAEA requested authorization for special inspection of two sites near Yongbyon. These sites were suspected to be undeclared nuclear waste storage depots holding reprocessing waste from a covert effort to obtain plutonium for nuclear weapons. The IAEA had acquired satellite photographs of the two sites and cited evidence from its earlier inspections that North Korea had reprocessed more spent fuel than had been reported to the agency. North Korea denied the IAEA access, claiming the sites were military ones not related to nuclear activities. In March 1993, North Korea announced a withdrawal from the NPT but later suspended the action, while refusing to permit further IAEA activity.
Bilateral negotiations on economic matters and cultural exchange between North Korea and South Korea came to a standstill. In direct bilateral negotiations, the United States insisted that North Korea permit inspection of the two sites. In mid-December, the U.S. Secretary of Defense repeated, in a television program, the U.S. concern that North Korea may have reprocessed, before any safeguards were in effect, spent fuel from a reactor that was shut down for about 100 days in 1989.10 In February 1994, North Korea agreed to permit IAEA inspections of seven sites where the agency had previously emplaced safeguards equipment.
However, as of now, the issues concerning the two suspect sites are unresolved, as is the prospect for further IAEA inspections.11
Yet the creation of a nuclear-free zone on the Korean peninsula, backed by China, Japan, Russia, and the United States, is still a possibility. Such a development could help stabilize relations throughout Northeast Asia and reinforce nonproliferation efforts elsewhere. Conversely, a nuclear weapon capability in North Korea would put pressure on South Korea and Japan to take steps that could destabilize the region and greatly weaken nonproliferation efforts generally. Thus, North Korea may be a more crucial test than Iraq for the viability of nonproliferation in the 1990s.
The Status of Proliferation Barriers and the U.S. Counterproliferation Initiative
The spread of de facto but undeclared nuclear weapon capability underscores the crumbling of the technical barrier to proliferation—over a 40-year period, the knowledge, the know-how, and even the special equipment to produce fissionable weapon materials have become available (see Assessment of Proliferation Issues for S&T Systems). Building and operating a major enrichment or reprocessing facility, however, remain formidable. A decade or so seems required in most countries for development and construction. Practical barriers to proliferation could still be effective deterrents if concerned nations show that they will take timely action—political, economic, and, as a last resort, military—given information from satellites, overflights, inspections (where allowed), and intelligence sources.
The recently announced U.S. "counterproliferation" initiative is a major shift in nonproliferation policy (Aspin, 1993; U.S. Department of Defense, 1993). The initiative goes well beyond political and economic efforts meant to deter the acquisition of nuclear weapons or other weapons of mass destruction; indeed, the Secretary of Defense has remarked on the diminished significance of efforts aimed simply at "prevention" of proliferation. The new initiative involves the potential use of military assets against a rogue nation or terrorist group that may have such weapons in their possession. The new policy gives priority to bolstering the ability of the armed forces to respond to the proliferation of weapons of mass destruction in the post—Cold War world—particularly in the former Soviet bloc and in hostile developing countries. The nuclear ambitions in Iran have already attracted congressional attention (Donnelly and Davis, 1992).
Yet deterring nuclear weapon proliferation requires that the political barriers are credibly expressed in institutions, such as the IAEA, that enjoy the support of the major powers and are acceptable to regional parties. Strengthened IAEA safeguards, under the sanction of a renewed NPT and perhaps buttressed by regional and bilateral agreements and safeguards means, could remain a key cooperative mechanism to forestall the further spread of nuclear weapon capability (Blix, 1992; Jennekens et al., 1992; Scheinman, 1992a; Nye, 1992). This mechanism could be part of a larger initiative on cooperative security in the post—Cold War world that was proposed by two officials of the U.S. Department of Defense (Carter et al., 1992). Counterproliferation means would remain a resort where cooperative means are not successful.
The revelations in Iraq, the situation in North Korea, and concerns about problems to come with Iran and Algeria stimulated proposals (1) to strengthen the capability of IAEA safeguards to detect undeclared nuclear facilities and nuclear activities and (2) to codify measures to deal with such facilities and activities when discovered (Blix, 1992; Jennekens et al., 1992; Natio and Rundquist, 1992; Nye, 1992; Fainberg, 1993). Several proposals would make special inspections an established IAEA policy whenever information available to the agency provides a reasonable basis for the action (Blix, 1992; Bunn, 1992; Nye, 1992; Scheinman, 1992a, b). However, top IAEA officials would need much better information, including intelligence data, than has been regularly available. Studies have identified potentially useful technical and nontechnical indicators of covert nuclear activities and facilities (Fainberg, 1993). Another possibility is cooperative assurances that could enhance verification that a nation is not conducting clandestine nuclear activities. Also, the Nuclear Suppliers Group could tighten its procedures and widen its membership to include the emerging nuclear suppliers.
Proposed improvements to deal with suspicious activities and suspected violations center on giving the IAEA more flexibility and authority to respond rapidly, for example, to send in its own inspection team on a few hours notice (Scheinman, 1992a). The IAEA would have to rely on the U.N. Security Council to back such a prerogative. Means to deal with uncooperative nations or proven violations would still depend on embargoes and economic sanctions, as with Iraq and as proposed with North Korea if that nation remains intransigent, and military sanction would be reserved as a last resort.
Another kind of confidence test looms in the near future. Article X of the NPT requires a recommitment to the treaty by all signatories after the treaty has been in force for 25 years, which will occur in July 1995. For years, a lack of substantial progress on reducing nuclear arsenals highlighted the discriminatory nature of the treaty and was a sore point at the 1975 and 1980 NPT review conferences. The end of the Cold War transformed that issue. With the break-up of the Soviet Union at the end of 1991, four nations—Belarus, Kazakhstan, Russia, and Ukraine—were created that had nuclear weapons on their territory, which raised a myriad of
problems not yet resolved.12 Such issues as nuclear security assurances, the reduction of nuclear weapon stockpiles, a cutoff of production of nuclear weapon materials by all nations, and delegitimization of nuclear weapon use are not only important initiatives in their own right but also address the concerns of many nations whose support is essential for the renewal of the NPT (see Scheinman, 1992b; Chrzanowski, 1993).
However, the commitment of the nuclear weapon nations to work toward a Complete Test Ban Treaty, an obligation contained in the Limited Test Ban Treaty of 1963, was a sore point at the review conference in 1990. The recent U.S. policy against testing is an important step but is not a substitute for a treaty involving all the nuclear weapon nations, especially China, which has continued to test. In addition, strengthened IAEA safeguards and their enforcement are now much more serious issues than was the case at previous review conferences.
Recent U.S. Policy on Nonproliferation and the Use of Plutonium
In late 1992, Japanese preparations for the use of plutonium in civil reactors made headlines. Japan shipped about 1.7 tons of plutonium, which was obtained from the reprocessing of Japanese LWR spent fuel in France, to feed Japan's Monju breeder reactor, which is scheduled to start operations in a few years. Because the Japanese spent fuel was of U.S. origin, the Bush administration had given permission for the shipment after obtaining the approval of Congress, as required under the 1987 Nuclear Nonproliferation Treaty. The shipment raised a storm of anxiety and criticism in many nations. Several Southeastern Asian nations even banned the shipment from passing through their waters. Moreover, the Japanese government's plans to make one or two such shipments a year for the next 18 years were not only disquieting to much of the public at large but also to Japanese industrialists who expressed public concern over the financial commitment on the horizon. On February 22, 1994, news reports indicated that the Japanese government decided to postpone, perhaps for as long as two decades, the previous plans for the extensive stockpiling of plutonium and the deployment of several breeder reactors.
With the change of presidential administrations in January 1993, U.S. nonproliferation policy was again the subject of major review, taking into account several factors: (1) the stalemate in North Korea, (2) the lessons from the IAEA special inspections in Iraq, (3) the public response to the Japanese plutonium shipment, and (4) the impending renewal of the NPT. In September 1993, the Clinton administration made a major policy pronouncement on nonproliferation and the use of plutonium: "… the United States does not encourage the civil
use of plutonium and, accordingly, does not itself engage in plutonium reprocessing for either nuclear power or nuclear explosive purposes. The United States, however, will maintain its existing commitments regarding the use of plutonium in civil nuclear programs in Western Europe and Japan" (White House, 1993; Davis and Donnelly, 1993).
The policy statement emphasizes the intention of giving nonproliferation greater priority in diplomacy, and in consideration of regional security and economic matters, and of seeking to promote nonproliferation efforts and making nonproliferation an integral part of relations with countries around the world. The policy also bears on the major U.S. initiative to obtain an extension of the NPT when it comes up for international review in 1995. The plutonium policy discourages any S&T undertaking with LWR spent fuel in the United States in the foreseeable future.
ASSESSMENT OF PROLIFERATION ISSUES FOR S&T SYSTEMS
This section assesses proliferation issues for S&T systems vis-a-vis the LWR once-through fuel cycle. For illustration, the four cases involving the three principal S&T transmutors—the ALMR, LWR, and ATW—are evaluated and reviewed by the committee:
Case 1 is the advanced liquid-metal reactor/integral fast reactor (ALMR/IFR) transuranic burner treated in terms of units comprising nine ALMRs integrated with a local pyroprocessing unit that handles ALMR fuel plus LWR spent fuel transported to the unit. (Centralized aqueous processing is covered in Case 4.)
Case 2 is the "baseline" Los Alamos National Laboratory (LANL) accelerator transmutation of waste (ATW) proposal with heavy-water moderation and onsite aqueous processing for the burning of transuranics (TRUs) and waste from LWRs.
Cases 3 are two versions of the advanced LANL ATW concepts with thorium fuel generating fissile 233U and using onsite processing. One is a self-contained energy producer burning its own waste; the other version burns waste from LWR spent fuel.
Case 4 is a hybrid system comprising ALMRs and once-through uranium-fueled LWRs with processing of spent fuel in large, centralized aqueous reprocessing and fuel fabrication facilities. This case involves plutonium in bulk form at the facilities and in fresh fuel transported to the reactors and is similar to cases evaluated in the 1970s.
The main proliferation issues for the four cases are summarized in Cases 1 through 4 at the end of the appendix. The discussion of issues to follow is organized in terms of three generic components—reprocessing, enrichment, and reactors—which are implemented with different technologies in the four cases.
Chapter 3 reviews the status of separations technologies and the facility requirements for reprocessing spent reactor fuel. Reprocessing facilities of 1,200-Mg/yr working capacity were used to separate plutonium for weapons at Hanford, Washington, or Savannah River, Georgia. Such a facility could separate perhaps a ton of weapons-grade plutonium per year or some 3 kg per day, depending on the concentration of plutonium in the fuel rods. Thus, 3 days production is enough for one to two nuclear weapons. The UP3 and THORP commercial aqueous reprocessing plants in Europe have a working capacity of 900 Mg/yr each—Case 3 of this appendix uses a reprocessing facility of that type and capacity. For a smaller plant (e.g., 300 Mg/yr) the corresponding time is about a week to separate enough plutonium for one weapon. Existing plants practice materials accountability at about 1% precision with 0.3% to perhaps 0.1% precision claimed to be possible with advanced automated designs. For the plant of 1,200-Mg/yr working capacity, an uncertainty of 1% is enough plutonium for a weapon in a time of about a year. Actual safeguards systems could do better by examining the measurements versus the records for patterns that reveal inconsistencies, and by using techniques for containment and surveillance (Schuricht and Larrimore, 1988). However, some observers conclude that the unaccounted material for a large reprocessing plant may exceed several significant quantities per year (Miller, 1990).
To the committee's knowledge, no existing reprocessing plant had facilitating safeguards techniques as a primary design constraint. In the early 1980s, the Oak Ridge National Laboratory (ORNL) conducted a study of a new facility for reprocessing fuel from the proposed Clinch River fast reactor (Birch et al., 1981). The concept sought to implement all-remote maintenance and accommodate the requirement for safeguards. With the cancellation of the Clinch River reactor, the reprocessing plant design was not carried through to the level of detail needed for construction. A remotely operated and maintained aqueous reprocessing or fabrication plant for bulk mixed-oxide (MOX) fuel—with optimized designs for automated materials accountability and for advanced surveillance and containment techniques and designed to accommodate resident safeguards inspectors at the facility—remains a design goal.13 However, an ongoing project in Japan for a large, new fuel reprocessing plant, based on aqueous technology, has international safeguards as a major design constraint and might become the first such plant constructed. Whether such a design would significantly affect the evaluation of national diversion scenarios is an unresolved question.
Proponents of pyroprocessing, planned by Argonne National Laboratory (ANL) for the ALMR/IFR system, suggest that the technology lends itself to small, secure facilities, self-contained at the reactor (see Chapter 3). Case 1 of this appendix assumes a system design of this type. An initial assessment has been made of the proliferation implications of a
conceptual IFR comprising a fast reactor that uses metallic fuel plus a collocated fuel reprocessing and refabrication plant that uses pyrometallurgical technology (Wymer et al., 1992). The study reached conclusions based on information from research and development on pyroprocessing and on generic considerations of what a commercial-scale reprocessing-refabrication facility would be like. However, the study lacked detailed flowsheets on the process, equipment specifications, and a real plant layout—the kind of data needed for a realistic evaluation of diversion scenarios. The flavor of the study conclusions can be gained from the following excerpt from its executive summary (Wymer et al., 1992:).
Although it is possible to conceive a variety of ways to remove and purify plutonium from the IFR fuel recycle process with the intention of using it in nuclear weapons, the removal scenarios require off-normal equipment operation or equipment modification and are, for the most part, readily detectable. A large amount of radioactivity remains with the fuel throughout the entire fuel cycle, and virtually all operations must be carried out remotely in inert-atmosphere hot cells. These facts make it difficult to carry out undetected covert operations to divert plutonium to weapons use and provide a substantial period of time between when a country intent on overt proliferation might abrogate the nonproliferation treaty and when it could produce its first weapons-grade plutonium.
The radioactivity of the fission products remaining in the plutonium from IFR, the mix of plutonium isotopes, and the presence of large amounts of uranium make it a less than optimum material for use in weapons production. The radioactivity would make handling and machining of the plutonium and assembly of a weapon very difficult. The relatively high 238Pu fraction would produce heat that would cause phase changes in the plutonium alloy as the temperature rises, resulting in degradation of the performance of the weapon. The heat also could be detrimental to other components in the fabricated weapon during storage.
The intrinsic radioactivity of the recycle plutonium product and the requirement of remote recycle operations in inert-atmosphere hot cells are favorable safeguard factors for IFR. On the other hand, inspectability and material accountability for verification purposes are relatively more difficult for the IFR recycle plant than for a plutonium/uranium redox extraction process (PUREX) plant and a conventional oxide fuel fabrication plant. It is important that the design of the commercial IFR fuel recycle plant give adequate attention to safeguards, inspectability, and accountability features. To provide adequate safeguards likely will require more than customary reliance on containment and surveillance and less reliance on material accountability at key points in the process
This brief excerpt regarding a generic pyroprocessing technology and plant indicates that the process, if practical, may have potential for the future if a realistic and detailed plant design
can adequately validate the conclusions. However, pyroprocessing is potentially able to accommodate a wide range of process parameters. Thus, one would want to give further examination to two possible modes of misuse: (1) If new feed material (e.g., low burn-up spent fuel containing little 240Pu) were introduced into an IFR from the outside and run through the system's pyroprocessing equipment, how long would it take to start obtaining plutonium from that equipment and what would be the rate of production? (2) If the normal system operation were altered by shortening the fuel irradiation time to reduce 240Pu concentration in the ALMR spent fuel, could an existing ALMR/IFR system produce weapons-grade plutonium? Further study is needed.
The methods for isotope separation depend on small differences in physical and chemical properties that are due to the slight differences in mass among the isotopes. Four methods have proven practical for production-scale separation of fissionable isotopes and, thus, for enrichment of uranium: (1) gaseous diffusion developed in the 1940s and employed by the United States and the former Soviet Union; (2) gas centrifuge and jet nozzle commercialized in the late 1960s in Europe and also employed by the former Soviet Union; (3) chemical separation developed in France and Japan in the 1980; and (4) laser-induced separation developed in the United States in the 1980s. The less efficient technique of electromagnetic isotope (calutron) separation, developed in the United States in the early 1940s and used to obtain the enriched uranium for the Hiroshima bomb, was adopted by Iraq for its covert uranium enrichment program.
Safeguards are challenging to employ effectively at a large enrichment facility. Consider, for example, an enrichment plant with a capacity of 1 million separative work unit/year (SWU/yr) using gaseous diffusion or centrifuge technology. Although some commercial plants are five to ten times larger, 1 million SWU/yr is typical of many operational facilities and is convenient for estimates. Numerous separative stages are required in such an enrichment plant, because each stage achieves only a small fractional isotope separation. Each stage typically consists of many individual units connected in parallel. Stages are cascaded in series by means of piping to achieve whatever degree of enrichment is desired. For enrichment at 0.2% tails assay, 236 SWU are expended per kilogram of 93% HEU produced, whereas to produce 3% LEU, 140 SWU are expended per kilograms fissile material or 4.3 SWU are expended per kilograms of 3% diluted fuel feed. Thus, the nominal 1 million SWU/yr plant configured for low enrichment from natural uranium feed material could produce about 20 tonnes of 3% LEU fuel feed material per month or 240 Mg/yr, which could serve the needs of about eight LWRs of nominal 1,000 MWe capacity.
Alternatively, the same plant reconfigured for HEU production—reconnecting units to configure more stages in series—could produce about 350 kg of HEU per month or enough nominally for about a dozen nuclear weapons per month. For centrifuge plants, which are much more readily reconfigured than diffusion plants, safeguards procedures were worked out in the 1980s by a working group and applied at plants in Europe (Menzel, 1983). Such safeguards employ tamper-proof seals and surveillance equipment on all entrances to the plants operating
areas to prevent the reconfiguration of the stages, with sampling of output and waste material for assay on regular inspections every few weeks and on random spot inspections.
The chemical separation approach is reportedly capable of substantial enrichment (Mikake et al., 1984). With many stages, it could produce HEU. A facility for the process is much like a conventional chemical processing plant. If such a plant is operated under safeguards with resident inspectors, then the risk that a modification for HEU production could go undetected may be low. However, much of the separative work is expended in getting to 3.5-4% LEU, so safeguards must also be applied to the LEU output and overall material balance. Otherwise, material diverted from a chemical separation plant (or centrifuge plant) producing LEU could be further enriched in a small, covert ''topping" plant, using the same or another enrichment technique, to achieve HEU from the combination. The topping plant itself might be hard to locate without some intelligence information.
Recently, laser isotope separation has been developed in the United States for purifying plutonium (i.e., separating 239Pu from other plutonium isotopes) and for enriching uranium. The process lends itself to a plant of modest industrial scale and was selected by the U.S. Department of Energy (DOE) in the mid-1980s as the technology of choice for enrichment in the United States. The high-power laser technology is very high-tech and may be difficult for many developing countries to acquire in the near term. However, other laser-induced chemistry applications would use much the same type of lasers, which may give impetus to their development and widespread commercial use. If so, it is likely that technology to practice the laser isotope technique would become generally available over the next decade or two.
The application of these considerations to the S&T cases depends on whether the case merely requires HEU for start-up or a periodic supply of LEU for make-up to support operating LWRs, as in Cases 1 and 3. For start-up on HEU, the reactors presumably could draw down existing HEU stocks, which could be augmented if necessary by a special campaign conducted in commercial-scale enrichment plants that exist to support the current once-through fuel cycle. Then those enrichment plants could be shut down or mothballed. A case requiring ongoing LEU make-up requires operating enrichment plants, albeit under safeguards. Of course, the perceived proliferation risk would depend strongly on where enrichment plants are located and the institutional arrangements that prevail. The Argentina–Brazil bilateral safeguards agreement covering their enrichment plants, which is backed up by IAEA inspection, is an example of a multilateral institutional arrangement that might be satisfactory in other instances (Redick, 1990; Krasno, 1992). Even then, abrogation scenarios (a nation renouncing a treaty or agreement and seizing the plant) would remain a potential proliferation risk (see the section Proliferation Issues in Chapter 6).
The first sections of this appendix briefly review the LWR once-through fuel cycle as the proliferation baseline and introduce two other types of thermal reactors—the HWR and the LGR. Reactors moderated with either heavy water or graphite permit on-line refueling, as discussed below. They were used for weapons-grade plutonium production by the major nuclear-weapon
nations in the past; a few nations continue to do so. Chapter 4 reviews the LWR in detail and also reviews fast reactors, such as the ALMR, that can operate efficiently as breeders.
A major class of national diversion scenarios entails diversion of spent fuel at a reactor site. A large reactor is not a trivial matter to safeguard. Reactor-grade plutonium is produced at a rate of about 0.9 of plutonium per MWt·day or 0.33 kg MWt/yr per MWt·year. Weapons-grade plutonium requires a shorter irradiation time than reactor-grade to suppress production of 240Pu and may need a greater fraction of the year for loading/unloading operations. For example, a 2,200 MWt reactor operating at 80% of nominal capacity would produce about 600 kg of reactor-grade plutonium per year. Such a reactor would produce less, for example 300 to 450 kg of weapons-grade per year depending on whether the reactor could be refueled on-line (i.e., a change of fuel rods by a machine without shutting down the reactor) or would require batch refueling involving a shutdown. 300 kg of plutonium per year is material for 40 to 60 weapons per year or 3.5 to 5 weapons per month.
IAEA safeguards defend against the diversion of spent-fuel rod bundles with tamper-proof seals and tags (Fischer and Szasz, 1985). Safeguards inspectors install these devices as the fuel rods are placed in the reactor. The tags are checked when the spent fuel is removed from the reactor for placement in the storage pool, and they are checked again in the pool on each inspection. The safeguards technologies also include gamma spectral measuring equipment and surveillance instrumentation. A reactor moderated with ordinary water (a LWR) normally requires batch refueling during a shutdown, which provides safeguards inspectors with an opportunity to be present while fuel is being loaded/unloaded. Inspectors can also make regular and randomly timed visits to check seals and tags on spent fuel in storage as well as read other safeguards instruments and check operating records to verify that there has been no unannounced shutdown of any consequence between scheduled shutdowns for refueling and maintenance.
Reactors for which on-line refueling is possible pose a severe challenge to a safeguards regime. The Russian RBMK-type graphite-moderated reactor, for example, uses a machine that moves progressively over the top of the core on a schedule to remove irradiated rods and insert fresh ones. The CANDU, an HWR, uses a similar machine for its core in which the fuel rods lie horizontally. Such reactors require more extensive safeguards than batch-refueled LWRs. The CANDU safeguards might serve as a model (Zarecki and Smith, 1981; Ferraris and Wredberg, 1982). Safeguards instrumentation uses core input and discharge counters and monitors the progress of the refueling machine with sealed surveillance equipment through the reactor's upper observation port. All rods entering or leaving the reactor are subjected to inspection, and reactor operating conditions are monitored with sealed detectors to substantiate the operating logs.
Fast reactors present yet another safeguards issue. In addition to fuel rods in the reactor core that contain plutonium, a fast reactor has blanket regions for breeding 239Pu in rods that contain 238U (natural or depleted uranium) and that could be changed while the reactor is operating (on-line). The blanket would be a special target in diversion scenarios that include covert substitution of blanket roads, which are taken away and reprocessed to recover the 239Pu. Thus, fast reactors would need an operating regime with an optimized design to facilitate containment and surveillance safeguards and a design to minimize the possibility of a covert
change of blanket rods. Finally, a new safeguards issue is raised with reactors that use fluidized fuel, like the ATW; there are no fuel rods to count! No safeguards scheme has been devised for such reactors.
Summary of Proliferation Issues for the Four Cases
Several STATS committee proposals would significantly change the present situation with the once-through LWR fuel cycle. Case 1 and Case 3 introduce fast reactors as transuranic (TRU) burners in which the core and blanket contain rods with TRU waste. Case 1 also uses fast reactors as plutonium breeders and has a pyroprocessing facility collocated on each site. Both cases require safeguards against covert on-line refueling and against substitution of blanket rods containing uranium for those containing TRU waste. The diverted rods could be reprocessed using the collocated pyroprocessing equipment or taken away and reprocessed elsewhere. The ALMR/IFR proposal has not presented a safeguards regime, so no detailed assessment is possible. Case 3 uses large centralized aqueous reprocessing and fuel fabrication facilities containing plutonium in bulk quantities and transports fuel rods containing plutonium to and from the reactors and the fuel processing sites. Thus, Case 3 raises plutonium diversion issues, as discussed above under Reprocessing.
The ATW fludized fuel, a heavy-water slurry in Case 3 and a molten salt in Case 3, which circulates in the reactor proper and the onsite reprocessing unit, requires a new safeguards regime, as noted above under Reactors. In Case 3, timing the reprocessing of the protactinium to avoid 232U (which decays to highly radioactive daughters) would enable the production of nearly pure 233U bomb material. In addition, the ATW would be an excellent source of neutrons for covert plutonium production in natural or depleted uranium. For example, if neutrons from the target were used with no further multiplication, the neutron flux would still be about one-twentieth of the normal flux for an ATW with a Keff of 0.95 and would have a hard spectrum.
To minimize the possibility of either covert plutonium production with target neutrons or diversion of either fluid fuel or separated processing streams, an ATW may require sealed entrances to the facilities and extensive monitoring that has continuous surveillance equipment and secure communications and perhaps also resident inspectors like an enrichment facility. The ATW proposal does not discuss safeguards requirements, so no detailed assessment is possible of the effectiveness of such safeguards. LANL has not assessed the feasibility of materials accountability safeguards with the intense radiation field of the fluid fuel (see Chapter 3).
Finally, there is another class of proliferation scenarios beyond diversion scenarios addressed by IAEA and other safeguards, namely abrogation scenarios, which involve seizure of facilities and stores that are under safeguards by a nation after treaty withdrawal or abrogation, followed by the rapid production of nuclear weapons (see Chapter 6). The S&T fuel cycles in general, and the four cases of this appendix in particular, introduce a critical, qualitative change relative to the once-through LWR fuel cycle. That change is the availability of facilities that could be seized for HEU or plutonium production and in which reactor-grade plutonium is normally available in bulk form. As noted in the section Proliferation Issues in Chapter 6, abrogation scenarios raise mainly political issues, although technological considerations can be
important in determining the time scale in which political and military responses by other nations could limit the production of the nuclear devices. Of the four cases, Case 4 with large centralized facilities and bulk stores, is perhaps the most vulnerable to abrogation scenarios, because the time scale for response by other nations would be the shortest.
CASE 1: INTEGRAL FAST REACTOR BREEDER/BURNER14
The units comprise nine ALMR modules integrated with a local pyroprocessing unit that handles ALMR fuel plus LWR spent fuel transported to the unit to be reprocessed. Any LWRs are assumed to be phased out as they reach the end of their operational life. They are replaced by ALMRs operating as breeders to provide the additional make-up for the waste-burner ALMRs. As accumulated LWR spent fuel is exhausted, ALMRs switch operation to breeder/burners.
Reactors: Nine 155-MWe ALMR modules. Waste-burner ALMRs operate with a breeder ratio of 0.65. ALMRs shift to a breeder ratio near unity to breed plutonium after the LWR waste is consumed. ALMR core and blanket rods could be substituted covertly to make low burn-up plutonium for weapons.
Enrichment: (a) Not required for ALMRs if start-up is on plutonium recovered from spent fuel. (b) For start-up on HEU, ALMRs could draw from existing supplies, augmented as necessary by a special campaign in existing enrichment facilities under safeguards. (c) 1 million SWU/yr per 8 operating LWRs until all LWRs are phased out.
Fuel Reprocessing and Refabrication: (a) ALMR fuel processing of 7.6 kgMg/d (2.8 MgHM/yr) capacity local to the reactor site, using pyroprocessing technology. (b) Additional LWR fuel processing that uses onsite pyroprocessing with a different front end; extra capacity depends on the desired rate for reprocessing the accumulated LWR spent fuel. (Alternatively, a large aqueous reprocessing plant and an associated fuel fabrication plant could be used for LWR spent fuel, as discussed in Case 4).
Spent-Fuel Storage: Temporary storage onsite.
Transportation: (a) Initial plutonium-or HEU-bearing fuel material for ALMR start-up. (b) For ALMR-burners, periodic shipments of plutonium-bearing LWR spent fuel is required; in addition, ALMR fuel occasionally may be transported between multireactor sites to maintain balance.
Waste Disposal: Temporary storage and permanent geological isolation of plutonium-bearing waste.
CASE 2: BASELINE ACCELERATOR TRANSMUTATION OF WASTE15
This is the "baseline" LANL ATW with onsite aqueous processing, which delivers about 1,600 MWe, to the electrical grid. Fluid fuel, consisting of a slurry of tiny particles in heavy water, is used to burn the TRUs, radioiodine, and technetium from accumulated LWR spent fuel.
Reactors: Accelerator-driven neutron-generator-multiplier assembly comprising a 1,600 MeV 250 mA proton accelerator with a tungsten target to produce neutrons that are multiplied in a heavy-water moderated assembly with Keff = 0.95. The system produces about 8,300 MWt total power burning the waste from past and existing LWRs containing TRUs and iodine and technetium fission products. The ATW neutrons could be used covertly to make low burn-up plutonium for weapons.
Enrichment: (a) Not required for an ATW if start-up is on plutonium-based spent fuel. (b) For start-up on HEU, ATW could draw from existing supplies, augmented as necessary by a special campaign in existing enrichment facilities under safeguards.
Fuel Reprocessing and Refabrication: (a) Fluid fuel reprocessing of 55 kgHM/day (20 MgHM/yr) onsite integrated with refabrication using aqueous technology. (b) Reprocessing of LWR spent fuel in a large facility (300 Mg/yr) with integrated fuel fabrication, to provide fissile make-up for the ATW.
Spent-Fuel Storage: Temporary pool storage onsite.
Transportation: (a) Initial plutonium-or HEU-bearing fuel material for ATW start-up. (b) Periodic shipments of plutonium-bearing LWR spent fuel.
Waste Disposal: Temporary storage and permanent geological isolation of plutonium-bearing waste.
CASE 3: ADVANCED ACCELERATOR TRANSMUTATION OF WASTE16
Consist of two versions of the LANL advanced ATW using fuel dissolved in a molten salt with onsite processing. The systems use thorium to generate fissile 233U and deliver 2,180 MWe to the electric grid. One is a self-contained cycle burning its own waste; the other version also burns LWR waste.
Reactors: Accelerator-driven neutron-generator-multiplier assembly to produce neutrons comprising a 800 MeV 110 mA proton accelerator with a molten-lead target that are multiplied in a graphite-moderated assembly with Keff=0.95. The system produces about 6,000 MWt total power in either version. The ATW neutrons could be used covertly to make low burn-up plutonium for weapons.
Enrichment: (a) Not required for an ATW if start-up is on plutonium-based spent fuel. (b) For start-up on HEU, ATW could draw from existing supplies, augmented as necessary by a special campaign in existing enrichment facilities under safeguards.
Fuel Reprocessing and Refabrication: Fluid fuel reprocessing on-site using a nonaqueous technology integrated with fuel refabrication. Version 1:9.8 kgHM/day (3.6 MgHM/yr); version 2:8.2 kgHM/day (3 MgHM/yr).
Spent-Fuel Storage: Version 1: temporary pool storage onsite.
Transportation: Version 1: periodic shipments of plutonium-bearing LWR spent fuel; version 2: no fuel transportation.
Waste Disposal: Temporary storage and permanent geological isolation of plutonium-bearing waste.
CASE 4: HYBRID ALMR/LWR SYSTEM17
The system consists of groups comprising 16 ALMR TRU burners and 30 LWRs burning technetium and iodine fission products, with aqueous reprocessing of both fuels in large central facilities with associated fuel fabrication. The fuel rods are transported to and from a large number of reactors. This case contrasts with Case 1 in that here the LWRs remain operational, supplying TRU make-up to the ALMRs; also, the reprocessing is centralized.
Reactors: (a) 400-MWe ALMRs that operate as waste burners with a breeding ratio assumed to be 0.8 in the CURE proposal. (b) 1,000-MWe LWRs to burn some waste, supply make-up for the ALMRs, and generate electrical power.
Enrichment: (a) Not required for ALMRs if start-up is from reprocessed spent fuel. For start-up on HEU, ALMRs could draw from existing supplies, augmented as necessary by a special campaign in existing enrichment facilities under safeguards. (b) 3.5 million SWU/yr required for each 30 operating LWRs.
Fuel Reprocessing and Refabrication: Central reprocessing facility of 750-Mg/yr working capacity per group using aqueous technology, with fabrication of 1,000 fuel rods/yr per group from input of 300 Mg/yr of uranium and 20 Mg/yr of plutonium.
Spent-Fuel Storage: Temporary pool storage onsite.
Transportation: (a) Initial plutonium-or HEU-bearing fuel material for ALMR start-up. (b) Periodic shipments of plutonium-bearing fuel between sites and centralized fuel-processing facility for the operating LWRs.
Waste Disposal: Temporary storage and permanent geological isolation of plutonium-bearing waste.
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