3
Criteria for Comparing Disposition Options

The primary motivation of the U.S. government in its search for the most suitable means of disposition of surplus weapons plutonium (WPu)—and thus the primary motivation driving the current study—is to minimize the security risks posed by the existence of this material. Our parent committee concluded in its 1994 report that the tens of thousands of plutonium pits that will emerge over the next decade from the dismantlement of surplus nuclear weapons in the United States and Russia must be regarded as a "clear and present danger to national and international security," and we agree.

Accordingly, our discussion of relevant criteria for comparing the options for WPu disposition begins with the security risks: their nature, the disposition-option characteristics that influence them, and the formulation of figures of merit to quantify or otherwise illuminate those influences. The issues of timing and capacity—how quickly an option can be put into operation and how rapidly it can process WPu thereafter—will be seen to be tightly intertwined with other aspects of security, and we treat these matters together here. We then turn to criteria related to economics; environment, safety, and health; and other considerations.



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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options 3 Criteria for Comparing Disposition Options The primary motivation of the U.S. government in its search for the most suitable means of disposition of surplus weapons plutonium (WPu)—and thus the primary motivation driving the current study—is to minimize the security risks posed by the existence of this material. Our parent committee concluded in its 1994 report that the tens of thousands of plutonium pits that will emerge over the next decade from the dismantlement of surplus nuclear weapons in the United States and Russia must be regarded as a "clear and present danger to national and international security," and we agree. Accordingly, our discussion of relevant criteria for comparing the options for WPu disposition begins with the security risks: their nature, the disposition-option characteristics that influence them, and the formulation of figures of merit to quantify or otherwise illuminate those influences. The issues of timing and capacity—how quickly an option can be put into operation and how rapidly it can process WPu thereafter—will be seen to be tightly intertwined with other aspects of security, and we treat these matters together here. We then turn to criteria related to economics; environment, safety, and health; and other considerations.

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options TABLE 3-1 Threats Associated with Surplus Weapons Plutonium Types of Threats 1. Diversion of the WPu by the original possessor nation for reincorporation into nuclear weapons ("breakout"), which may be   a. overt, or   b. covert. 2. Theft of the WPu by or for other countries or subnational groups, with or without the complicity of insiders in the custodial organization, by means that are   a. forcible, or   b. overt but not forcible (as could occur under loss of national authority), or   c.. covert 3. Harmful influences of the management of WPu on   a. the strength and stability of institutions for nuclear weapons management and monitoring in the United States and the former Soviet Union;   b. incentives and disincentives for further nuclear arms reductions in the United States, the former Soviet Union, and other nuclear-weapon states;   c. incentives and disincentives for acquisition of nuclear weapons by other countries; and   d. management of reactor plutonium in ways that increase its accessibility to prospective bomb-makers. Time Frames in Which the Threats May be Operative   • the near term, roughly the next 10 years, within which the quantities of WPu accumulated from dismantlement activities are increasing and most disposition options would be in their developmental or initial operational stages;   • the middle term, roughly from 10-50 years hence, within which most disposition options would be in full operation and at the end of which the bulk of the surplus WPu would have been processed; and   • the long term, beyond 50 years hence, wherein the surplus WPu would be in whatever final form and location had resulted from the disposition option selected.

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options CRITERIA RELATED TO SECURITY AND TIMING The Context for Security Concerns and Criteria In view of the linkages, noted earlier, between U.S. and Russian choices for disposition of excess WPu, we have been attentive in this report to circumstances in both countries. We have also been attentive to the implications, for choices about management of surplus WPu, of the existence of civilian stocks of both separated and unseparated plutonium, which pose security risks in widely varying degrees and which altogether contain considerably more plutonium than the military stocks. It is necessary to ask, more specifically, what standards of physical protection and monitoring are appropriate for all of the various forms of plutonium that occur in both the nuclear-weapons and the nuclear-energy sectors. Related questions include: Is it worthwhile to invest significant resources-or to tolerate significant additional delays, risks, and uncertainties-to transform the small stock of surplus WPu into a form that is substantially more difficult to recover for use in weapons than the larger and growing stock of plutonium in spent fuel? Should the existing levels of security and monitoring for separated and unseparated civilian plutonium be upgraded, regardless of what is decided about the disposition of WPu? Could the options that might become available for eliminating surplus WPu, or otherwise making it less accessible for use in weapons than is plutonium in civilian spent fuel, be expanded (with tolerable cost, uncertainties, and timing) to do the same with the global stock of plutonium in spent fuel if that were deemed desirable? How might choices about the disposition of WPu influence decisions about the management of reactor plutonium in ways that affect-for better or for worse-the danger that the latter might be used in weapons? Questions (a) and (b) relate to the strategy for managing the security risks from plutonium of all kinds, and we return to them shortly. Issues (c) and (d) relate to the properties and implications of particular candidate options for the disposition of WPu, and we address them in the subsequent sections devoted to those options. Specific Security Concerns and Threat Characteristics It is useful, for purposes of developing criteria relating to security, to subdivide the security threats associated with surplus WPu using the framework presented in Table 3-1, which distinguishes among threats of diversion (by the

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options original possessor nation), theft (by other countries or subnational groups), and harmful influences (with respect to nuclear weapons management, arms control, and nonproliferation). Options for the disposition of WPu should then be judged with respect to: how the options would affect the difficulty, duration, cost, and detectability of attempts—within the categories of diversion and theft listed under items (1) and (2) in Table 3-1—to acquire WPu and carry out the processing and fabrication steps necessary to fashion it into functional nuclear bombs, and on how the options might influence the weapon management, arms control, and nonproliferation institutions, incentives, and outcomes indicated under item (3) in Table 3-1. Ideally, these evaluations should take into account the interaction of the time dimensions of different disposition options with the possible changes over time in the relative importance of different threats. Candidate disposition options typically consist of several steps, beginning with intact nuclear weapons, proceeding through some number of intermediate processing, storage, and transport steps, and ending with either the physical destruction of the plutonium (by fission or transmutation) or its disposal in a form and location where it is intended to remain until its disappearance via radioactive decay. 1 Evaluation of the security benefits and liabilities of any such option, with respect to the threats described above, requires assessing the security risks, with respect to each type of threat, of each step the option entails. Such an assessment must take into account the barriers to acquisition and weapons use of the material associated with the form of the material at each step, the additional barriers to acquisition associated with the way the step is implemented, the quantities of material at risk at each step and the time interval during which it is at risk, and the interaction of these risk factors with the characteristics of the threat. These factors are summarized in Table 3-2. A Matrix Scheme for Characterizing Options The foregoing considerations suggest a matrix approach to characterization of the security implications of different options for the disposition of WPu, in which the rows of the matrix are the steps in an option and the columns portray, 1   It should be noted that the dominant plutonium isotope, 24,000-year half-life plutonium-239, decays into 700,000,000-year half-life uranium-235, which is also a nuclear-explosive material.

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options TABLE 3-2 Factors Governing Security Risks of Disposition Steps 1. Relevant quantitative characteristics: duration, integrated inventory, dilution   a. start dates and end dates for the step in question;   b. integrated inventory, i.e., average inventory in step times duration in years (kilograms-years); and   c. dilution of plutonium in accompanying material (kilogram of material per kilogram of plutonium). 2. Barriers to the acquisition and use of the material to make nuclear explosives, specifically   a. barriers intrinsic to the form of the material, including     i. isotopic barriers, meaning the relative difficulty of making nuclear explosives with material of this isotopic composition, or the difficulty of suitably altering its isotopic composition;     ii. chemical barriers, meaning the extent and difficulty of chemical processing required to separate the weapons usable substance(s) from accompanying dilutants and contaminants;     iii. radiologic barriers associated with the radiation fields and internal dose potentials of the weapon-usable substance(s) and accompanying materials; and     iv. barriers of mass and bulk, relating to the difficulty of moving the material in the course of theft or diversion, and the difficulty of concealing such activity.   b. barriers dependent on the details of the option's implementation, including     i. locational barriers, such as site isolation, difficult terrain, burial depth, difficulty of excavation and tunneling;     ii. containment barriers, such as massive containers, vaults, buildings, fences, detectors, alarms; and     iii. institutional barriers, such as proximity, capability, and reliability of guard forces, and intensity and reliability of monitoring. 3. The characteristics of the threat, including   a. its type in the categorization scheme of Table 3-1;   b. complicity of custodial organization or individuals within it;   c. capabilities of attacking forces (numbers, weapons, training, organization, determination) in the case of forcible theft; and   d. knowledge, skills, money, and technology available to the prospective bomb-makers.

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options TABLE 3-3 Format for Characterizing Security Risks of a Disposition Option   Time and Quantity Dilution (kg of material per kg of Pu) Qualitative Evaluations (scale 0 to 4) of Intrinsic Barriersa Implementation-Dependent Barriers Qualitative evaluation of vulnerability (low, medium, high) based on threat-barrier interactions with respect to threats of Step Start Date End Date Integrated Inventory (kg-yr)   Isotopic Chemical Radiologic Mass/ Bulk Location Containment Institutional Overt Diversion Covert Diversion Forcible Theft Covert Theft A   B   C   D   E   F   G   H   I   J   a Intrinsic barriers refer to form of plutonium at end of step. Example: once-through mixed-oxide (MOX)/spent fuel option in light-water reactor (LWR), followed by eventual emplacement of spent fuel in geologic repository. Step A: Storage as pits. B: Conversion to oxide. C: Transport as oxide. D: Fabrication to MOX. E: Transport as MOX. F: Storage as MOX. G: Burnup in LWR. H: Spent fuel storage. I: Spent fuel transport. J: Repository disposal.

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options for each step, the quantitative and qualitative risk factors and the vulnerability to different types of threat in the light of those factors. The format for such a matrix is illustrated in Table 3-3 for a disposition option centered around converting the WPu into spent light-water reactor fuel. In Chapter 6 we fill in a few such matrices for the plutonium management options of greatest interest. In the following paragraphs we elaborate on the justifications for the entries in this scheme. Start Dates The date at which operations in a particular step would be expected to commence determines the beginning of the period of potential vulnerability for the step and is relevant for consideration of the interaction of (potentially) time-varying threats with the "opportunities" presented by the disposition option. The start date of the first disposition step beyond the storage of pits is a particularly informative indicator of security risk, since it reflects the duration of a phase of plutonium management that is problematic both from the standpoint of the attractiveness, for weapons purposes, of the stored material and from the standpoint that delay in moving beyond pit storage may call into question the commitment of the possessor states to actually demilitarizing this material, with potentially harmful influences on the prospects for further nuclear arms reductions and for nonproliferation. This first start date beyond pit storage depends on the state of scientific and technical readiness of the disposition option and the research and development time needed to remedy any defects in these respects: on the time needed to construct all of the relevant facilities; on the time needed to accomplish any necessary licensing steps; and on the time needed to gain acceptance for the option by the relevant publics and decision-makers (which might include, for example, local and state as well as federal officials, electric utility managements, or foreign governments). End Dates Clearly, the overall security risk associated with a disposition option depends, among other factors, on the lengths of time that the WPu spends in its most weapon-usable forms and most vulnerable locations and processes within the option—hence the relevance of durations of the steps within an option, as determined by the combination of start date and end date. These durations depend on the quantity of plutonium to be processed altogether and on the rate at which it can be processed. We base our quantitative estimates in this study on a nominal quantity of 50 tons of WPu, roughly the amount expected to become surplus in the United States by the year 2005. Processing rates are based on scales of operation we judge plausible in light of the capacities of existing relevant facilities (if any) and the trade-offs among cost, timing, and other aspects

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options of security. (This question of scale is addressed in detail in subsequent chapters dealing with individual options and in Chapter 6, dealing with comparisons.) Integrated Inventory Somewhat more informative than duration alone as an indicator of the security-risk "exposure" associated with a given step in plutonium disposition is the integrated inventory for that step, defined as the integral under the curve of quantity of WPu in the step versus time. As explained in Appendix A at the end of this chapter, this indicator can be calculated for processing and transport steps as well as for storage steps, given sufficient information about how these operations will be conducted. For the purposes of the preliminary comparisons undertaken in Chapter 6, which necessarily are based on quite sketchy and tentative characterizations of the options, we calculate integrated inventories only for two phases of the disposition process—the phase in which the WPu exists in the form of pits and the phase between conversion of the pits to oxides and the loading of this material into a reactor or melter (marking a great decrease in vulnerability). These two integrated inventory figures are, in our view, reasonably informative indicators2 of the timing aspect of security, and they are calculable with a minimum of assumptions about the details of the disposition options. Dilution An additional quantitative figure provided for each step is the degree of dilution of the plutonium in whatever matrix contains it, measured in kilogram of total material per kilogram of plutonium. This dilution figure can be used to determine how much material must be moved and processed to acquire a weapon's worth of plutonium. Intrinsic Barriers Our qualitative evaluations of barriers will employ a scale in which 0 means "negligible," 1 means "small," 2 means "medium," 3 means "large," and 4 means "very large.” This is not intended to be a linear scale but rather to denote qualitatively significant differences in the barriers to weapons use of the material. In cases where the differences do happen to be more or less quantifiable (as 2   We note that integrated inventory, like other indices, is an imperfect measure of security hazard. better in relation to some categories of threats than in relation to others. For example, the risk of forcible theft of a few bombs' worth of material from a particular facility probably will not depend very much on whether there is I ton of plutonium there or 50 tons; but the risks of covert diversion or theft—and of overt diversion—do increase, in many circumstances, with quantity as well as with duration.

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options with, e.g., the radiologic barrier), the difference between adjacent levels is an order of magnitude (factor of 10) or more. The meaning of the levels in relation to the different barriers is elaborated further in the following subparagraphs. Isotopic Composition. Relevant aspects include fractions of plutonium-240 (Pu-240) and Pu-242, which affect critical mass and difficulty of design; fraction of Pu-238, which complicates design through its high heat generation; and fraction of Pu-241, which governs buildup of heat-generating and radiologically hazardous americium-241. We take high-enriched uranium (HEU) as the 0 ("negligible") reference point for isotopic barriers, and characterize weapons-grade plutonium (approximately 90 percent Pu-239) as 1, typical reactor-grade plutonium (approximately 60 percent Pu-239) as 2, and very-high-burnup plutonium (40 percent Pu-239 or less) as 3. Uranium with uranium-235 (U-235) or U-233 content less than 20 percent would qualify as 4, but no plutonium composition relevant to this study would so qualify. Chemical Form. Relevant aspects include whether the plutonium is in metallic form (the most convenient for immediate use in a weapon, but not necessarily the most convenient for further processing or for storage if such steps will be part of a weapons effort) or oxide, carbide, nitrate, etc., and admixture of impurities (such as other metals, oxides, or carbides, or fission products, or other neutron absorbers, which, variously, affect chemical processing requirements and radiological hazard to bomb-makers). We take pure plutonium metal to be the 0 reference point for chemical barriers, and characterize pure plutonium oxides as 1, mixed uranium and plutonium oxides (MOX)—including MOX mixed with additional dilutents or neutron absorbers other than fission products—as 2, and plutonium embedded in spent fuel or vitrified radioactive waste as 4. (Here the jump from level 2 to 4 is not because the chemistry per se is very much harder, but because the penetrating radiation from the fission products necessitates that the chemistry be done using degrees of shielding and remote handling that greatly increase the difficulty.) Radiologic Hazard. This barrier depends both on the gamma-emitting properties of the material, which govern the radiation field and shielding requirements associated with approaching and handling the material, and the beta- and alpha-emitting properties governing the hazards that occur if as a result of processing or dispersal the material is inhaled or ingested. We take natural, low-enriched, or depleted uranium to be the 0 reference point for radiologic hazard, and characterize HEU as 1, WPu in metal or plutonium oxide as 2, reactor plutonium in metal or plutonium oxide as 3, and plutonium in spent fuel or mixed with high-level radioactive wastes as 4.3 The twenty-fold or more dilution from 3   It should be noted that the gap between level 3 and 4 is very large in this case, amounting to a qualitative difference. While both WPu and reactor plutonium can be handled in small glove-box facilities, the penetrating gamma radiation from most commercial spent fuel or from large vitrified high-level waste logs being produced or planned for production in several countries is so intense as

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options plutonium metal or oxide to MOX reduces the radiologic hazard one level: WPu in MOX is characterized as 1, and reactor plutonium in MOX as 2. Mass/Bulk. This barrier relates to whether the form of the material permits ready partitioning in a way that facilitates concealment on the person of a thief or divertor (as would be the case with small quantities of HEU or plutonium metal or oxide, taken as level 0), or is readily portable by one person although somewhat more difficult to conceal (as in the case of a pit, level 1), or can be moved by one person but only with some difficulty and little chance of concealment (fuel assemblies weighing tens of kilograms, level 2), or requires a forklift (approximately 100 kg or more, level 3) or a crane (approximately 1,000 kg or more, level 4). Implementation-Dependent Barriers For these barriers, too, it is convenient to employ a scale of qualitative distinctions ranging from 0 for negligible barriers to 4 for very large ones. Location/Exposure. We associate level 0 with transport, 1 with processing at multiple sites, 2 with processing at a single site or storage at multiple sites, and 3 with storage at a single site, and we add 1 if the sites are remote or otherwise difficult of access. Containment. We associate level 0 with storage containers that can be opened by hand or ordinary tools and are not equipped with seals; and with material in unsealed processing equipment that can be similarly opened. Level 1 is for containers and processing equipment with seals that render any tampering detectable after the fact. Level 2 is for containers and processing equipment requiring more substantial tools (such as industrial cutting equipment) to open, and also equipped with seals. The characteristics of the next level of containment then add 0, 1, or 2 to the rating: 0 is for containment that could be breached quickly and easily by a single individual (such as an ordinary industrial building behind a chain-link fence); 1 denotes a significant extra degree of difficulty, making it unlikely that an individual or small group could enter the facility and reach the material before guard forces could respond (as might be achieved by alarmed fences, intrusion-detection devices, special locks and reinforcement on doors and other penetrations, etc.); and level 2 denotes a significant further level of difficulty (such as imposed by a highly engineered vault or vault-like building, deep burial, etc.) requiring such quantities of people, equipment, and time to overcome that such an intrusion could not be accomplished covertly, even with the assistance of insiders.4     to require remotely operated facilities to handle materials in these forms. Such facilities represent a substantial increase in the sophistication required for successful processing. 4   It should be noted that the mere presence of fences, alarms, and vaults does not ensure an effective containment system; repeated vulnerability analysis and testing is required to determine whether there are weak points in the system that may have been overlooked.

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options Institutional Barriers. Here 0 would denote an absence of guards or other protective services beyond reliance on local police forces on the usual basis. Level 1 denotes typical industrial security in terms of private guard forces and monitoring of personnel entering and leaving. Level 2 denotes armed guard and monitoring capabilities that would be typical of a nuclear weapons laboratory such as Livermore, including the ability to counter intrusions that involve an insider at the facility. Level 3 denotes a capability (such as would characterize a nuclear weapons storage site) to successfully defend against organized attack by well-armed intruder groups—possibly including the participation of more than one insider—and corresponding inspection and monitoring capabilities. Level 4 means the same physical capabilities as 3, but with multinational or international participation that reduces the possibility of access to the material by the possessor country or by subnational groups under conditions of civil disorder. The Threat and Vulnerability Interaction Our characterization of vulnerability in the matrix format of Table 3-3 is presented in relation to four classes of threat: overt and covert diversion (categories 1.a and 1.b in Table 3-1), and forcible theft and covert threat (categories 2.a and 2.c). Harmful influences (all of category 3) do not lend themselves to characterization in the disaggregated step-by-step format of the matrix and so must be treated separately. Vulnerability at each step to each of the four threat categories considered are characterized simply as "low," "medium," or "high," based on our judgment about the effectiveness of the relevant barriers against the indicated threats. Any more discriminating characterization than this probably would not be warranted in light of the uncertainties associated with threats and barriers alike. Of course, the overall security risk associated with any combination of disposition option and threats will be disproportionately influenced by the characteristics of the most vulnerable step or steps in that option, because the threats are all associated with human intervenors who can be expected to seek out the points of greatest vulnerability. Accordingly, our security-risk comparisons among disposition options—presented in Chapter 6—stress the identification and characterization, for each option, of the most vulnerable step or steps. The foregoing matrix scheme for characterizing security hazards bears some relation to official classification schemes for nuclear materials subject to safeguards, such as those of the U.S. Department of Energy (USDOE 1993c), the U.S. Nuclear Regulatory Commission (NRC) (OFR 1992c), and the International Atomic Energy Agency (IAEA 1987). The DOE scheme, based on a combination of material quantities and "attractiveness levels" related to our "intrinsic barriers," is shown in Table 3-4. The NRC classification is summarized in Table 3-5. The IAEA scheme is similar, defining "significant quantities" of different categories of material and characterizing "conversion times"

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options APPENDIX C:AVOIDED COST AND ASSOCIATED PITFALLS The avoided-cost idea is clear in concept, but choosing a figure for the avoided cost poses problems. Consider the case of a new nuclear-power plant built by the government for the purpose of plutonium disposition. On what basis should the avoided-cost credit for its electricity output be calculated? All of the obvious choices are problematic. The national-average or even regional-average price of electricity to consumers would not be a satisfactory basis, because such prices must cover the costs of transmission and distribution as well as of generation. Using the national-average or regional-average cost of electric utility generation ("busbar" cost) would avoid the extraneous inclusion of transmission and distribution, but would still be problematic in that the average cost typically is lower than the avoided cost (because the new source replaces the costliest of the existing ones). Calculation of actual avoided costs in a given service region, although widely practiced in connection with determinations by public utility commissions of how much must be paid by electric utilities to independent power producers, entails complicated considerations of capacity credits and energy credits that are highly dependent on the circumstances of individual service regions as well as on the characteristics of the new source; thus this approach does not lend itself to use in a preliminary, national-scope assessment of the sort we are undertaking here. The foregoing approaches also suffer from uncertainty about the future: Will other electricity costs have gone up or down by the time that reactors are in operation using WPu? A further problem that can arise with these approaches is the misleading impression produced when avoided-cost estimates based on private-sector generating costs are credited against the costs of plutonium disposition options assumed to have been financed at the low cost of money associated with government borrowing. The result is an artificially low net cost-or an artificially high net revenue-that arises from nothing other than the government's capacity to borrow money for power-plant construction at lower rates than the private sector can borrow. The apparent net gain to a government project from this discrepancy in private versus public cost of money is real in the sense that the government could, in principle, actually collect electricity revenues from its project that are based on the private-sector avoided costs, and in this way could reduce the apparent net costs of the project; but it is artificial and misleading in the

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options sense that government borrowing at lower-than-private-sector rates amounts to a public subsidy which, while regarded as appropriate for strictly governmental functions in the common interest, is regarded as inappropriate, in our society, for activities that compete with the private sector. (That is why the Office of Management and Budget (OMB) insists that economic evaluations of government projects that interact in any way with the private sector should assume a real cost of money comparable to private-sector rates rather than the lower cost of money associated with government borrowing.) The foregoing problem is largely avoided if the government project is costed based on OMB's recommended real cost of money of 7 percent per year, approximating a private-sector rate. The fact that government projects do not pay for property taxes or insurance, however, can be considered a further subsidy, which, accordingly, confers an additional artificial economic benefit on a government project that is credited with private-sector avoided costs.15 As noted above, we here calculate fixed charges based on 7-percent per year real cost of money, both with and without an increment of 2 percent per year of initial investment for property taxes and insurance. With the private-versus-public cost of money pitfall circumvented in this way, a temptingly simple prescription for calculation of the avoided-cost credit would be to assume that the avoided cost is that associated with an identical nuclear reactor using low-enriched uranium (LEU) rather than mixed-oxide (MOX) fuel. This assumption would reduce the new facility, multipurpose case (lower right in Table 3-9) to the preexisting facility, multipurpose case (lower left in Table 3-9), for which it is only necessary to calculate the incremental costs associated with substituting MOX for LEU. This approach would escape most of the region-specific complexity of the usual avoided-cost calculations, and it would have the further benefit of reducing the associated uncertainties about the future to a relatively circumscribed set of questions attached to the future economics of MOX and LEU. It would actually be realistic, moreover, for any region in which there is a plausible case that (1) new baseload generating capacity will be needed in the time frame at issue for plutonium disposition and (2) nuclear energy would be a reasonable choice to meet this need. The first of these conditions—a plausible need for new baseload generating capacity over the next 5-10 years—is satisfied for most places in the United States where plutonium disposition might be contemplated. The weakness in the case for using the same-reactor-but-with-LEU approach to avoided cost is in the second condition: few analysts today would argue that nuclear plants would be likely to be chosen, in the absence of the plutonium disposition mission, for new 15   For a 7-percent per year real cost of money and nominal plant lifetime of 30 years, the fixed charge rate without allowance for property taxes and insurance would be 0.0806 per year; an allowance of 2 percent for these costs would make it 0.1006 per year, representing about a 25-percent increase in the fixed charge rate and hence in the annual capital charges.

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options capacity needs in the United States in the next 5-10 years. And to the extent that the options more likely to be chosen would have electricity costs lower than those of nuclear plants using LEU, basing the avoided-cost estimates on the nuclear case would overestimate those avoided costs and thus lead to an underestimate of the true cost of plutonium disposition using the MOX option. These considerations point to the conclusion that the best way to estimate avoided costs for our purposes is to project the cost of the electricity generated by the options most likely to be chosen in the next decade for new baseload capacity, in the absence of a plutonium disposition program, in the regions where new (or newly completed) reactors for plutonium disposition would operate. These are the electricity sources on which reliance would be reduced by electricity generation in connection with plutonium disposition.16 The problem of predicting what electricity-generation technologies will be chosen for new baseload capacity becomes more difficult, obviously, the further in the future is the time frame in which one is interested. For the period 5-10 years hence, however, in which plutonium disposition using newly built (or newly completed) reactors of existing types could begin, a rather good case can be made that the baseload-generation technology of choice in most parts of the United States is likely to be combined-cycle, natural-gas-fired power plants.17 When the cost of electricity from such plants in the period 2000-2030 is estimated using the approaches and assumptions described in this section, with allowance for uncertainties in the future price of natural gas, the result of the levelized annual cost approach is $0.04-$0.06 per kilowatt-hour (kWh);18 a range of $0.05-$0.08/kWh appears in a recent review of mostly rather small projects for combined-cycle gas-fired baseload electricity generation (Kahn et al. 1993), but a recent analysis of the economic prospects of operating pluto- 16   The avoided-cost estimates obtained in this way will of course differ from those that would be obtained by the same-reactor-but-with-LEU method only insofar as the projected generation costs of the expected new capacity differ from those projected for plutonium disposition reactors using LEU instead of MOX. 17   See Kahn et al. (1993), Hudson (1993), USDOE (1993b). This is what is planned, for example, in Washington state, which would be a leading contender for exercising the MOX option for plutonium disposition by virtue of the location there of a partially completed MOX fabrication facility as well as two partially completed nuclear reactors potentially available for the plutonium disposition mission. 18   A figure of $0.047/kWh follows from Hudson's (1993) estimate of $600 (1992 dollars) per kWe total overnight capital cost for a combined-cycle gas-fired power plant, interest during construction at r = 0.07 for 4.5 years yielding a multiplier of 1.2 (interpolated in Table 3-7), capacity factor of 0.75, fixed charge rate = 0.1006/yr (corresponding to r = 0.07, n = 30 years, and property tax and insurance assessment of 0.02/yr), natural gas cost in 2015 of $4.25 (1992 dollars) per million Btu (British thermal unit) (USDOE 1993b), heat rate 7,600 Btu/kWh, and nonfuel operation and maintenance costs of 0.004 1992 dollars/kWh (Hudson 1993). Sensitivities: natural gas price ±30 percent yields ±$0.01/kWh; overnight construction cost 30 percent higher adds $0.003/kWh: real cost of money r = 0.10 adds $0.004/kWh (actual cost of money employed by firms in the wholesale electricity market may be higher still).

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options nium disposition reactors in the Northwest United States uses a range of $0.037-$0.043/kWh for gas-fired combined-cycle baseload power generation in that region (SAIC 1993); the DOE PDS analysis uses $0.030/kWh for the reference revenue from electricity sales and explores sensitivity to a range from $0.022/kWh to $0.060/kWh (USDOE 1993a). (All figures have been converted to 1992 dollars. For our analysis we choose a reference value of $0.050/kWh with a judgmental 70-percent confidence interval of ±$0.015/kWh.

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options APPENDIX D:PREDICTED DAMAGES FROM THE DOSES PERMITTED BY STANDARDS The dose limits are all below the levels that produce symptoms of acute radiation sickness, which are seen only at 0.5-1 sievert (Sv) (50-100 rem) and above. The potential consequences of exposures not exceeding these limits are therefore confined to the so-called “latent" effects, of which the ones of greatest concern are increased incidence of cancer and genetic defects. The dose-response relations governing the magnitudes of the increases to be expected from doses in the indicated ranges have been the subject of much study—and an equal amount of controversy—extending over the past half-century. The source of the controversy is that at dose rates close to those received by everyone from natural background radiation, which are in the range of 1 mSv (100 mrem) per year to the whole body, the increased incidences of cancer and genetic defects predicted from downward linear extrapolation of incidences observed at higher dose rates are too small to be unambiguously detected either in animal experiments of practical scale or in human epidemiological studies with their inescapable array of confounding factors. Virtually all of the national and international regulatory and advisory bodies dealing with radiation hazards have taken the position for many years, however, that standards and policy should be based on the assumption that increases in the incidence of cancer and genetic defects persist in linear proportion to the dose, down to the lowest doses and dose rates experienced (the "linear hypothesis").19 The most recent comprehensive review of this subject by the National Research Council's Committee on Biological Effects of Ionizing Radiation (National Research Council 1990, p. 4, hereinafter BEIR V) underscores this position, finding that the latest data "do not contradict the hypothesis, at least with respect to cancer induction and hereditary genetic defects, that the frequency of such effects increases with low-level radiation as a linear, nonthreshold function of dose." The report gives the dose-response relation for cancer as a population weighted lifetime excess risk of death of cancer of 0.8 percent (90-percent confidence interval 0.6-1.2 percent) from a whole-body dose of 0.1 Sv, quickly delivered, and indicates that some reduction in this risk—"possibly by a factor of 2 or more"—is to be expected for gamma and beta (but not alpha and neutron) radiation that is slowly delivered. 20 19   The question is not, as sometimes misstated, the slope of the dose-response curve for doses near zero, but rather the slope of the curve for doses near natural background, since that is the level to which any anthropogenic dose, however small, is added. 20   In contrast to a view often expressed in earlier studies, moreover, that the linear hypothesis provides an upper limit to the plausible consequences of low-level radiation exposure, the BEIR V report states (p. 6) that "The Committee recognizes that its risk estimates become more uncertain when applied to very low doses. Departures from a linear model at low doses, however, could either increase or decrease the risk per unit dose."

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options Expressed in terms of population dose (the product of the size of the exposed population and the average dose in that population, measured in person-sieverts or person-rem), the best-estimate dose-response relations are 800 excess cancer deaths per 104 person-Sv (million person-rem) for gamma and beta radiation at high dose rates or neutron and alpha irradiation at any dose rate, and 400 excess cancer deaths per 104 person-Sv for gamma and beta radiation at low dose rates. The incidence of excess genetic defects induced by radiation is considerably more uncertain, but the estimates given in the BEIR V report are equivalent to 30-70 excess genetic defects per 104 person-Sv—an incidence rate some 10 times less than that of excess cancer deaths, and spread over a considerably longer (multigeneration) period. We focus, then, on the cancer deaths as the dominant latent consequence. The once-in-a-lifetime emergency dose limit of 0.25 Sv, whole body, to a member of the public would correspond, at the dose-response relation of 0.8-percent chance of cancer death per 0.1 Sv (appropriate to rapid delivery of the dose, as could be the case for an individual near a reactor at the time of an accidental release of radioactivity), to a 2-percent chance of dying of cancer. If the dose is delivered slowly (as from ground contamination at a greater distance from an accidental release) and consists mainly of gamma and beta radiation, use of the factor of 2 credit for dose protraction gives a 1-percent chance of dying of cancer from this dose. These figures can be compared to the 20- to 25-percent chance of dying of cancer, in industrial societies, from the sum of all causes. The increase in the chance of cancer death from the allowable one-time emergency dose, then, is in the range of 4 to 10 percent of the preexisting chance. (Of course, the probability that any given individual in a society will actually experience such an emergency dose in his or her lifetime is very low, and this would be the case even if the probabilities of reactor accidents were much higher than we believe them to be.) A dose-rate limit of 1 mSv per year, whole body, to members of the public from routine releases of radioactivity in various contexts appears in NRC, EPA, and IAEA regulations (see "Some Relevant Standards Limiting Doses and Emissions" on p. 94). Taking the dose-response relation to be 0.4- to 0.8-percent chance of cancer death per 0.1 Sv (the lower figure for gamma and beta radiation, with credit for dose protraction, and the higher one for alpha particles and neutrons, where no such credit is applied), the added chance of cancer death experienced by an individual receiving this dose rate would be 0.004-0.008 percent per year of such exposure. The chance of death from all causes in the U.S. population is about 0.9 percent per year and the chance of death from cancer is about 0.2 percent per year (US Dept of Commerce 1992). The chance of dying eventually of cancer is currently about 19.5 percent in the U.S. popula-

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options tion, a figure that would be increased to 20.0-20.5 percent21 by continuous lifetime exposure at the 1-mSv/yr limit (National Research Council 1990). At the 0.1-mSv/yr limit allowable in NRC and EPA regulations for exposures received by an individual member of the public from a single facility, the predicted incremental probabilities of death from cancer would of course be 10 times smaller. The occupational dose limit of 0.05 Sv per year would correspond, at 0.40.8 percent probability of cancer death per 0.1 Sv, to an extra chance of cancer death of 0.2-0.4 percent per year. Exposure to this dose rate continuously from the age of 18 to the age of 65 would produce an extra probability of cancer death of 15 percent-raising the preexisting probability of death from cancer from about 20 to 35 percent-according to the best estimate of the BEIR V report based on a calculation accounting for age- and gender-specific susceptibilities in a working population of half men and half women. Actual average doses in the nuclear industry are, fortunately, about 10 times lower than permitted by the standard. Downward revision of this standard is under consideration. 21   This is based on a 90-percent confidence interval of 0.5-1.0 percent for the increment, according to a calculation in BEIR V accounting for age- and gender-specific susceptibilities. The three-figure precision on the total is illusory but serves to indicate the size of the change.

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options IAEA 1986: International Atomic Energy Agency. Definition and Recommendations for the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter in the Ocean, 1972. Safety Series No. 78. Vienna: IAEA, 1986. IAEA 1986: International Atomic Energy Agency. Principles for Limiting Releases of Radioactive Effluents into the Environment. Safety Series No. 77. Vienna: IAEA, 1986. IAEA 1987: International Atomic Energy Agency. IAEA Safeguards Glossary. Vienna: IAEA, 1987. IPPNW/IEER 1992: International Physicians for the Prevention of Nuclear War and Institute for Energy and Environmental Research. Plutonium: Deadly Gold of the Nuclear Age. Cambridge, Mass.: International Physicians Press, 1992. Kahn et al. 1993: Edward Kahn, Adele Milne, and Suzie Kito. The Price of Electricity from Private Power Producers. LBL-34578. Energy and Environment Division, Berkeley, Calif.: Lawrence Berkeley Laboratory, October 1973. NAS 1979: National Academy of Sciences, Committee on Science and Public Policy and Committee on Literature Survey of Risks Associated with Nuclear Power. Risks Associated with Nuclear Power: A Critical Review of the Literature. Summary and Synthesis Chapter. Washington, D.C.: The Academy, 1979. NAS 1994: National Academy of Sciences, Committee on International Security and Arms Control. Management and Disposition of Excess Weapons Plutonium. Washington, D.C.: National Academy Press, 1994. National Research Council 1980: National Research Council, Committee on Nuclear and Alternative Energy Systems . Energy in Transition 1985-2000. San Francisco: W.H. Freeman, 1980. National Research Council 1989: National Research Council. The Nuclear Weapons Complex: Management for Health, Safety, and the Environment. Washington, D.C.: National Academy Press, 1989. National Research Council 1990: National Research Council, Committee on the Biological Effects of Ionizing Radiation. Health Effects of Exposure to Low Levels of Ionizing Radiation (BEIR V). Washington, D.C.: National Academy Press, 1990. National Research Council 1992: National Research Council, Committee on Future Nuclear Power Development. Nuclear Power: Technical and Institutional Options for the Future. Washington, D.C.: National Academy Press, 1992. OECD 1976: Organization for Economic Co-operation and Development, Nuclear Energy Agency. Estimated Population Exposures from Nuclear Power Production and Other Radiation Sources. Paris: OECD, 1976.

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options OFR 1992a: Office of the Federal Register. U.S. Code of Federal Regulations: Title 10 (Energy), Chapter I (Nuclear Regulatory Commission). Washington, D.C.: U.S. Government Printing Office, 1992. OFR 1992b: Office of the Federal Register. U.S. Code of Federal Regulations: Title 40 (Protection of Environment), Chapter I (Environmental Protection Agency). Washington, D.C.: U.S. Government Printing Office, 1992. OFR 1992c: Office of the Federal Register. U.S. Code of Federal Regulations, Title 10, Part 73, "Nuclear Regulatory Commission: Physical Protection of Plant and Materials." Washington, D.C.: U.S. Government Printing Office, 1992. OMB 1992: Office of Management and Budget. "Guidelines and Discount Rates for Benefit-Cost Analysis of Federal Programs." OMB Circular A-94. Washington D.C., October 29, 1992. OTA 1984: Office of Technology Assessment. Nuclear Power in an Age of Uncertainty. OTA-E-216. Washington, D.C.: U.S. Government Printing Office, 1984. SAIC 1993: John R. Honekamp, Vice President, Science Applications International Corporation. "Isaiah Project Proposal Economic Analysis." Letter to Matthew Bunn, Staff Director of the Committee on International Security and Arms Control plutonium study, National Academy of Sciences, Washington, D.C., November 9, 1993. US Dept. of Commerce 1992: U.S. Department of Commerce, Bureau of the Census. Statistical Abstract of the United States, 112th ed. Washington, D.C.: U.S. Government Printing Office, 1992. USDOE 1988: U.S. Department of Energy. Nuclear Energy Cost Data Base—A Reference Data Base for Nuclear and Coal-Fired Power Plant Generation Cost Analysis . DOE/NE 0095. Washington, D.C.: U.S. Department of Energy, September 1988. USDOE 1993a: U.S. Department of Energy, Office of Nuclear Energy. Plutonium Disposition Study: Technical Review Committee Report, 2 Vols., Washington, D.C., July 2, 1993. USDOE 1993b: U.S. Department of Energy, Energy Information Administration. Annual Energy Outlook 1993. DOE/EIA-0383(93). Washington, D.C.: U.S. Department of Energy, 1993. USDOE 1993c: U.S. Department of Energy. "Control and Accountability of Nuclear Materials." Order 5633.3A. U.S. Department of Energy, Washington, D.C., February 12, 1993. USEPA 1973: U.S. Environmental Protection Agency, Office of Radiation Programs. Environmental Analysis of the Uranium Fuel Cycle. Washington, D.C.: Environmental Protection Agency, 1973. USNRC 1975: U.S. Nuclear Regulatory Commission. Reactor Safety Study: An Assessment of Accident Risks in U.S. Commercial Nuclear Power Plants.

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Management and Disposition of Excess Weapons Plutonium: Reactor-Related Options WASH-1400 / NUREG-75/014. Springfield, Va.: National Technical Information Service, October 1975. USNRC 1976: U.S. Nuclear Regulatory Commission. Final Generic Environmental Statement on the Use of Recycle Plutonium in Mixed Oxide Fuel in Light-Water Cooled Reactors. NUREG-0002. Springfield, Va.: National Technical Information Service, August 1976. USNRC 1987: U.S. Nuclear Regulatory Commission. Reactor Risk Reference Document. NUREG-1150. Springfield, Va.: National Technical Information Service, February 1987. USNRC 1989: U.S. Nuclear Regulatory Commission. Severe Accident Risks: An Assessment for Five U.S. Nuclear Power Plants. NUREG 1150. Springfield, Va.: National Technical Information Service, June 1989.