The Spent-Fuel Standard for Disposition of Excess Weapon Plutonium Application to Current DOE Options (2000) / Chapter Skim
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Clarifying the Spent-Fuel Standard
Clarifying the Spent-Fuel Standard
Pages 11-31
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From page 11... ...
Rather, it describes a condition in which weapons plutonium has become roughly as difficult to acquire, process, and use in nuclear weapons as it would be to use plutonium in commercial spent fuel for this purpose. The rationale for the spent-fuel standard is, first, that the bulk, composition, and ionizingradiation field of spent fuel pose very appreciable barriers to the theft or diversion of this material and extraction of contained plutonium for use in nuclear weapons and, second, that the existence in the world of many hundreds of tons of civilian plutonium in spent fuel means that there 11
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From page 12... ...
Dependence on intrinsic properties only The CISAC reports also stressed that meeting the spent-fuel standard depends only on the intrinsic properties of the final plutonium form associated with a disposition option. "Intrinsic" means, in this context, the properties of the smallest plutonium-containing item that could be removed from an interim or final repository for the dispositioned form, or from a vehicle transporting plutonium in this form to such a repository, without a degree of physical processing likely to be impractical for anybody but the host state itself.
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From page 13... ...
The spent-fuel standard was not developed to describe overall proliferation resistance, but only to describe the contribution to overall proliferation resistance that should appropriately be sought from the intrinsic properties of the final plutonium form. The original CISAC formulations about this standard were intended to make clear that it should be regarded as (a)
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From page 14... ...
· At the same time, the spent-fuel standard is not sufficient because, as the original CISAC reports stressed, the intrinsic barriers to acquiring, processing, and using in weapons the plutonium embedded in typical spent fuel are not high enough for this material to be considered adequately "self protecting." Thus additional engineered and institutional barriers are appropriate for this material and for other plutonium forms with intrinsic barriers comparable to those of typical spent fuel. Indeed, society should plan to increase these engineered and institutional barriers against the weapons use of spent fuel and comparable material over time (including, eventually, by emplacement of the material in a monitored geologic repository)
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From page 15... ...
. First, not only is a judgment on intrinsic properties of the final plutonium form insufficient (even though necessary)
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From page 16... ...
Defining and implemenUng standards for disposition of excess weapons plutonium is important, but it is not a substitute for and should not distract attention from these other steps. Application of the standard to final plutonium forms in the initial CISAC study The first volume of the CISAC plutonium study (1994)
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From page 17... ...
10~3 With respect to security of the final plutonium forms, the current-reactor options obviously meet the spent-fuel standard, and the Panel judges that the vitrification option meets this standard also. The plutonium In the spent fuel assembly would be of lower isotopic quality for weapon purposes than the still weapons-grade plutonium In the glass log, but since nuclear weapons could be made even with the spent fuel plutonium this difference is not decisive.
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From page 18... ...
This design was developed subsequent to the 1995 CISAC report's determination that the then-current vitrification-with-wastes immobilization option and the once-through MOX option both meet the spent-fuel standard. In the new variant—called the "can-in-canister" approach plutonium oxide is incorporated in ceramic pucks that themselves contain no fission products; the pucks are stacked in an array of cans suspended on a frame in a large steel canister; and molten borosilicate glass, bearing fission products, is poured into the canister to solidify around the cans and thus contain them in a massive, highly radioactive glass log.
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From page 19... ...
DOE's choice of the heterogeneous can-~n-can~ster approach allowed staying with the original glass composition to contain the fission products, while gaining the improved performance of ceramic as the pluton~um-conta~n~ng material (including greater durability under repository conditions and greater ease of nondestructive assay for verification purposes) and avoiding criticality concerns attendant on adding multiple critical masses of plutonium to 1,700 kilograms of molten glass and fission products at a time.
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From page 20... ...
MOX or the relatively low mass and radiation field associated with spent CANDU MOX fuel assemblies would make these plutonium forms significantly more proliferation prone than typical spent fuel from lightly enriched uranium (LEU) -fueled LWRs.
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From page 21... ...
Interactions of threats and barriers The three main classes of proliferation threats to which intrinsic barriers provided by final plutonium forms are germane are as follows: (1) "Host-nation breakout" means that the country legitimately holding the dispositioned plutonium elects to recover it for re-use in its nuclear arsenal.
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From page 22... ...
We summarize our judgments on the interaction of threats and intrinsic barriers in Table 1, which arranges the characteristics of final plutonium forms according to the barriers these characteristics provide at different steps in the proliferation chain and indicates the relative importance of these barriers against the three classes of proliferation threats. The relative-importance ratings reflect a combination of the needs/capabilities of the threat groups with the nature of the barriers.
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From page 23... ...
c Importance depends on sensor capabilities. d Importance depends on degree of proliferant state concern with detection.
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From page 24... ...
to a state engaged in open breakout, and of only low consequence to a state engaged in clandestine breakout. But we believe it is of high importance in relation to theft for a proliferant state or a subnational group, because concentration even more than individual item size determines the scale of the entire theft operation (personnel and equipment)
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From page 25... ...
This barrier would be greater against theft for a proliferant state or a subnational group, but we rate it as "moderate" in importance rather than "high" for two reasons: first, even the highest radiation fields associated with spent fuel and other plutonium-disposition forms would not produce immediately incapacitating doses if the thieves took modest precautions; and, second, many potential thieves (and their bosses) might not give high priority to the avoidance of the kinds of doses that would be involved (either out of ignorance or out of willingness to bear the risk or impose it on someone else—in exchange for expected high reward)
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From page 26... ...
The intrinsic barriers against these activities and the bases for our judgments about their relative importance are as follows: . The technical difficulty of mechanical disassembly of the plutoniumcontaining items would be a barrier of only low importance in the context of host-nation breakout, inasmuch as such nations would have facilities adequate to handle this rather easily for any imaginable disposition form.
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From page 27... ...
We judge the importance of this barrier to be "moderate to high" in the case of theft for a proliferant state, depending on who is doing the processing and, in the event it is being done by the proliferant state, depending on the importance attached to concealment and on the sophistication of the facilities available to the particular state. The radiation, criticality, and toxic hazards during the separation process are barriers of only low importance in the case of host-nation breakout, because these nations have ample facilities and experience for minimizing these risks.
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From page 28... ...
These considerations In combination lead us to rate the detectability barriers as "zero to moderate" for the case of host-nation breakout, "moderate to high" In the case of theft for a proliferant state, and "high" for the case of the theft for a subnational group. The last set of intrinsic barriers addressed In Table 1 are those against the utilization of the plutonium that the proliferators are able to separate for the fabrication of functional nuclear weapons.
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From page 29... ...
But, as emphasized In the previous CISAC plutonium reports and In other unclassified but authoritative studies, the differences do not preclude the design and construction of effective nuclear weapons from typical spentfuel plutonium, at all levels of sophistications We rate the barrier posed by isotopic deviations from weapons grade as "moderate" In importance for host-nation breakout In Table 1 mainly because recovery of weapons-grade plutonium from dispositioned forms would permit production of weapons from existing designs without new nuclear-explosive tests, whereas use of plutonium of different isotopic compositions would be likely to entail design modifications and, even if not, would probably require new nuclear-explosive tests to confirm that the change in isotopic composition had not unacceptably degraded performance. In the case of theft for a proliferant state we rate the barrier likewise as "moderate" In importance: such a state would probably prefer to avoid if possible the burdens posed by isotopic deviations for design, fabrication, and maintenance of nuclear weapons, but it would also probably have the capabilities to cope with these burdens In ways that achieved a level of weapon performance adequate for a proliferant state's initial purposes.
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From page 30... ...
With respect to the ''theft for proliferant state" and "theft for subnational group" threats, various military and civilian stocks of already separated plutonium and highly enriched uranium are likely to remain more attractive targets for proliferators than spent fuel or dispositioned plutonium forms would be for some years to come. It is, nonetheless, important to move forward now with plutonium disposition- and, in that connection, important to determine the compliance of candidate approaches with the spent-fuel standard both because disposition of excess plutonium is a process that will require decades under the best of circumstances (during which time it may be hoped that the stocks of warheads, separated plutonium, and highly enriched uranium will have been greatly reduced)
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From page 31... ...
the technical difficulty of chemical separation of the plutonium from solution, and (d) the size of the aids to detection of these activities provided by their thermal, chemical, and nuclear signatures and the scale of the needed facilities.
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