In the absence of shielding, "ordinary" nuclear weapons-those containing kilogram quantities of ordinary weapon-grade (6 percent plutonium-240) plutonium or uranium-238-can be detected by neutron or gamma counters at a distance of tens of meters. Objects such as missile canisters can be radiographed with high-energy x-rays to reveal the presence of the dense fissile core of any type of nuclear warhead, or the radiation shielding that might conceal a warhead. If subjected to neutron irradiation, the fissile core of any type of unshielded warhead can also be detected by the emission of promptor delayed-fission neutrons at a distance on the order of 10 meters.Devices capable of detecting the presence of nuclear weapons could be useful in verifying compliance with various arms control agreements. Examples include monitoring a ban of nuclear weapons on ships, verifying limits on the number of nuclear warheads on individual ballistic missiles, and verifying limits on the nuclear versions of dual-capable weapons such as sea-launched cruise missiles.To the best of our knowledge, all nuclear weapons contain at least several kilograms of fissile material-material that can sustain a chain reaction. Such material provides the energy for fission explosives such as those that destroyed Hiroshima and Nagasaki; it is also used in the fission triggers of

has had a good safety record, with the ma-

This report assesses the economics of reprocessing versus direct disposal of spent nuclear fuel. The breakeven uranium price at which reprocessing spent nuclear fuel from existing light-water reactors (LWRs) and recycling the resulting plutonium and uranium in LWRs would become economic is assessed, using central estimates of the costs of different elements of the nuclear fuel cycle (and other fuel cycle input parameters), for a wide range of range of potential reprocessing prices. Sensitivity analysis is performed, showing that the conclusions reached are robust across a wide range of input parameters. The contribution of direct disposal or reprocessing and recycling to electricity cost is also assessed. The choice of particular central estimates and ranges for the input parameters of the fuel cycle model is justified through a review of the relevant literature. The impact of different fuel cycle approaches on the volume needed for geologic repositories is briefly discussed, as are the issues surrounding the possibility of performing separations and transmutation on spent nuclear fuel to reduce the need for additional repositories. A similar analysis is then performed of the breakeven uranium price at which deploying fast-neutron breeder reactors would become competitive compared with a once-through fuel cycle in LWRs, for a range of possible differences in capital cost between LWRs and fast-neutron reactors. Sensitivity analysis is again provided, as are an analysis of the contribution to electricity cost, and a justification of the choices of central estimates and ranges for the input parameters. The equations used in the economic model are derived and explained in an appendix. Another appendix assesses the quantities of uranium likely to be recoverable worldwide in the future at a range of different possible future prices.iii

In Part I we calculated 10 CFR 61 "Class-C" specific activity limits for all long-lived radionuclides with atomic number less than 88 (Ra). These calculations were based on the whole-body dose. We also estimated the production of these radionuclides from all naturally occurring elements with atomic numbers less than 84 (Po) in the first wall of a typical fusion reactor, and thereby derived concentration limits for these elements in first-wall materials, if the first wall is to be suitable for Class-C disposal. In Part II we use the "effective dose equivalent" (EDE), which is a much better indication of the risk from radiation exposure than the whole-body dose, to calculate specific activity limits for all long-lived radionuclides up to Cm-248. In addition, we have estimated the production of long-lived actinides and fission products from possible thorium and uranium impurities in first-wall structures. This completes our study of long-lived radionuclides that are produced from all elements that occur in the earth's crust at average concentrations greater than one part per trillion.