ABSTRACT
The types of light- and heavy-water reactors, operated under safeguards, with no reprocessing of spent fuel and early removal of spent rods from the storage pond, provide a standard to be used in evaluating how readily the proliferation of other technologies can be limited. Such a standard or benchmark obviously only makes sense if international agreements for the use of nuclear power preclude other means of legitimately obtaining nuclear explosive materials, a point often overlooked in criticism of "once-through" systems. The thorium-uranium-233 breeder "denatured" with uranium-238 might also meet the benchmark test of proliferation safety while saving greatly on uranium. This might be done by preirradiation of fresh fuel, by spiking it with fission products, or by leaving some fission products in the fuel during reprocessing. However, the suitability of incorporating fission products in thermal reactors is even more questionable than it would be in fast reactors.
