The long-term (>1000 years) hazard of radioactive waste emplaced in a geologic repository could be reduced by separating the most significant long-lived radionuclides and transmitting them to stable products by bombardment with neutrons in power reactors. A cost-risk-benefit analysis of this concept shows that, while it is technically feasible to partition and transmute the principal long-lived constituents, there are no cost-risk-benefit incentives that can be identified. The cost of partitioning and transmuting the actinide elements is estimated to be $9.2 million/ GW(electric). yr [1.28 mill/kWh(electric)]. The shortterm radiological risk is increased by 0.003 health-effect/GW(electric). yr, and the expected long-term benefit (i.e., incremental risk reduction from a repository) is 0.06 health-effect/GW(electric ).yr integrated over 1 million years. The latter is only ∼0.001% of the health effects expected from natural background radiation and is equivalent to $32 400 per person-rem saved. If nonradio logical risks are included, the short-term risk actually exceeds the long-term benefits.
