The application of gas-cooled reactor technologies to the transmutation ofnuclear waste

Nuclear waste from commercial power plants contains large quantities of plu tonium, other fissionable actinides, and long-lived fission products that p ose longterm safe storage problems. Along with materials from weapons decom missioning programs, they are also a proliferation concern. Based on curren t levels of global nuclear power generation, it is estimated that by 2015 t here will be more than 250,000 tons of spent fuel worldwide. This waste wil l contain over 2,000 tons of plutonium. (There is also more than 100 tons o f plutonium becoming available from disarmament programs.) The disposal of this nuclear waste from commercial and defense programs has become a significant environmental and political issue. Long-term uncertai nties are hampering the acceptability of a geologic repository for spent fu el in the U.S. The greatest concerns are with the potential for radiation r elease and exposure from the waste, and the possible diversion of fissionab le material. The development of high-power accelerators has brought up the possibility o f a technological solution to the problem. This is the so-called accelerato r transmutation of waste (ATW), in which an intense beam of protons is used to produce a large, high-energy neutron flux in a spallation target. The t arget is surrounded by a multiplying medium of the plutonium and actinide w aste, which is destroyed by neutron fission and capture. This paper describes the application of gas-cooled technology to the ATW, w hich can result in the elimination of weapons-useful material in the waste in one pass, without intermediate reprocessing, along with at least an orde r of magnitude reduction in the amount of reactor-generated transuranic (TR U) waste. Repository heat loads and the radio-toxicity of the waste are dra matically reduced. The process provides a waste form that is highly resista nt to corrosion. It is also passively safe and does not produce mixed waste . The use of gas-cooled nuclear technology also provides maximum flexibility in the transmutation approach, and can allow the use of a direct-cycle gas- turbine generator power conversion system to produce electricity with 47% e fficiency. Economic analyses suggest that gas-cooled transmutation systems are economically viable and would attract private investment for deployment . (C) 2001 Elsevier Science Ltd. All rights reserved.