Radiological and environmental aspects of Th-U fuel cycle facilities

Abstract

The comparatively higher level of thorium reserves and the absence of long lived actinides of environmental concern offer real advantages for utilization of thorium in nuclear reactors. While use of uranium is likely to continue for some more time in view of investments already made, a shift to thorium eventually is an imperative necessity. It is in fact inevitable for a country like India. The paper presents a detailed comparative analysis of occupational radiation exposures as well as environmental releases. Different stages such as mining, fuel fabrication, reactor operation, spent fuel storage and reprocessing are considered. The factors that need to be taken into account include among others, the relatively lower occupational exposures and environmental releases in sodium cooled fast reactors compared to LWRs, the occurrence of thorium as surface deposits obviating the need for deep mining as in the case of uranium and the special dose reduction measures that need to be devised to minimize occupational exposures due to daughter products of 232U present in 233U during fuel fabrication operations. If once through mode of fuel cycle is to be adopted, thorium oxide materials are likely to be more enduring than would be the case with uranium.