Thorium fuel cycle radiotoxicity

One of the advantages often cited for the thorium fuel cycle is a significant reduction in the production of long-lived transuranic actinides. It has lower "radiotoxicity" than uranium-based fuels, and so fhe source term in the waste management vault will be lower. 

The MSR (see Fig. 2.7) embodies the very special feature of a liquid fuel. MSR concepts, which may be used as efficient burners of transuranic elements from spent LWR fuel, also have a breeding capability in any kind of neutron spectmm ranging from thermal (with a thorium fuel cycle) to fast (with a uranium—plutonium fuel cycle). Whether configured for burning or breeding, MSRs have considerable promise for the minimization of radiotoxic nuclear waste. 

Thorium-to- U breeders with actinide recycle would produce several orders of magnitude less transuranic waste than a conventional LWR once-through cycle and significantly less than even a U-Pu fast breeder (based on 0.1% losses during fuel processing). This leads to the radiotoxicity of waste being less than the equivalent uranium ore used in LWRs within a few hundred years. 

Nonetheless, many proponents of the thorium cycle promote this feature, and indeed, many detractors of tiie nuclear industry cite the long-term radiotoxicity in spent uranium-based fuels as a major issue. 

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