An Estimate of the Contribution of Spent Fuel Products to the Releasable Source Term in Spent Fuel Transport Casks*

The radioactive source terms pertinent to spent fuel transport cask safety assessments are of three distinct origins; residual contamination within the cask due to previous transport and handling operations, \"crud\" deposited on the fuel rods in the course of reactor operation, and the radioactive material contained within the rods. Although the last source overwhelms the others in terms of inventory, its release into the cask, and thence into the biosphere, requires the breach of an additional release barrier, viz., the fuel rod cladding. Hence an evaluation of the fuel source term is complicated by the need to address the likelihood of fuel cladding failure during transport.