Analytic Methods for Fuel-Cycle Safety Studies

Battelle-Northwest (BNW) is conducting safety studies of the following nuclear fuel cycle operations: reprocessing, transportation of radioactive material, decommissioning of facilities, and waste management. Various methods and depths of analysis are used in these studies, but all involve safety quantification in terms of risk, relating probabilities and consequences of potential accidents. This paper describes the methods used for these safety studies. Highlighted are areas in which BNW contributions have extended the analytic methods: 1) a risk-based fault-tree analytic method for identification, preliminary evaluation, and screening of potential release sequences; 2) improved treatment of deposition and resuspension in airborne transport of radionuclides; and 3) groundwater transport models of radionuclide chains in soil columns, including the effects of convection, difusion, sorption, and generation and decay. Areas needing additional development are identified.