Year
2011
Abstract
A methodology was developed previously by SRNL to show that Al-SNF with cladding breaches can be directly transported in standard casks and maintained within the allowable release rates. This novel approach may be extended to other nuclear material systems. Utilizing an adaptation to the methodology, a containment analysis has been performed for the scenario of non-routine transfer of a damaged 9975 package containing plutonium metal from K-area monitored storage to F-area on the Savannah River Site. A multiple barrier system with each barrier having a defined leakage rate of less than 1x10-3 cm3/sec of air at Standard Temperature and Pressure was analyzed to determine the number of barriers needed to transport the package under normal transportation conditions to meet transportation requirements for containment. The barrier system was analyzed parametrically to achieve a composite system that met the federal requirements for the maximum permissible release rate. The multiple barrier system acts to retard the release of radioactivity. That is, a build-up in the radioactivity release rate occurs with time. For example, a system with three barriers (e.g., sealed plastic barrier) with a total free volume of 4,500 cm3 could be transported for a total time of up to approximately 10 days with a release rate within the permissible rate. Additional number of barriers, or volume of the barriers, or both, would extend to this period of time. For example, a system with seven barriers with a total free volume of 4,500 cm3 could be transported for up to 100 days. Plastic bags are one type of barrier used in movement of radioactive materials and capable of achieving a leak rate of 1x10-3 cm3/sec of air at STP. Low-density polyethylene bags can withstand high temperature (up to 180°C); a barrier thickness of 10 mils should be suitable for the barrier system.