EQ6 Calculations for Chemical Degradation of TRIGA Codisposal Waste PacKages

The Monitored Geologic Repository Waste Package Operations of the Civilian Radioactive Waste Management System Management & Operating Contractor (CRWMS M&O) performed calculations to provide input for disposal of spent nuclear fuel (SNF) from the Training, Research, Isotopes, General Atomics (TRIGA) reactor (Ref. 1). The TRIGA SNF has been considered for disposal at the potential Yucca Mountain site. Because of the high content of fissile material in the fuel, the waste package design requires special consideration of the amount and placement of neutron absorbers, and of the possible loss of absorbers and fuel materials over geologic time. For some waste packages, the corrosion-allowance material and the corrosion- resistant material may breach (Ref. 3), allowing the influx of water. Water in the waste package moderates neutrons, increasing the likelihood of a criticality event within the waste package; and the water may, in time, gradually leach the fissile components and neutron absorbers out of the waste package, further affecting the neutronics of the system.