Thermal response of the waste package/MPC and EBS

Thermal evaluations of the multi-Purpose Canister in repository emplacement have been performed by the Yucca Mountain Site Characterization Project Managing and Operating Contractor (YMP-M ampersand O). Thermal effects have been a major study area of the Mined Geologic Disposal System (MGDS). In the past the project has concentrated primarily on borehole-emplaced waste packages, but the Multi-Purpose Canister (MPC) with a capacity of twenty-one pressurized water reactor (PWR) fuel assemblies (or more) will likely be drift emplaced with a multi-barrier disposal container or overpack. This study investigates the thermal behavior of the waste package/MPC and its effect on the repository near-field. Results indicate that peak internal temperatures occur one to five years post emplacement, and the timing of the peak is highly dependent on the choice of design basis fuel and thermal loading. The maximum acceptable capacity of the MPC, with ten year old fuel, was determined to be twenty-one PWRs based on the current peak temperature goal of 350 degrees C; however, higher capacities can be achieved if older fuel is substituted