Spent fuel dry storage technology development: thermal evaluation of isolated drywell containing spent fuel (1.25 kW PWR spent fuel assembly)

A spent fuel Isolated Drywell Test was conducted at the Engine-Maintenance, Assembly and Disassembly (E-MAD) facility on the Nevada Test Site utilizing a pressurized water reactor spent fuel assembly having a decay heat level of approximately 1.25 kW. The fuel assembly was encapsulated inside the E-MAD Hot Bay and placed in an instrumented near-surface drywell is located 50 feet from an adjacent drywell. Instrumentation provided to measure canister, liner and soil temperatures consisted of thermocouples which were inserted into tubes on the outside of the canister and drywell liner and thermocouples which were attached to plastic pipe and grouted into holes in the soil. Temperatures from the isolated drywell and the adjacent soil were recorded throughout the nine month Isolated Drywell Test. Canister and drywell liner temperatures reached their peak values (3230F and 2620F, respectively) during October, 1980. Thereafter, all temperatures began to decrease in response to the decay heat and seasonal atmospheric temperature changes. This thermal response is comparable to that of the approximately 1.0 kW spent fuel assemblies previously tested at E-MAD where peak canister and liner temperatures of 2540F and 2030F were recorded. A previously developed computer model was utilized to predict the thermal response of the surrounding soil are presented and are compared with the test data