Assessment of the Maximum Temperature of Simplified High Heat Radioactive Glass in Interim Storage and Deep Geological Disposal

Ensuring the thermal stability of heat-generating nuclear waste glass canisters in interim storage and the thermal stability of bentonite in the deep geological repository are crucial to preserving the function of the waste form. Yet thermal stability might be challenged by further heated air conditions and excessive heat load in the waste form, such that the maximum temperature would be higher than the glass transition temperature undesirably. The finite element method was carried out for the n × n × 4 (n = 1, 3, 5) multicanister system for the sake of predicting the maximum temperatures of interim storage. The internal heat source amount and exiting air temperature of the system were varied to see different storage environments. The maximum heat load of a 15.8 kW/m³ canister was in a safe range (glass transition temperature of 500°C), whereas an 18.6 kW/m³ canister was not. There is a possibility to extend thermal stability to a system larger than n = 5 for 15.8 kW/m³ based on the converging maximum temperature trends. Besides, the maximum temperature of the canister and bentonite clay in a deep geological repository is potentially below the thermal criterion if the canister cools down for about 65 to 70 years.