Thermal analysis of plutonium storage containers

Experimental results were obtained for four different values of heat generation rate (15, 20, 25 and 30W), and three different values of outside container temperature (20, 25 and 30°C). A constant temperature boundary condition was imposed on the outside surfaces of the container by circulating a constant temperature fluid. The purpose of the outside boundary condition was to enable basis for comparison between the experimental and numerical results. Heat generation caused by the decay of the plutonium was simulated by passing an electric current through a resistor placed in the center of a hollow bowling ball sized stainless steel sphere, referred to as the plutonium pit simulator. Experiments were performed with air, argon and helium as the backfill gases. The lowest temperatures were recorded with heHum as the backfill gas. The maximum temperatures registered in the ALR8(SI) container exceeded the safety Hmit of 60°C for most of the cases. According to the results, only using helium as a backfill gas can guarantee that the maximum temperature wiU not exceed the safety Hmit, for heat generation rates less than 20W. For higher heat generation rates, the limit will be exceeded for any tested backfill gas.