THERMOCOUPLE PLACEMENT AND HOT-SPOTS IN RADIOACTIVE-WASTE TANKS

Analytical solutions to the differential equation describing the condu ction of heat from an instantaneous point source were used to analyze the detectability of hot spots in radioactive waste tanks and the pote ntial for thermally initiating runaway chemical reactions. Graphs are presented based upon diffusivities, times, temperatures and heat gener ation rates which are representative of conditions in the high-level l iquid waste storage tanks at Hanford. These calculations suggest that achievable temperatures in these tanks are not sufficiently high to in itiate runaway reactions. They also suggest that placing thermocouples sufficiently close together to be of use either in locating hot spots , or in alerting the operators in time to have their actions influence subsequent developments, is not practical.