Thermal Analysis of Irradiation Experiments in the ATR

Reactor material testing in the INL's Advanced Test Reactor (ATR) involves modeling and simulation of each experiment to accurately determine the irradiation temperature. This paper describes thermal analysis of capsule experiments using gas gap temperature control and provides data on recent material tests that validate the modeling results. Static capsule experiments and lead-out capsule experiments are discussed. The source of temperature variation in capsule experiments and ways to mitigate these variations are also explained. Two examples of instrumented lead-out capsule experiments, TMIST-1 and UCSB-2, are presented. A comparison of measured and calculated temperatures is used to validate the thermal models and to ascertain the accuracy of the calculated temperature