Calibration of Thermal Power in the 3 MW TRIGA MARK II Research Reactor and Validation under Forced Convection Cooling

Neutronic instruments are commonly used by reactor operators to monitor reactor power; however, thermal methods remain the standard for calibrating reactor power during routine operation. This paper presents the results of thermal power calibration for the 3 MW TRIGA MARK II research reactor, comparing two heat transfer approaches: the calorimetric method and the heat balance method. Calibration data were validated under forced convection cooling conditions. The calorimetric method was applied at a low power level of 100 kW, yielding a thermal power measurement of 98 kW, closely matching the reactor’s design specifications. The heat balance method was employed at higher power levels of 1 MW, 1.5 MW, and 2 MW, based on measurements of inlet and outlet coolant temperatures and water flow rate in the primary cooling loop. The thermal power values obtained were 831.5 kW, 1293.5 kW, and 1755.4 kW, respectively. Deviations were mainly attributed to limitations in analog instrumentation, fluctuations in mass flow rate, and measurement uncertainties. Comparison of the two methods indicated that the calorimetric method provided more accurate and reliable power calibrations, whereas the heat balance method exhibited greater discrepancies. Overall, the findings underscore the suitability of the calorimetric method for precise thermal power calibration of TRIGA MARK II reactors.