The Thermal Power Calibration of the SLOWPOKE-2 SMR

Abstract

This thesis presents an experimental and computational methodology for accurately determining the thermal power output of the Royal Military College (RMC) SLOWPOKE-2 small modular reactor (SMR). Accurate determination of reactor thermal power is essential for calibration, fuel management, and compliance with International Atomic Energy Agency (IAEA) safeguards. Historically, the thermal power at RMC's SLOWPOKE-2 has been inferred from neutron flux measurements calibrated through older fuel configurations, potentially introducing systematic uncertainties post-refuelling. Two complementary experimental techniques were developed to provide a robust and independent calibration. First, a controlled immersion heater assembly comprising two 1.5 kW single-phase heaters and one 6 kW three-phase heater was installed in the reactor pool. Five distinct power levels (1.5 kW, 3 kW, 6 kW, 7.5 kW, and 9 kW) were used to correlate measured thermal profiles, recorded by an eight-channel type-K thermocouple array, to the known heater power, establishing a reliable calibration constant (𝜅 = 1590 ± 40 °C·min⁻¹·kW⁻¹). This calibration yielded reactor power estimates systematically 10% – 20% higher than the control room’s nominal reactor powers at similar neutron flux setpoints, indicating potential inaccuracies in existing reactor instrumentation. Second, a heat balance method was implemented through Python, calculating power added based on measured temperature gradients from the thermocouple array, deionized water properties, and heat losses (convection, conduction, and evaporation). This method independently validated the calibration findings, estimating reactor power outputs similarly above nominal values, with uncertainties ranging between ±2% and ±10%. Additionally, neutron flux data collected from B10+ and He-3 detectors before and after refuelling allowed for an analysis of the fissile isotopic changes. Using a power-to-Δ𝑇 correlation between reactor core inlet and outlet temperatures, a Neutron-Flux-to-Power Ratio was experimentally estimated using the B10+ and He-3 detectors, respectively. These values agree in magnitude with the weighted isotopic composition estimate at (-1.95%) by CNL using MNCP simulations, but differ in relative magnitudes before and after refuelling, highlighting potential model or experimental approximations. Ultimately, these findings establish a dual-method approach for precise reactor thermal power calibration and provide preliminary insight that may support future improvements in fuel monitoring and proliferation safeguards.