Simulating self-powered neutron detector responses to infer burnup-induced power distribution perturbations in next-generation light water reactors

Towards Realistic and High Fidelity Models for Nuclear Reactor Power Synthesis Simulation with Self-Powered Neutron Detectors

“…Two studies have been devised to achieve this: (1) a study of the impact of SPND uncertainties when they are used to infer power distributions in next-generation PWRs, and (2) a high-fidelity study on perturbation detection in the Texas A&M Testing, Research, Isotopes, General Atomics Reactor (TAMU TRIGA). A weighting function based-method is being considered for both studies as implemented by the authors in earlier works [27,28,29]. Because iterative processes contain built-in layers of complexity, this approach has been coined the point-based iterative (PBI) method.…”

“…The first-mentioned study leveraged neutronics models of the Westinghouse AP1000 and the NuScale Small Modular Reactor (SMR) which had been used in a previous study for power perturbation analysis in which the perturbations were induced by fissile material burnup [29]. The neutronics calculations are semi-heterogeneous, which in this case means that the a priori knowledge of the power distributions comes from fully heterogeneous geometries.…”

“…The theoretical underpinnings of the PBI method considered herein, which is fundamentally a weighting function-based method relative to the literature, are explained in full detail in a previous report [29]. However, an abridged explanation of the mathematics is provided in this section.…”

“…This methodology was adapted by foreign and domestic industry [25,26]. Previous studies by the authors of this report have investigated how a weighting function-based method performs in the context of optical fiber-based gamma thermometers in theoretical [27] and university research reactors [28], as well as in the context of SPNDs in next-generation PWRs [29]. Note that a layer of sophistication was built into the methodology associated with these studies: an iterative process was implemented to ensure consistency among the working equations.…”

Testing of an Optical Fiber--Based Gamma Thermometer in the High Flux Isotope Reactor Gamma Irradiation Facility

“…Thermocouple data can also be used to infer aspects of the volumetric power distribution [15]. A variety of algorithms exist to solve the inverse (i.e., a volumetric power distribution from in situ and ex situ sensor responses) [16][17][18].…”