2026-10-14T21:38:53Z https://www.scidb.cn/oai

10.57760/sciencedb.hjs.00749 2026-07-09T12:28:22Z

2026-07-09 Simulation study based on the development of lanthanum bromide-cesium iodide anti-Compton γ detector spectrometer doi:10.57760/sciencedb.hjs.00749 en [Background]: The Thorium Molten Salt Reactor (TMSR), as one of the representative reactor types in the fourth-generation advanced nuclear energy systems, produces a significant volume of high-level radioactive offgas during operation. Prior to discharge, it is essential to characterize and process the radioactive nuclides contained in this offgas in order to reduce its radioactivity to levels compliant with safe emission standards. [Purpose]: This study aims to develop a high-performance gamma‑ray detection system for identifying radioactive nuclides in the offgas, thereby providing reliable experimental data to support offgas treatment processes. [Methods]: First, Monte Carlo simulations were conducted using Geant4 software to evaluate the energy resolution and detection efficiency of LaBr3:Ce and CsI:Tl detectors for a 137Cs radioactive source under varied geometrical and operational conditions. The simulations systematically varied detector dimensions and configurations to compare the two scintillator materials. Based on these simulation results, the optimized parameters for standalone LaBr3:Ce and CsI:Tl detectors were determined. Subsequently, the performance of an anti‑Compton gamma‑ray spectrometer, composed of a central LaBr3:Ce detector surrounded by multiple CsI:Tl detectors, was simulated in Geant4. For the integrated spectrometer, the energy deposition and coincidence events between the central and surrounding detectors were analyzed to evaluate the Compton suppression capability. [Results]: The simulations of standalone detectors with a 137Cs standard source yield the following optimized geometries: a cylindrical LaBr3:Ce detector (2 inches in diameter and length) and a regular hexagonal prismatic CsI:Tl detector (55 mm across flats and 200 mm in length). The integrated LaBr3:Ce–CsI:Tl anti‑Compton gamma‑ray spectrometer, comprising one LaBr3:Ce detector and six CsI:Tl detectors, is tested in simulation using a 137Cs source. The results give a Compton suppression factor (CSF) of 5.13, and the Compton‑to‑peak ratio improves from 14.69 (without suppression) to 75.36 (with suppression). [Conclusions]: The LaBr3:Ce–CsI:Tl anti‑Compton gamma‑ray spectrometer developed in this study effectively suppresses Compton scattering events, leading to a substantial enhancement in spectral quality. Such a detection system can therefore provide reliable experimental data to support the treatment of radioactive offgas generated by thorium‑based molten salt reactors. Lanthanum bromide detector; Cesium iodide detector; Thorium molten salt reactor; Geant4; Anti-Compton gamma spectrometer liu ming shuai Yu Chenggang Ma Chunwang Chen Jingen Cai Xiangzhou PUBLIC https://creativecommons.org/licenses/by-nc-sa/4.0/ dataset Science Data Bank