Computed tomography neutron detector system to observe power distribution in a core with long neutron flight path

Fukaya, Yuji; Okita, Shoichiro; Nakagawa, Shigeaki; Goto, Minoru; Ohashi, Hirofumi

Annals of Nuclear Energy, 168, p.108911_1 - 108911_7, 2022/04

https://doi.org/10.1016/j.anucene.2021.108911

A power distribution monitoring system by using a moving detector for a core with a long neutron flight path has been proposed. High Temperature Gas-cooled Reactor (HTGR) and Fast Reactor (FR) has a long neutron flight path and the neutrons reach to detector far from fuel assembly in the center of the core unlike Light Water Reactor (LWR). By using the feature, power distribution can be observed with a few detectors by moving the detector and computed tomography technology similar to X-ray Computed Tomography (CT). For a small-sized core, the power distribution can be evaluated only by an ex-core neutron detector. For a large-sized core with inner detectors, the power distribution can be observed with a small number of in-core detectors even if the deployment is limited due to material integrity conditions such as temperature environment. The feasibility is numerically confirmed by simulations of the HTGR core and its detector response. It is expected to observe the power distribution in the core of HTGR and FR, which is difficult continuously to deploy in-core detectors because of high temperature and/or high irradiation damage.

原子炉内出力分布の測定方法及びその装置

深谷 裕司; 中川 繁昭; 沖田 将一朗

not registered

JP, 2021-188522  Patent licensing information

【課題】高温ガス炉、高速炉などのように中性子検出器の挿入場所が限られた原子炉の炉内出力分布の測定を可能とすること。 【解決手段】原子炉の圧力容器内の複数燃料要素の出力密度と、圧力容器内外の複数中性子検出器の位置における中性子検出器からの出力信号と、燃料要素及び中性子検出器の位置に関する検出器感度との関係を表す中性子輸送方程式に基づいて炉心の出力分布を測定する方法であって、検出器感度に関する疑似逆行列と中性子検出器からの出力信号行列との積から原子炉の炉心の出力分布を算出する。