Abstract

A novel ex-core-detector–based core power reconstruction method is presented. The method uses power correlations between fuel regions and can be applied to a real-time small reactor core monitoring system especially for the detection of abnormal behavior. The use of ex-core detectors reduces the installation and maintenance costs of small modular reactors (SMRs) compared to conventional in-core detectors. To construct the power distribution with ex-core-detector count rates, it is necessary to account for the scattering and absorption reactions of neutrons within the core that make it difficult to extract information directly from the central core region. In the proposed method, detector responses and power correlations are preevaluated and revised by mathematical transformation. Monte Carlo simulations using the realistic SMR core design MoveluX^TM demonstrated that the present method is capable of reconstructing the core power distributions within an average error of 10% using the count rates of the ex-core detectors. Also, the reconstruction successfully identified the position of abnormal power peaks in the central core region and an unbalanced power distribution.

摘要

提出了一种新的基于核心检测器的核心功率重建方法。该方法利用燃料区域之间的功率相关性，可应用于实时小型反应堆堆芯监控系统，特别是异常行为的检测。与传统的堆内探测器相比，堆外探测器的使用降低了小型模块化反应堆 (SMR) 的安装和维护成本。为了构建具有核外探测器计数率的功率分布，有必要考虑核内中子的散射和吸收反应，这使得直接从中心核心区域提取信息变得困难。在所提出的方法中，检测器响应和功率相关性通过数学变换进行了预评估和修正。使用真实 SMR 核心设计 MoveluX 的蒙特卡罗模拟^TM证明，本方法能够使用外核探测器的计数率在 10% 的平均误差内重建核功率分布。此外，重建成功确定了中心核心区域的异常功率峰值位置和功率分布不平衡。