Abstract

In this paper, detailed verification and experimental validation of the formulations and algorithms of the Multi-stage Response-function Transport (MRT)–based Real-time Analysis for Particle-transport and In-situ Detection (RAPID) code system is presented. In particular, RAPID’s fission matrix formulation for eigenvalue calculations and its detector response function for reaction rate calculations have been examined in this study. As part of a collaboration between Virginia Tech and the Jožef Stefan Institute (JSI), RAPID is used to simulate dosimetry experiments performed at the JSI TRIGA Mark II reactor. In these measurements, wire dosimeters are irradiated at different axial and radial locations in the reactor, and their signature activity is measured. The RAPID calculations require the determination of the fission neutron source distribution and the ${ }^{197}$Au(n,$\gamma$)${ }^{198}$Au reaction rates in the wires. In addition, the Monte Carlo code Serpent is used for comparison of the RAPID-calculated criticality eigenvalue, three-dimensional fission neutron source distribution. The validation results show excellent agreement of RAPID with both the experiments and the reference Serpent calculation, with an average relative difference of about 3% with respect to the measurements.

摘要

在本文中，提出了基于多级响应函数传输 (MRT) 的实时粒子传输和原位检测 (RAPID) 代码系统的公式和算法的详细验证和实验验证。特别是，本研究已经检查了用于特征值计算的 RAPID 裂变矩阵公式及其用于反应速率计算的探测器响应函数。作为弗吉尼亚理工大学和 Jožef Stefan 研究所 (JSI) 合作的一部分，RAPID 用于模拟在 JSI TRIGA Mark II 反应堆上进行的剂量测定实验。在这些测量中，金属丝剂量计在反应堆的不同轴向和径向位置受到照射，并测量它们的特征活性。${ }^{197}$金(n,$\gamma$)${ }^{198}$电线中的金反应速率。此外，蒙特卡罗代码Serpent用于比较RAPID计算的临界特征值、三维裂变中子源分布。验证结果显示 RAPID 与实验和参考 Serpent 计算的极好一致性，与测量值的平均相对差异约为 3%。