Abstract This paper presents the verification and validation elements of the UNIST in-house Monte Carlo code, MCS, for the multi-cycle and multi-physics analyses of high-fidelity, large-scale commercial pressurized water reactors (PWRs). Analysis on the neutronic performance with thermal/hydraulic (T/H) feedback is the key to detecting the complex behavior of an operating nuclear power reactor. The MCS solutions with T/H feedback, TH1D, of the consortium for advanced simulation of light water reactors (CASL) virtual environment for reactor applications (VERA) core physics benchmark progression problems 6 and 7 showed excellent agreement in eigenvalues, temperature and power profiles with the MC21/COBRA-IE, MC21/CTF and VERA-CS solutions for the single assembly and whole core of Watts Bar Nuclear 1 (WBN1) Cycle 1 under beginning-of-cycle and hot-full-power condition. Furthermore, the core depletion analysis is one of the most compelling advances for reactor analysis. Therefore, this work is significantly focused on the nuclide depletion simulation coupled with TH1D of the first two cycles of WBN1 to address the VERA core physics benchmark problems 9 and 10. MCS is one of the few Monte Carlo codes that have the capability of depletion calculation for both WBN1 Cycles 1 and 2. The accuracy of MCS simulation of WBN1 Cycle 1 is within 40 ppm and 30 ppm in critical boron concentration (CBC) for all burnup points, compared with the measured data and VERA-CS solutions, respectively. To demonstrate the multi-cycle refueling capability of MCS, the WBN1 Cycle 2 is simulated and compared with the solutions of VERA-CS only, because of the lack of available measured data. MCS shows excellent agreement compared with VERA-CS within 30 ppm in CBC, and the average bias for the entire Cycle 2 is approximately 20 ppm. These results provide confidence in MCS’s capability in high-fidelity, multi-cycle calculations of the practical PWR core.

中文翻译：

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VERA全核多周期耗尽问题的MCS/TH1D分析

摘要 本文介绍了 UNIST 内部蒙特卡罗代码 MCS 的验证和验证要素，用于高保真、大型商业压水反应堆 (PWR) 的多循环和多物理分析。用热/水力 (T/H) 反馈分析中子性能是检测运行中核动力堆复杂行为的关键。轻水反应堆高级模拟 (CASL) 反应堆应用虚拟环境 (VERA) 核心物理基准进展问题 6 和 7 的具有 T/H 反馈的 MCS 解决方案 TH1D 在特征值、温度和功率分布方面表现出极好的一致性使用 MC21/COBRA-IE，MC21/CTF 和 VERA-CS 解决方案，用于在周期开始和热全功率条件下瓦特巴核 1 (WBN1) 周期 1 的单个组件和整个核心。此外，堆芯损耗分析是反应堆分析最引人注目的进步之一。因此，这项工作的重点是结合 WBN1 前两个周期的 TH1D 的核素消耗模拟，以解决 VERA 核心物理基准问题 9 和 10。 MCS 是少数具有消耗计算能力的蒙特卡罗代码之一WBN1 循环 1 和 2。与测量数据和 VERA-CS 溶液相比，WBN1 循环 1 的 MCS 模拟精度在临界硼浓度 (CBC) 中的所有燃耗点分别在 40 ppm 和 30 ppm 以内。为了演示 MCS 的多循环加油能力，由于缺乏可用的测量数据，WBN1 Cycle 2 仅与 VERA-CS 的解决方案进行模拟和比较。在 CBC 中，MCS 与 VERA-CS 相比在 30 ppm 内显示出极好的一致性，并且整个周期 2 的平均偏差约为 20 ppm。这些结果为 MCS 在实际 PWR 堆芯的高保真、多周期计算能力提供了信心。