Study on potential burnable poison materials for a small modular block-type HTGR design using MgO-BeO as a composite-based moderators

IF 1.9 3区工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY

Nuclear Engineering and Design Pub Date : 2024-11-28 DOI:10.1016/j.nucengdes.2024.113742

Irwan L. Simanullang, Nozomu Fujimoto

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Abstract

Preliminary analysis of MgO-BeO composite material used as a moderator in a 50 MWt block-type high-temperature gas-cooled reactor (HTGR) was performed in our previous study. The target burnup of 80 GWd/t was achieved with a uniform fuel composition of 17 wt% ²³⁵U enrichment and 6 kg of heavy metal per fuel block. However, this resulted in high excess reactivity and a peak in axial power distribution at the core center. Therefore, this study aims to reduce excess reactivity by incorporating burnable poison (BP) material and optimize the axial power profile by introducing a nonuniform fuel composition in the core. Neutronic calculations were performed using the Monte Carlo MVP3.0 code developed by the Japan Atomic Energy Agency (JAEA). In this study, three fuel enrichments of ²³⁵U, ranging from 15 wt% to 20 wt%, were distributed across the core while maintaining a constant fuel packing fraction of 45 %. The results showed that the higher power density distribution shifted from the core’s center to its upper part, leading to lower power density in the bottom region than the top. In addition, excess reactivity was reduced by inserting BP rods. Several parametric calculations were performed to achieve minimal excess reactivity without compromising the burnup target. The results showed that the BP rod with a radius of 0.7 cm and 12 wt% of Gd₂O₃ can reduce the excess reactivity from 25.5 %Δk/k to 13.47 % Δk/k.

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以MgO-BeO为复合缓速剂的小型模块式HTGR设计中潜在可燃有毒材料的研究

我们在之前的研究中对MgO-BeO复合材料作为50mwt块状高温气冷堆（HTGR）慢化剂进行了初步分析。达到80 GWd/t的目标燃耗，均匀燃料组成为17wt % 235U富集，每个燃料块含6 kg重金属。然而，这导致了高过剩反应性和轴向功率分布在核心中心的峰值。因此，本研究旨在通过加入可燃毒物（BP）材料来降低过度反应性，并通过在堆芯中引入不均匀的燃料成分来优化轴向功率分布。中子计算使用由日本原子能机构（JAEA）开发的蒙特卡洛MVP3.0代码进行。在这项研究中，三种235U的燃料富集，从15% wt%到20% wt%，分布在整个堆芯中，同时保持恒定的45%的燃料填充分数。结果表明：高功率密度分布由核心中心向核心上部偏移，导致底部区域的功率密度低于顶部区域；此外，通过插入BP棒降低了过度反应性。在不影响燃耗目标的情况下，进行了几个参数计算以达到最小的过量反应性。结果表明，半径为0.7 cm、Gd2O3质量分数为12 wt%的BP棒可以将反应活性从25.5% Δk/k降低到13.47% Δk/k。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Nuclear Engineering and Design 工程技术-核科学技术

CiteScore

3.40

自引率

11.80%

发文量

377

审稿时长

5 months

期刊介绍： Nuclear Engineering and Design covers the wide range of disciplines involved in the engineering, design, safety and construction of nuclear fission reactors. The Editors welcome papers both on applied and innovative aspects and developments in nuclear science and technology. Fundamentals of Reactor Design include: • Thermal-Hydraulics and Core Physics • Safety Analysis, Risk Assessment (PSA) • Structural and Mechanical Engineering • Materials Science • Fuel Behavior and Design • Structural Plant Design • Engineering of Reactor Components • Experiments Aspects beyond fundamentals of Reactor Design covered: • Accident Mitigation Measures • Reactor Control Systems • Licensing Issues • Safeguard Engineering • Economy of Plants • Reprocessing / Waste Disposal • Applications of Nuclear Energy • Maintenance • Decommissioning Papers on new reactor ideas and developments (Generation IV reactors) such as inherently safe modular HTRs, High Performance LWRs/HWRs and LMFBs/GFR will be considered; Actinide Burners, Accelerator Driven Systems, Energy Amplifiers and other special designs of power and research reactors and their applications are also encouraged.