A PHITS based-computational model of a TRIGA-fueled subcritical reactor for gamma dose mapping

IF 2.6 3区工程技术 Q1 NUCLEAR SCIENCE & TECHNOLOGY

Nuclear Engineering and Technology Pub Date : 2024-07-20 DOI:10.1016/j.net.2024.07.043

Jowi Rapha P. Cruz , Alvie A. Astronomo , Gil Nonato Santos , Ryan U. Olivares

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Abstract

Since 1988, the Philippines lacked local access to a nuclear facility, creating a significant void in this field of study for Filipinos. However, after a hiatus of 34 years, this gap was addressed with the recent authorization granted to Philippine Research Reactor 1 (PRR-1) Subcritical Assembly for Training, Education, and Research (SATER), allowing it to resume operations. In this work, a PHITS-based computational model was developed for the recently commissioned PRR-1 SATER. The model utilized a simplified model of the Training, Research, Isotope, General Atomics (TRIGA) fuel that releases photons with 0.6617 MeV energy from the Cs-137 fission product in the fuel. Compared to previous works on photon transport mapping, which utilized average source definition, this study employed individually defined fuel intensities and compared them with the averaged source definition for the fuel. The two fuel source definitions showed noticeable differences inside the reactor tank which is relevant for mixed-field irradiation applications of a research reactor. However, defining the fuel rods by their average strength is sufficient for radiation protection purposes. Simulations were also performed for fuel source definitions based on the average and ±1 standard deviation of the gamma intensity. Gamma doses received by cylindrical phantoms positioned at 0.5 m from the surface of the reactor tank for 500 h were found to be 1 % of the radiation dose limits per year and 4 % of the average dose limit for 5 years as stipulated by the Code of Philippine Nuclear Research Institute (PNRI) Regulations. Loss of water accident was also analyzed based on a conservative exposure time of 500 h. This resulted in a dose value that is only 45.5 % of the dose identified as the emergency turnback guidance of the IAEA. Lastly, PHITS calculated values of gamma doses were found to agree well, with 0.98 ratio, when compared with gamma doses measured at specified locations in the reactor. Results of this study confirm the inherent safety of the PRR-1 SATER in terms of radiological shielding for Cs-137 photons.

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基于 PHITS 的 TRIGA 燃料亚临界反应堆伽马剂量测绘计算模型

自 1988 年以来，菲律宾当地一直缺乏核设施，造成了菲律宾人在这一研究领域的重大空白。然而，在中断 34 年之后，菲律宾 1 号研究堆（PRR-1）培训、教育和研究亚临界组件（SATER）最近获得授权，可以恢复运行，从而弥补了这一空白。在这项工作中，为最近投入运行的 PRR-1 SATER 开发了一个基于 PHITS 的计算模型。该模型采用了培训、研究、同位素、通用原子公司（TRIGA）燃料的简化模型，燃料中的 Cs-137 裂变产物释放出能量为 0.6617 MeV 的光子。与以往利用平均光源定义进行光子传输绘图的工作相比，本研究采用了单独定义的燃料强度，并与燃料的平均光源定义进行了比较。两种燃料源定义在反应堆罐内显示出明显的差异，这与研究反应堆的混合场辐照应用有关。不过，以平均强度定义燃料棒足以达到辐射防护的目的。还根据伽马强度的平均值和 ±1 标准偏差对燃料源定义进行了模拟。根据菲律宾核研究所（PNRI）条例守则的规定，在距离反应堆水箱表面 0.5 米处放置的圆柱形模型在 500 小时内接收到的伽马剂量为每年辐射剂量限值的 1%，5 年平均剂量限值的 4%。失水事故也根据 500 小时的保守辐照时间进行了分析，得出的剂量值仅为国际原子能机构（IAEA）确定的紧急回流指导剂量的 45.5%。最后，PHITS 计算出的伽马剂量值与在反应堆指定位置测得的伽马剂量值的比值为 0.98，两者吻合得很好。这项研究结果证实了 PRR-1 SATER 对 Cs-137 光子的辐射屏蔽是安全的。

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 Technology 工程技术-核科学技术

CiteScore

4.80

自引率

7.40%

发文量

431

审稿时长

3.5 months

期刊介绍： Nuclear Engineering and Technology (NET), an international journal of the Korean Nuclear Society (KNS), publishes peer-reviewed papers on original research, ideas and developments in all areas of the field of nuclear science and technology. NET bimonthly publishes original articles, reviews, and technical notes. The journal is listed in the Science Citation Index Expanded (SCIE) of Thomson Reuters. NET covers all fields for peaceful utilization of nuclear energy and radiation as follows: 1) Reactor Physics 2) Thermal Hydraulics 3) Nuclear Safety 4) Nuclear I&C 5) Nuclear Physics, Fusion, and Laser Technology 6) Nuclear Fuel Cycle and Radioactive Waste Management 7) Nuclear Fuel and Reactor Materials 8) Radiation Application 9) Radiation Protection 10) Nuclear Structural Analysis and Plant Management & Maintenance 11) Nuclear Policy, Economics, and Human Resource Development