Multi-layer shielding optimization of a high activity 241Am-Be mixed field irradiation facility

IF 1.6 3区工程技术 Q3 CHEMISTRY, INORGANIC & NUCLEAR Applied Radiation and Isotopes Pub Date : 2025-01-04 DOI:10.1016/j.apradiso.2025.111662

N.A. Kotb , A.H.M. Solieman , T. El-Zakla , T.Z. Amer , S. Elmeniawi , M.N.H. Comsan

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Abstract

Neutron and gamma-ray shielding design for a 30Ci (1.11TBq) ²⁴¹Am-Be irradiation facility is studied using MCNP5 Monte Carlo simulation code. The study focuses on the optimization of the shielding layers of the previously planned neutron irradiation facility. The shielding design aims at reducing the effective dose rate down to 10 μSv/h for occupationally exposed workers as recommended by the International Commission on Radiological Protection (ICRP) (20 mSv per year for workers). The dose rate calculations consider not only ²⁴¹Am-Be produced neutrons but also gamma rays from the ²⁴¹Am decay, ¹²C∗ de-excitation, and neutron interaction with source and facility materials. Different materials (paraffin, borated-paraffin, beryllium, copper, tantalum, tungsten, zinc, bismuth, and lead) have been investigated as neutron and gamma shields. The choice of the shielding materials is based on their effectiveness (the total weight of the facility and the cost). Among several configurations, shielding layers consisting of 10 cm paraffin wax, 2.5 cm lead, and 31.5 cm borated-paraffin wax are found sufficient to meet the safety requirements, leading to a cubic facility of 104.2 cm overall length. Some irradiation parameters are estimated for the final design; namely neutron and gamma spectra as well as flux and absorbed dose components. In addition, the occupational exposure is assessed considering ICRP exposure conditions to calculate the effective dose rate along with the isodose distribution.

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高活度241Am-Be混合场辐照设施多层屏蔽优化。

利用MCNP5蒙特卡罗模拟程序研究了30Ci (1.11TBq) 241Am-Be辐照装置的中子和伽马射线屏蔽设计。研究的重点是对原规划的中子辐照设施的屏蔽层进行优化。屏蔽设计的目的是将职业暴露工人的有效剂量率降低到国际放射防护委员会（ICRP）建议的10 μSv/h（工人每年20 mSv）。剂量率计算不仅考虑了241Am- be产生的中子，而且考虑了241Am衰变产生的伽马射线、12C *去激发以及中子与源和设施材料的相互作用。不同的材料（石蜡、硼化石蜡、铍、铜、钽、钨、锌、铋和铅）已被研究作为中子和伽马屏蔽。屏蔽材料的选择是基于它们的有效性（设施的总重量和成本）。在几种配置中，由10 cm石蜡、2.5 cm铅和31.5 cm硼酸石蜡组成的屏蔽层足以满足安全要求，导致总长度为104.2 cm的立方设施。为最终设计估算了辐照参数；即中子谱和伽马谱以及通量和吸收剂量分量。此外，考虑ICRP照射条件对职业照射进行评估，计算有效剂量率和等剂量分布。

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来源期刊

Applied Radiation and Isotopes 工程技术-核科学技术

CiteScore

3.00

自引率

12.50%

发文量

406

审稿时长

13.5 months

期刊介绍： Applied Radiation and Isotopes provides a high quality medium for the publication of substantial, original and scientific and technological papers on the development and peaceful application of nuclear, radiation and radionuclide techniques in chemistry, physics, biochemistry, biology, medicine, security, engineering and in the earth, planetary and environmental sciences, all including dosimetry. Nuclear techniques are defined in the broadest sense and both experimental and theoretical papers are welcome. They include the development and use of α- and β-particles, X-rays and γ-rays, neutrons and other nuclear particles and radiations from all sources, including radionuclides, synchrotron sources, cyclotrons and reactors and from the natural environment. The journal aims to publish papers with significance to an international audience, containing substantial novelty and scientific impact. The Editors reserve the rights to reject, with or without external review, papers that do not meet these criteria. Papers dealing with radiation processing, i.e., where radiation is used to bring about a biological, chemical or physical change in a material, should be directed to our sister journal Radiation Physics and Chemistry.