摘要
为了确保西安200 MeV质子应用装置(Xi'an 200 MeV Proton Application Facility,XiPAF)升级之后的辐射安全,对束流垃圾桶进行了屏蔽设计与残余剂量评估。首先分析了不同材料的中子产额特征,选择聚乙烯作为低中子产额的靶芯材料。基于FLUKA蒙特卡罗模拟设计了复合结构束流垃圾桶,主体屏蔽材料为铁,外围屏蔽材料为含硼聚乙烯。计算结果表明,束流垃圾桶尾部侧面和横向侧面的最大剂量当量率分别为4.2 mSv·h^(−1)和3.2 mSv·h^(−1),满足5.5 mSv·h^(−1)的设计限值。与传统石墨靶芯相比,聚乙烯靶芯在上游方向的剂量降低约75%。对连续出束1 h、1 d、1 w三种工况的残余剂量分析显示,桶入口处剂量衰减至2.5μSv·h^(−1)所需时间均为2~3 h。研究结果为中能质子加速器束流垃圾桶设计提供了重要参考,有助于确保XiPAF工作人员的辐射安全。
[Background]The Xi'an 200 MeV proton application facility(XiPAF)is planned for upgrade and transformation into a versatile experimental facility for both proton and heavy-ion applications,requiring comprehensive radiation protection design for operational safety.[Purpose]This study aims to develop a radiationsafe beam dump design ensuring compliance with operational dose limits during operation and minimizing postirradiation residual doses.[Methods]Firstly,the neutron yield characteristics of different target materials were analyzed using FLUKA Monte Carlo simulations to determine the optimal core material with low neutron production.Then,a composite structure beam dump was designed with polyethylene as the target core material,iron as the main shielding material,and borated polyethylene as the outer shielding layer.Finally,shielding performance was quantified via ambient dose equivalent rate mapping at critical locations,and residual dose decay kinetics were modeled for three operational scenarios:1-h,1-d,and 1-w continuous irradiation at maximum beam intensity of 1.3×1010 protons per second.[Results]The computational results show that the maximum ambient dose equivalent rates at the rear and transverse sides of the beam dump are 4.2 mSv·h^(−1)and 3.2 mSv·h^(−1)respectively,both below the design limit of 5.5 mSv·h^(−1).Compared to traditional graphite core,polyethylene demonstrates approximately 75%lower upstream dose while maintaining equivalent downstream shielding performance.Analysis of residual dose under the three operational scenarios shows consistent decay patterns,with all cases reaching the dose constraint of 2.5μSv·h^(−1)after 2~3 h cooling time.[Conclusions]The polyethylene-core composite beam dump design provides effective radiation protection for the XiPAF facility upgrade,with significantly reduced neutron backscattering compared to conventional graphite targets.The residual radioactivity analysis indicates that facility access can be safely permitted within 2~3 h after beam shutdown for all typical operational scenarios.These results provide practical reference for radiation protection design of beam dumps at similar intermediate-energy proton accelerator facilities.
作者
王迪
陈伟
吕伟
闫逸花
于俊英
王敏文
王忠明
WANG Di;CHEN Wei;LYU Wei;YAN Yihua;YU Junying;WANG Minwen;WANG Zhongming(National Key Laboratory of Intense Pulsed Radiation Simulation and Effect,Northwest Institute of Nuclear Technology,Xi'an 710024,China)
出处
《核技术》
2026年第1期44-52,共9页
Nuclear Techniques
