铝合金材料在14 MeV中子辐照下的活化特性分析

Analysis of activation characteristics of aluminum alloy irradiated by 14 MeV neutrons

铝合金是激光惯性约束聚变(ICF)装置中最常用的结构材料之一,将直接受到高能量、高产额的中子辐照。评估铝合金材料在14 MeV中子辐照下的活化特性,可为我国ICF装置的材料选取提供参考。采用FISPACT活化计算软件,计算并比较了三种不同牌号的铝合金材料在14MeV中子辐照后产生的比活度和剂量率,并分析了不同元素对比活度和剂量率的贡献。结果表明,铝合金的比活度和剂量率在冷却一周之内下降了3个数量级。铝合金的活化主要来自Al元素、Mn元素和Zn元素,主要活化产物为24 Na,54 Mn和65Zn。Al元素在冷却一周内对比活度(剂量率)的贡献大于90%,其余两种元素在两周之后占主导作用,其贡献之和超过50%。通过选取低Mn,Zn质量分数的铝合金,可降低材料在活化后的放射性水平。

Aluminum alloy,as a kind of important structural materials used in laser-driven Inertial Confinement Fusion (ICF) facilities,will be exposed to high-energy neutrons with high yields.The activation level of aluminum alloys should be taken into account when selecting the materials used in ICF facilities during design.Specific activities and dose rates for three different aluminum alloys after irradiation by 14 MeV neutrons were calculated and compared using the FISPACT inventory code.The results show that both specific activity and dose rate decrease 3 magnitudes in one week after irradiation.It is found that aluminum contributes to more than 90% of the total activity (dose rate) in the first week while Manganese and zinc in aluminum alloys are dominant in longer cooling times.The main residual nuclides are 24 Na,54 Mn and 65 Zn.For safety considerations,it is better to choose aluminum alloys with lower Mn and Zn contents.