低活化钢中子辐照肿胀的能谱效应及嬗变气体影响机制研究

Due to the good radiation resistance and low activation performance, RAFM steels have been selected as the primary candidate structural materials for fusion DEMO and the first fusion power plant. They will undergo volume swelling and other irradiation damage behaviors under the high energy neutron irradiation in the fusion reactors. Since most of the experimental data for irradiation damage in fusion materials are usually from the fission neutron irradiation facilities, like fission reactors, the key to predict their irradiation damage behaviors under fusion neutron irradiation is to establish a reliable fission-fusion correlation. This project will focus on the two essential distinct factors between fission and fusion neutron irradiations – neutron energy spectrum and transmutation gas. The effects of these two factors on irradiation-induced swelling in RAFM steels will be investigated, using the combination methods between modeling (e.g. molecular dynamics simulation, first principle calculation, and rate theory methods etc.) and experiments. Based on the models for void-swelling and gas bubble-swelling, the spatial-dependent rate-theory model for irradiation-induced swelling in RAFM steels will be established, which reflects the effects of neutron energy spectrum and transmutation gas. This model can be used to predict the irradiation-induced swelling behaviors in RAFM steels under the fusion neutron irradiation conditions. It also provides theoretical and methodology support to develop a reliable fission-fusion correlation.

低活化钢以其良好的抗辐照低活化性能被选为聚变示范堆或第一座聚变电站的首选结构材料，在高能聚变中子辐照下会产生体积肿胀等辐照损伤行为。而聚变材料的中子辐照损伤数据通常是由裂变堆等裂变中子辐照模拟实验获得的，因此预测材料聚变中子辐照损伤行为的关键环节是建立可靠的裂变-聚变相关性。本项目拟针对聚变与裂变中子辐照环境的不同关键因素—中子能谱和嬗变气体，研究这两个关键因素对低活化钢辐照肿胀的影响机制，采用分子动力学模拟、第一性原理和速率理论等模拟方法和相关实验相结合的方法，在空洞肿胀和气泡肿胀的模型基础上，建立空间依赖的能反映中子能谱和嬗变气体效应的低活化钢辐照肿胀的速率理论模型。该模型可预测低活化钢在聚变条件下的辐照肿胀行为，并为建立可靠的裂变-聚变相关性提供理论和方法上的支持。

低活化钢以其良好的抗辐照低活化性能被选为聚变示范堆或第一座聚变电站的首选结构材料，在高能聚变中子辐照下会产生体积肿胀等辐照损伤行为。本项目以建立裂变-聚变相关性模型为牵引，针对聚变与裂变中子辐照环境的关键不同因素—中子能谱和嬗变气体，开展了不同能量中子辐照下低活化钢中级联碰撞的大规模分子动力学模拟，结合第一性原理计算获得了低活化钢辐照缺陷的动力学和热力学关键参数，研究了低活化钢辐照肿胀过程中的中子能谱效应和嬗变气体影响机制。在收集和整理了现有低活化钢中子辐照实验与模拟数据的基础上，结合对中子能谱和嬗变气体效应机制的理解，针对低活化钢辐照肿胀建立了空间依赖的团簇动力学模型和速率理论模型。利用这些模型，模拟了低活化钢中点缺陷、位错、位错环、空洞/气泡等辐照缺陷的形核长大演化过程，计算了材料在不同辐照条件下的辐照肿胀，并用中子/离子辐照实验数据验证了模型的有效性。基于裂变中子辐照肿胀数据验证过的模型，预测了低活化钢的聚变中子辐照肿胀行为，分析了低活化钢辐照肿胀的温度效应、剂量率效应及嬗变气体效应等，以模型为桥梁建立了聚变-裂变中子辐照肿胀相关性。本项目研究对评估辐照肿胀对低活化钢等结构材料在聚变堆中服役安全性的影响具有重要意义，也为新型高性能抗辐照结构材料研发提供了理论和方法支持。