车载质子直线加速器中子源长寿命固态锂靶系统关键问题研究

Neutron is an advanced tool for many research fields because of its unique characters. It plays a vital role in BNCT, activation analysis, neutron radiography, nondestructive inspection and so on. Transportable accelerator-driven neutron source overcomes the limited applications due to the huge volume and heavy weight of common accelerator-driven neutron source. It can be applied in the working places on site. Proton linac based neutron source with solid lithium target is an excellent candidate for the transportable neutron source. Development of a long-life and reliable target is a key step for the successful design of such kind of neutron source. In this research, after proposing a novel target system configuration, three key issues as follows will be solved: (1) the relationships between blistering threshold of backing material and hydrogen diffusion coefficient with the proton incident energy and material temperature; (2) an enhanced heat transfer model for the target system; (3) a performance evaluation model to evaluate the hydrogen ion distribution and temperature distribution on the whole target system. Finally the prototypes of the target system will be manufactured, and its performance will be verified by carrying out the experiments on neutron source. Thus the whole package including the basic theory, calculation and design methods, prototype manufacture and performance verification for the solid lithium target system aiming for proton linac based transportable neutron source will be developed.

中子在放射治癌、活化分析、中子照相、无损探伤等领域发挥重要作用。车载加速器中子源克服了传统加速器中子源受体积、重量等限制而不可移动导致应用范围受限的问题，能非常便利地在工作现场实现应用。采用固态锂靶的车载质子直线加速器中子源是其理想形式。能否开发长寿命可靠固态锂靶系统是决定能否实现该中子源的关键。本申请项目在完成新型固态锂靶系统结构设计的基础上，拟重点解决以下三个关键问题：（1）靶系统衬底材料氢鼓泡阈值与氢扩散系数相关因素；（2）固态锂靶系统强化传热传质问题；（3）长寿命固态锂靶系统综合性能评价方法。最后将完成固态锂靶实物原型制造及辐照测试，实现固态锂靶系统开发所需的“基础理论→设计计算→原型制造→实验验证”的完整体系。

中子在放射治癌、活化分析、中子照相、无损探伤等领域发挥重要作用。车载加速器中子源克服了传统加速器中子源受体积、重量等限制而不可移动导致应用范围受限的问题，能非常便利地在工作现场实现应用。采用固态锂靶的车载质子直线加速器中子源是其理想形式，能否为其开发出长寿命可靠固态锂靶系统是决定能否实现该中子源的关键。我们针对车载质子直线加速器中子源长寿命固态锂靶系统设计研制中的关键问题进行了深入研究。首先，我们开展了车载质子加速器中子源中紧凑型加速器的开发，实现了加速器系统的小型化与轻量化，确定了质子能量为2.5 MeV，靶上束斑均方根值为7.5 mm(对应束斑半径为2.25 cm)；对氢在靶结构材料中的扩散效应和DPA损伤进行了计算，宏观层面上评估了对靶结构材料中的氢效应，通过第一性原理计算研究了钒中氢气气泡成核的原子机制，探索了钒中形成氢分子的空位团的最小尺寸；出于靶结构材料中子衰减作用最小化的考量，提出了边缘冷却靶结构，通过对其的参数化研究和与传统背部冷却靶结构的比较，对其冷却效果、结构强度和出射中子衰减情况等进行了评估；完成了锂靶系统的设计和实物原型制造，通过传热实验验证了本课题的理论和设计工作。