Development of Multi-Section Multi-Division Reactor-In-Core Controlled Irradiation Capsule and Fundamental Processes of Neutron Radiation Damage

本研究的主要技术任务是研制反应堆堆芯辐照舱，实现系统辐照的精确控制，最终目标是建立对中子辐射损伤基本过程的统一认识。第一步是开发多分区受控辐照舱，并进行辐照和辐照后实验。二是多分区多节可移动可控辐照舱的研制，利用日本材料试验堆对常规和改进两种控温方式的堆芯辐照缺陷结构进行了严格的比较，证实了不同材料和缺陷结构类型的差异可达100%。这表明对改进控制的基本需要。在国际上首次将辐照与裂变和聚变中子辐照进行了比较，发现相关因子随材料和辐照温度的不同而变化很大。本项目辐照舱研制的最后一步是设计和建造多分区多节可控辐照舱。利用这种先进的胶囊，可以在辐照过程中的任意时间从辐照场中取出部分样品，而不会干扰辐照条件，如温度。该胶囊的最重要和最困难的性能是热介质和试样容器之间的机械非接触与热接触的兼容，并通过几个步骤的模型实验建立的设计。最后完成了与安装在反应堆中的尺寸完全相同的模型试验，并计划在1993年进行第一次试验辐照，并适当安排JMTR的运行周期。

Development of reactor in-core irradiation capsules to enable perfectly control of systematic irradiations is the major technical task of this research project, and the establishment of unified understanding of fundamental neutron radiation damages processes is the final aim. The first step was to develop multi-division controlled irradiation capsules and to perform irradiations and post-irradiation experiments. The second was the development of multi-division multi-section removable controlled irradiation capsule.Comparison of the defect structures introduced by the two modes of temperature control, conventional and improved, was strictly made for in-core irradiation with Japan Materials Testing Reactor, and the difference up to 100 % was confirmed to exist depending on the kind of materials and the type of defect structures, indicating the essential needs for the improved control. It became possible for the first time in the world to compare the irradiations with fission and fusion neutron irradiation, and the correlation factors were found to vary widely depending on materials and irradiation temperature.The final step of the development of irradiation capsule in the present project was to design and construct the multi-division multi-section controrable irradiation capsule. With this advanced capsule, parts of samples can be removed from the irradiation field at an arbitorary time during irradiation without disturbing the irradiation condition such as temperatures. Most important and difficult performance of this capsule was mechanical uncontact compatible with thermal contact between thermal-media and specimen container, and the design was established after several steps of model experiments. Final mock-up test with exactly the same dimension as that installed in the reactor was finished, and the first trial irradiation is scheduled to be performed in the year of 1993 with a suitable arrangement of operation cycle of JMTR.