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

研制反应堆堆芯辐照胶囊以实现对系统辐照的完美控制是本课题的主要技术任务，建立对中子辐射损伤基本过程的统一认识是本课题的最终目标。第一步是研制多分区受控辐照胶囊，并进行辐照和辐照后实验。二是研制了多段、多段可移动可控辐照胶囊。用日本材料试验堆对堆芯辐照进行了严格的常规和改进两种温度控制模式所引入的缺陷结构的比较，证实根据材料种类和缺陷结构类型的不同，存在高达100%的差异，表明改进控制的必要性。世界上第一次有可能将辐照与裂变和聚变中子辐照进行比较，并发现相关因素因材料和辐照温度的不同而有很大差异。本项目辐照胶囊开发的最后一步是设计和建造多分区多截面可控辐照胶囊。有了这种先进的胶囊，在辐照过程中，部分样品可以在任意时间从辐照场中移除，而不会影响温度等辐照条件。该胶囊的最重要和最困难的性能是与热介质与试样容器的热接触相适应的力学不接触性能，设计是经过几个步骤的模型实验确定的。与反应堆内安装的尺寸完全相同的最后模型试验已经完成，并计划在适当安排JMTR的运行周期后，于1993年进行第一次试验辐照。

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.