海外炉を用いた中性子照射試験,2; キャプセル温度制御システムを用いた照射試験の実施(共同研究)

Irradiation test using foreign reactor, 2; Study of irradiation test with capsule temperature control system (Joint research)

大森 崇純 ; 冬島 拓実 ; 佐谷戸 夏紀 ; 斎藤 長月; 高部 湧吾; 遠藤 泰一; 井上 修一 ; Wojtania, G.*; Migdal, M.*; 武内 伴照   ; 竹本 紀之 

Omori, Takazumi; Fuyushima, Takumi; Sayato, Natsuki; Saito, Nagatsuki; Takabe, Yugo; Endo, Yasuichi; Inoue, Shuichi; Wojtania, G.*; Migdal, M.*; Takeuchi, Tomoaki; Takemoto, Noriyuki

材料研究、RI製造などの中性子照射研究の中核を担っていた材料試験炉(Japan Materials Testing Reactor: JMTR)の廃止が決定された。それに伴い、国内で照射試験及び照射試験炉の運転技術や照射技術の継承を行うことが困難な状況となっている。こうした課題に対処するため、海外の照射炉を用いてJMTRの照射機能の一部を代替するJMTR代替照射を開始することとなった。その足掛かりとして「ポーランド国立原子力研究センターと日本原子力研究開発機構との間の試験研究炉の研究開発のための共同研究取決め」に基づき、ポーランド国立原子力研究センター(NCBJ)が所有するMARIA炉(出力30MW)を中性子照射場として選定し、JMTRの有する照射技術の一つである温度制御システムを有する併用型温度制御装置をMARIA炉に導入し、照射試験を実施した。本照射試験の結果、150日間を超える照射期間を経ても今回導入した併用型温度制御装置及びJMTR型照射試験システムは問題なく稼働し、キャプセル内の熱電対温度や照射時におけるLVDT及びSPGDからの出力をオンラインで計測しながら試験を行うことができることを確認した。さらに、JMTRの照射試験技術である照射キャプセルの一定温度制御において、材料照射試験におけるニーズの高い300Cで実施し、温度変化の大きくなる原子炉出力上昇時には6.3Cの範囲、出力降下時には26.0Cの範囲で制御することができた。これらの結果から、JMTRの照射試験技術である照射温度制御を伴った照射試験がMARIA炉においても実施可能であり、代替照射場として提供しうることが確認できた。

Japan Materials Testing Reactor (JMTR), which served as the core facility for neutron irradiation research including materials research and radioisotope production, has been decommissioned. As a result, it has become difficult to continue conducting irradiation tests domestically, as well as to transfer the operational expertise and irradiation technologies associated with test reactors, to address these challenges, it was decided to initiate JMTR alternative irradiation, in which foreign irradiation reactors are utilized to partially substitute for JMTR's irradiation capabilities. As a first step, based on the "Arrangement between the National Centre for Nuclear Research and the Japan Atomic Energy Agency for Cooperation in Research and Development on Testing Reactor". The MARIA reactor (30 MW) owned by the National Centre for Nuclear Research (NCBJ) was selected as the neutron irradiation facility, a temperature control system, which is one of JMTR's irradiation technologies, was introduced into the MARIA reactor, and irradiation tests were conducted. The results of this irradiation test confirmed that the combination of the newly introduced temperature control device and the JMTR irradiation test system operates without issues even after an irradiation period exceeding 150 days, it was also demonstrated that the tests could be conducted while continuously measuring the thermocouple temperature inside the capsule during irradiation, as well as the output of the LVDT and SPGD. Furthermore, regarding the constant temperature control of the irradiation capsule at 300C constant temperature control test, which is highly demanded in materials irradiation testing, was conducted, during reactor power increases, when temperature fluctuations become significant, temperature control was maintained within 6.3C, while during power decreases, it was controlled within 26.0C. These results indicate that irradiation testing with irradiation temperature control system developed by JMTR, can also be performed in the MARIA reactor, it was confirmed that it can be offered as an alternative irradiation field.