Investigation on structural integrity of graphite component during high temperature 950C continuous operation of HTTR

HTTRにおける950C高温連続運転中の黒鉛構造物の構造健全性の検討

角田 淳弥 ; 島崎 洋祐 ; 柴田 大受 

Sumita, Junya; Shimazaki, Yosuke; Shibata, Taiju

高温ガス炉(HTGR)の構造物として黒鉛が使用される。炉心構造物及び炉心支持黒鉛構造物は炉心の冷却性能を確保するため構造健全性を維持するように設計されるが、設計要求を満足することを確認するため、原子炉運転中に炉内構造物の温度測定を実施する。また、サーベイランス試験及びテレビカメラを用いた供用期間中検査(ISI)を実施する。本論文では、高温工学試験研究炉(HTTR)における950C高温連続運転期間中の炉心構造物及び炉心支持黒鉛構造物が設計要求を満足することを確認した。また、冷却材温度に直接関係する黒鉛の照射寸法変化について、燃料ブロックの温度履歴を考慮して評価し、温度履歴を評価した場合には照射寸法変化の大きさが1000Cで照射した場合と比較して約1.2倍になることを示した。さらに、サーベイランス試験及びISIの計画について示した。

Graphite material is used for internal structures in High Temperature Gas-cooled Reactor (HTGR). The core components and graphite core support structures are so designed as to maintain the structural integrity to keep core cooling capability. In order to confirm that the core components and graphite core support structures satisfy the design requirement, the temperatures of the reactor internals are measured during the reactor operation. Surveillance test of graphite specimens and in-service inspection (ISI) using TV camera are planned in conjunction with the refueling. This paper describes the evaluation results of the integrity of the core components and graphite core support structures during the high temperature 950C continuous operation, reactor outlet temperature of 950C for 50 days, in HTTR (High Temperature Engineering Test Reactor). The design requirements of the core components and graphite core support structure were satisfied during the high temperature 950C continuous operation. The dimensional change of graphite which directly influences the temperature of coolant was evaluated with considering the temperature profiles of fuel block. The magnitude of irradiation-induced dimensional change was about 1.2 times larger than that of isotherm for 1000C. In addition, the programs of surveillance test and ISI using TV camera were introduced.