Leak-tightness characteristics concerning the containment structures of the HTTR

HTTRの原子炉格納施設に関する気密性能

坂場 成昭 ; 飯垣 和彦 ; 近藤 雅明; 江森 恒一

Sakaba, Nariaki; Iigaki, Kazuhiko; Kondo, Masaaki; Emori, Koichi

HTTRの原子炉格納施設は、原子炉格納容器,サービスエリア及び非常用空気浄化設備で構成され、減圧事故等におけるFPの原子炉外への放出を抑制させるものである。原子炉格納容器は、減圧事故時の圧力及び温度挙動に耐え、漏えい率が規定されている。また、サービスエリアは、非常用空気浄化設備により負圧に保たれる。本論文では、原子炉格納施設の気密性能について、系統別総合機能試験等により評価した結果を示す。試験の結果、原子炉格納容器の漏えい率は、規定値0.1%/dを十分満たし、サービスエリアは、非常用空気浄化設備により規定の負圧が保たれること等が確認された。

The containment structures of the HTTR consist of the reactor containment vessel, the service area, and the emergency air purification system, which minimise the release of fission products in postulated accidents which lead to fission product release from the reactor facilities. The reactor containment vessel is designed to withstand the temperature and pressure transients and to be leak-tight in the case of a rupture of the primary concentric hot gas duct, etc. The pressure inside the service area is maintained at a negative pressure by the emergency air purification system. The emergency air purification system will also remove airborne radio-activity and will maintain a correct pressure in the service area. The leak-tightness characteristics of the containment structures are described in this paper. The measured leakage rates of the reactor containment vessel were enough less than the specified leakage limit of 0.1%/d confirmed during the commissioning tests and annual inspections. The service area was kept the design pressure well below its allowable limitation by the emergency air purification system which filter efficiency of particle removal and iodine removal were well over the limited values. The obtained data demonstrates that the reactor containment structures were fabricated to minimise the release of fission products in the postulated accidents with fission product release from the reactor facilities.