Feasibility study of reactor radiation photon spectroscopy in Fugen for nuclear decommissioning

Kaburagi, Masaaki   ; Miyamoto, Yuta ; Mori, Norimasa; Iwai, Hiroki ; Tezuka, Masashi  ; Kurosawa, Shunsuke*; Tagawa, Akihiro ; Takasaki, Koji  

Nuclear decommissioning has recently accelerated, particularly following the accident at Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Holdings. -ray/X-ray (radiation photon) spectroscopy provides information on the types of radionuclides with radiation photon emissions. Radiation photon spectroscopy in a control rod guide tube positioned at the center of Fugen was conducted. Fugen is a prototype advanced thermal reactor with 165 MWe electric power generation that is being decommissioned. The dose rates measured in a control rod guide tube positioned at the center of the reactor were 4.19.1 Gy/h. The dose rate considerably increased at a position close to a tank that contained Co caused by the radioactivation of stainless steel. Radiation photon spectroscopy was performed without radiation shielding, identifying Co with an energy resolution better than 5.4% at 1333 keV and Nb with an energy resolution better than 5.9% at 871 keV.