[1D05-08] Measurement technologies

11:25 AM - 11:40 AM JST(2:25 AM - 2:40 AM UTC)

[1D07] Development of Clearance Measurement and Evaluation Method for Concrete in BWR Buildings(1) Investigation of Contamination Conditions

*Takehisa Ohkura¹, Masato Watanabe¹, Ryosuke Tanaka², Naoya Matsushita², Takahiro Fukuhara³, Kazuhiko Takaji⁴ (1. Chubu Electric Power, 2. TCC, 3. Advanced Fusion Technology, 4. TAKENAKA CORPORATION)

Keywords:

Clearance,BWR,Concrete,Radioactive concentration,Secondary contamination,Penetration,Carbon 14

A contamination survey was conducted in the torus room on the basement second floor of Unit 2 at the Hamaoka Nuclear Power Plant. This study was performed as a preliminary investigation for removal and clearance of part of the concrete in the room. Areas with cracks in the protective coating and a drain funnel of the lowest level section were examined. The results showed that Carbon 14 (C-14) was detected in the concrete beneath the coating, although the concentration was well below the clearance level. The ratio of C-14 to Cobalt 60 (Co-60) exceeded 1, indicating that C-14 is the dominant radionuclide. C-14 was detected on horizontal surfaces, while it was not detected on sloped surfaces or in the funnel section.