新型転換炉ふげん発電所における系統化学除染技術の開発と経験

抄録

Fugen, a heavy-water-moderated pressure-tube type reactor, has operated satisfactorily for over 17 years since the start of commercial operation in March 1979. In August 1989 at the 8tb annual inspection, the full system decontamination of primary reactor circulation system was successfully performed for the first time in Japanese operational power reactors, which yielded the large reduction of occupational radiation exposure. Research & Development on the full system decontamination has been conducted since 1977, and the reagent KD203, a dilute chelate one, was selected through fundamental capability tests and application tests for the use.
Prior to the decontamination, the structure material integrity tests and evaluations with the reagent KD203 were conducted. Slow Strain Rate Tension (SSRT) tests and Uni-axial Constant Load (UCL) tests for stainless steel, and SSRT tests for the pressure tube material were performed. From the results it was confirmed that tbe reagent never affected harmful influence upon the Fugen structulral materials on general corrosion, stress corrosion cracking, hydrogen degradation and the integrity of pressure tube rolled joints.