Abstract
In the case of clearance inspection for materials used at nuclear facilities, the applicants of clearance licenses have to show that the radioactivity concentration is lower than the clearance level, and it is necessary for the regulatory body to confirm this claim. Corrosion products might be generated on alloys in the period between the first measurement in the facility and the confirmation measurement by the regulatory body. Corrosion products shield radiation and cause a drop in radiation count rates. In order to investigate the growth of corrosion products on alloys in actual warehouse environments, carbon steel and stainless steel coupon specimens were set in warehouses of five facilities. The weight increases of the coupon specimens caused by the generation of corrosion products were measured over one year at each warehouse. The decrease in the radiation count rate as a result of shielding by the corrosion products on coupon specimens at each warehouse was estimated, referring to a previous report on the relationship between the amount of corrosion products and the decrease in the radiation count rate.
