2024 年 58 巻 4 号 p. 209-219
The standard related to surface contamination in controlled areas is called as the surface contamination limit and one-tenth of the surface contamination limit is used as the criterion for determining the contamination level when target materials are removed from a controlled area. The values of the surface contamination limit for the removal of target materials are 0.4 Bq/cm2 for alpha emitters and 4 Bq/cm2 for non-alpha emitters, which are widely used in radiological protection in nuclear and RI facilities in Japan. It is pointed out that there is a considerable degree of conservatism in deriving those values; however, its background basis is not well investigated or discussed. In this study, we attempted to clarify the derivation of surface contamination standards by examining the assumed scenarios, the utilized data and the recent estimations of surface contamination standards related to clearance levels.
