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Okoshi, Minoru
Dekomisshoningu Giho, (26), p.2 - 12, 2002/11
The concept of clearance has been introduced by the International Atomic Energy Agency in 1996 and is very useful for the management of very low-level solid materials generating from the decommissioning of nuclear facilities. Therefore, the European Commission (EC) derived the specific clearance levels for metals, buildings and building rubble in RP 89 and 113, respectively. The EC also derived the general clearance levels for all solid materials generating from the regulated facilities in RP 122. Comparing the clearance levels of Japan with the unrounded levels of EC, the differences of levels are small. The biggest difference is found in Fe-55 and the EC's clearance level is about one fifth of Japanese clearance level. This is caused because the EC considers the direct ingestion of cleared building rubble by children and used the conservative ingestion rate of it. EC's discussions related to the clearance levels are very useful for Japan to derive our own clearance levels and to clear materials from regulatory control.
Okoshi, Minoru
Hoken Butsuri, 37(3), p.197 - 207, 2002/09
The concept of clearance has been introduced by IAEA in 1996 and is very useful for the management of very low-level solid materials generating from the decommissioning of nuclear facilities. Therefore, the Nuclear Safety Commission of Japan started the derivation of clearance levels for solid materials arising from nuclear reactors in 1997 and published the reports in 1999 and 2001, respectively. EC also published the several guides to clear metals, concrete, building and other solid materials from regulatory control. Some organizations including IAEA and USNRC are still discussing how to derive the clearance levels. In this exposition, the present status of clearance in Japan and other organizations and countries is summarized. And some information to realize the concept of clearance is given, and the problems related to the clearance are also discussed.
