2010 Volume 9 Issue 2 Pages 199-206
To release materials with considerably low radioactive concentrations arising from decommissioning activities of nuclear installations, it is required to confirm that the sum of “the ratio of radioactive concentration (D)”/“clearance level (C)” is lower than or equal to the reference value by the reliable measurement and evaluation of radioactive concentration. When the radioactive concentration is evaluated by using a statistical method where samples are taken from the materials, the following two points should be taken into account: (1) a conservative evaluation that prevents underestimation caused by statistical uncertainties and (2) an error that may lead to a wrong decision where the materials are not released due to a highly conservative evaluation. In this paper, we propose a method to determine the number of samples required for clearance verification based on a statistical theory in a consistent manner, where uncertainties in the sum of D/C are taken into account.
