RADIOISOTOPES

Both in the waste disposal related to natural origin radioactive nuclide, and in that related to transuranium nuclides, we found it appropriate to determine the threshold specific activities referring to the typical radium content of 10 nCi/g in crust. In this review, exemption and clearance concepts are rearranged in terms of radioactive waste disposal. Some in Japanese regards exemption and clearace are the threshold points that the materials trangient themselves from radioactive to non radioactive after their concentration verification. However, on the assumption of LNT model, we do have no threshold to non radioactive, thus, exemption and clearance systems are applied in flexible in overseas and its flexibility is clearly shown in the field of radioactive waste management. As IAEA noted, the internationally agreeable clearance levels are needed since the articles and materials are circulate worldwide after the clearance verification. However, for waste disposal is at the end of the circulation, their criteria can be determined by the member states where the diposal site is located. Herewith, exemption and clearance implementation by the member states are studied for the purpose of contribution to apply flexibilities to the radiation protection policy in Japan.