MOX燃料施設における眼の水晶体の線量評価の現状と課題

Abstract

At the JAEA MOX fuel facilities, workers engaged in glove box operations uses two personal dosemeters, one worn on the trunk under a protective apron and the other at the collar over the apron. The recorded lens of the eye dose is based on the photon dose measured by the collar dosemeter plus the neutron dose measured by the under-apron dosemeter. To estimate preliminarily the potential impact of the ICRP-proposed eye dose limit which reduced down to 20 mSv per year on the current plant operation, we carried out an investigation of the dose records for the workers over last 11 years. Of a total of 2,843 workers' records analyzed, no worker's annual eye dose exceeded the proposed limit of 20 mSv; about 0.9 % was greater than 15 mSv, with a maximum of 18.9 mSv. This result suggests that keeping the eye dose under 20 mSv per year would be achievable without an extremely major impact on plant operation; but the fact that the effective dose is certain to be limited by the eye dose likely to be closer to the relevant dose limit will result in more stringent administrative control on the eye dose and might require, if necessary, additional shield and a protective eyewear for some workers.