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Am and 
Sr/Y sources in terms of the eye lens monitoring in the nuclear facilities吉富 寛; 古渡 意彦
Radiation Protection Dosimetry, 188(2), p.191 - 198, 2020/02
被引用回数：2 パーセンタイル：23.63(Environmental Sciences)This paper highlights the issues of exposure inhomogeneity that are relative to eye lens monitoring for low-energy photons from Am and beta-rays from Sr/Y including a personal protective equipment because eye lens exposure has been concerned more than before due to the proposed reduction of relevant dose limit. These nuclides are common sources in the nuclear industry, which are particularly of concern. Our previous study presented a quantitative estimation of exposure inhomogeneity, which was applied to simple but typical exposure situations to the radionuclides. For the present study, exposure inhomogeneity of Am was approximately within a factor of 1.6, implying a rather homogeneous situation than expected. Regarding Sr/Y exposure, estimation from both 
(10) and (0.07) on trunk would lead to an over- or underestimation by a factor of more than ten. In contrast, (3) measurement on trunk will improve by up to a factor of two. With respect to the personal protective equipment, lead apron and protective glasses are effective for the 60-keV photons for both anterior-posterior (AP) and rotational (ROT) irradiations, while a full-face respirator can reduce the eye lens dose by approximately 17% for Sr/Y betas. As a whole, this study demonstrated that the effect of protective equipment can be effectively incorporated into the homogeneity evaluation.
横山 須美*; 浜田 信之*; 辻村 憲雄
International Journal of Radiation Biology, 95(8), p.1103 - 1112, 2019/08
被引用回数：9 パーセンタイル：62.87(Biology)In 2011, the ICRP recommended reducing an occupational equivalent dose limit for the lens of the eye. Since then, there have been extensive discussions toward regulatory implementation of such new occupational dose limit. In Japan, the Radiation Council established a Subcommittee in July 2017 to discuss the feasibility of implementing the new occupational lens dose limit. In March 2018, the Radiation Council requested all relevant government ministries and agencies to take necessary actions toward implementation of the new occupational dose limit, considering a series of discussions made by the Subcommittee. According to the currently available information, the new occupational lens dose limit will be implemented into regulations in Japan, most likely in April 2021. Epidemiological and biological studies on radiation effects on the lens and studies on lens dose measurements have been conducted in Japan, some of which have been funded by the Japanese Nuclear Regulation Authority. This paper provides an overview of the recent discussions toward regulatory implementation and the current status of the studies related to radiation exposure of the lens and its effect in Japan.
吉富 寛; 古渡 意彦; 萩原 雅之*; 長畔 誠司*; 中村 一*
no journal, ,
ICRPによる眼の水晶体の線量限度低減勧告を受けて、眼の周辺での追加モニタリングやモニタリング量についての議論がなされている。眼の水晶体被ばくの管理には、追加モニタリングを要求すべき作業者をもれなく特定し、確実かつ適切にモニタリングを実施することが必要である。しかし、これまで追加モニタリング実施の意思決定は経験的で曖昧であることが課題であった。IAEA技術文書でも指摘されているように、その意思決定には被ばくの不均等性が重要な因子である。そこで、著者らは、これまで眼の水晶体モニタリングに係る被ばくの不均等性を表す定量化指標(HI)を導入し、事前評価したHIによってモニタリング要否の判断を行う枠組みを提案した。本研究では、加速器施設における作業場において、このHIによる被ばくの不均等性の評価を試みた。経験的に均等被ばく、及び不均等被ばくと考えられる状況に適用し、計算により評価した値とファントム実験により得られた実測値とを比較した。何れのケースにおいても適切にモデリングを行えば、実測値を再現し、被ばくの不均等性を定量的に評価できた。また、放射化した空気による被ばく状況に関しては、経験的には均等被ばく状況と考えられたが、その不均等性は大きく線源の広がりや
線の影響を考慮する必要があることが分かった。
