Assessment of inhomogeneity of exposure to radiation workers in homogeneous exposure situations in Nuclear Industry and Accelerator Facility by using Monte Carlo calculations coupled with a mathematical phantom; Exposure to the lens of the eye in homogeneous exposure situation due to gamma and beta rays

モンテカルロ計算を用いた原子力及び加速器施設における均等被ばく状況下での放射線業務従事者の被ばくの不均一性に関する検討; 線及び線による均等被ばく状況下での眼の水晶体への被ばく

古渡 意彦; 吉富 寛   

Kowatari, Munehiko; Yoshitomi, Hiroshi

The recommended annual limit of equivalent dose to the lens of the eye has decreased to 20 mSv y from the current limit of 150 mSv y. In terms of occupational exposure to radiation workers, exposure inhomogeneity plays an important role when estimating the eye lens dose from readings of dosimeters worn by workers on their trunk. The authors focused on homogeneous exposure situations that radiation workers may encounter in nuclear and accelerator facilities. Moreover, the authors investigated how radiation workers are exposed non-homogeneously in homogeneous exposure scenarios, where radiation workers may usually be encountered, regardless of their radiation works. In our previous study, we proposed a methodology to quantitatively evaluate the inhomogeneity of exposure. The homogeneity of exposure was evaluated by performing Monte Carlo calculations with a mathematical phantom under the isotropic and rotational irradiation geometries due to gamma and beta rays. (3)/(10) exceeded 1.0 even in the case of homogeneous exposure to gamma rays. Even in the homogeneous exposure scenarios, the (3) might exceed the revised annual dose limit for radiation workers who are exposed close to annual dose limit.