Radiation exposure to the lens of the eye for Japanese nuclear power plant workers

Yokoyama, Sumi*; Tatsuzaki, Hideo*; Tanimura, Yoshihiko; Yoshitomi, Hiroshi; Hirao, Shigekazu*; Aoki, Katsunori; Tachiki, Shuichi*; Ezaki, Iwao*; Hoshi, Katsuya; Tsujimura, Norio

Journal of Radiological Protection, 42(3), p.031504_1 - 031504_17, 2022/09

https://doi.org/10.1088/1361-6498/ac7913

In Japan, the radiation-dose limit for the lens of the eye was revised in April 2021. Consequently, for workers, the numerical values of the equivalent dose to the lens of the eye are equal to those of the effective dose. Radiation workers, radiation safety officers and licensees must comply with regulations related to radiation protection and optimize protection. The new guidelines on dose monitoring of the lens of the eye developed by the Japan Health Physics Society recommend for the dose to be estimated near the eye for accurate estimation, when the dose to the lens approaches or exceeds the management criteria. However, there is limited information regarding the non-uniform exposure of nuclear power plant workers. In this study, the dose equivalents of high-dose-rate workplaces and the personal doses of 88 workers were estimated at four Japanese commercial nuclear power plant sites (RWR: 3 units and BWR: 3 units) and the dose to the lens of the eye and the exposure situations of the workers were analyzed.

Exposure inhomogeneity from Am and Sr/Y sources in terms of the eye lens monitoring in the nuclear facilities

Yoshitomi, Hiroshi; Kowatari, Munehiko

Radiation Protection Dosimetry, 188(2), p.191 - 198, 2020/02

https://doi.org/10.1093/rpd/ncz275

Assessment of equivalent dose of the lens of the eyes and the extremities to workers under nonhomogeneous exposure situation in nuclear and accelerator facilities by means of measurements using a phantom coupled with Monte Carlo simulation

Yoshitomi, Hiroshi; Hagiwara, Masayuki*; Kowatari, Munehiko; Nishino, Sho; Sanami, Toshiya*; Iwase, Hiroshi*

Proceedings of 14th International Congress of the International Radiation Protection Association (IRPA-14), Vol.3 (Internet), p.1188 - 1195, 2017/11

http://www.irpa.net/docs/IRPA14%20Proceedings%20Volume%203.pdf

The equivalent doses to the lens of the eye and extremities for radiation workers should be assessed properly to ensure that the dose limits are not exceeded. Recently, the following two issues has pressed demand on more appropriate evaluation of the equivalent doses of the lens of the eye and extremity. One is the new occupational dose limit for the lens of the eye the ICRP recommended. The other is growing demand on handling of highly activated materials in the maintenance works of an accelerator and contaminated materials during the decommissioning works of nuclear facility, which increases the potential exposure risk to the extremities to a wider variety of radio-nuclides. Since the points to be assessed for the exposures to the lens of the eye and the extremities are apart from the trunk, the homogeneity of the radiation fields would be significantly impact on the assessment of these equivalent doses. However, there has been no sufficient and available method to identify the nonhomogeneous situations systematically in terms of the eye lens or extremity monitoring. The goal of this study is to provide the framework to identify the nonhomogeneous exposure situations. In order to fulfil this purpose, newly proposed indices to represent the homogeneity were calculated by Monte Carlo simulation incorporated with mathematical phantom, verifying the benchmark measurements. Important parameters that significantly impact on these indices were also shown from the various trials of calculations of homogeneity indices.

Quantitative estimation of exposure inhomogeneity in terms of eye lens monitoring for radiation workers in the accelerator facility

Yoshitomi, Hiroshi; Kowatari, Munehiko; Hagiwara, Masayuki*; Nagaguro, Seiji*; Nakamura, Hajime*

no journal, , 

no abstracts in English

Non-uniform exposure to the body trunk and some practical criteria on multibadging/multiple dosimetry

Tsujimura, Norio; Yokoyama, Sumi*

no journal, , 

no abstracts in English

Investigation on dosimetric issues about high-dose inhomogeneous radiation accidents; Evaluation of effective dose and organ doses

Kowatari, Munehiko*; Yoshitomi, Hiroshi; Tanimura, Yoshihiko; Kurihara, Osamu*

no journal, , 

no abstracts in English