著者

三浦 美和 林田 りか 高尾 秀明 小野 孝二 松田 尚樹

出版者

Japanese Society of Radiation Safety Management

雑誌

日本放射線安全管理学会誌 (ISSN:13471503)

巻号頁・発行日

vol.12, no.1, pp.46-53, 2013

---

From October to December 2010, just before the radiological accident at the Tokyo Electric Power Company Fukushima Daiichi nuclear power plant, 71 radiation professionals belonging to the radiation facilities in Japan were asked what they consider as a "safe" dose of radiation for themselves, their spouse, parents, children, brothers and friends. Although the "safe" dose varied widely from less than 1 mSv/y to higher than 100 mSv/y, the average dose was 35.6 mSv/y that was around the middle point between the exposure dose limits for annual average (20 mSv/y) and for any single year (50 mSv/y). Similar results were obtained from another surveys for the members of Japan Radioisotope Association (36.9 mSv/y) and for the Oita Prefectural Hospital (36.8 mSv/y). Among the family members and friends, the minimum average "safe" dose was 8.5 mSv/y for children, to whom 50% of responders claimed the "safe" dose less than 1 mSv. Gender, age and specialty of the responder also affected the "safe" dose. These findings suggest that the perception of radiation risk varies widely and that the legal exposure dose limit derived from the regulatory science may act as an anchor of safety even in radiation professionals. The different level of risk perception for different target groups in radiation professionals appears similar to those in non-professional whole population. The gap between these characteristics of real radiation professionals and the generally accepted picture of radiation professionals might take a part in a state of confusion after the radiological accident.

著者

Midori ISOBE Hiroyuki MORI Narufumi OKADA Yuriko MANNAMI Hiroaki TERATO

出版者

Japanese Society of Radiation Safety Management

雑誌

Radiation Safety Management (ISSN:13471511)

巻号頁・発行日

vol.22, pp.1-6, 2023 (Released:2023-12-09)

参考文献数

6

---

Radiation shielding is one of the necessary procedures in radiation protection. The lead blocks are commonly used to shield against gamma- and X-rays. However, due to lead's biotoxicity, the development of alternative materials is required. We developed a novel ceramic product as a non-biotoxic shielding material composed mainly of iron (III) oxide. In this study, the radiation shielding performance against gamma-rays was evaluated and its potential as a radiation shielding material was investigated. We measured the gamma-ray amount transmitted through the ceramic specimens using a NaI scintillation counter with three different gamma sources (133Ba, 137Cs, and 60Co). The order of shielding ability of the sample with the same volume was lead > iron > the ceramics. The effects of piling the blocks and the type of jointing agent used in the gaps on the shielding ability were also observed for considering actual use.

著者

Takahira TAKEMOTO Kazutaka OHSAWA Naoki MATSUDA

出版者

Japanese Society of Radiation Safety Management

雑誌

Radiation Safety Management (ISSN:13471511)

巻号頁・発行日

vol.19, pp.49-57, 2020 (Released:2020-06-26)

参考文献数

24

---

To support the safe return of residents after the TEPCO Fukushima Daiichi Nuclear Power Plant accident, cleaning methods and materials for the removal of radiocesium (137Cs) from household surfaces were compared. A spot contaminated with 137Cs on a vinyl floor sheet or a glass plate was wiped in different moisture conditions with different cleaning materials, including a paper sheet, cellulose sponge, polyester sheet, and a polyesterpolyamide sheet. Radioactive solid particles on a vinyl sheet were wiped with miniature mops made of cellulose sponge, polyester microfiber, or cotton yarn. There was little difference in the removal of radioactivity among cleaning materials when the contaminated spot was wiped in wet conditions. The removal of contaminated particles depended on the structure of the mop. The use of an abrasive and a detergent worked well for the vinyl sheet and the glass plate, respectively. These observations suggested that, in appropriate conditions, effective decontamination was achievable by regular indoor cleaning with commercially available cleaning devices.

著者

Water Analysis Group

出版者

Japanese Society of Radiation Safety Management

雑誌

Radiation Safety Management (ISSN:13471511)

巻号頁・発行日

vol.12, no.1, pp.22-30, 2013 (Released:2013-04-12)

---

The removal rate of radioactive materials from contaminated water was experimentally obtained using various materials and commercial water purifiers with the aim of enabling the public to easily remove radioactive materials from rainwater and tap water contaminated by radioactive 131I, 134Cs, and 137Cs released by the Fukushima Daiichi Nuclear Power Plant accident using readily obtainable instruments and materials at home. Since it was difficult to obtain contaminated tap water, contaminated rainwater was used as samples in our experiments. In the rainwater, 131I, 132I, 134Cs, 137Cs, 132Te, 129mTe, and 129Te were detected. The abundance ratio of the isotopes depended on the location and date of collection, and the abundance of 131I was 12 to 26 times higher than that of 137Cs. Most of the radioactivity in the rainwater originated from 131I. The removal rate was obtained in the case of using readily available materials and water purifiers at home and in a university laboratory. The results of model experiments using nonradioactive I3- and radioactive 125I instead of 131I suggested that activated carbon was effective. On the basis of these results, we investigated the removal rates of radioactive iodine and cesium using five different pot-type water purifiers with activated carbon as the basic adsorbent, to which ion-exchange resin, a hollow fiber membrane, or a ceramic was added. Approximately 90 to 99% of 131I and 94 to 100% of 137Cs were removed by consecutive purifications using the pot-type water purifiers. These results indicated that these water purifiers can be easily used to remove 131I and 137Cs at home, although special care is required when boiling using an electric kettle because it causes the concentration of 131I. Faucet-mounted- and countertop-type water purifiers with activated carbon as the basic material are expected to have a similar performance to pot-type water purifiers, although this requires future experimental verification. We found that 1-9% of the radioactive 131I remained in the rainwater samples after repeated treatment with the pot-type commercial water purifiers, depending on the sampling location and time, and that some of the residual isotopes were adsorbed on silica nanoparticles. Furthermore, to improve the removal rate, it is necessary to develop a removal method for the remaining components.

著者

小島 正美

出版者

Japanese Society of Radiation Safety Management

雑誌

日本放射線安全管理学会誌 (ISSN:13471503)

巻号頁・発行日

vol.12, no.1, pp.4b-6, 2013