著者
長岡 鋭 坂本 隆一 斎藤 公明 堤 正博 森内 茂
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.23, no.4, pp.309-315, 1988 (Released:2010-02-25)
参考文献数
15
被引用文献数
3 4

In order to clarify the diminution characteristics of terrestrial gamma ray exposure rate due to snow cover, measurements were performed on the ground with and without snow cover. The diminution factors observed were 0.36-0.17 for 12-23g/cm2 of water equivalent of the snow cover. According to a calculation by the Monte Carlo method, the corresponding diminution factors were 0.32-0.16. They agreed well as a whole, while the fluctuation of the diminution factors based on the measured exposure rate were fairly large. The fluctuation is deemed to be due to the inhomogeneity in the distribution of the snow cover as well as the gamma ray field. The fluctuation is expected to decrease with increase in the degree of their homogeneity.
著者
古田 悦子
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.45, no.3, pp.253-261, 2010 (Released:2011-07-12)
参考文献数
15

Recently many Japanese wear jewelry as personal ornaments, particularly bracelets. The jewelry is made of gems, jewels, noble metals and so on. Some kinds of jewelry include much amount of radioactive elements more than that of natural range in ores which are in our living-environment. The radioactive concentrations of 25 kinds of jewels and gems, which were easily purchased on a market or through the Internet, were analyzed by HPGe. The bracelet which was made of ceramics showed the highest radioactive concentration and it was estimated as approx. 800 Bq g-1 of 232Th and 140 Bq g-1 of 238U by assuming radioactive equilibrium among the nuclides in the decay series. Moreover, there was a high radioactive concentration gem including 60 Bq g-1 of 232Th and 300 Bq g-1 of 238U. The radioactive materials added in the ceramics should be monazite analyzed by a prompt gamma-ray activation analysis method. Though the ceramics became the object of the NORM management by the concentration, the radioactivity of one bracelet does not exceed 8,000 Bq. So, all these jewelry samples do not have to manage as NORM as consumer products according to the guideline by Japanese government. However, the jewelry's activity by deliberate addition of radioactive materials is deemed to be unjustified exposure, that the ICRP led the consideration. It is considered that the NORM guideline should take in the consideration of ICRP and prohibit the addition of radioactive materials to jewelry.
著者
山田 裕司 宮本 勝宏 小泉 彰
出版者
Japan Health Physics Society
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.21, no.4, pp.237-244, 1986
被引用文献数
3

It is very important in a nuclear air cleaning system that HEPA (High Efficiency Particulate Air) filter is for reduction of releasing amounts of airborne radioactive particles. HEPA filter, by definition, has a minimum collection efficiency of 99.97% for 0.3μm particles. However, <i>DF</i> (Decontamination Factor), which is necessary for safety management, can not be directly derived from the efficiency. And the current standard defined for 0.3μm particles has no scientific justification, because it has been found that the most penetrating particle size through HEPA filter is not always 0.3μm.<br>In the present paper, a numerical experiment was made in order to estimate a relationship between <i>DF</i> and the efficiency. And new standard, in which the minimum <i>DF</i> is able to be easily obtained, was proposed. In the multistage filtration system, it was found that lower values of <i>DF</i> was possible to be experimentally indicated in the second and the third stages, even if the collection performance of the each filter is the same.
著者
福井 正美
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.18, no.4, pp.425-430, 1983
著者
篠原 邦彦 大内 浩子 近本 一彦 谷口 和史 永井 博行 森本 恵理子 米澤 理加 渡辺 浩
出版者
日本保健物理学会
雑誌
保健物理 (ISSN:03676110)
巻号頁・発行日
vol.44, no.4, pp.374-379, 2009 (Released:2011-01-12)
参考文献数
19
被引用文献数
1

In the field of atomic energy and radiation utilization, radiation risk is considered as one of the social uneasy factors. About the perception of risks, there is a gap between experts and general public (non-experts). It is said that the general public tends to be going to judge risk from intuitive fear and a visible concrete instance whereas the experts judge it scientifically. A company, an administration or experts should disclose relating information about the risks and communicate interactively with the stakeholders to find the way to solve the problem with thinking together. This process is called “risk communication”. The role of the expert is important on enforcement of risk communication. They should be required to explain the information on the risks with plain words to help stakeholders understand the risks properly. The Japan Health Physics Society (JHPS) is the largest academic society for radiation protection professionals in Japan, and one of its missions is supposed to convey accurate and trustworthy information about the radiation risk to the general public. The expert group on risk communication of ionizing radiation of the JHPS has worked for the purpose of summarizing the fundamental matters on radiation risk communication. “Lecture on risk communication for the members of the JHPS.” which has been up on the JHPS web-site, and the symposium of “For better understanding of radiation risk.” are a part of the activities. The expert group proposes that the JHPS should enlighten the members continuously for being interested in and practicing risk communication of radiation.