文献一覧: Japan Health Physics Society (出版者)

1 0 0 0 HEPAフィルタの捕集効率と除染係数

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 1

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, DF (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. In the present paper, a numerical experiment was made in order to estimate a relationship between DF and the efficiency. And new standard, in which the minimum DF is able to be easily obtained, was proposed. In the multistage filtration system, it was found that lower values of DF 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.

2011-11-26 13:45:08
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1 0 0 0 薄窓型2πガスフロー計数管のブラトー特性

著者: 南賢太郎佐藤信之
出版者: Japan Health Physics Society
雑誌: 保健物理 (ISSN:03676110)
巻号頁・発行日: vol.3, no.4, pp.411-412, 1968

2011-08-28 20:24:22
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1 0 0 0 個人装飾品に含まれる放射性物質 : 放射能濃度と被ばく線量の検討

著者: 古田悦子
出版者: Japan Health Physics Society
雑誌: 保健物理 : hoken buturi (ISSN:03676110)
巻号頁・発行日: vol.45, no.3, pp.253-261, 2010-09-01

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.