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

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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.