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Masuyama, Koichi; Arakawa, Yuto; Otsuka, Yoshikazu; Yokosuka, Yoshiyuki; Kobayashi, Makoto; Akiyama, Isamu; Shimizu, Isamu
no journal, ,
no abstracts in English
Nakajima, Junya; Yokosuka, Yoshiyuki; Arakawa, Yuto; Shimizu, Isamu; Umehara, Takashi
no journal, ,
In NUCEF we monitor the radiation level continuously with 81 radiation monitors. Although these monitors are checked periodically, failures have occurred due to various reasons. Then we accumulated all monitor failures which had happened in recent 18 years, and categorized them by reason. This allowed us to find that the number of the failure much differs from monitor to monitor, and that there was a deviation between the reasons of the failure. After that, about degradation of GM tube used as dust monitor, which is by far the most of all reasons, we investigated the relation between the average cps and the interval of exchange. As a result, we couldn't find any causal relationship between the both. On the other hand, to improve the failure situation, we have exchanged expendables periodically, and furthermore, the result of the failure analysis should be fed back for better preventive maintenance.
Arakawa, Yuto; Fujii, Katsutoshi; Mimura, Ryuji; Nakashio, Nobuyuki; Onuma, Isamu; Shishido, Nobuhito; Umehara, Takashi
no journal, ,
no abstracts in English
Sakashita, Koichi; Kasugai, Yoshimi; Harada, Masahide; Seki, Kazunari; Sato, Koichi; Kato, Saori; Arakawa, Yuto
no journal, ,
no abstracts in English
Sakashita, Koichi; Arakawa, Yuto; Kasugai, Yoshimi; Ishii, Tetsuro
no journal, ,
Radioactive concentration of short-lived gas nuclides produced via air activation by neutron in the hot-cell was measured using a plastic scintillator gas monitor in Materials and Life Science Experimental Facility at J-PARC. However, conversion factors (CF), the ratio of radioactive concentration to count rate, had been unknown for the short-lived nuclides of 
C, 
N and 
O. Therefore we evaluated them with Monte Carlo method using Geant4. As a result, the CF's were shown to be almost constant in the energy region of 
-rays emitted from these short-lived nuclides and 
Ar. Then we adopted the CF of Ar, which is certified by the vendor, as those of the short-lived nuclides.