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Journal Articles

Monitoring of airborne $$^{14}$$C discharge at RI facilities; A Comparison of collection and oxidation methods

Ueno, Yumi; Koarashi, Jun; Iwai, Yasunori; Sato, Junya; Takahashi, Teruhiko; Sawahata, Katsunori; Sekita, Tsutomu; Kobayashi, Makoto; Tsunoda, Masahiko; Kikuchi, Masamitsu

Hoken Butsuri, 49(1), p.39 - 44, 2014/03

The Japan Atomic Energy Agency has conducted a monthly monitoring of airborne $$^{14}$$C discharge at the forth research building (RI facility) of the Tokai Research and Development Center. In the current monitoring, $$^{14}$$C, which exists in various chemical forms in airborne effluent, is converted into $$^{14}$$CO$$_{2}$$ with CuO catalyst and then collected using monoethanolamine (MEA) as CO$$_{2}$$ absorbent. However, this collection method has some issues on safety management because the CuO catalyst requires a high heating temperature (600$$^{circ}$$C) to ensure a high oxidation efficiency and the MEA is specified as a poisonous and deleterious substance. To establish a safer, manageable and reliable method for monitoring airborne $$^{14}$$C discharge, we examined collection methods that use different CO$$_{2}$$ absorbents (MEA and Carbo-Sorb E) and oxidation catalysts (CuO, Pt/Alumina and Pd/ZrO$$_{2}$$). The results showed 100% CO$$_{2}$$ collection efficiency of MEA during a 30-day sampling period under the condition tested. In contrast, Carbo-Sorb E was found to be unsuitable for the monthly-long CO$$_{2}$$ collection because of its high volatile nature. Among the oxidation catalysts, the Pd/ZrO$$_{2}$$ showed the highest oxidation efficiency for CH$$_{4}$$ at a lower temperature.

Oral presentation

Evaluation of protection factors obtained by Mask-man test apparatus

Yoshitomi, Hiroshi; Pangsub, K.; Hoshi, Shintaro; Takahashi, Teruhiko; Shishido, Nobuhito; Onodera, Junichi

no journal, , 

Workers to put full-face mask have checked their protection factors (PFs) by mask-man test apparatus before their works in the Reactor Fuel Examination Facility (RFEF) of JAEA. Analyzing these data, we could fit the distribution of the PFs for the inexperienced workers to the hybrid lognormal distribution. On the other hand, those of the experienced workers could be fitted to the lognormal distribution whose average was about 3000. If the PF is less than 200, then the worker have to check his mask-fit and retry to measure. Taking into account of the result of the retrial, we could also fit them to the lognormal distribution whose average was about 2000 even in those of the inexperienced workers. Next, we tried to correlate PF with BMI (Body Mass Index) to evaluate the individual PFs easily. As a result, we obtained the correlation coefficient is 0.5. In conclusion, we can tentatively say that if the workers have considerable experience using mask-man test apparatus, to put full-face mask can prevent them from inhalation of the radioactive dust about 2000 times more, and moreover we can estimate the individual PFs from their BMIs to some extent.

Oral presentation

Estimation of counting-loss of neutron survey meters used for monitoring burst neutrons at JAEA NSRR

Fujii, Katsutoshi; Takahashi, Teruhiko; Saegusa, Jun; Shishido, Nobuhito; Mochizuki, Kaoru*; Nojima, Shun; Akiyama, Isamu; Shimizu, Isamu

no journal, , 

In NSRR, pulse operation is performed. The correction of counting-loss is needed under the condition that large amount of neutrons have detected in a short period of time. This time, counting-loss of the neutron survey meter(type NSN1) is estimated used for monitoring Burst neutrons at NSRR.

Oral presentation

Radiation management for removing of radioactive liquid waste pipeline

Takahashi, Teruhiko; Niinuma, Shinichi; Futagawa, Kazuo; Otsuka, Yoshikazu; Muto, Yasushi; Sakai, Toshiya; Umehara, Takashi; Shimizu, Isamu; Umino, Takaaki; Yamada, Satoshi; et al.

no journal, , 

no abstracts in English

Oral presentation

Application test of blast method using for decontamination and MOX powder collection from low level radioactive waste

Kobayashi, Daisuke; Iida, Masayoshi; Takahashi, Naoki; Yoshimoto, Katsunobu; Nemoto, Ryo*; Miura, Susumu*; Numao, Teruhiko*; Nakayashiki, Hiroshi*

no journal, , 

no abstracts in English

Oral presentation

Investigation about $$^{14}$$C monitoring in RI facilities

Ueno, Yumi; Takahashi, Teruhiko; Sawahata, Katsunori; Kikuchi, Masamitsu; Tsunoda, Masahiko

no journal, , 

no abstracts in English

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