Radiation monitoring using manned helicopter around the Fukushima Daiichi Nuclear Power Station in the fiscal year 2014 (Contract research)

Sanada, Yukihisa; Mori, Airi; Ishizaki, Azusa; Munakata, Masahiro; Nakayama, Shinichi; Nishizawa, Yukiyasu; Urabe, Yoshimi; Nakanishi, Chika; Yamada, Tsutomu; Ishida, Mutsushi; et al.

JAEA-Research 2015-006, 81 Pages, 2015/07

JAEA-Research-2015-006.pdf:22.96MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (NPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPP. These results of the aerial radiation monitoring using the manned helicopter in the fiscal 2014 were summarized in the report.

27th report of ITPA topical group meeting

Osakabe, Masaki*; Shinohara, Koji; Toi, Kazuo*; Todo, Yasushi*; Hamamatsu, Kiyotaka; Murakami, Sadayoshi*; Yamamoto, Satoshi*; Idomura, Yasuhiro; Sakamoto, Yoshiteru; Tanaka, Kenji*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 85(12), p.839 - 842, 2009/12

http://ci.nii.ac.jp/naid/40016957892

no abstracts in English

Development of high temporal and spatial quality, high intensity laser system

Kiriyama, Hiromitsu; Ochi, Yoshihiro; Mori, Michiaki; Tanaka, Momoko; Okada, Hajime; Kosuge, Atsushi; Yoshida, Fumiko; Shimomura, Takuya; Sasao, Hajime; Nakai, Yoshiki*; et al.

no journal, , 

We describe two specific high intensity laser systems that are being developed in our laboratory for many applications such as high field science and nonlinear optics. We report on an ultra-high intensity petawatt-class Ti:sapphire chirped-pulse amplification laser system that can produce a pulse energy of 18 J with 30 fs pulse duration for studying extremely high intensity laser matter interaction process and a small-scaled Yb:YAG chirped-pulse amplification laser system that can generate a pulse energy of 100 m J of 500 fs pulse duration for compact, high efficiency, high repetition system. We discuss the basic design aspects and present the results from our experimental investigations of these laser systems.

Analysis of each radionuclides discharged by the Fukushima Daiichi Nuclear Power Station accident measured by airborne surveys

Nishizawa, Yukiyasu; Yoshida, Mami; Sanada, Yukihisa; Torii, Tatsuo

no journal, , 

Many radioactive substances were released by the Fukushima Daiichi Nuclear Power Plant accident occurred on March 11, 2011 in the atmosphere. A lot of short half-life nuclides which are I, Te, etc., in addition to longer half- lived nuclides such as Cs and Cs. The estimated release amount of these nuclides from the reactor 1st to 3rd unit is reported, but it's found to be quite different in the short half-lived nuclides by the reactor units. Because the radioactivity ratio of Cs and Cs was slight different between the reactor units, it can be considered that the valuable source is obtained by the measurement of Cs/Cs ratio in the environment around the Fukushima Daiichi Nuclear Power Station at the present stage when the nuclides with short half-lives had already decayed. We have measured high-resolution -ray spectrum using an unmanned helicopter equipped with LaBr(Ce) detector in a 3-km range from the power station which was near to the release source of the radioactive cesium. Because the LaBr(Ce) detector has high resolution of rays, the discrimination of many nuclides is possible. In addition, there is extremely much number of the data provided by the distribution measurement with the unmanned helicopter. Because a new map was illustrated by the analysis of the Cs/Cs ratio, we report the outline.

The Current situations and issues of the airborne radiation monitoring, 3; Distribution of the Cs-134/Cs-137 ratio around the Fukushima Daiichi Nuclear Power Plant using an unmanned helicopter radiation monitoring system

Nishizawa, Yukiyasu; Yoshida, Mami*; Sanada, Yukihisa; Torii, Tatsuo

no journal, , 

no abstracts in English

Contribution of fungal hyphal elongation to radiocesium transfer in deciduous broad-leaved litter

Sasaki, Yoshito; Niizato, Tadafumi; Amamiya, Hiroki*; Yoshida, Kaori

no journal, , 

Radiocesium deposited in the forest released by the accident at the Fukushima Daiichi Nuclear Power Station would remain in the forest and part of it would circulate due to the small amount of outflow from the forest. One possible source of dissolved radiocesium that is easily taken up by organisms is the litter layer. To clarify the contribution of fungal mycelial elongation in the transfer of radiocesium in the litter layer, we investigated the effect of the presence of fungi on the transfer of radiocesium from litter Cs(H) with high radiocesium concentration to litter Cs(L) with low radiocesium concentration. Fungal growth was observed in the test plots where the fungi were present. Regardless of with or without fungi, the Cs-137 concentration of Cs(L) reached about 50 Bq/kg on the 50th day, and then gradually increased to about 100 Bq/kg on the 150th day. This result suggested that the radiocesium was transferred by a physical force other than the hyphal elongation of the fungus in the litter layer.

Estimation of radiocesium transfer from the canopy to the forest floor in Japanese konara oak stands of the Abukuma Mountains, Fukushima

Niizato, Tadafumi; Sasaki, Yoshito; Amamiya, Hiroki*; Yoshida, Kaori*; Kimiyama, Kazuhiro*

no journal, , 

Of the radioactive materials released from the TEPCO's Fukushima Daiichi NPP accident, it is necessary to monitor Cs-137 distribution and effects over the long term because of its long half-life of approximately 30 years. In this study, monitoring of Cs-137 transfer from the forest canopy to the forest floor in the forested mountainous area were carried out in several forest areas in the Abukuma Mountains of Fukushima Prefecture, where the geographical conditions such as rainfall, tree density and tree species are almost the same. The results indicated that the amount of Cs-137 transfer by litterfall, stemflow and rainfall in the forests differ in each forested area, depending on the initial deposition and chemical form of Cs-137 in the forest.