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Journal Articles

A Knowledge-sharing activity on the environmental radiation monitoring results affected by the Fukushima-Daiichi Nuclear Power Plant Accident at Tokai-Oarai area in Ibaraki Prefecture

Nakano, Masanao; Hosomi, Kenji; Nishimura, Shusaku; Matsubara, Natsumi; Okura, Takehisa; Kuramochi, Akihiko; Kawasaki, Masatsugu; Takeuchi, Erina; Fujii, Yutaka*; Jinno, Tsukasa*; et al.

Hoken Butsuri (Internet), 55(2), p.102 - 109, 2020/06

After the Fukushima-Daiichi Nuclear Power Station (1F) Accident in March 2011, the increase was significantly observed in a part of the result of the environmental radiation monitoring in Ibaraki prefecture. "The review meeting of the environmental effect from 1F accident" was established to discuss technically the fluctuation of monitoring data. The review meeting collected the monitoring data from the four nuclear operators, and discussed a fluctuating trend, $$^{134}$$Cs/$$^{137}$$Cs activity ratio, and so on. In this report, the results of the dose rate and $$^{137}$$Cs in fallout, surface soil, flatfish and seabed sediment are introduced. Also the problem solving in the review meeting is introduced.

Journal Articles

Guidance for ${it in situ}$ gamma spectrometry intercomparison based on the information obtained through five intercomparisons during the Fukushima mapping project

Mikami, Satoshi; Ishikawa, Daisuke*; Matsuda, Hideo*; Hoshide, Yoshifumi*; Okuda, Naotoshi*; Sakamoto, Ryuichi*; Saito, Kimiaki

Journal of Environmental Radioactivity, 210, p.105938_1 - 105938_7, 2019/12

 Times Cited Count:1 Percentile:10.3(Environmental Sciences)

Five intercomparisons of in situ $$gamma$$ spectrometry by 6-7 participating teams have been conducted between December 2011 and August 2015 at sites in Fukushima prefecture which affected by the fallout of FDNPS accident occurred in March 2011. The evaluated deposition densities agreed within 5-6% in terms of coefficient of variation (CV) for radiocesium ($$^{134}$$Cs and $$^{137}$$Cs), by our best achievement, and the ratio of $$^{134}$$Cs/$$^{137}$$Cs in deposition density agreed within 1-2% in CV, through five intercomparisons. These results guarantee the accuracy of the measurements of the mapping project. Two different methods for intercomparison were conducted: (1) sequential measurements at an identical point; and (2) simultaneous measurements in a narrow area within 3 m radius. In a comparison between the two methods at a site, no significant difference was observed between the results. The standard protocols for the two different intercomparison methods were proposed based on our experience.

Journal Articles

Repeatability and reproducibility of measurements of low dissolved radiocesium concentrations in freshwater using different pre-concentration methods

Kurihara, Momo*; Yasutaka, Tetsuo*; Aono, Tatsuo*; Ashikawa, Nobuo*; Ebina, Hiroyuki*; Iijima, Takeshi*; Ishimaru, Kei*; Kanai, Ramon*; Karube, Jinichi*; Konnai, Yae*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 322(2), p.477 - 485, 2019/11

 Times Cited Count:2 Percentile:42.44(Chemistry, Analytical)

We assessed the repeatability and reproducibility of methods for determining low dissolved radiocesium concentrations in freshwater in Fukushima. Twenty-one laboratories pre-concentrated three of 10 L samples by five different pre-concentration methods (prussian-blue-impregnated filter cartridges, coprecipitation with ammonium phosphomolybdate, evaporation, solid-phase extraction disks, and ion-exchange resin columns), and activity of radiocesium was measured. The z-scores for all of the $$^{137}$$Cs results were within $$pm$$2, indicating that the methods were accurate. The relative standard deviations (RSDs) indicating the variability in the results from different laboratories were larger than the RSDs indicating the variability in the results from each separate laboratory.

Journal Articles

Utilization of $$^{134}$$Cs/$$^{137}$$Cs in the environment to identify the reactor units that caused atmospheric releases during the Fukushima Daiichi accident

Chino, Masamichi; Terada, Hiroaki; Nagai, Haruyasu; Katata, Genki; Mikami, Satoshi; Torii, Tatsuo; Saito, Kimiaki; Nishizawa, Yukiyasu

Scientific Reports (Internet), 6, p.31376_1 - 31376_14, 2016/08

 Times Cited Count:38 Percentile:98.68(Multidisciplinary Sciences)

Journal Articles

Source term estimation for the Fukushima Daiichi Nuclear Power Station accident by combined analysis of environmental monitoring and plant data through atmospheric dispersion simulation

Nagai, Haruyasu; Terada, Hiroaki; Chino, Masamichi; Katata, Genki; Mikami, Satoshi; Saito, Kimiaki

Proceedings of 16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-16) (USB Flash Drive), p.4044 - 4052, 2015/08

JAEA has estimated the atmospheric releases of radionuclide during the Fukushima Daiichi Nuclear Power Station (FNPS1) accident by comparing measurements of air concentration of a radionuclide or its dose rate in the environment with the ones calculated by atmospheric transport and deposition model (ATDM). To improve our source term, we are trying to develop more sophisticated estimation method and use new information from severe accident analysis and observation data. As the first step of new trial, we used $$^{134}$$Cs/$$^{137}$$Cs ratios of inventories in FNPS1 reactors Unit 1 to 3 and those in surface deposition. By considering temporal change in $$^{134}$$Cs/$$^{137}$$Cs ratio of released plume and ATDM simulations, spatial distribution of $$^{134}$$Cs/$$^{137}$$Cs ratio in surface deposition was explained. This result can be used to specify from which reactor the dominant release occurred for each time period, and consequently provide useful information to severe accident analysis for the FNPS1 case.

Journal Articles

Migration of radioactive $$^{85}$$Sr,$$^{134}$$Cs and $$^{60}$$Co through a loess soil layer

Z.Li*; H.Wang*; Takebe, Shinichi; Tanaka, Tadao

Materials Research Society Symposium Proceedings, Vol.353, 0, p.1109 - 1115, 1995/00

no abstracts in English

JAEA Reports

Field test of radionuclide migration; Cooperative research between JAERI and CIRP

*; Yamamoto, Tadatoshi; ; Takebe, Shinichi; Ogawa, Hiromichi; Tanaka, Tadao; Mukai, Masayuki; Komiya, Tomokazu; S.Li*; Z.Wang*; et al.

JAERI-Research 94-009, 44 Pages, 1994/07

JAERI-Research-94-009.pdf:1.69MB

no abstracts in English

JAEA Reports

Determination of distribution ratio for $$^{60}$$Co,$$^{85}$$Sr and $$^{134}$$Cs in loess medium

Tanaka, Tadao; Ogawa, Hiromichi; Z.Li*; H.Wang*; *

JAERI-M 94-077, 17 Pages, 1994/06

JAERI-M-94-077.pdf:0.61MB

no abstracts in English

JAEA Reports

Preliminary investigation on determination of radionuclide distribution in field tracing test site

Tanaka, Tadao; Guo, Z.*; Mukai, Masayuki; Takebe, Shinichi; S.Li*; *

JAERI-M 93-235, 17 Pages, 1993/12

JAERI-M-93-235.pdf:0.55MB

no abstracts in English

Oral presentation

Investigation on distribution of radioactive substances in Fukushima, 9; Analysis of temporal changes in ambient dose equivalent rates in forests over 6 years following the FDNPP accident

Malins, A.; Imamura, Naohiro*; Niizato, Tadafumi; Kim, M.; Sakuma, Kazuyuki; Shinomiya, Yoshiki*; Miura, Satoru*; Machida, Masahiko

no journal, , 

We analyzed changes in ambient dose equivalent rates ($textit{.{H}}$*(10)) between 2011 and 2017 in forests in Fukushima Prefecture. PHITS was used to calculate the effects of changes in the distribution of $textsuperscript{134}$Cs and $textsuperscript{137}$Cs within forests on $textit{.{H}}$*(10). The transfer of radiocesium from the crowns of evergreen coniferous trees to the forest floor appeared to cause slower decreases in $textit{.{H}}$*(10) at 1 m height in early years than expected by the rate of $textsuperscript{134}$Cs and $textsuperscript{137}$Cs decay.

Oral presentation

Using PHITS to calculate ambient dose equivalent rates in radiocesium contaminated forests

Malins, A.; Imamura, Naohiro*; Niizato, Tadafumi; Kim, M.; Sakuma, Kazuyuki; Shinomiya, Yoshiki*; Miura, Satoru*; Machida, Masahiko

no journal, , 

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