Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Ji, Y.-Y.*; Ochi, Kotaro; Hong, S. B.*; Nakama, Shigeo; Sanada, Yukihisa; Mikami, Satoshi
Radiation Physics and Chemistry, 179, p.109205_1 - 109205_11, 2021/02
Times Cited Count：7 Percentile：70.8(Chemistry, Physical)In situ gamma-ray spectrometry using diverse survey platforms has been conducted in contaminated areas with several dose rate levels around the Fukushima Daiichi Nuclear Power Plant (FDNPP). Six survey sites, including two evacuation zones around the FDNPP, were selected for ground-based gamma-ray spectrometry using HPGe (high purity Ge) and LaBr
(Ce) detectors to assess the radioactive cesium deposition in the ground. The diverse levels of radioactivity of 
Cs were then distributed to six survey sites from 30 to 3000 kBq m
in the measurement period of October 2018. A method to directly calculate the depth profile using in situ measurement was introduced so as to have representation over a wide area, and the results were successfully compared with those of sample analysis at one point in the site.
Sanada, Yukihisa; Torii, Tatsuo
Nihon Genshiryoku Gakkai-Shi ATOMO
, 57(2), p.94 - 98, 2015/02
In Fukushima, quick and direct technique to measure a wide area of bottom of water is needed. We developed the plastic scintillation fiber (PSF) since accident at 1F. Therefore, the PSF was applied to measurement of irrigation pond. Here, the measuring method and the monitoring result are reported.
Suzuki, Motoe
JAERI-Research 94-022, 36 Pages, 1994/10
JAERI-Research-94-022.pdf:1.28MB
no abstracts in English
JAERI-M 85-095, 185 Pages, 1985/07
no abstracts in English
*; ;
JAERI-M 6497, 111 Pages, 1976/03
no abstracts in English
Iimoto, Takeshi*; Maedera, Ikuhiko*; Nunokawa, Jun*; Matsuzawa, Hajime*; Kurokawa, Sumihiko*; Yanagawa, Yukihide*; Someya, Seiichi*; Hashimoto, Makoto; Seya, Natsumi; Okawa, Yasuhisa; et al.
no journal, ,
no abstracts in English
Katengeza, E.*; Ochi, Kotaro; Sanada, Yukihisa; Iimoto, Takeshi*
no journal, ,
Katengeza, E.*; Sanada, Yukihisa; Yoshimura, Kazuya; Ochi, Kotaro; Iimoto, Takeshi*
no journal, ,
The rate of temporal change of radiocesium concentration in bottom sediments is governed not only by its physical decay but also by various ecological processes. In this study, the decreasing trend of radiocesium concentration over wide pond areas of surface sediments (up to 10 cm depth), due to ecological processes, was investigated using plastic scintillation fibers (PSF) and was quantified by the ecological half life. PSF measurements were conducted between 2013 and 2019. Their conversion factors ((Bq/kg)/cps) were obtained by comparison between detected radiation counting rate obtained by PSF and the concentration of radiocesium in sediment cores collected from coinciding positions within the same ponds. A forest catchment pond exhibited the longest ecological half life and may indicate catchment derived radiocesium input as was partly evident in the spatial temporal patterns of radiocesium concentration at this pond's inlet.
Katengeza, E.*; Sanada, Yukihisa; Ochi, Kotaro; Iimoto, Takeshi*
no journal, ,
When radiocesium (RCs) deposits in water bodies, it tends to concentrate at the waterbed due to its strong adsorption to sediments. Monitoring wide areas of so-contaminated waterbed is challenging by traditional sediment sampling. In-situ techniques that can directly measure radioactivity in the waterbed are important solutions. However, their accuracy is generally lower than that of sediment sampling. This study presents the status of research on the application of in-situ radioactivity measurement technology in the waterbed focusing on RCs monitoring in Fukushima as spearheaded by the Japan Atomic Energy Agency (JAEA).
Katengeza, E.*; Sanada, Yukihisa; Ochi, Kotaro; Iimoto, Takeshi*
no journal, ,
The calibration factor (CF) was determined by comparing the counting rate obtained by plastic scintillation fibers (PSF) with the average radiocesium (RCs) concentration in the top 10 cm of sediment core samples in previous study. The systematic biases and measurement uncertainty of estimated RCs concentration were evaluated by comparing against the RCs concentration in sampled sediment cores averaged over depths, ranging from 5 cm to 30 cm in 5 cm increments. When the calibration depth is 10 and 15 cm, the normalized mean square and relative deviation of PSF-derived RCs concentration against RCs concentration in sampled sediment were comparable. Thus, it may be necessary to revise calibration depth in order to sustainably optimize radiocesium concentration measurements by the PSF technique.
