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Nakajima, Junya; Hirota, Seiko*; Tsuji, Tomoya; Watanabe, Yuki; Sakoda, Akihiro; Kobayashi, Noriko*
Hoken Butsuri (Internet), 58(1), p.13 - 20, 2023/04
no abstracts in English
Watanabe, Yuki; Tsuji, Tomoya; Hirota, Seiko*; Hokama, Tomonori; Nakajima, Junya; Tsujiguchi, Takakiyo*; Kimura, Tatsuki*; Koike, Hiromi*; Nakamura, Kaori*; Kuwata, Haruka*; et al.
Hoken Butsuri (Internet), 57(1), p.54 - 64, 2022/03
no abstracts in English
Kataoka, Noriaki*; Nakajima, Junya; Otsu, Saori; Takahashi, Akina; Takamiya, Kei; Umeda, Masayuki; Nishiono, Kanoko*
Hoken Butsuri (Internet), 56(1), p.28 - 31, 2021/03
no abstracts in English
Yamada, Ryohei; Kono, Takahiko; Nakajima, Junya; Hirouchi, Jun; Tsuji, Tomoya; Umeda, Masayuki; Igarashi, Yu*; Koike, Hiromi*
Hoken Butsuri (Internet), 56(1), p.32 - 38, 2021/03
no abstracts in English
Kataoka, Noriaki*; Nakajima, Junya; Miwa, Kazuji; Hirota, Seiko*; Tsubota, Yoichi; Yamada, Ryohei; Fujimichi, Yuki*; Ishikawa, Junya*; Sunaoshi, Masaaki*
Hoken Butsuri (Internet), 54(2), p.140 - 145, 2019/06
It is the written report of the joint meeting of young researchers in the field of radiation protection and radiation biology.
Cs from the Fukushima Daiichi Nuclear Power Plant accident; Simulations based on identical input dataSato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qu
lo, D.*; et al.
Journal of Geophysical Research; Atmospheres, 123(20), p.11748 - 11765, 2018/10
Times Cited Count：40 Percentile：85.28(Meteorology & Atmospheric Sciences)A model intercomparison of the atmospheric dispersion of Cs emitted following the Fukushima Daiichi Nuclear Power Plant accident was conducted by 12 models to understand the behavior of Cs in the atmosphere. The same meteorological data, horizontal grid resolution, and an emission inventory were applied to all the models to focus on the model variability originating from the processes included in each model. The multi-model ensemble captured 40% of the observed Cs events, and the figure-of-merit in space for the total deposition of Cs exceeded 80. Our analyses indicated that the meteorological data were most critical for reproducing the Cs events. The results also revealed that the differences among the models were originated from the deposition and diffusion processes when the meteorological field was simulated well. However, the models with strong diffusion tended to overestimate the Cs concentrations.
Nakajima, Junya
Hoken Butsuri, 52(2), p.136 - 138, 2017/06
The 15th Annual Meeting of Japanese Society of Radiation Safety Management was held at Okayama University from November 30th to December 2nd. In addition to some general sessions, two special lectures, two invited lectures, one morning lecture, one symposium and one session of planning committee were arranged. This is a report of the 15th Annual Meeting of Japanese Society of Radiation Safety Management.
Kawasaki, Masatsugu; Nakajima, Junya; Yoshida, Keisuke; Kato, Saori; Nishino, Sho; Nozaki, Teo; Nakagawa, Masahiro; Tsunoda, Junichi; Sugaya, Yuki; Hasegawa, Rie; et al.
JAEA-Data/Code 2017-004, 57 Pages, 2017/03
JAEA-Data-Code-2017-004.pdf:2.34MB
In emergency situation of nuclear facilities, we need to estimate the radiation dose due to radiation and radioactivity to grasp the influence range of the accident in the early stage. Therefore, we prepare the case studies of dose assessment for public exposure dose and personal exposure dose and contribute them to emergency procedures. This document covers about accidents of nuclear facilities in Nuclear Science Research Institute and past accident of nuclear power plant, and it can be used for inheritance of techniques of emergency dose assessment.
Yamada, Katsunori; Fujii, Katsutoshi; Kanda, Hiroshi; Higashi, Daisuke; Kobayashi, Toshiaki; Nakagawa, Masahiro; Fukami, Tomoyo; Yoshida, Keisuke; Ueno, Yumi; Nakajima, Junya; et al.
JAEA-Review 2013-033, 51 Pages, 2013/12
JAEA-Review-2013-033.pdf:2.73MB
After the accident at Fukushima Dai-ichi Nuclear Power Plant, various numerical criteria relevant to radiation protection were defined. We surveyed these criteria through internet. As a result of survey, the following 13 items were identified: (1) criteria for taking stable iodine tablets, (2) criteria for the screening of surface contamination, (3) evacuation area, sheltering area, etc., (4) activity concentrations in food, drinking water, etc., (5) dose limit for radiation workers engaged in emergency work, (6) guideline levels of radioactive substances in bathing areas, (7) criteria for use of school buildings and schoolyards, (8) restriction on planting rice, (9) acceptable activity concentrations in feedstuff, (10) acceptable activity concentrations in compost, (11) criteria for export containers and ships, (12) criteria for contaminated waste, (13) standards for radiation workers engaged in decontamination work. In this report, the basis of and issues on these criteria are summarized.
Kato, Junya; Miyauchi, Atsushi; Aoshima, Atsushi; Shiotsuki, Masao; Yamashita, Teruo; Nakajima, Masayoshi; Morikawa, Yo; Miura, Akihiko; Fukui, Toshiki*; Yamasaki, Akito*; et al.
no journal, ,
no abstracts in English
Kikuchi, Masamitsu; Umehara, Takashi; Shishido, Nobuhito; Kuramochi, Akihiko; Fujii, Katsutoshi; Nakajima, Junya
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.
Muto, Yasunobu; Yamada, Junya; Seya, Natsumi; Shimizu, Takehiko; Takasaki, Koji; Nakajima, Akemi
no journal, ,
no abstracts in English
Tsuchida, Hidetsugu*; Nakajima, Kaoru*; Yokoe, Junya*; Sugiyama, Motohiko*; Ota, Yushi*; Majima, Takuya*; Shibata, Hiromi*; Tomita, Shigeo*; Sasa, Kimikazu*; Hirata, Koichi*; et al.
no journal, ,
no abstracts in English
Nakajima, Junya; Yamada, Katsunori; Yokoyama, Hiroya; Shishido, Nobuhito; Muto, Yasushi
no journal, ,
We implement C-14 monitoring of exhaust in such a way as to measure mono-ethanolamine which is a collector of 
CO
with a liquid scintillation counter. Since Aquasol-2, which we have used so far was finished selling, we have done technical examinations on Insta-Gel plus and Ultima Gold for the alternative cocktail of Aquasol-2. In the result, as for the both cocktails, we confirmed that mono-ethanolamine can merge into the cocktails with some chemical additive, and detection limits of C-14 can comply the law limit of C-14 concentration of exhaust. However, chemical luminescence of Ultima Gold was so intense that it might affect the measurement in the case of measuring H-3 at the same time. Because of this, we chose Insta-Gel plus as the alternative cocktail.
Sato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Grahn, H.*; Br
nnstr
m, N.*; von Schoenberg, P.*; Kondo, Hiroaki*; Terada, Hiroaki; Nagai, Haruyasu; et al.
no journal, ,
The second intercomparison of atmospheric model targeting on the radionuclide (i.e. Cs) released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) on March 2011 is conducted. Thirteen atmospheric models, which include both the Lagrangian- and Eulerian-based dispersion models, participate in this model intercomparison project (MIP). The purposes of this MIP are to (1) understand the transport process of the radionuclide in atmosphere, (2) estimate the uncertainties in wet and dry deposition process among the models, (3) reveal the essential key processes to reproduce the plume of Cs, (4) assess the multi-model ensemble mean, and (5) obtain the knowledge for improving the physical processes of the models. To exclude the uncertainties of the model results originated from the emission inventory, all models used the same emission inventory. The meteorological data with fine spatiotemporal resolution, which was calculated by the Japanese operational weather forecast model coupled with the local ensemble transform Kalman Filter data assimilation system, was applied for all models to reduce the uncertainties originated from the difference in the meteorological field. As well as the comparison among the models, the comparison between the models and in-situ measurement from the national suspended particle matter (SPM) sampling network are conducted. The comparisons between the model results and the SPM data indicate that the Cs concentration near the FDNPP transported without precipitation process was relatively well reproduced by using the meteorological data with fine spatiotemporal resolution. On the contrary, Cs concentration accompanied with precipitation has large inter-model spread. In the presentation, we will discuss the more detailed analyses about the physical process to determine the Cs concentration.
Cs from the Fukushima Daiichi Nuclear Power Plant Accident using identical input dataSato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qulo, D.*; et al.
no journal, ,
An intercomparison of atmospheric dispersion model targeting on the physical process of Cs released from the Fukushima Daiichi Nuclear Power Plant was conducted. Twelve atmospheric models participated in this project. To exclude the uncertainties of the model result due to the emission inventory and meteorological data, all models used the same emission and meteorological data. Concentration of Cs from the national suspended particle matter monitoring network and the deposition density by the aircraft were used for the comparison between results of the model and observation. Our analyses elucidated the figure of merit in space (FMS) of the model ensemble mean was improved from a previous model intercomparson about the accumulated deposition. The model ensemble mean captured approximately 36% of the observed high concentration. The inter-model spread of the capture rate was from 8% to 38%. It was originated from the difference in deposition and diffusion processes among the models.
Cs from the Fukushima Daiichi Nuclear Power Station Accident using identical meteorological data and source termSato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qulo, D.*; et al.
no journal, ,
no abstracts in English
Cs) from the Fukushima Daiichi Nuclear Power Station Accident using identical meteorological data and source termSato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qulo, D.*; et al.
no journal, ,
no abstracts in English
Nakajima, Junya; Yamada, Katsunori; Hasegawa, Rie; Umeda, Masayuki; Seki, Masakazu; Muto, Yasushi; Sawahata, Katsunori
no journal, ,
STACY (Static Experiment Critical Facility) has been under remodeling work. During the demolition work of the previous model of STACY, we conducted radiation management for both internal exposure and external exposure taking the characteristics of the previous model into consideration. As a result, any contamination and internal exposure of the all workers was detected, and external exposure of the all workers were less than the detection limit.
