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Journal Articles

Estimation of environmental releases of radioactive materials

Chino, Masamichi*; Nagai, Haruyasu

Environmental Contamination from the Fukushima Nuclear Disaster; Dispersion, Monitoring, Mitigation and Lessons Learned, p.50 - 61, 2019/00

Temporal variations in the amount of radionuclides released into the atmosphere during the Fukushima Daiichi Nuclear Power Station accident and their atmospheric dispersion are essential to evaluate the environmental impacts and resultant radiological doses to the public. We have estimated the atmospheric releases during the accident by comparing measurements with calculations by atmospheric deposition model. UNSCEAR compared several estimated source terms and used our source term for estimating levels of radioactive material in the terrestrial environment and doses to the public. To improve our source term, we recently made detailed source term estimation by using additional monitoring data and WSPEEDI including new deposition scheme.

JAEA Reports

Activities on predictions of atmospheric dispersion of radionuclides for nuclear tests by North Korea

Ishizaki, Shuhei; Hayakawa, Tsuyoshi; Tsuzuki, Katsunori; Terada, Hiroaki; Togawa, Orihiko

JAEA-Technology 2018-007, 43 Pages, 2018/10

JAEA-Technology-2018-007.pdf:5.67MB

When North Korea has carried out a nuclear test, by a request from Nuclear Regulation Authority (NRA), Nuclear Emergency Assistance and Training Center (NEAT) predicts atmospheric dispersion of radionuclides by WSPEEDI-II system in cooperation with Nuclear Science and Engineering Center (NSEC), and submits the predicted results to NRA as the activity to assist responses by the Japanese Government. This report explains frameworks of the Japanese Government and Japan Atomic Energy Agency (JAEA) to cope with nuclear tests by North Korea, and describes a series of activities by NEAT regarding predictions of atmospheric dispersion of radionuclides in response to the 5th and 6th nuclear tests carried out by North Korea in September 2016 and September 2017. Future plans and issues to be solved for responses to nuclear tests are also described in this report, together with an outline of a computer program system used in the predictions.

Journal Articles

Estimation of radionuclide deposition process by cloud and fog water at mountainous area; Comparison of observed data of airborne radiation monitoring and reproduction calculation

Sanada, Yukihisa; Katata, Genki*; Kaneyasu, Naoki*

Isotope News, (759), p.18 - 21, 2018/10

no abstracts in English

JAEA Reports

Development of a calculation method for atmospheric dispersion database that can immediately provide calculation results for any source term and period from hindcast to short-term forecast (Joint research)

Terada, Hiroaki; Tsuzuki, Katsunori; Kadowaki, Masanao; Nagai, Haruyasu; Tanaka, Atsunori*

JAEA-Data/Code 2017-013, 31 Pages, 2018/01

JAEA-Data-Code-2017-013.pdf:9.52MB

We developed an atmospheric dispersion calculation method that can respond to various needs for dispersion prediction in nuclear emergency and prepare database of information useful for planning of emergency response. In this method, it is possible to immediately get the prediction results for provided source term by creating a database of dispersion calculation results without specifying radionuclides, release rate and period except release point. By performing this calculation steadily along with meteorological data update, it is possible to immediately get calculation results for any source term and period from hindcast to short-term forecast. This function can be used for pre-accident planning such as optimization of monitoring plan and understanding events to be supposed for emergency response. Spatiotemporal distribution of radioactive materials reproduced by source term estimated inversely from monitoring based on this method is useful as a supplement to monitoring.

Journal Articles

User interface of atmospheric dispersion simulations for nuclear emergency countermeasures

Hamuza, E.-A.; Nagai, Haruyasu; Sagara, Hiroshi*

Energy Procedia, 131, p.279 - 284, 2017/12

 Percentile:100

In this study we would like to propose a method to use atmospheric dispersion simulations by WSPEEDI for consideration of crisis management on radionuclide dispersion from a nuclear power plant. WSPEEDI can simulate and output crucial information regarding environmental distribution of radionuclides and weather pattern for nuclear emergency countermeasures, thus this study will make use of its output to display the effective information for evacuation planning from a radionuclide dispersion. We will be assembling database of atmospheric dispersion outputs for one year by using WSPEEDI for a nuclear facility, then the database will be analysed to make the summary that has useful information for nuclear emergency managements. WSPEEDI outputs are converted into numeric information showing dispersion characteristics so that users can understand WSPEEDI predictions easily.

Journal Articles

Examination of $$^{131}$$I and $$^{137}$$Cs releases during late phase of Fukushima Daiichi NPP accident by using $$^{131}$$I/$$^{137}$$Cs ratio of source terms evaluated reversely by WSPEEDI code with environmental monitoring data

Hidaka, Akihide; Yokoyama, Hiroya

Journal of Nuclear Science and Technology, 54(8), p.819 - 829, 2017/08

AA2016-0500.pdf:0.44MB

 Times Cited Count:5 Percentile:12.06(Nuclear Science & Technology)

To clarify what happened during the Fukushima accident, the phenomena within RPV and the discussion of ties with the environmental monitoring are very important. However, the previous study has not necessarily advanced until the present that passed almost six years from the accident. The present study investigated $$^{131}$$I and $$^{137}$$Cs release behaviors during the late phase of the accident based on $$^{131}$$I/$$^{137}$$Cs ratio of the source terms that were recently evaluated backward by WSPEEDI code based on environmental monitoring data. The $$^{131}$$I release from the contaminated water in the basement of 1F2 and 1F3 reactor buildings was evaluated to be about 10% of $$^{131}$$I source term. The increase in $$^{137}$$Cs release from March 21 to 23 and from March 30 to 31 could be explained by the release of CsBO$$_{2}$$ which is formed as a result of chemical reactions of Cs with B$$_{4}$$C due to re-ascension of the core temperature caused by slight shortage of the core cooling water.

Journal Articles

Development of a short-term emergency assessment system of the marine environmental radioactivity around Japan

Kobayashi, Takuya; Kawamura, Hideyuki; Fujii, Katsuji*; Kamidaira, Yuki

Journal of Nuclear Science and Technology, 54(5), p.609 - 616, 2017/05

 Times Cited Count:2 Percentile:42.02(Nuclear Science & Technology)

The Japan Atomic Energy Agency has, for many years, been developing a radionuclide dispersion model for the ocean, and has validated the model through application in many sea areas using oceanic flow fields calculated by the ocean model. The Fukushima Dai-ichi Nuclear Power Station accident caused marine pollution by artificial radioactive materials to the North Pacific, especially to coastal waters northeast of mainland Japan. In order to investigate the migration of radionuclides in the ocean caused by this severe accident, studies using marine dispersion simulations have been carried out by JAEA. Based on these as well as the previous studies, JAEA has developed the Short-Term Emergency Assessment system of Marine Environmental Radioactivity (STEAMER) to immediately predict the radionuclide concentration around Japan in case of a nuclear accident.

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:10 Percentile:8.68(Multidisciplinary Sciences)

Journal Articles

Development of a long-range atmospheric transport model for nuclear emergency and its application to the Chernobyl nuclear accident

Terada, Hiroaki; Chino, Masamichi

Proceedings of 2nd International Conference on Radioactivity in the Environment, p.15 - 18, 2005/10

The previous version of Worldwide version of System for Prediction of Environmental Emergency Dose Information (WSPEEDI) has been composed of mass-consistent wind field model WSYNOP and particle dispersion model GEARN. Because WSYNOP has no capability to predict meteorological fields, its accuracy and resolution depends on meteorological input data, and it is impossible to treat physical processes realistically. To improve these problems, an atmospheric dynamic model MM5 is introduced and applied to the Chernobyl accident for the verification. Two calculation cases are conducted, CASE-1 a calculation for European region Domain-1, and CASE-2 a domain nesting calculation for Domain-1 and the region around Chernobyl Domain-2. The air concentration and surface deposition of $$^{137}Cs calculated by CASE-1 agree well with the measurements by statistical analysis and comparison for the horizontal distribution. In the result of CASE-2, the detailed distribution of surface $$^${137}$Cs deposition around Chernobyl which was impossible to calculate in CASE-1 is predicted with high accuracy.

Journal Articles

Research activities for development of CTBT-related technologies in JAERI

Shinohara, Nobuo; Asano, Yoshie; Hirota, Naoki*; Hokida, Takanori; Inoue, Yoji; Kumata, Masahiro; Nakahara, Yoshinori*; Oda, Tetsuzo*; Uchikoshi, Takako*; Yamamoto, Yoichi

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 3 Pages, 2005/10

Research activities of JAERI related to the CTBT verification regime are presented in the International Conference. The subjects of this presentation are (1) an overview of the CTBT verification regime, (2) construction and operation of the radionuclide monitoring stations of Okinawa (RN37) and Takasaki (RN38) and the certified radionuclide laboratory (RL11), and (3) preparation of the National Data Center at Tokai (JAERI NDC) for radionuclide data. The RN38 station has been certified by the CTBTO/PrepCom and sending the measured data every day. The infrastructures and operational manuals for RN37 and RL11 are now preparing for their operations. The JAERI NDC has experimentally analyzed and evaluated the radionuclide data from all over the world through International Data Center (IDC). As an example of the JAERI NDC works, atmospheric dispersion backtracking system has been developing by using WSPEEDI (Worldwide Version of System for Prediction of Environmental Emergency Dose Information) code to estimate a source location of radionuclide release by nuclear explosion/accident.

Journal Articles

Improvement of Worldwide version of System for Prediction of Environmental Emergency Dose Information (WSPEEDI), 2; Evaluation of numerical models by $$^{137}$$Cs deposition due to the Chernobyl nuclear accident

Terada, Hiroaki; Chino, Masamichi

Journal of Nuclear Science and Technology, 42(7), p.651 - 660, 2005/07

 Times Cited Count:13 Percentile:28.49(Nuclear Science & Technology)

The prediction performance of WSPEEDI (Worldwide version of System for Prediction of Environmental Emergency Dose Information), which consists of the atmospheric dynamic model MM5 and the Lagrangian particle dispersion model GEARN-new, is evaluated by measurements of precipitation and surface deposition of $$^{137}$$Cs over Europe during the Chernobyl accident. It is concluded that MM5/GEARN-new can predict $$^{137}$$Cs deposition distribution with good accuracy when accurate precipitation is predicted by using a explicit scheme on cloud microphysics with ice phase processes. High-resolutional calculation is also conducted for the area surrounding Chernobyl by a nesting method. MM5/GEARN-new can predict quite a realistic distribution of $$^{137}$$Cs deposition around Chernobyl which was not calculated by the previous version.

Journal Articles

Status of research activities for development of CTBT-related technologies in JAERI

Shinohara, Nobuo; Inoue, Yoji; Uchikoshi, Takako*; Oda, Tetsuzo*; Kumata, Masahiro; Kurosawa, Yoshiaki; Hirota, Naoki*; Hokida, Takanori; Nakahara, Yoshinori*; Yamamoto, Yoichi

Dai-25-Kai Kaku Busshitsu Kanri Gakkai Nippon Shibu Nenji Taikai Rombunshu, p.51 - 58, 2005/00

The Japan Atomic Energy Research Institute (JAERI) conducts researches and developments related to Comprehensive Nuclear-Test-Ban Treaty (CTBT) on the basis of Japan's pragmatic and progressive efforts toward peaceful use of atomic energy and non-proliferation with the goal of realizing a peaceful and safe world free from nuclear weapons. The Treaty aims for the establishment of a global verification regime comprising an International Monitoring System (IMS) and the JAERI has engaged in the following activities: construction and operation of the radionuclide monitoring stations at Okinawa (RN37) and Takasaki (RN38) and the certified radionuclide laboratory at Tokai (RL11) as specified in Annex 1 of CTBT Protocol, and preparation of the National Data Center at Tokai (JAERI NDC). Research activities of JAERI related to the CTBT verification regime are presented in the paper. The subjects of this presentation are (1) an overview of the CTBT verification regime, (2) construction and operation of RN37, RN38 and RL11, and (3) preparation of the JAERI NDC for radionuclide data.

Journal Articles

Experimental verification for real-time environmental emergency response system; WSPEEDI by European tracer experiment

Furuno, Akiko; Terada, Hiroaki; Chino, Masamichi; Yamazawa, Hiromi*

Atmospheric Environment, 38(40), p.6989 - 6998, 2004/12

 Times Cited Count:19 Percentile:53.28(Environmental Sciences)

We have been developing the computer-based emergency response system WSPEEDI which predicts long-range atmospheric dispersion of radionuclides discharged into the atmosphere due to a nuclear accident. The first version of WSPEEDI has a shortage that the spatial and temporal variation of the atmospheric boundary layer was very simply parameterized. Therefore we have developed the new version accomplished with the atmospheric dynamic model, in which the turbulent diffusivity in the mixing layer is calculated with a turbulence closure model. This paper describes the results of performance evaluation of the new version of WSPEEDI by comparing the simulation results with the European Tracer Experiment data. As a result of the verification, it was shown that the increase in the horizontal resolution largely improved the accuracy of the model prediction. The use of the turbulence closure model instead of the simple parameterization largely contributed to improve reproducibility of horizontal distribution of plumes.

Journal Articles

Improvement of Worldwide Version of System for Prediction of Environmental Emergency Dose Information (WSPEEDI), 1; New combination of models, atmospheric dynamic model MM5 and particle random walk model GEARN-new

Terada, Hiroaki; Furuno, Akiko; Chino, Masamichi

Journal of Nuclear Science and Technology, 41(5), p.632 - 640, 2004/05

 Times Cited Count:19 Percentile:19.84(Nuclear Science & Technology)

The new version of WSPEEDI (Worldwide version of System for Prediction of Environmental Emergency Dose Information) is developed by introducing the combination of models, the atmospheric dynamic model MM5 and the Lagrangian particle dispersion model GEARN-new to improve the prediction capability. One of the improvements by the new system is that Environmental contaminations in multi domains are predicted simultaneously, and the other is that more precise physical processes are considered by using predicted meteorological conditions with high resolution in time and space. The performance of the system is evaluated for the test calculations of hypothetical nuclear accident in the East Asia region and the Chernobyl accident. The results of test calculation in East Asia seem to be reasonable and the calculated surface air concentrations of $$^{137}$$Cs from Chernobyl show good agreement with measurements.

Journal Articles

Present status and future prospect on System for Prediction of Environmental Emergency Dose Information, SPEEDI

Chino, Masamichi; Adachi, Takeo

Nippon Genshiryoku Gakkai-Shi, 45(5), p.296 - 301, 2003/05

no abstracts in English

Journal Articles

Real-time environmental contamination assessment system during nuclear emergency

Terada, Hiroaki; Furuno, Akiko; Chino, Masamichi

Proceedings from the International Conference on Radioactivity in the Environment (CD-ROM), 4 Pages, 2002/09

The present study aims to expanding the capability of WSPEEDI, so that it can be applied to atmospheric releases of radionuclides in the world for terrorist attack as well as nuclear accident. A terrorist attack would be possible in any time, any place and any scale. Altough WSPEEDI has already had a function to acquire global meteorological forecasts to generate a geographical map at arbitrary region in the world, it had no capability for simultaneous multi-scale predictions. Thus, the combination of models, non-hydrostatic meteorological model MM5 and atmospheric dispersion model GEARN, is introduced to WSPEEDI. MM5 can forecast local and regional meteorological condition simultaneously by domain nesting calculations. By the input of meteorological condition generated by MM5, GEARN can forecast multi-scale environmental contaminations considering detailed boundary layer and precipitation processes. Using this improved WSPEEDI, we made test calculations assuming a nuclear accident or terrorist attack in Asia.

JAEA Reports

Atmospheric dispersion simulations of volcanic gas from Miyake Island by SPEEDI

Nagai, Haruyasu; Furuno, Akiko; Terada, Hiroaki; Umeyama, Nobuaki; Yamazawa, Hiromi; Chino, Masamichi

JAERI-Research 2001-012, 28 Pages, 2001/03

JAERI-Research-2001-012.pdf:1.77MB

Japan Atomic Energy Research Institute is advancing the study for prediction of material circulation in the environment to cope with environmental pollution, based on SPEEDI (System for Prediction of Environmental Emergency Dose Information) and WSPEEDI (Worldwide version of SPEEDI), which are originally developed aiming at real-time prediction of atmospheric dispersion of radioactive substances accidentally released from nuclear facility. As a part of this study, dispersion simulation of volcanic gas erupted from Miyake Island is put into practice. After the stench incident at the west Kanto District on 28 August 2000 caused by volcanic gas from Miyake Island, simulations dealing with atmospheric dispersion of volcanic gas from Miyake Island have been carried out. This report describes the details of these studies.

Journal Articles

Development of an atmospheric dispersion backtracking software for CTBT verification systems

Hokida, Takanori; Yamamoto, Yoichi; Yamazawa, Hiromi

Dai-22-Kai Kaku Busshitsu Kanri Gakkai Nippon Shibu Nenji Taikai Rombunshu, p.149 - 156, 2001/02

no abstracts in English

Journal Articles

Reactivity accident of nuclear submarine at Vladivostok

Takano, Makoto; Romanova, V.*; Yamazawa, Hiromi; Sivintsev, Y.*; Compton, K.*; Novikov, V.*; Parker, F.*

Journal of Nuclear Science and Technology, 38(2), p.143 - 157, 2001/02

no abstracts in English

65 (Records 1-20 displayed on this page)