El-Asaad, H.*; Nagai, Haruyasu; Sagara, Hiroshi*; Han, C. Y.*
Annals of Nuclear Energy, 141, p.107292_1 - 107292_9, 2020/06
Atmospheric dispersion simulations can provide crucial information to assess radioactive plumes in the environment for nuclear emergency preparedness. However, it is a difficult and time-consuming task to make simulations assuming many possible scenarios and to derive data from a vast number of results. Therefore, an interface was developed to assist users in conveying characteristics of plumes from simulation results. The interface uses a large database that contains WSPEEDI-II simulations for the first 20-days of radioactive release from the Fukushima Daiichi Nuclear Power Plant, and it displays essential quantitative data to the user from the database. The user may conduct sensitivity analysis with the help of the interface by changing release condition to generate many different case scenarios.
Terada, Hiroaki; Nagai, Haruyasu; Tanaka, Atsunori*; Tsuzuki, Katsunori; Kadowaki, Masanao
Journal of Nuclear Science and Technology, 57(6), p.745 - 754, 2020/06
We have estimated source term and analyzed processes of atmospheric dispersion of radioactive materials released during the Fukushima Daiichi Nuclear Power Station (FDNPS) accident by the Worldwide version of System for Environmental Emergency Dose Information. On the basis of this experience, we developed an dispersion calculation method that can respond to various needs in a nuclear emergency and provide useful information for emergency-response planning. By this method, if a release point is known, it is possible to immediately obtain the prediction results by applying provided source term to the database of dispersion-calculation results prepared in advance. With this function, it is easy to compare results by applying various source term with monitoring data, and to find out the optimum source term, which was applied for the source term estimation of the FDNPS accident. By performing this calculation with past meteorological-analysis data, it is possible to immediately get dispersion-calculation results for various source term and meteorological conditions. This database can be used for pre-accident planning, such as optimization of a monitoring plan and understanding of events to be supposed in considering emergency countermeasures.
Terada, Hiroaki; Nagai, Haruyasu; Tsuzuki, Katsunori; Furuno, Akiko; Kadowaki, Masanao; Kakefuda, Toyokazu*
Journal of Environmental Radioactivity, 213, p.106104_1 - 106104_13, 2020/03
In order to assess the radiological dose to the public resulting from the Fukushima Daiichi Nuclear Power Station accident in Japan, the spatial and temporal distribution of radioactive materials in the environment is necessary to be reconstructed by computer simulations with the atmospheric transport, dispersion and deposition model (ATDM) and source term of radioactive materials discharged into the atmosphere is essential. In this study, we carried out refinement of the source term and improvement of ATDM simulation by using an optimization method based on Bayesian inference with various measurements (air concentration, surface deposition, and fallout). We also constructed the spatiotemporal distribution of some major radionuclides in the air and on the surface (optimized dispersion database) by using the optimized release rates and ATDM simulations which is used for the comprehensive dose assessment by coupling with the behavioral pattern of evacuees from the accident.
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.
Ishizaki, Shuhei; Hayakawa, Tsuyoshi; Tsuzuki, Katsunori; Terada, Hiroaki; Togawa, Orihiko
JAEA-Technology 2018-007, 43 Pages, 2018/10
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.
Sanada, Yukihisa; Katata, Genki*; Kaneyasu, Naoki*
Isotope News, (759), p.18 - 21, 2018/10
no abstracts in English
Terada, Hiroaki; Tsuzuki, Katsunori; Kadowaki, Masanao; Nagai, Haruyasu; Tanaka, Atsunori*
JAEA-Data/Code 2017-013, 31 Pages, 2018/01
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.
Hamuza, E.-A.; Nagai, Haruyasu; Sagara, Hiroshi*
Energy Procedia, 131, p.279 - 284, 2017/12
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.
Hidaka, Akihide; Yokoyama, Hiroya
Journal of Nuclear Science and Technology, 54(8), p.819 - 829, 2017/08
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 I and Cs release behaviors during the late phase of the accident based on I/Cs ratio of the source terms that were recently evaluated backward by WSPEEDI code based on environmental monitoring data. The I release from the contaminated water in the basement of 1F2 and 1F3 reactor buildings was evaluated to be about 10% of I source term. The increase in Cs release from March 21 to 23 and from March 30 to 31 could be explained by the release of CsBO which is formed as a result of chemical reactions of Cs with BC due to re-ascension of the core temperature caused by slight shortage of the core cooling water.
Hidaka, Akihide; Yokoyama, Hiroya
Journal of Nuclear Science and Technology, 54(8), P. i, 2017/08
no abstracts in English
Kobayashi, Takuya; Kawamura, Hideyuki; Fujii, Katsuji*; Kamidaira, Yuki
Journal of Nuclear Science and Technology, 54(5), p.609 - 616, 2017/05
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.
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
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 ^Cs deposition around Chernobyl which was impossible to calculate in CASE-1 is predicted with high accuracy.
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.
Terada, Hiroaki; Chino, Masamichi
Journal of Nuclear Science and Technology, 42(7), p.651 - 660, 2005/07
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 Cs over Europe during the Chernobyl accident. It is concluded that MM5/GEARN-new can predict 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 Cs deposition around Chernobyl which was not calculated by the previous version.
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.
Furuno, Akiko; Terada, Hiroaki; Chino, Masamichi; Yamazawa, Hiromi*
Atmospheric Environment, 38(40), p.6989 - 6998, 2004/12
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.
Terada, Hiroaki; Furuno, Akiko; Chino, Masamichi
Journal of Nuclear Science and Technology, 41(5), p.632 - 640, 2004/05
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 Cs from Chernobyl show good agreement with measurements.
Chino, Masamichi; Adachi, Takeo
Nippon Genshiryoku Gakkai-Shi, 45(5), p.296 - 301, 2003/05
no abstracts in English
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.