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JAEA Reports

Consideration on utilization of atmospheric dispersion models for a nuclear emergency preparedness and response

Togawa, Orihiko; Okura, Takehisa; Kimura, Masanori; Nagai, Haruyasu

JAEA-Review 2021-021, 61 Pages, 2021/11

JAEA-Review-2021-021.pdf:3.72MB

Triggered by the Fukushima Daiichi Nuclear Power Station accident, there have been a lot of arguments among various situations and levels about utilization of atmospheric dispersion models for a nuclear emergency preparedness and response. Most of these arguments, however, were alternative and extreme discussions on whether predictions by computational models could be applied or not for protective measures in a nuclear emergency, and it was hard to say that these arguments were politely conducted, based on scientific verification in an emergency response. It was known, on the other hand, that there were not a few potential users of atmospheric dispersion models and/or calculation results by the models within the Japan Atomic Energy Agency (JAEA) and outside. However, they seemed to have a lack of understanding and a misunderstanding on proper use of different kinds of atmospheric dispersion models. This report compares an outline of models and calculation method in atmospheric dispersion models for a nuclear emergency preparedness and response, with a central focus on the models which have been developed and used in the JAEA. Examples of calculations by these models are also described in the report. This report aims at contributing to future consideration and activities for potential users of atmospheric dispersion models within the JAEA and outside.

JAEA Reports

Transfer and operation of WSPEEDI-II automatic calculation system for responses to nuclear tests by North Korea

Nemoto, Miho*; Ebine, Noriya; Okamoto, Akiko; Hosaka, Yasuhisa*; Tsuzuki, Katsunori; Terada, Hiroaki; Hayakawa, Tsuyoshi; Togawa, Orihiko

JAEA-Technology 2021-013, 41 Pages, 2021/08

JAEA-Technology-2021-013.pdf:2.52MB

When North Korea has carried out nuclear tests, Nuclear Emergency Assistance and Training Center (NEAT) predicts atmospheric dispersion of radionuclides by using the WSPEEDI-II upon requests from Nuclear Regulation Authority (NRA) and submits the predicted results to NRA in cooperation with Nuclear Science and Engineering Center (NSEC). This is a part of the activity of NEAT supporting the Japanese Government in emergency responses. The WSPEEDI-II automatic calculation system specialized for responses to nuclear tests by North Korea was developed by NSEC and was used for responses to three nuclear tests from February 2013 to September 2017. This report describes the transfer and installation of the calculation system to NEAT, and the subsequent maintenance and operation. Future issues for responses to nuclear tests are also described in this report.

JAEA Reports

Investigation and consideration on evaluation of radiation doses to residents in the case of a nuclear emergency

Hashimoto, Makoto; Kinase, Sakae; Munakata, Masahiro; Murayama, Takashi; Takahashi, Masa; Takada, Chie; Okamoto, Akiko; Hayakawa, Tsuyoshi; Sukegawa, Masato; Kume, Nobuhide*; et al.

JAEA-Review 2020-071, 53 Pages, 2021/03

JAEA-Review-2020-071.pdf:2.72MB

In the case of a nuclear accident or a radiological emergency, the Japan Atomic Energy Agency (JAEA), as a designated public corporation assigned in the Disaster Countermeasures Basic Act and the Armed Attack Situation Response Law, undertakes technical supports to the national government and local governments. The JAEA is requested to support to evaluate radiation doses to residents in a nuclear emergency, which is specified in the Basic Disaster Management Plan and the Nuclear Emergency Response Manual. For the dose evaluation, however, its strategy, target, method, structure and so on have not been determined either specifically or in detail. This report describes the results of investigation and consideration discussed in the "Working Group for Radiation Dose Evaluation at a Nuclear Emergency" established within the Nuclear Emergency Assistance and Training Center to discuss technical supports for radiation dose evaluation to residents in the case of a nuclear emergency, and aims at contributing to specific and detailed discussion and activities in the future for the national government and local governments, also within the JAEA.

JAEA Reports

Registration and related activities of the Japan Atomic Energy Agency for the response and assistance network of the International Atomic Energy Agency

Togawa, Orihiko; Hayakawa, Tsuyoshi; Tanaka, Tadao; Yamamoto, Kazuya; Okuno, Hiroshi

JAEA-Review 2020-017, 36 Pages, 2020/09

JAEA-Review-2020-017.pdf:2.24MB

In 2010, the government of Japan joined the Response and Assistance Network (RANET) of the International Atomic Energy Agency (IAEA), in order to contribute to offering international assistance in the case of a nuclear accident or radiological emergency. At that occasion, the Japan Atomic Energy Agency (JAEA) was registered as the National Assistance Capability (NAC) having resources capable of the External Based Support (EBS) in the following seven areas: (1) aerial survey, (2) radiation monitoring, (3) environmental measurements, (4) assessment and advice, (5) internal dose assessment, (6) bioassay and (7) dose reconstruction. After the registration, three inquiries were directed to the JAEA about a possibility of its support. However, the JAEA's assistance has not eventually been realized. On the other hand, the JAEA participated almost every year in the international Convention Exercise (ConvEx) carried out by the IAEA in connection with RANET. This report describes an outline of the RANET and related activities of the JAEA for RANET registration and participation in the ConvEx.

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

Concentration of iodine-129 in surface seawater at subarctic and subtropical circulations in the Japan Sea

Suzuki, Takashi; Otosaka, Shigeyoshi; Togawa, Orihiko

Nuclear Instruments and Methods in Physics Research B, 294, p.563 - 567, 2013/01

 Times Cited Count:4 Percentile:37.15(Instruments & Instrumentation)

no abstracts in English

Journal Articles

A Study of released radionuclide in the coastal area from a discharge pipe of nuclear fuel reprocessing plant in Rokkasho, Aomori, Japan

Kobayashi, Takuya; In, Teiji*; Ishikawa, Yoichi*; Kawamura, Hideyuki; Nakayama, Tomoharu*; Shima, Shigeki*; Awaji, Toshiyuki*; Togawa, Orihiko

Progress in Nuclear Science and Technology (Internet), 2, p.682 - 687, 2011/10

When the reprocessing plant is in routine operation, radionuclides are released to the coastal ocean as scheduled. Released radionuclides migrate in the ocean by physical, chemical and biological processes. Thus, for environmental safety, it is important to understand the migration behavior due to routine releases of radionuclides to the coastal ocean from the reprocessing plant. A numerical simulation model system that consists of an ocean general circulation model and a particle random-walk model to describe the radionuclide migration behavior in Rokkasho coastal region has been developed. The particle random-walk model, SEA-GEARN, calculates the radionuclides migration in the ocean. The system has been applied to simulate the nowcast of Rokkasho coastal region in 2007 and hypothetical radionuclide release has been carried out.

Journal Articles

Assessment system of marine environment in the Japan Sea

Kawamura, Hideyuki; Kobayashi, Takuya; Togawa, Orihiko; Onitsuka, Go*

Proceedings of 7th International Conference on Natural Computation (ICNC '11)/8th International Conference on Fuzzy Systems and Knowledge Discovery (FSKD '11), p.1742 - 1746, 2011/07

An assessment system of marine environment in the Japan Sea is developed in Japan Atomic Energy Agency to calculate a movement of pollutants such as radionuclides and their effect on Japanese people. The assessment system consists of three models, ocean general circulation model, particle random-walk model, and dose assessment model. The assessment system was applied so far to a numerical experiment of an oil spill accident and a numerical experiment for reproduction of concentration of anthropogenic radionuclides in the Japan Sea. In addition, the lower trophic level ecosystem model is being developed to estimate a suspended solid in the Japan Sea.

Journal Articles

Surface concentrations of $$^{129}$$I around the subarctic front in the Japan Sea

Suzuki, Takashi; Otosaka, Shigeyoshi; Togawa, Orihiko

Dai-13-Kai AMS Shimpojiumu Hokokusho, p.69 - 72, 2011/01

no abstracts in English

Journal Articles

Numerical experiment for strontium-90 and cesium-137 in the Japan Sea

Kawamura, Hideyuki; Ito, Toshimichi; Kobayashi, Takuya; Otosaka, Shigeyoshi; Hirose, Naoki*; Togawa, Orihiko

Journal of Oceanography, 66(5), p.649 - 662, 2010/10

 Times Cited Count:2 Percentile:7.46(Oceanography)

A numerical experiment is performed to reproduce a distribution of concentrations of $$^{90}$$Sr and $$^{137}$$Cs and estimate their total amounts in the Japan Sea. The concentrations of $$^{90}$$Sr and $$^{137}$$Cs in the surface layer is in the range of 1.0-1.5 Bq/m$$^{3}$$ and 2.0-2.5 Bq/m$$^{3}$$. The concentrations in the intermediate and deep layer are higher than those observed in the northwestern Pacific Ocean, indicating active winter convection in the Japan Sea. The total amounts of $$^{90}$$Sr and $$^{137}$$Cs in the seawater is evaluated to be 1.34 PBq (1 PBq = 10$$^{15}$$ Bq) and 2.02 PBq, which demonstrates an estimation by observational data in the Japan Sea expeditions between 1997 and 2002 by Japan Atomic Energy Agency. The total amounts of $$^{90}$$Sr and $$^{137}$$Cs vary corresponding to deposition at the sea surface with the maximums of 4.86 PBq for $$^{90}$$Sr and 7.33 PBq for $$^{137}$$Cs in the mid-1960s.

Journal Articles

Simulation of concentrations of anthropogenic radionuclides in the Japan Sea

Kawamura, Hideyuki; Ito, Toshimichi; Kobayashi, Takuya; Otosaka, Shigeyoshi; Hirose, Naoki*; Togawa, Orihiko

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 4 Pages, 2010/10

This study aims to demonstrate many findings in the Japan Sea expeditions by Japan Atomic Energy Agency between 1997 and 2002 making use of an ocean general circulation model. A numerical experiment is performed between 1945 and 2000 with deposition at the sea surface by global fallout as main source of anthropogenic radionuclides. The concentrations of $$^{90}$$Sr and $$^{137}$$Cs in the surface layer are approximately in the range of 1.0-1.5 Bq/m$$^{3}$$ and 2.0-2.5 Bq/m$$^{3}$$ and they exponentially decrease with depth from the sea surface to the sea bottom. Total amounts of $$^{90}$$Sr and $$^{137}$$Cs in the seawater of the Japan Sea are estimated to be about 1.34 PBq (1 PBq = 10$$^{15}$$ Bq) and 2.02 PBq in the numerical experiment, which demonstrates observational estimations in the Japan Sea expeditions. Time series of the total amounts show that they attain the maximums of 4.86 PBq for $$^{90}$$Sr and 7.33 PBq for $$^{137}$$Cs in 1964.

Journal Articles

A Numerical simulation of $$^{129}$$I in the atmosphere emitted from nuclear fuel reprocessing plants

Nishizawa, Masato; Suzuki, Takashi; Nagai, Haruyasu; Togawa, Orihiko

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 4 Pages, 2010/10

Suzuki et al. (${it Quaternary Geochronology}$, ${bf 3}$, 268-275, 2008) estimated that more than 80% of Iodine-129 ($$^{129}$$I) in seawater in the Japan Sea came from nuclear fuel reprocessing plants. Considering the distance from the main nuclear reprocessing plants in Europe to the Japan Sea and the time scales of atmospheric and ocean circulations, large portion of $$^{129}$$I in the Japan Sea is presumed to be transported through the atmosphere. In the present study, a global chemical transport model, MOZART-4, is applied to investigate the behavior of $$^{129}$$I emitted from nuclear fuel reprocessing plants in Europe (Sellafield in the UK and La Hague in France) and to estimate the distribution in the atmosphere and deposition in remote sites. The result of numerical simulation for more than fifty-year period from the 1950s is validated by comparison with measurements of $$^{129}$$I around the world and analyzed to clarify the characteristic of the distributions of concentration and deposition of $$^{129}$$I. The modeled concentrations of $$^{129}$$I in precipitation in Europe and depositions in Japanese waters are in the same order as measurements. The emitted $$^{129}$$I to the atmosphere is distributed and deposited all over the Northern Hemisphere due to the prevailing westerlies. The emission of $$^{129}$$I to the atmosphere is thus important in considering the transport and deposition of $$^{129}$$I to remote sites.

Journal Articles

Seawater circulation in the Japan Sea based on iodine-129

Suzuki, Takashi; Minakawa, Masayuki*; Kabuto, Shoji; Togawa, Orihiko

Dai-12-Kai AMS Shimpojiumu Hokokushu, p.69 - 72, 2010/05

no abstracts in English

Journal Articles

The Vertical profiles of iodine-129 in the Pacific Ocean and the Japan Sea before the routine operation of new nuclear fuel reprocessing plant

Suzuki, Takashi; Minakawa, Masayuki*; Amano, Hikaru; Togawa, Orihiko

Nuclear Instruments and Methods in Physics Research B, 268, p.1229 - 1231, 2010/04

 Times Cited Count:24 Percentile:86.24(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Preliminary result of dissolved organic radiocarbon in the western North Pacific Ocean

Tanaka, Takayuki; Otosaka, Shigeyoshi; Wakita, Masahide*; Amano, Hikaru*; Togawa, Orihiko

Nuclear Instruments and Methods in Physics Research B, 268(7-8), p.1219 - 1221, 2010/04

 Times Cited Count:9 Percentile:56.9(Instruments & Instrumentation)

Dissolved organic carbon (DOC) in seawater is one of the largest reservoirs of organic matter on the earth's surface, holding approximately as much carbon as available in atmospheric CO$$_{2}$$. As a result of the huge carbon reservoir, the role and dynamics of DOC have become of greater interest in the global carbon cycle. It has been suggested that dissolved organic radiocarbon ($$Delta$$$$^{14}$$C-DOC) in seawater is a powerful tool to understand the dynamics of DOC and its researches have been carried out using AMS. However, there are very few data in the world oceans because of the difficulties of the measurement technique. Although it has been represented that the western North Pacific plays an important role in the carbon cycle from the viewpoint of a terminal of the deep water circulation in the world oceans and a high biological activity, $$Delta$$$$^{14}$$C-DOC has not been measured yet. In this study, we obtained its vertical profile in the western North Pacific for the first time.

Journal Articles

Radiocarbon in the Japan Sea during the last 10 years

Aramaki, Takafumi*; Togawa, Orihiko; Otosaka, Shigeyoshi

JAEA-Conf 2010-001, p.39 - 43, 2010/03

no abstracts in English

Journal Articles

The Estimation of turnover time in the Japan Sea bottom water by $$^{129}$$I

Suzuki, Takashi; Minakawa, Masayuki*; Togawa, Orihiko

JAEA-Conf 2010-001, p.15 - 18, 2010/03

no abstracts in English

Journal Articles

A Global-scale dispersion analysis of iodine-129 from nuclear fuel reprocessing plants

Nishizawa, Masato; Suzuki, Takashi; Nagai, Haruyasu; Togawa, Orihiko

JAEA-Conf 2010-001, p.105 - 108, 2010/03

no abstracts in English

JAEA Reports

Establishment of database for Japan Sea parameters on marine environment and radioactivity (JASPER), 2; Radiocarbon and oceanographic properties

Otosaka, Shigeyoshi; Suzuki, Takashi; Tanaka, Takayuki; Ito, Toshimichi; Kobayashi, Takuya; Kawamura, Hideyuki; Minakawa, Masayuki*; Aramaki, Takafumi*; Senju, Tomoharu*; Togawa, Orihiko

JAEA-Data/Code 2009-020, 27 Pages, 2010/02

JAEA-Data-Code-2009-020.pdf:2.45MB

The database for the Japan Sea parameters on marine environment and radionuclides (JASPER) has been established by the Japan Atomic Energy Agency as a product of the Japan Sea Expeditions. By the previous version of the database, data for representative anthropogenic radionuclides were opened to public. And now, data for radiocarbon and fundamental oceanographic properties (salinity, temperature, dissolved oxygen) including nutrients (silicate, phosphate, nitrate and nitrite) are released as the second volume of the database. In the second volume, 20,398 data records are stored including 2,695 data for temperature, 2,883 data for salinity, 2,109 data for dissolved oxygen, 11,051 data for the nutrients, and 1,660 data for radiocarbon. The database will be a strong tool for the continuous monitoring for contamination by anthropogenic radionuclides, studies on biogeochemical cycle, and development and validation of models for numerical simulations in the sea.

JAEA Reports

Improvement of the marine radionuclides prediction code in the off Shimokita Region

Kobayashi, Takuya; Togawa, Orihiko; Ito, Toshimichi; Otosaka, Shigeyoshi; Kawamura, Hideyuki; Hayashi, Keisuke*; Shima, Shigeki*; Nakayama, Tomoharu*; In, Teiji*

JAEA-Research 2009-040, 63 Pages, 2009/12

JAEA-Research-2009-040.pdf:12.19MB

A spent nuclear fuel reprocessing plant has the possibility of routine releases of liquid radioactive wastes from a discharge pipe to the off Shimokita region during its operations. Thus, for environmental safety, it is important to assess the migration processes of released radionuclides from the plant. Therefore, an ocean circulation prediction code and an oceanic radionuclides migration prediction code, which were developed by Japan Atomic Energy Agency, has been improved to describe the migration behavior of radionuclides in the off Shimokita region. Parameters on characteristics and dynamics of particulate materials in seawater have also been obtained in the study area for the adjustment and verification of the oceanic radionuclides migration prediction code. This report summarizes the primary results of the study which was carried out at the off Shimokita region from FY2003 to 2008.

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