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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.
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.
Sato, Haruo
PNC TN8410 97-202, 205 Pages, 1998/01
This thesis summarizes the results investigated in order to establish a basic theory on the predictive method of diffusion coefficients of nuclides in compacted sodium bentonite which is a candidate buffer material and in representative rocks for the geological disposal of radioactive waste by measuring the pore structural factors of the compacted bentonite and rocks such as porosity and tortuosity, measuring diffusion coefficients of nuclides in the bentonite and rocks, acquiring basic data on diffusion and developing diffusion models which can quantitatively predict nuclide migration in long-term. This consists of 7 chapters. Chapter 1 is the introduction, in which conventional studies on nuclide migration in buffer materials and rocks for the geological disposal of radioactive waste carried out to date are reviewed, and those problems are summarized as well as the objectives of this study are described. Besides, the difinition of geological disposal is explained. In Chapter 2, it is described on non-steady state diffusion of HTO, Sr-90, Tc-99, I-129, Cs-137, Np-237, Am-241 and Pu in purified sodium bentonite, Kunipia-F, in which the rate of constituent Na-smectite was raised approximately 100wt%. In-diffusion experiments were carried out in a range of bentonite densities of 200 
2000 kg
m
under ambient aerobic conditions at room temperature (20 23
C), and apparent diffusion coefficients (Da) were obtained. The apparent diffusion coefficients decreased with increasing dry density of bentonite. It was quantitatively indicated from diffusion experiments using HTO that these Da values include the effect of geometric retardation such as the tortuosity factor of compacted bentonite. It was experimentally clarified that Da is not affected by diffusion time based on diffusion experiments for different experimental periods using Sr and Cs. Moreover, it was also experimentally clarified that Da is not affected by tracer ...
Kawamura, Hideyuki; Kobayashi, Takuya; Kamidaira, Yuki
no journal, ,
This study aims to validate accuracies of forecast of the Short-Term Emergency Assessment system of Marine Environmental Radioactivity (STEAMER) developed at JAEA by using forecast and reanalysis ocean current data. Oceanic dispersion simulations were carried out in the northwestern Pacific Ocean for 30 days from first day of every month between 2015 and 2017. It was assumed that 
Cs was continuously released into the ocean from the Fukushima Daiichi Nuclear Power Plant. The released Cs was inclined to disperse by mesoscale eddies in the northern part and by the Kuroshio Extension in the southern part. The simulation results with forecast ocean current data were similar to those with reanalysis ocean current data in the early periods and differences between them were remarkable after that. The cause must be accuracies of variable ocean current in the coastal ocean rather than phenomena with long time scale such as the Kuroshio Extension.
Han, C. Y.*; Ebata, Shuichiro*; Sagara, Hiroshi*; Takeshita, Kenji*; Matsumoto, Yoshihisa*; Chiba, Satoshi*; Furuno, Akiko; Nagai, Haruyasu
no journal, ,
In Tokyo Institute of Technology, the nuclear human resource development program, "the Advanced Nuclear 3S Education and Training (ANSET)", was established in 2017, supported by Nuclear Regulatory Authority. This paper introduces the exercise on "Environmental Dynamics of Radioactive Material" of this program.