The Aerial radiation monitoring in Japan after the Fukushima Daiichi Nuclear Power Plant accident

Sanada, Yukihisa; Sugita, Takeshi; Nishizawa, Yukiyasu; Kondo, Atsuya*; Torii, Tatsuo

Progress in Nuclear Science and Technology (Internet), 4, p.76 - 80, 2014/04

https://doi.org/10.15669/pnst.4.76

The ambient dose-rate and the deposition concentration of radioactive cesium was measured by using helicopters in the whole area of Japan to investigate the influence of the radioactivity that released in the atmosphere due to the disaster of the Fukushima Daiichi NPP (Nuclear Power Plant), Tokyo Electric Power Company (TEPCO), occurred by the East Japan earthquake and tsunami on March 11, 2011. As a result, the deposition of radioactive cesium on the ground discharged from the Fukushima Daiichi NPP was obtained, and it was clarified that the scattered range of the cesium had been almost limited from the southern part of Tohoku to Kanto areas. The variation distribution of the dose-rate of Japan was also revealed in this measurement.

Study to improve recriticality evaluation methodology after severe accident (Joint research)

Kugo, Teruhiko; Ishikawa, Makoto; Nagaya, Yasunobu; Yokoyama, Kenji; Fukaya, Yuji; Maruyama, Hiromi*; Ishii, Yoshihiko*; Fujimura, Koji*; Kondo, Takao*; Minato, Hirokazu*; et al.

JAEA-Research 2013-046, 53 Pages, 2014/03

JAEA-Research-2013-046.pdf:4.42MB

The present report summarizes the results of a 2-year cooperative study between JAEA and Hitachi-GE in order to contribute to the settlement of the Fukushima-Daiichi Nuclear Power Plants which suffered from the severe accident on March 2011. In the present study, the possible scenarios to reach the recriticality events in Fukushima-Daiichi were investigated first. Then, the analytical methodology to evaluate the time-dependent recriticality events has been developed by modelling the reactivity insertion rate and the possible feedback according to the recriticality scenarios identified in the first step. The methodology developed here has been equipped as a transient simulation tool, PORCAS, which is operated on a multi-purpose platform for reactor analysis, MARBLE. Finally, the radiation exposure rates by the postulated recriticality events in Fukushima-Daiichi were approximately evaluated to estimate the impact to the public environment.

Investigation of radionuclide distribution using aircraft for surrounding environmental survey from Fukushima Dai-ichi Nuclear Power Plant

Torii, Tatsuo; Sanada, Yukihisa; Sugita, Takeshi; Kondo, Atsuya*; Shikaze, Yoshiaki; Takahashi, Masaki; Ishida, Mutsushi; Nishizawa, Yukiyasu; Urabe, Yoshimi

JAEA-Technology 2012-036, 182 Pages, 2012/12

JAEA-Technology-2012-036.pdf:41.89MB

We carried out aerial radiation monitoring (ARM) of all Japan area in order to investigate the influence of the radio cesium which was emitted into the atmosphere by disaster of the Fukushima Dai-ichi Nuclear Power Plant of Tokyo Electric Power Co., Inc.. AMS can measure a ray quickly by flight from 300 m height above the ground. Moreover, ARM has an advantage which can grasp self-possessed quantity distribution of an air dose rate and radioactive cesium in "field", and is visually intelligible. Although there were apparatus and the technique of ARM in our country, sufficient preparations for wide area monitoring were not made. Therefore, it fixed based on the method of the U.S. Department of Energy (DOE) about the method of the conversion to all radiation dose, and the conversion method to radiocesium deposition and the method of mapping. It is possible to discriminate from a background (cosmic-ray, self-contamination and natural nuclides) at the time of western-part-of-Japan measurement by improving of the method in parallel to data acquisition. By this monitoring, it was able to check about the distribution situation of the air dose rate of the Japanese whole region, or the radioactive cesium deposition. Here, the measurement technique and a result are described.

Japanese fast reactor program for homogeneous actinide recycling

Ishikawa, Makoto; Nagata, Takashi; Kondo, Satoru

Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR 2008) (CD-ROM), 8 Pages, 2008/09

In Japan, the significance of the development of fast reactor (FR) cycle technology has been seriously recognized in the national fundamental nuclear energy policy. Further, nuclear energy as a whole is indispensable worldwide to meet the expansion of energy demand and the solution of environmental problem such as global climate change. Under such circumstances, Japan launched the FR Cycle Technology Development (FaCT) Project in 2006. In FaCT, the design study and the R&D on innovative technologies regarding the main concept are conducted in order to present the conceptual designs of demonstration and commercial FR cycle facilities by around 2015. The main purpose of the near-term R&Ds by 2010 is to judge whether adoption of innovative technologies is feasible. The R&D program on the innovative technologies will be further extended toward 2015, with the demonstration FR expected to be operated in 2025. The concept of the FR cycle system has various aspects from the viewpoints of safety and reliability, economy, sustainability (consisting of reduction of environmental burden, waste management and efficient utilization of uranium resource), and proliferation resistance. The homogeneous recycling of an entire amount of actinides has a significant advantage from these development targets. In the present paper, we will discuss about our scenario of the homogeneous actinide recycling in the FR cycle system, based on our recent studies in the FaCT Project. The studies on the scenario of nuclear energy policy, the management and development of minor actinide (MA)-bearing fuel, reactor physics related to MA-loaded FR cores, and typical nuclear design of MA-loaded FR cores have shown the feasibility to recycle all MA in the future FR-equilibrium society. Also presented are the R&D programs to demonstrate the homogeneous actinide recycling, which are extensively conducted as one of the key national projects in Japan, as well as utilizing international cooperation.

Seismic probabilistic safety assessment methodology development and application to a model plant

Sobajima, Makoto; ; Kondo, Masaaki; ; Muramatsu, Ken;

10th Pacific Basin Nuclear Conf. (10-PBNC), 1, p.629 - 636, 1996/00

no abstracts in English

An Analysis of mechanical disassembly phase by SIIMMER-II: Comparison of space-time neutronics with point-kinetics model

; ;

PNC TN941 84-86, 100 Pages, 1984/05

PNC-TN941-84-86.pdf:2.36MB

A mechanical disassembly phase of a core disruptive accident (CDA) in a liquid-metal fast breeder reactor (LMFBR) is usually analyzed by a VENUS-type disassembly code. In Japan the VENUS-PM2 code has been developed and utilized to analyze the Phase. This code couples the Lagrangian hydrodynamics with the point-kinetics model with the first-order perturbation theory. The accuracy of the point-kinetics model, however, may be justified only within the extent that a neutron flux shape is not distorted as a result of material motion. In this study the SIMMER-II code with the space- and time-dependent neutronics option was used to analyze the disassembly phase, and the results were compared with the former analysis by VENUS-PM2. In order to separate the effect of the difference in neutronics models, input parameters of the SIMMER-II fluid dynamics model were adjusted to simulate the material motion as calculated by VENUS-PM2. The disassembly phase, calculated in this study, was postulated to result from a recriticality event due to the collapse of a whole-core boiling pool during the late transition phase. The major conclusions obtained from this study can be summarized as follows: (1)The SIMMER-II code with the space-time neutronics option (diffusion or transport theory) is applicable to the disassembly phase analysis. (2)The material motion calculated by VENUS-PM2 can be simulated successfully by the SIMMER-II fluid dynamics model. (3)The calculated power and reactivity histories by the point-kinetics model of VENUS-PM2 agreed fairly well with those by the diffusion or transport calculations by SIMMER-II within the time scale in which the energy release was important. This is because the flux distortion due to material motion was relatively small in the disassembly from the transition phase recriticality postulated in this study. (4)Further study may be recommended to confirm the above conclusions especially for those disassemblies in which larger ...

Construstion of an Anticomptor Ge(Li) Gamma-Ray Spectrometer with Comptor Shield NaI(Ti) Scintillators and it's Applications to Low Level Counting

;

JAERI-M 6555, 45 Pages, 1976/05

JAERI-M-6555.pdf:1.77MB

no abstracts in English

A Compilation of Gamma-Ray Spectra with a Ge(Li) Detector

; ; ;

JAERI-M 4968, 42 Pages, 1972/09

JAERI-M-4968.pdf:0.83MB

no abstracts in English

Measurements of Thermal Neutron Flux in In-Code Experimental Holes of JRR-4 Using Activation Detectors

;

JAERI-M 4860, 28 Pages, 1972/06

JAERI-M-4860.pdf:0.79MB

no abstracts in English

In-Core Neutron Measurements Using Self-Powered Neutron Detectors

; ;

Hitachi Hyoron, 54(5), p.399 - 403, 1972/00

http://digital.hitachihyoron.com/pdf/1972/05/1972_05_02.pdf

no abstracts in English