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Oral presentation

History of the radioactive pollution in Japan; Hiroshima, Nagasaki, Chernobyl, and Fukushima

Yamazaki, Hideo*; Ishizu, Naoto*; Kokubu, Yoko

no journal, , 

Our country has experienced radioactive pollution of many times, such as atomic bombs of Hiroshima and Nagasaki, global fallout from nuclear weapon tests and the accident of Chernobyl until now. The radioactive pollution has been released even in now from the Fukushima Nuclear Power Plant, which was damaged by the Eastern Japan earthquake disaster. We report the historical trend of radioactive pollution in our country and the actual condition of present incident. We analyzed soils and sediment cores collected in Nagasaki and determined the spatiotemporal distribution of the radionuclide released from the Nagasaki atomic bomb. Some surface soils in Fukushima City (55km from nuclear power plant) was measured by $$gamma$$-ray spectrumetry and some radionuclides such as $$^{131}$$I and $$^{134}$$Cs were detected.

Oral presentation

Phenomena during severe accidents in light water reactors

Moriyama, Kiyofumi

no journal, , 

no abstracts in English

Oral presentation

Effect of large-scale seismic loading on crack growth rate and structural reliability of nuclear reactor piping

Yamaguchi, Yoshihito; Li, Y.*; Katsuyama, Jinya; Onizawa, Kunio

no journal, , 

In recent years, Japanese nuclear power plants experienced multiple large earthquakes, such as Niigata-ken Chuetsu-Oki Earthquake in 2007 and the Great East Japan Earthquake in 2011. The magnitude of these earthquakes exceeded the design-base condition for some nuclear power plants. Therefore it is an important issue to establish the evaluation method of excessive loading on the structural integrity of reactor components. In this study, the crack growth behaviors were investigated based on an elastic-plastic fracture mechanics parameter, J-integral. It was indicated that the crack growth due to the cyclic excesive loading could be the sum of fatigue and ductile crack growth. The retardation effect on the crack growth due to excessive loading was observed from experiments. An evaluation method for the amount of crack growth under cyclic excessive loading is suggested based on J-integral. The effect of excessive loading on the failure probability of piping is also evaluated by probabilistic fracture mechanics analysis.

Oral presentation

Report of Division of Clean-up in Expert Committee on Nuclear Safety Investigation, Atomic Energy Society of Japan

Inoue, Tadashi*; Takahashi, Fumiaki; Morokuzu, Muneo*

no journal, , 

no abstracts in English

Oral presentation

Possibility of production and condensation of hydrogen from boiling water under irradiation in the Fukushima Daiichi F4 fuel storage pool

Yamashita, Shinichi; Hirade, Tetsuya; Matsuura, Chihiro*; Iwamatsu, Kazuhiro; Taguchi, Mitsumasa; Katsumura, Yosuke*

no journal, , 

Fukushima Daiichi Nuclear Power Plant Unit-4 was under an inspection on the day of Tohoku earthquake, and all of the fuels were cooled in the fuel storage pool. However, the explosion occurred only four days after the cooling of the pool stopped. Later, the pool was investigated and it was clarified that the fuels were not so damaged and the water was not contaminated with radioisotopes. There are several explanations of the cause of the explosion. We picked up one possibility that the radiolysis of the water was the source of the hydrogen and that the vapor condensation could make the high hydrogen density behind the cold roof or walls, and investigated by an experiment of boiled water radiolysis by $$gamma$$-rays. The results can explain some of the typical things happened on the explosion of Unit-4.

Oral presentation

X-ray crystallographic analysis of $$beta$$-lactamase derived from ${it Chromohalobacter}$ sp.560

Arai, Shigeki; Yonezawa, Yasushi; Okazaki, Nobuo; Tamada, Taro; Tokunaga, Hiroko*; Ishibashi, Matsujiro*; Tokunaga, Masao*; Kuroki, Ryota

no journal, , 

We determined the crystal structure of halophilic $$beta$$-Lactamase obtained from ${it Chromohalobacter}$ sp.560 by X-ray crystallography. Since halophilic enzymes can bind many metal ions on its molecular surface, we are tring to find the Na$$^{+}$$, Mg$$^{2+}$$ and Cs$$^{+}$$ binding sites of halophilic $$beta$$-Lactamase from determined crystal structure.

Oral presentation

Local-scale atmospheric dispersion simulation of radionuclides discharged from Fukushima Daiichi Nuclear Power Plant by WSPEEDI-II

Katata, Genki; Nagai, Haruyasu; Terada, Hiroaki; Chino, Masamichi; Furuno, Akiko; Nakayama, Hiromasa

no journal, , 

no abstracts in English

Oral presentation

Reactor core melting in nuclear accident

Kudo, Tamotsu

no journal, , 

no abstracts in English

Oral presentation

Application of numerical simulation system of JAEA to predict the environmental transport of radioactive materials discharged from the Fukushima Nuclear Power Plant

Nagai, Haruyasu; Chino, Masamichi; Terada, Hiroaki; Katata, Genki; Nakayama, Hiromasa

no journal, , 

Japan Atomic Energy Agency has been applying its numerical simulation system to predict the environmental transport of radioactive materials discharged from Fukushima Daiichi Nuclear Power Plant. As the first step, the source term of radioactive materials discharged from the plant into the atmosphere has been estimated by coupling environmental monitoring data with atmospheric dispersion simulations by SPEEDI and WSPEEDI under the assumption of unit release rate (1 Bq/h). As the next step, we are planning to apply our numerical simulation system for material transport in the atmospheric, terrestrial, and oceanic environments, SPEEDI-MP. The method and preliminary results of source estimation and our future plan will be presented.

Oral presentation

Analysis of environmental radiation level from Fukushima nuclear accident

Furuta, Sadaaki

no journal, , 

no abstracts in English

Oral presentation

Examinations of TMI-2 debris

Nagase, Fumihisa

no journal, , 

no abstracts in English

Oral presentation

Hydrogen production in radiolysis of the mixture of mordenite and seawater

Kumagai, Yuta; Nagaishi, Ryuji; Kimura, Atsushi; Taguchi, Mitsumasa; Nishihara, Kenji; Yamagishi, Isao; Ogawa, Toru

no journal, , 

For decontamination of radioactive water, zeolite is a suitable adsorbent for radioactive Cs. The management of hydrogen produced by water radiolysis is an important issue of safety. Thus hydrogen production from the mixture of mordenite-type zeolite and water was studied. In particular, we focused on the influence of the incorporation of seawater into the mixture. The hydrogen yield from the mixture decreased monotonically as the weight fraction of seawater was decreased. However, the measured yield was higher than the yield expected from the direct radiolysis of water in the mixture. Moreover the hydrogen yield was not so effectively decreased by the dilution of seawater in the mixture as in seawater alone. Therefore the additional formation of hydrogen should be considered in the evaluation of hydrogen production from radiolysis of the mixture of mordnite and water.

Oral presentation

Evaluation of gaseous iodine release during the Fukushima Daiichi accident

Moriyama, Kiyofumi; Maruyama, Yu; Nakamura, Hideo

no journal, , 

no abstracts in English

Oral presentation

Personal monitoring for assistance staff to Fukushima

Suzuki, Takehiko; Murayama, Takashi; Miyauchi, Hideaki; Sato, Yoshitaka; Oi, Yoshihiro; Tachibana, Haruo; Yoshitomi, Hiroshi

no journal, , 

Nuclear Science Research Institute is assisting activities concerning the accident of the Fukushima No.1 Nuclear Power Station including the environmental monitoring and the resident's house decontamination, etc. In these assistance, we executing the personal monitoring to assistance staff, because there was fear of the external exposure and the internal exposure. We did by the measurement and the evaluation method of the personal monitoring in consideration of the rise of the environmental background level. We introduce the method of use to evaluate the exposed dose etc.

Oral presentation

Examination of the containment vessel conditions during the Fukushima Daiichi NPP accident by simple heat and mass balance model

Shibamoto, Yasuteru; Moriyama, Kiyofumi; Nakamura, Hideo

no journal, , 

no abstracts in English

Oral presentation

Proposal for the decontamination method of the radioactive substances by the chemical reaction, 2

Ema, Akira; Kado, Kazumi; Suzuki, Kazuhiko*

no journal, , 

In the nuclear industry, when the nuclear facilities are dismantled, the decontamination work of the radioactive substances is carried out. The selection of the decontamination method is a big problem because the enlargement of decontamination plant and increases of disposal cost is caused. In this study, we propose the new decontamination method of the uranium compounds by IF$$_{7}$$ gas. In this presentation, we show the full-scale exam result and so on by using the actual uranium enrichment plant.

Oral presentation

Overview of dispersion analysis by JAEA for radionuclides discharged from the Fukushima Daiichi Nuclear Power Plant into the environment

Nagai, Haruyasu; Katata, Genki; Terada, Hiroaki; Furuno, Akiko; Kobayashi, Takuya; Nakayama, Hiromasa; Chino, Masamichi

no journal, , 

no abstracts in English

Oral presentation

Dose reconstruction with protective measures for the Fukushima Daiichi Nuclear Power Plant accident, 4; Study on doses to the public from food consumption

Iijima, Masashi; Homma, Toshimitsu; Kimura, Masanori; Takahara, Shogo; Kinase, Sakae

no journal, , 

no abstracts in English

Oral presentation

Radionuclides migration forecast in the off Fukushima region

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

no journal, , 

The radionuclides migration forecasting system in the off Fukushima region and near Japan region has been developed to predict the accidental releases of liquid radioactive materials from the Fukushima Dai-ichi Nuclear Poower Plant in Japan.

Oral presentation

Research issues on the safety assessment for disposal of contaminated liquid

Maeda, Toshikatsu; Yamaguchi, Tetsuji; Tanaka, Tadao

no journal, , 

no abstracts in English

2742 (Records 1-20 displayed on this page)