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Sawaguchi, Takuma
no journal, ,
no abstracts in English
Takai, Shizuka
no journal, ,
Disaster wastes contaminated by the Fukushima Daiichi nuclear disaster are desired to reuse positively to reduce their amount and to utilize effectively. The part of materials contaminated in the living environment has been reused for various uses. In this research, we analyzed the dose for worker and public when contaminated concrete is reused as road construction materials, and we estimated the condition which contaminated disaster wastes can be reused in. As a result, if we set the shielding materials under 30 cm from the ground, contaminated concrete up to 2700 Bq/kg can be reused as the road construction materials. This result is used for the guide for reuse of disaster wastes in ministry of the environment. We also analyzed the dose for public considering the investigation in ministry of the environment on the present use of reused products, and we checked the safety for the investigated use of reused product.
Katsuyama, Jinya; Nishiyama, Yutaka; Udagawa, Makoto; Yamaguchi, Yoshihito; Katsumata, Genshichiro
no journal, ,
no abstracts in English
Hata, Kuniki
no journal, ,
no abstracts in English
Yamaguchi, Tetsuji; Maeda, Toshikatsu; Mukai, Masayuki; Iida, Yoshihisa; Hemmi, Ko; Sawaguchi, Takuma; Sakamaki, Keiko
no journal, ,
no abstracts in English
Kataoka, Masaharu; Mukai, Masayuki; Hirota, Naoki; Yamaguchi, Tetsuji
no journal, ,
no abstracts in English
Udagawa, Yutaka
no journal, ,
no abstracts in English
Takahara, Shogo
no journal, ,
no abstracts in English
Amaya, Masaki; Mihara, Takeshi; Udagawa, Yutaka
no journal, ,
To confirm the safety of reactor design, safety reviews are performed under accident conditions as well as under normal operation conditions. These accidents are called Design Basis Accidents (DBAs), and the Reactivity Initiated Accident (RIA) and the Loss-of-Coolant Accident (LOCA) are selected as DBAs in the safety review of nuclear power plant. These presentations show the outline of the current safety researches conducted in the fuel safety research group, and present the results obtained from the recently started experiments on mechanical properties of post-LOCA cladding, a ballooning and burst behavior of the cladding under LOCA condition, and a high temperature oxidation behavior of the cladding under steam atmosphere containing nitrogen.
Amano, Yuki; Watanabe, Koji; Suzuki, Shinya; Tashiro, Shinsuke; Yamane, Yuichi; Abe, Hitoshi; Yoshida, Kazuo; Uchiyama, Gunzo
no journal, ,
no abstracts in English
Chimi, Yasuhiro
no journal, ,
In the Materials and Water Chemistry Research Group, in order to provide the technical information for the safety regulation of the Japanese government on the ageing management technical evaluation for the current commercial light water reactors (LWRs), water chemistry studies and irradiation tests on materials degradation in the structural components for LWRs (i.e. irradiation embrittlement of reactor pressure vessels and irradiation-assisted stress corrosion cracking (IASCC) of reactor core shroud) under simulated LWR water and irradiation conditions will be performed by using the Japan Materials Testing Reactor (JMTR).
Hidaka, Akihide
no journal, ,
During the process of core cooling at Fukushima Daiichi Nuclear Power Plants accident, large amount of contaminated water was accumulated in the basements of the reactor buildings at Units 1 to 4. Most of iodine dissolved into water becomes I
and some of I species could be changed to I
. Certain fraction of iodine in water could be released to atmosphere due to gas-liquid partition and contribute to increase in the release to environment. A lot of evaluations for I-131(
I) release have been performed so far by the MELCOR calculation or the SPEEDI reverse estimation. The SPEEDI reverse predicted significant release until March 26, 2011 while no prediction in MELCOR after March 17. The present study showed that iodine release from accumulated water due to gas-liquid partition may explain the release between March 17 and 26.
Abe, Satoshi; Ishigaki, Masahiro; Shibamoto, Yasuteru; Okagaki, Yuria; Satou, Akira; Takeda, Takeshi; Irwanto, D.; Yonomoto, Taisuke
no journal, ,
no abstracts in English
Abe, Hitoshi; Masaki, Tomoo; Watanabe, Koji; Tashiro, Shinsuke; Yamane, Yuichi; Amano, Yuki; Yoshida, Kazuo; Uchiyama, Gunzo
no journal, ,
The release and transport characteristics of radioactive materials under the boiling and drying accident of the high active liquid waste (HALW) in a reprocessing plant have been studied. It has been reported that Ru, which is one of the important nuclides for evaluating public dose from the volatile viewpoint, is released mainly with progressing dryness of HALW. In this work, to grasp the release behavior of Ru, release ratio of Ru with thermal decomposition of Ru nitrate, which would be in the dried HALW, was measured and release rate constant of Ru from the nitrate was estimated. It was found that the calculation result of release rate of Ru from the nitrate with rise of temperature by using the constant could well simulate the result acquired from the beaker-scale experiment.
Tashiro, Shinsuke
no journal, ,
The data concerning the release and transport of aerial radioactive materials from high-level liquid waste (HLLW) under boiling and dryness process has been acquired. Using the labo-scaled apparatus, the mocked HLLW (mHLLW), referred from the actual composition of HLLW, was boiled or dried with the external heater, to observe the release behavior of Ruthenium (Ru, probably released as RuO
) and non-volatile elements (NVE, Cesium and so on). From the results up to the boiling of mHLLW to mock the upward velocity of steam from HLLW under the hypothetical boiling accident in the actual HLLW storage tank, the accumulated release ratio (ARR) of NVE was about 4 
10
. From the results up to the dryness of mHLLW, it was found that the release behavior of RuO was refrained under the higher concentration of the nitrite ion in HLLW and that RuO was remarkably released under going to dryness of HLLW, so that the ARR of Ru was about three figures higher than NVE.
Tamaki, Hitoshi
no journal, ,
no abstracts in English
Nagase, Fumihisa; Sugiyama, Tomoyuki; Amaya, Masaki
no journal, ,
JAEA has a plan to obtain data on the onset conditions of fuel melting and on the fuel degradation behavior regarding a single fuel rod system by using the Nuclear Safety Research Reactor (NSRR) in the Nuclear Science Research Institute. The outline of this plan is presented.
Ebine, Noriya
no journal, ,
In order to provide the technical information for the safety regulation on the aging management technical evaluation for the current commercial light water reactors (LWRs), wall thinning of the steel piping and verification of the countermeasures against SCC using the served materials of "Fugen" Power Station retired after 25 years operation have been investigated. Reliability of the wall thinning rate of the steel piping was examined referring the inspection data and the predicted calculations. Using these results, wall thinning data base was established. The validity of the management of pipe wall thinning at Fugen was examined. For SCC, there was no observed crack by metallurgical structure observations and ultrasonic inspections. It was thought that SCC was controlled judging also from the measurements of residual stress and the analysis of heat affected zone. The effectiveness of SCC management techniques at Fugen was examined.