Sato, Sohei; Umemoto, Michitaka*; Homma, Toshimitsu
JAERI-Data/Code 2005-009, 114 Pages, 2005/09
JAERI has conducted the analytical studies on the PSA, the severe accidents, and the optimization of protective actions. Based on the results of these studies, JAERI is investigating the method for taking urgent protective actions more reasonably. If an accident occurs in a NPP, early protective actions are carried out. To implement these actions more effectively, emergency preparedness and emergency planning are important, and especially prompt evacuation is expected to reduce a large amount of radiation exposures. To examine the effect of early protective measures by using a PSA method, estimation of the parameter uncertainty related in the time for early protective actions is needed. For this purpose, we have developed an analytical method for urgent protective actions, and estimated the movement distance. This report provides a brief description of the method for estimating the movement distance, input data for this analysis, and the result. Moreover, the problem on the method of evacuation distance analysis and usefulness of this method for emergency planning were discussed.
Wakai, Eiichi; Jitsukawa, Shiro; Tomita, Hideki*; Furuya, Kazuyuki; Sato, Michitaka*; Oka, Keiichiro*; Tanaka, Teruyuki*; Takada, Fumiki; Yamamoto, Toshio*; Kato, Yoshiaki; et al.
Journal of Nuclear Materials, 343(1-3), p.285 - 296, 2005/08
The dependence of helium production on radiation-hardening and -embrittlement has been examined in a reduced-activation martensitic F82H steel doped with B, B and B+B irradiated at 250C to 2.2 dpa. The total amounts of doping boron were about 60 massppm. The range of He concentration produced in the specimens was from about 5 to about 300 appm. Tensile and fracture toughness tests were performed after neutron irradiation. 50 MeV-He irradiation was also performed to implant about 85 appm He atoms at 120C by AVF cyclotron to 0.03 dpa, and small punch testing was performed to obtain DBTT. Radiation-hardening of the neutron-irradiated specimens increased slightly with increasing He production. The 100 MPam DBTT for the F82H+B, F82H+B+B, and F82H+B were 40, 110, and 155C, respectively. The shifts of DBTT due to He production were evaluated as about 70C by 150 appmHe and 115C by 300 appmHe. The DBTT shift in the small punch testing was evaluated as 50C.
Wakai, Eiichi; Sato, Michitaka*; Okubo, Nariaki; Sawai, Tomotsugu; Shiba, Kiyoyuki; Jitsukawa, Shiro
Nippon Kinzoku Gakkai-Shi, 69(6), p.460 - 464, 2005/06
no abstracts in English
Taguchi, Tomitsugu; Jitsukawa, Shiro; Sato, Michitaka*; Matsukawa, Shingo*; Wakai, Eiichi; Shiba, Kiyoyuki
Journal of Nuclear Materials, 335(3), p.457 - 461, 2004/12
F82H (Fe-8Cr-2W) and its variant doped with 2%Ni were irradiated up to 20 dpa at 300C in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. Post irradiation tensile testing was performed at room temperature. During testing, the images of the specimens including the necked region were continuously recorded. Tests on cold worked material were also carried out for comparison. From the load-displacement curves and the strain distributions obtained from the images, flow stress levels and strain hardening behavior was evaluated. A preliminary constitutive equation for the plastic deformation of irradiated F82H is presented. The results suggest that the irradiation mainly causes defect-induced hardening while it did not strongly affect strain hardening at the same flow stress level for F82H irradiated at 300C. The strain hardening of Ni doped specimens was, however, strongly affected by irradiation. Results provide basics to determine allowable stress levels at temperatures below 400C.
Wakai, Eiichi; Sato, Michitaka*; Sawai, Tomotsugu; Shiba, Kiyoyuki; Jitsukawa, Shiro
Materials Transactions, 45(2), p.407 - 410, 2004/01
no abstracts in English
Hamajima, Takataro*; Hanai, S.*; Wachi, Y.*; Shimada, M.*; Ono, Michitaka*; Martovetsky, N.*; Zbasnik, J.*; Moller, J.*; Takahashi, Yoshikazu; Matsui, Kunihiro; et al.
IEEE Transactions on Applied Superconductivity, 10(1), p.812 - 815, 2000/03
no abstracts in English
Sato, Nobuaki*; Saso, Michitaka*; Umeda, Miki; Fujii, Yasuhiko*; Amemiya, Kiyoshi*
no journal, ,
This paper outlines agricultural approaches of remediation activity in contaminated areas outside of the Fukushima Daiichi Nuclear Power Plant. About the decontamination examination of contaminated areas, we have tried the land scale test of a rice field before and after planting by the use of currently recommended methods. For the radioactive nuclide migration control of rice by wet rice production, several types of decontamination methods such as zeolite addition and potassium fertilization in the soil were examined, and investigated the validity of the cesium migration control for the brown rice by the combination of those methods.