Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Tamura, Itaru; Kashima, Yoichi; Soyama, Kazuhiko
JAEA-Research 2014-029, 12 Pages, 2015/03
Neutron guide tubes, which are installed near reactor cores, are damaged by neutrons and rays irradiation. Those glass substrates which contain boron material are affected by (n, ) reaction, and ionization effect of rays on material strength decrease duration of use of neutron guide tubes. In order to increase resistance to radiation, we have fabricated a supermirror with Ni-P metallic substrate. The substrate roughness with 0.2 - 0.3 nm (rms) was produced by super- polishing. The neutron reflectivity reached 76 % for an m=3 supermirror.
Yagi, Masahiro; Watanabe, Masanori; Oyama, Koji; Yamamoto, Kazuyoshi; Komeda, Masao; Kashima, Yoichi; Yamashita, Kiyonobu
Applied Radiation and Isotopes, 67(7-8), p.1225 - 1229, 2009/07
Times Cited Count:11 Percentile:59.85(Chemistry, Inorganic & Nuclear)Yagi, Masahiro; Watanabe, Masanori; Oyama, Koji; Komeda, Masao; Yamamoto, Kazuyoshi; Kashima, Yoichi
JAEA-Technology 2008-015, 91 Pages, 2008/03
The irradiation experimental device is designed by surveying analytically an irradiation condition to improve the neutron flux distribution of the radial direction on NTD-Si by using neutron transportation calculation Monte Carlo calculation code MCNP5 in order to develop neutron irradiation technology for the large-diameter silicon to 12 inches diameter at the maximum and an irradiation experiment will be performed in JRR-4. Thus the validity of the design technique of the irradiation device will be confirmed by this experiment. The irradiation experimental device is installed in the side of the core tank outer wall. A 12 inches silicon ingot of 60cm in height is irradiated in a reflector cover which surrounds the silicon ingot for increasing the flux. The silicon ingot is rotated during irradiation in order to require the condition of uniformly distributed thermal neutron flux over whole circumferences. A uniform irradiation condition was achieved by the pass-through core method, in which silicon ingot moved up and down with rotating. The condition was satisfied when silicon was covered with the thermal neutron filter, which is made from aluminum alloy of thickness of 2mm with natural boron element ratio of 1.5%, and was moved in the range from -42mm to 22mm for the center of the reactor core. The deviation of the Si-30 neutron absorption reaction rate was range from -3.2% to +5.3% in the intermediate volume of 40cm height and the neutron absorption reaction ratio of the circumference to the center was within 1.09 in the volume.
Hirane, Nobuhiko; Ishikuro, Yasuhiro; Nagadomi, Hideki; Yokoo, Kenji; Horiguchi, Hironori; Nemoto, Takumi; Yamamoto, Kazuyoshi; Yagi, Masahiro; Arai, Nobuyoshi; Watanabe, Shukichi; et al.
JAEA-Technology 2006-028, 115 Pages, 2006/03
JRR-4, a light-water-moderated and cooled, swimming pool type research reactor using high-enriched uranium plate-type fuels had been operated from 1965 to 1996. In order to convert to low-enriched-uranium-silicied fuels, modification work had been carried out for 2 years, from 1996 to 1998. After the modification, start-up experiments were carried out to obtain characteristics of the low-enriched-uranium-silicied fuel core. The measured excess reactivity, reactor shutdown margin and the maximum reactivity addition rate satisfied the nuclear limitation of the safety report for licensing. It was confirmed that conversion to low-enriched-uranium-silicied fuels was carried out properly. Besides, the necessary data for reactor operation were obtained, such as nuclear, thermal hydraulic and reactor control characteristics. This report describes the results of start-up experiments and burnup experiments. The first criticality of low-enriched-uranium-silicied core was achieved on 14th July 1998, and the operation for joint-use has been carried out since 6th October 1998.
Kashima, Yoichi; Taki, Mitsumasa; Kikuchi, Masamitsu; Sasajima, Hideo; Nakamura, Takehiko
JAERI-Tech 2003-088, 100 Pages, 2003/12
A new experiment plan is in progress to perform pulse-irradiation experiments at the NSRR with irradiated fuel rods in the high temperature and high pressure capsules. This report describes the results of the public dose evaluation for the design basis accident and postulated accidents with the models that follow the ICRP Publication 60. It was confirmed that the results met the criteria for safety design and siting with ample margins.
Nakamura, Takehiko; Katanishi, Shoji; Kashima, Yoichi; Yachi, Shigeyasu; Yoshinaga, Makio; Terakado, Yoshibumi
Journal of Nuclear Science and Technology, 39(3), p.264 - 272, 2002/03
Times Cited Count:8 Percentile:47.9(Nuclear Science & Technology)In order to study fuel behavior under abnormal transients and accidents, the control system of the Nuclear Safety Research Reactor (NSRR) of the Japan Atomic Energy Research Institute (JAERI) was modified to achieve high power transients. With this new operational mode, called Shaped Pulse (SP), transients at the maximum power of 10 MW can be conducted for a few seconds. This new operational mode supplements the previous Natural Pulse (NP) operation at the maximum power of 23 GW for milliseconds. For high power transient operation, a simulator using a point kinetic model was developed, and characteristics of the NSRR in the new operational mode were examined through tests and calculations. With the new operational mode, new types of fuel irradiation tests simulating power oscillations of boiling water reactors (BWRs) can to be conducted in the NSRR. Reactor characteristics and capability, such as control rod worth, feedback reactivity, and operational limits of the NSRR for SP operations are discussed.
Fuketa, Toyoshi; Ishijima, Kiyomi; Tanzawa, Sadamitsu; Nakamura, Takehiko; Sasajima, Hideo; Kashima, Yoichi; ;
JAERI-Research 95-005, 53 Pages, 1995/01
no abstracts in English
Uchida, Masaaki; Nakamura, Jinichi; Ichikawa, Michio; Kashima, Yoichi; ; ; Iwai, Takashi
JAERI-M 88-202, 53 Pages, 1988/10
no abstracts in English
Yagi, Masahiro; Kashima, Yoichi; Nagadomi, Hideki; Watanabe, Shukichi
no journal, ,
no abstracts in English
Yagi, Masahiro; Kashima, Yoichi; Watanabe, Masanori; Yamamoto, Kazuyoshi
no journal, ,
The irradiation experimental device is designed by surveying analytically an irradiation condition to improve the neutron flux distribution of the diameter direction on NTD-Si by using Monte Carlo calculation code MCNP5 in order to develop neutron irradiation technology for the large-diameter silicon to 12 inches diameter at the maximum. Some irradiation experiment will be performed to confirm validity of the design technique in JRR-4 by using the experimental device for the 12 inches NTD-Si ingot. The experimental device is installed in the No.1 reactor pool side of the core tank outer wall. The 12 inches silicon of 60 cm in height is irradiated in a reflector cover which surrounds the silicon for increasing the flux. The silicon also is irradiated with rotating in order to require the condition of uniformly distributed thermal neutron flux over whole circumferences. A uniform irradiation condition was achieved by the pass-through core method with adding the thermal neutron filter which covers the silicon surface and is able to move up and down with rotating. The condition was satisfied when silicon was covered with the thermal neutron filter, which is made from aluminum alloy of 2 mm thickness with natural boron element ratio of 1.5%, and was run in the range from -42 mm to 22 mm for the center of the reactor core. The deviation of the Si-30 neutron absorption reaction rate was range from -3.22% to +5.27% in the intermediate volume of 40 cm height and the neutron absorption reaction ratio of the circumference to the center was within 1.09 in the volume.
Kashima, Yoichi; Yagi, Masahiro; Watanabe, Masanori; Yamamoto, Kazuyoshi
no journal, ,
In JRR-4, a irradiation experimental device for 12 inches NTD-Si (Neutron Transmutation Doping Silicon) ingot will be installed to confirm the validity of the uniform irradiation condition which has been derived analytically in order to develop neutron irradiation technology for the large-diameter NTD-Si semiconductor to 12 inches diameter at the maximum. In installation, various limitations occurred, but some design policy was set in consideration of these limitations and the mechanical design of the irradiation experimental device was performed. As the result of mechanical design, it is possible to produce the irradiation experimental device which satisfied the irradiation condition derived by analysis without interfering it with an existing device in the future.
Kashima, Yoichi
no journal, ,
Explain verbally about Fukushima Research and Development sector's general situation about decommissioning of Fukushima Daiichi Nuclear Power Station owned by TEPCO, and about Naraha center's developing services for users' remote control technology development.