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Kato, Chiaki; Yamagishi, Isao; Sato, Tomonori; Yamamoto, Masahiro*
Zairyo To Kankyo, 70(12), p.441 - 447, 2021/12
Zeolite particles have been used in a Cs adsorption vessel for purification of contaminated water in Fukushima Dai-ichi Nuclear Power Station (1F). The used Cs adsorption vessels were kept in storage space on 1F site. The risk of localized corrosion of stainless steel used in the vessel was worried. To evaluate the risk of localized corrosion, using specially designed electrochemical testing apparatus was used under gamma-ray irradiation test. And, real size mock-up test conducted. The results showed the potential change caused by creation of H
O by water radiolysis decreased by zeolite particles and the enrichment of chloride ion concentration in the vessel do not propagate during dry up procedure of Cs adsorption vessel. These data indicate the risk of localized corrosion of Cs adsorption vessel may stay at considerably low level.
-ray irradiationMotooka, Takafumi; Nagaishi, Ryuji; Yamagishi, Isao
QST-M-2; QST Takasaki Annual Report 2015, P. 95, 2017/03
We conducted ray irradiation test using simulated carbonate slurry to investigate the cause of stagnant water over the high integrity container (HIC). This test was performed at Co-60 irradiation facility in Takasaki Advanced Radiation Research Institute. We observed a rise in water level, air bubbles in the slurry, a supernatant when the carbonate slurry with 95 g/L density was irradiated by ray at a dose rate of 8.5 kGy/h. The cause of the rise in water level was regarded as the volume expansion by the gas retention of the carbonate slurry. It was suggested that the cause of stagnant water over the high integrity container might be the volume expansion by the gas retention.
Kato, Chiaki; Sato, Tomonori; Ueno, Fumiyoshi; Yamagishi, Isao
Proceedings of 17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, Vol.2, p.1357 - 1374, 2016/05
With respect to the long-term storage of the zeolite-containing spent Cs adsorption vessels used at the Fukushima Daiichi Nuclear Power Station, the corrosion of the vessel material is one of the most important issues. In this study, we performed electrochemical tests on stainless steel specimens in zeolite-containing artificial seawater under gamma-ray irradiation. The spontaneous potential ESP and critical pitting potential VC of the type 316L steel in systems in contact with various zeolites were measured in order to evaluate the corrosion resistance of the steel. In addition, the water sample was analyzed after being irradiated, in order to determine the concentrations of various dissolved oxidants such as oxygen and hydrogen peroxide, which can accelerate the corrosion process. The steady-state rest potential increased with an increase in the dose rate; however, the increase was suppressed in contact with the zeolites. The VC value of the steel when in contact with the zeolites was slightly smaller than the VC value in bulk water; however, the choice of the zeolite used as herschelite, IE96 and IE911 hardly affect the VC value. The concentration of HO in the bulk water under irradiation also increased with the increase in the dose rate. This increase was suppressed in the systems in contact with the zeolites, owing to the decomposition of the HO by the zeolites. A clear relationship was observed between ESP and the HO concentration. As contact with the zeolites caused the increase in ESP under irradiation to be suppressed, it can be concluded that the presence of zeolites in the spent Cs adsorption vessels can reduce the probability of the localized corrosion of the stainless steel in the vessels.
Co -ray irradiation facilitiesUno, Sadanori; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Nagao, Yuto; Yamasaki, Shota; Agematsu, Takashi; Kawashima, Ikuo*; Yagi, Norihiko*; Takagi, Masahide*; et al.
JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 172, 2016/02
This paper reports on the operation status of the -ray irradiation facilities and the electron accelerator in fiscal 2014 at the Takasaki Advanced Radiation Research Institute of JAEA. The -ray irradiation facilities were operated smoothly, whereas the electron accelerator stopped for five months because of successive troubles of discharge due to deterioration of equipment over thirty-four years. The annual operation times of the -ray irradiation facilities of the first, second and food buildings were 19,907, 13,831 and 7,293 hours, respectively, and that of the electron accelerator was 746 hours. The -ray irradiation facilities were replenished with new five sources of 2.22 PBq, and twenty old sources were removed for disposal. The electron accelerator was repaired for each trouble, however, the complete recovery has not yet been achieved.
Hijikata, Yasuto*; Mitomo, Satoshi*; Matsuda, Takuma*; Murata, Koichi*; Yokoseki, Takashi*; Makino, Takahiro; Takeyama, Akinori; Onoda, Shinobu; Okubo, Shuichi*; Tanaka, Yuki*; et al.
Proceedings of 11th International Workshop on Radiation Effects on Semiconductor Devices for Space Applications (RASEDA-11) (Internet), p.130 - 133, 2015/11
-ray irradiationKato, Chiaki; Sato, Tomonori; Nakano, Junichi; Ueno, Fumiyoshi; Yamagishi, Isao
Proceedings of 2014 Nuclear Plant Chemistry Conference (NPC 2014) (USB Flash Drive), 9 Pages, 2014/10
As a part of consideration for long-term storage of spent zeolite adsorption vessels in the Fukushima Daiichi Nuclear Power Station, corrosion of vessel material in the spent zeolite adsorption vessel is one of important issue. We performed electrochemical tests of stainless steel (type 316L) in the zeolite containing artificial seawater under -ray irradiation. Steady spontaneous potential (Esp) and pitting potential (VC), of type 316L was measurement. Co -rays source was used under irradiation. Dose rate of -ray irradiation was controlled for 5 kGy/h and 400 Gy/h. In anode polarization curves, there was no clear difference under irradiation and non-irradiation. The corrosion potential of type 316L increased with increasing time after -ray irradiation. The Esp was shifted to nobler by -rays irradiation, while increasing Esp was suppressed by contacted with zeolite.
lrradiated p-channel 6H-SiC MOSFETs; High total doseLee, K. K.; Oshima, Takeshi; Ito, Hisayoshi
IEEE Transactions on Nuclear Science, 50(1), p.194 - 200, 2003/02
Times Cited Count：29 Percentile：85.30(Engineering, Electrical & Electronic)p-channel SiC MOSFETs were fabricated on n-type 6H-SiC epitaxial layer. The effects of -ray irradiation on the charecteristics of the MOSFETs were studied. Threshold voltage shifts to negative voltage side and the channel mobility reduces due to irradiation. Although the degradation of the channel mobility of the p-channel SiC MOSFETs is 10 times faster than n-channel SiC MOSFETs, p-channel SiC MOSFETs show 100 times stronger radiation resistance than Si MOSFETs. The values of interface traps and oxide-trapped-charge generated sue to irradiation were estimated from the subthreshold characteristics. As the result,it is concluded that the decrease in channel mobility can be explained by the generation of interface traps.
H.H.Mai*; Tachibana, Hiroyuki; Kojima, Takuji
Radiation Physics and Chemistry, 53(1), p.85 - 91, 1998/00
Times Cited Count：5 Percentile：44.03(Chemistry, Physical)no abstracts in English
Kojima, Takuji; Morishita, Norio; Ito, Hisayoshi; S.Biramontri*
Applied Radiation and Isotopes, 47(4), p.457 - 459, 1996/00
Times Cited Count：4 Percentile：39.16(Chemistry, Inorganic & Nuclear)no abstracts in English
JAERI-M 86-157, 35 Pages, 1986/11
no abstracts in English
; ; ; ;
JAERI-M 83-177, 75 Pages, 1983/10
no abstracts in English
Tasaka, Kanji
Nuclear Technology, 29(2), p.239 - 248, 1976/02
Times Cited Count：1no abstracts in English
; ; Kitahara, Tanemichi;
JAERI-M 6200, 22 Pages, 1975/08
no abstracts in English
; ; ; ; ;
JAERI-M 5225, 55 Pages, 1973/04
no abstracts in English
single crystals after gamma-ray irradiation;
Japanese Journal of Applied Physics, 3, p.126 - 127, 1964/00
no abstracts in English
-ray irradiationMotooka, Takafumi; Yamagishi, Isao
no journal, ,
Mixtures of zeolite IE96 and artificial seawater (ASW) were poured in cylindrical tubes, and irradiated by Co-60 -rays. In the case of a zeolite bed which was fully immersed in ASW, the zeolite bed level increased slightly (1.8%) and an ASW phase formed onto the bed. The ASW level increased with the irradiation dose. In the case of a partial immersion, which simulates a drained zeolite vessel, the zeolite bed level was un-changed (0.0%).
