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Asada, Naoki; Sasaki, Shunichi; Rachi, Reona; Komori, Tsuyoshi; Suzuki, Hisanori; Takeuchi, Kenji; Uchida, Naoki
Nihon Hozen Gakkai Dai-20-Kai Gakujutsu Koenkai Yoshishu, p.5 - 8, 2024/08
no abstracts in English
Yokochi, Masaru; Sasaki, Shunichi; Yanagibashi, Futoshi; Asada, Naoki; Komori, Tsuyoshi; Fujieda, Sadao; Suzuki, Hisanori; Takeuchi, Kenji; Uchida, Naoki
Nihon Hozen Gakkai Dai-20-Kai Gakujutsu Koenkai Yoshishu, p.1 - 4, 2024/08
Tokai Reprocessing Plant, which is shifted to decommissioning stage, stores large amount of high-level radioactive liquid waste (HLLW) generated by reprocessing of spent nuclear fuels in High-level Active Waste facility (HAW). Radioactive risk related to HLLW has been concentrated in HAW until the completion of vitrification. Natural disasters such as earthquake may damage cooling function of HAW. Therefore, HAW must improve earthquake resistance, as exchanging the ground around HAW facility and pipe trench by concrete. This earthquake resistance construction starts from July of 2020 and completed in March 2024. This report summarizes the construction work and describes the inspection results after the construction.
Matsushita, Akira*; Tsuchida, Noriyuki*; Ishimaru, Eiichiro*; Hirakawa, Naoki*; Gong, W.; Harjo, S.
Journal of Materials Engineering and Performance, 33(13), p.6352 - 6361, 2024/07
Times Cited Count：0 Percentile：0.00(Materials Science, Multidisciplinary)Ambai, Hiromu; Nishizuka, Yusuke*; Sano, Yuichi; Uchida, Naoki; Iijima, Shizuka; Shiwaku, Hideaki; Yaita, Tsuyoshi
Journal of Nuclear Science and Technology, 56(2), p.193 - 200, 2019/02
Times Cited Count：2 Percentile：18.04(Nuclear Science & Technology)During the accident that occurred at the Fukushima Daiichi Nuclear Power Plant, a large volume of seawater was introduced as coolant into the storage pools for spent nuclear fuel. If this fuel is reprocessed, some components of seawater will be mixed with the nitric acid solution containing metal ions in the reprocessing process where stainless steels are used as structural material. In this study, we investigated the effect of seawater components in high active liquid waste (HAW) containing nitric acid and metal ions as fission products on the corrosion behavior of SUS316L stainless steel. Corrosion tests were conducted in surrogate HAW containing artificial seawater (ASW). Intergranular corrosion was observed in the HAW with ASW, where Ru increased the corrosion potential to the transpassive region. An increase in the amount of ASW led to a decrease in the corrosion rate and suppression of intergranular corrosion. Interactions between Ru ions and seawater components, such as chloride ions, were indicated by the results of extended Xray absorption fine structure spectroscopy and cyclic voltammetry analyses of the solution containing ASW and HAW.
-ray irradiationSano, Yuichi; Ambai, Hiromu; Takeuchi, Masayuki; Iijima, Shizuka; Uchida, Naoki
Journal of Nuclear Materials, 493, p.200 - 206, 2017/09
Times Cited Count：9 Percentile：61.18(Materials Science, Multidisciplinary)Concerning the Fukushima Daiichi Nuclear Power Plant accident, we investigated the effect of chloride ion on the corrosion behavior of SUS316L stainless steel, which is a typical material for the equipment used in reprocessing, in HNO
solution containing seawater components, including under the -ray irradiation condition. Electrochemical and immersion tests were carried out using a mixture of HNO and artificial seawater (ASW). In the HNO solution containing high amounts of ASW, the cathodic current densities increased and uniform corrosion progressed. This might be caused by strong oxidants, such as Cl
and NOCl, generated in the reaction between HNO and Cl
ions. The corrosion rate decreased with the immersion time at low concentrations of HNO, while it increased at high concentrations. Under the -ray irradiation condition, the corrosion rate decreased due to the suppression of the cathodic reactions by the reaction between the above oxidants and HNO generated by radiolysis.
Ambai, Hiromu; Sano, Yuichi; Nishizuka, Yusuke*; Iijima, Shizuka; Uchida, Naoki
Zairyo To Kankyo, 66(5), p.169 - 172, 2017/05
We study the effect of sulfate ion which is one component of seawater or concrete on the corrosion behavior in high active liquid waste tank environment. The corrosion tests were conducted using SUS316L and surrogate high active liquid waste containing some metal ions and nitric acid. The results showed that sulfate ion inhibited the corrosion rates. The XPS results indicated the attachment of sulfate ion to material surfaces suppressed the anode reaction.
-ray irradiationAmbai, Hiromu; Nishizuka, Yusuke*; Sano, Yuichi; Uchida, Naoki; Iijima, Shizuka
QST-M-2; QST Takasaki Annual Report 2015, P. 90, 2017/03
The spent fuel stored in the storage pools at the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company Holdings, Inc. is exposed with the environment containing seawater components, owing to the injection of seawater into the storage pools. Therefore, during reprocessing, it is expected that the spent fuel will be contaminated with seawater components, and the influence of seawater on reprocessing needs to be investigated. We conducted the corrosion tests of the HAW storage tanks under -ray irradiation, and revealed that no significant effect of seawater components was emerged.
Sano, Yuichi; Ambai, Hiromu; Takeuchi, Masayuki; Iijima, Shizuka; Uchida, Naoki
Proceedings of European Corrosion Congress 2016 (EUROCORR 2016) (USB Flash Drive), 10 Pages, 2016/09
During the Fukushima Daiichi Nuclear Power Plant accident, significant volume of seawater was injected into the storage pool for spent nuclear fuel as the coolant. In this study, we investigated the effect of seawater components on the corrosion behavior of SUS316L stainless steel in HNO solution. Electrochemical and immersion tests were carried out using a mixture of HNO and artificial seawater (ASW). In the HNO solution containing high amounts of ASW, the cathodic current densities increased and uniform corrosion progressed. This might be caused by strong oxidants, such as Cl and NOCl, generated in the reaction between HNO and Cl ions. In addition, pitting corrosion occurred simultaneously at low HNO concentrations. The corrosion rate decreased with the immersion time at low concentrations of HNO, while it increased at high concentrations. It is assumed that the cathodic reactions proceed slowly and the anodic reactions are gradually prevented by the growth of an oxide film on the surface of the coupon in low-concentration HNO. On the other hand, high-concentration HNO triggers a vigorous cathodic reaction, which disturbs the growth of the oxide film and activates the anodic reactions. This competition between the cathodic and anodic reactions causes a change in the corrosion rates with the immersion time in a mixture of HNO and ASW.
Takahashi, Naoki; Yoshinaka, Kazuyuki; Harada, Akio; Yamanaka, Atsushi; Ueno, Takashi; Kurihara, Ryoichi; Suzuki, Soju; Takamatsu, Misao; Maeda, Shigetaka; Iseki, Atsushi; et al.
Nihon Genshiryoku Gakkai Homu Peji (Internet), 64 Pages, 2016/00
no abstracts in English
Iijima, Shizuka; Uchida, Naoki; Taguchi, Katsuya; Washiya, Tadahiro
JAEA-Review 2015-018, 39 Pages, 2015/11
JAEA-Review-2015-018.pdf:3.95MB
There is a possibility that the fuel assemblies stored in the spent fuel pool (SFP) at Fukushima Daiichi NPS (or Nuclear Power Station) are not only exposed to seawater and concrete fragments, but also damaged by fallen rubbles. We checked the reprocessing experiences of leak fuels at Tokai Reprocessing Plant and overseas reprocessing facilities, and the storage conditions and the checked and inspected results of the fuel stored in the SFP at Fukushima Daiichi NPS, after that, we listed up the technological problems with reprocessing damaged nuclear fuels and selected elements of the research for the purpose of drawing indicators to make a judgmental decision of the possibility of damaged nuclear fuels reprocessing. And we drew the indicators to make a judgmental decision on the possibility of reprocessing based on the results of the examination and the study about elements of the research.
Irisawa, Eriko; Ueno, Fumiyoshi; Uchida, Naoki; Taguchi, Katsuya
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 3 Pages, 2015/05
][1]benzothiophene monolayer on bismuth-terminated Si(111) vicinal surfaces with wettability optimizationOtomo, Manabu; Tsuchida, Yuya*; Muraya, Naoki*; Yanase, Takashi*; Sakai, Seiji; Yonezawa, Tetsu*; Nagahama, Taro*; Hasegawa, Tetsuya*; Shimada, Toshihiro*
Journal of Physical Chemistry C, 117(22), p.11555 - 11561, 2013/06
Times Cited Count：2 Percentile：8.37(Chemistry, Physical)We report in-plane orientation control of newly developed high-mobility organic semiconductor: 2,7-diphenyl[1]benzothieno[3,2-][1]benzothiophene (DPh-BTBT). As previously reported on monolayer pentacene, it was revealed that bunched steps on vicinal Si(111) with bismuth termination break the surface symmetry and reduce three-fold symmetry of DPh-BTBT grains into quasi-single orientation. Interestingly, the critical step height necessary for the orientation control was different from that of pentacene. We examined several mechanisms of orientation control and concluded that the facet nano structure fabricated by step bunching is working as an anisotropic template. We will also show the wettability control of bismuth terminated silicon surface and show that the growth mode of DPh-BTBT is dependent on the surface nanostructure of Bi-Si.
Kondo, Yoshikazu; Uchida, Naoki; Terunuma, Hirotaka; Tanaka, Kosuke; Oyama, Koichi; Katsurai, Kiyomichi; Washiya, Tadahiro
Proceedings of International Conference on Advanced Nuclear Fuel Cycle; Sustainable Options & Industrial Perspectives (Global 2009) (CD-ROM), p.277 - 280, 2009/09
The composition of sludge in the dissolver after dissolution of PWR and ATR fuels at the Tokai Reprocessing Plant (TRP) was analyzed. As a result the presence of zirconium molybdate was confirmed by the analysis of X-ray diffraction (XRD). To clarify the formation behavior of the precipitates of zirconium molybdate, investigated the dependence of HNO concentration on the precipitation with Mo and Zr solution. To evaluate the adhesion on the metal surface (stainless steel and Ti metal), the deposition amounts of the precipitates of zirconium molybdate on the metal were also examined. In addition, it reports on the comparative result of executing a chemical dissolution of the precipitates by using the solutions of NaOH, CHO
-HNO and HO-HNO.
Kamiyama, Takashi*; Seki, Naoki*; Iwasa, Hirokatsu*; Uchida, Tsutomu*; Ebinuma, Takao*; Narita, Hideo*; Igawa, Naoki; Ishii, Yoshinobu; Bennington, S. M.*; Kiyanagi, Yoshiaki*
Physica B; Condensed Matter, 385-386(1), p.202 - 204, 2006/11
Times Cited Count：7 Percentile：34.19(Physics, Condensed Matter)no abstracts in English
Shimizu, Ryo; Takaya, Akikazu; Shirozu, Hidetomo; Uchida, Naoki; Tanaka, Kosuke; Yamaguchi, Akira; Aoto, Kazumi; Watahiki, Masaru
Nihon Genshiryoku Gakkai Wabun Rombunshi, 4(3), p.203 - 212, 2005/09
It was occurred that process solution leaked from the steam jet in the acid recovery process of Tokai reprocessing plant. So we retrieved the jet from the cell and observed the inside. As a result, it was revealed that a defect by corrosion, which penetrated the inside of the structure, arose from the steam nozzle root in the suction room of the jet. To ascertain why such failure occurred, we carried out observation of metallurgical structure of the jet, an analysis of temperature distribution of the structure involving verification using mock-ups and evaluation of material by corrosion test. Consequently, the origin of the corrosion defect was pin hole which was occurred on the surface of the end of the material at the steam nozzle root, where nitric acid fluid was contacted, and then the defect progressed along the temperature of about 120 of the structure. Anisotropy of the material, possibly originating in the manufacturing process, was observed from the result of evaluation of material by corrosion test. Finally, we devised a new design of improved corrosion resistance on the result of the whole investigations.
Shirozu, Hidetomo; Shimizu, Ryo; Takaya, Akikazu; Uchida, Naoki; Tanaka, Kosuke; Yamaguchi, Akira; Aoto, Kazumi
Saikuru Kiko Giho, (21), p.41 - 55, 2003/00
The cause of the failure, which had occurred in the steam jet (273J202) in the acid recovery process of Tokai reprocessing plant, was investigated.
Nishihara, Tetsuo; Muto, Yasushi; Uchida, Shoji*; Yoshioka, Naoki*
JAERI-Tech 2001-077, 44 Pages, 2001/12
JAERI-Tech-2001-077.pdf:2.16MB
JAERI has conducted the feasibility study of the HTGR gas turbine system from 1996 to 2000 sponsored by MEXT. This report concludes the safety criteria and rationalization of the safety items in the HTGR system.With respect to the safety criteria, the same value for the LWR is selected as the limit of radiation exposure. Probability of the design basis event (DBE) and beyond design basis event (BDBE) is set lower than those for the LWR to get higher safety margin. Adequate initial events and mitigation system are selected to consider the event sequence. The concept of the probability analysis is applied to identify DBEs and BDBEs. It is found that some safety items can be rationalized in consideration of the safety features of the HTGR. Finally, the safety class and design category of the items in the HGTR-GT are classified.
Sakurama, Naoki*; Sakaguchi, Seiichiro*; Uchida, Shunsuke*
PNC TJ202 72-13, 91 Pages, 1972/02
PNC-TJ202-72-13.pdf:3.69MBPNC-TJ202-72-13T.pdf:1.63MB
no abstracts in English
Sugai, Eiji; Hata, Katsuro; Kikuchi, Hideki; Terunuma, Hirotaka; Uchida, Naoki; Taguchi, Katsuya
no journal, ,
no abstracts in English
Murakami, Manabu; Sato, Takehiko; Nakajima, Masayoshi; Ishiyama, Koichi; Uchida, Naoki; Sumi, Hirotaka; Omura, Masami
no journal, ,
no abstracts in English
