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Journal Articles

Corrosion behavior of a titanium alloy in hot nitric acid condensate

Takeuchi, Masayuki; Sano, Yuichi; Nakajima, Yasuo; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*

Journal of Energy and Power Engineering, 7(6), p.1090 - 1096, 2013/06

The corrosion behavior of a titanium-5% tantalum alloy (Ti-5Ta) in hot nitric acid condensate was investigated to understand aging behavior of reprocessing equipments. On the basis of long-term immersion tests, it was determined that the corrosion of Ti-5Ta in nitric acid condensate is accelerated with an increase in the concentration. The corrosion rate was nearly constant during the immersion test and the coupons suffered from uniform corrosion. In addition, it is important to note that the nitric acid concentration in the condensate increased on addition of metal salts to the heated nitric acid solution. The larger valence of metal ions was contributed to the increase in the concentration of nitric acid condensate. Consequently, the metal salt in the heated nitric acid solution accelerates the corrosion of Ti-5Ta in the condensate. Therefore, the nitric acid condensate condition should be carefully considered for the corrosion environment of titanium and its alloys.

Journal Articles

Effects of oxidation states of Np on polarization curve of stainless steel in boiling 3M-HNO$$_{3}$$

Kato, Chiaki; Ueno, Fumiyoshi; Yamamoto, Masahiro; Ban, Yasutoshi; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*

ECS Transactions, 53(21), p.45 - 55, 2013/05

 Times Cited Count:2 Percentile:18.52

Neptunium ion contained as one of the fission products in reprocessing solutions is known as a corrosion accelerator of the stainless steel. But it is not clear why remarkable acceleration of corrosion is caused by a slight amount of the Np ion in boiling nitric acid solution. Neptunium has several oxidation states in nitric acid solution. These changeable oxidation states of Np in nitric acid solution are regarded as the cause. Therefore an evaluation of the electrochemical behaviors on stainless steel in nitric acid solution related to the oxidation state of Np is required in order to understand the corrosion acceleration mechanism. A specially designed electrochemical test cell integrated with optical cell for spectroscopic analysis was used for this purpose. From results of electrochemical tests, cathodic reaction on stainless steel was activated by Np ions. Np(VI) ion made the corrosion potential shift nobler than Np(V) and nobler corrosion potential causes increasing corrosion current and accelerating corrosion of stainless steel in nitric acid solution. Np(V) was easily oxidized to Np(VI) in nitric acid solution and Np(VI) was the stable state in boiling 3M-HNO$$_{3}$$. It was considered that role of Np ions was that of mediator to accelerate corrosion due to activating cathodic reaction and re-oxidizing cycle in boiling 3M-HNO$$_{3}$$.

Journal Articles

Corrosion study of titanium-5% tantalum alloy in hot nitric acid condensate

Takeuchi, Masayuki; Sano, Yuichi; Nakajima, Yasuo; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*

Proceedings of 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference (ICONE-20 & POWER 2012) (DVD-ROM), 6 Pages, 2012/07

A long-term corrosion tendency and metal salt effect in heating nitric acid solution on corrosion behavior of titanium-5% tantalum alloy (Ti-5Ta) in hot nitric acid condensate condition were mainly researched to discuss the aging behavior of reprocessing equipments such as evaporators made of titanium or its alloy. The hot pure nitric acid solution with continuous renewing such as the nitric acid condensate condition is severe corrosion environment for their materials because of the corrosion inhibition effect from titanium ions as corrosion products or oxidizing ions in nitric acid solution. From the results of the long-term corrosion test for total 11,000 hrs, the corrosion of Ti-5Ta in the nitric acid condensate was accelerated with increase of the nitric acid concentration in the condensate. The corrosion rate was nearly constant during the immersion time and the test coupons suffered a uniform corrosion. Thus, from the viewpoints of nitric acid corrosion, the life-time of the reprocessing equipments made of titanium or its alloy will be roughly estimated based on the results of average corrosion rate in operation. It was also found that the kind and concentration of metal salt in the heating nitric acid solution gave a remarkable effect on the concentration of nitric acid vapor and the corrosion of Ti-5Ta in the hot nitric acid condensate. Most of the evaporators for reprocessing plants include metal ions in the heating nitric acid solution, so the metal salt effect is one of the corrosion factors to control the corrosion behavior of titanium alloy in condensate. The nitric acid concentration in the condensate increases by adding the metal salts in the heating nitric acid solution, in addition, the larger valence of metal ions was contributed to the increase of nitric acid concentration in the condensate. Consequently, the metal salts effect in the heating nitric acid solution accelerates the corrosion of Ti-5Ta in the nitric acid condensate.

Journal Articles

Study on corrosion of stainless steel in boiling nitric acid under heat transfer conditions

Ueno, Fumiyoshi; Shiraishi, Hironori; Inoue, Shun; Motooka, Takafumi; Kato, Chiaki; Yamamoto, Masahiro; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*

Proceedings of 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference (ICONE-20 & POWER 2012) (DVD-ROM), 8 Pages, 2012/07

In PUREX process for spent fuel reprocessing plants, heating portions in the components are severely corroded in the boiling solution under heat transfer (HT) conditions. In this paper, authors have focused on the effects of surface temperature and heat flux on corrosion rates (CRs) of stainless steels in boiling nitric acid under HT conditions. Two types of cells for HT and immersion conditions were applied for corrosion tests. Test solution used was 33 mol/m$$^{3}$$ vanadium added to 3 kmol/m$$^{3}$$ nitric acid solution, and was heated at boiling temperature under atmospheric pressure. Additionally, a boiling curve which was indicated the relation between heat flux and degree of superheating was investigated experimentally. Surface temperatures during corrosion tests were estimated from a boiling curve. The results showed that CR did not depend on heat flux, but depended on surface temperature. Arrhenius plots on CRs indicated that CR was accelerated by solution boiling against non-boiling.

Journal Articles

Characterization of hydrogen embrittlement of Ti and Ti-5Ta alloys using constant load test

Yokoyama, Kenichi*; Murata, Yusuke*; Shiimori, Fusae*; Sakai, Junichi*; Yamamoto, Masahiro; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*

Fushoku Boshoku Kyokai Dai-58-Kai Zairyo To Kankyo Toronkai Koenshu, p.11 - 12, 2011/09

Characteristics of hydrogen embrittlement of pure Ti and Ti-5Ta alloys were evaluated by stress loading and constant load tests. Mechanical properties of these materials were affected by hydride formation of surface layers. Although elongation was reduced by hydrogen absorption, embrittlement was observed only in the surface hydride area. It is also suggested that Ti-5Ta alloy was better susceptibility of hydrogen embrittlement than pure Ti.

Journal Articles

Analysis of dissolved hydrogen concentration utilizing of channel-flow-electrode method

Miura, Tatsuya*; Nishikata, Atsushi*; Tsuru, Toru*; Yamamoto, Masahiro; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*

Fushoku Boshoku Kyokai Dai-58-Kai Zairyo To Kankyo Toronkai Koenshu, p.15 - 16, 2011/09

There exist some equipments made of Ti or Ti-5Ta alloy in the spent nuclear fuel reprocessing plant. These equipments are investigated for failure by hydrogen embrittlement. To evaluate the stabilities of hydrogen in the solutions using at the reprocessing plant, channel-flow-ellectrode (CFE) method was utilized. The method to determine the dissolved hydrogen concentration was considered from the results of anodic polarization curves.

Journal Articles

Hydrogen absorption of titanium and Ti-5Ta in nitric acid solutions under irradiation

Shiimori, Fusae*; Sakai, Junichi*; Yokoyama, Kenichi*; Motooka, Takafumi; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*

Fushoku Boshoku Kyokai Dai-58-Kai Zairyo To Kankyo Toronkai Koenshu, p.13 - 14, 2011/09

In reprocessing plants, hydrogen gas was released by radiolysis of aqueous solution. The relationship of the amount of hydrogen gas and the amount of hydrogen absorption to titanium and Ti-5Ta were not clear. In this study, hydrogen was absorbed to titanium by the cathode charging and irradiation. Then, the amount of the hydrogen gas from solutions and the amount of the hydrogen absorbed to titanium was compared. It was found that a very small amount of the hydrogen by radiolysis was absorbed to titanium. It was suggested that the difference of the hydrogen absorption rate was caused by the difference of the hydrogen concentration on the metal surface.

Journal Articles

Electrochemical measurements in boiling nitric acid solutions containing radioactive elements by using small cell with a portion for spectral analysis function

Kato, Chiaki; Ueno, Fumiyoshi; Yamamoto, Masahiro; Hakamatsuka, Yasuyuki; Ban, Yasutoshi; Morita, Yasuji; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*

Zairyo To Kankyo, 60(2), p.69 - 71, 2011/02

It was reported that the metric ions such as Pu and Np contained in reprocessing solutions would accelerate corrosion of stainless steals due to those ions changing higher oxidizer. It's difficult that those ions was used in laboratory test because of radioactive elements. However it's important to understand oxide stats of those ions and electrochemical behavior on stainless steals in order to estimate corrosion rate of materials in reprocessing plats. Furthermore laboratory test with very a little solution volume is demanded for handling radioactive elements. This paper shows that developed a small electrochemical cell with a spectral analysis function and those results of polarization curves on stainless steals and oxide stats of Np(IV)/Np(V) and Pu(IV)/Pu(VI) in boiling nitric acid solutions.

Journal Articles

Polarization measurement in boiling nitric acid solution including the radioactive elements by using a small test cell with the spectral analysis

Kato, Chiaki; Ueno, Fumiyoshi; Yamamoto, Masahiro; Hakamatsuka, Yasuyuki; Ban, Yasutoshi; Morita, Yasuji; Uchiyama, Gunzo; Nojima, Yasuo*; Fujine, Sachio*

Fushoku Boshoku Kyokai Dai-57-Kai Zairyo To Kankyo Toronkai Koenshu, p.43 - 46, 2010/10

Reprocessing process solution including Pu and Np may accelerate corrosion of the stainless steel because of oxidizing states in boiling nitric acid. The small electrochemical test cell with a spectral analysis function was developed for the purpose of evaluating corrosion of the stainless steel and oxidizing states of Pu and Np ions in a boiling nitric acid solution. The relationship between corrosion states of the stainless steel and oxidizing states in boiling nitric acid solution can be confirmed.

Journal Articles

The Suppression effect of natural barrier for the radionuclide migration under the practice environment

Tanaka, Tadao; Mukai, Masayuki; Maeda, Toshikatsu; Matsumoto, Junko; Ogawa, Hiromichi; Munakata, Masahiro; Kimura, Hideo; Bamba, Tsunetaka; Fujine, Sachio

Genshiryoku eye, 49(2), p.76 - 79, 2003/02

no abstracts in English

Journal Articles

Solvent extraction behaviors of minor nuclides in nuclear fuel reprocessing process

Uchiyama, Gunzo; Asakura, Toshihide; Hotoku, Shinobu; Mineo, Hideaki; Kamei, Kazushige; Watanabe, Makio; Fujine, Sachio

Journal of Radioanalytical and Nuclear Chemistry, 246(3), p.683 - 688, 2000/12

 Times Cited Count:10 Percentile:40.67(Chemistry, Analytical)

no abstracts in English

Journal Articles

PARC process for an advanced PUREX process

Uchiyama, Gunzo; Mineo, Hideaki; Hotoku, Shinobu; Asakura, Toshihide; Kamei, Kazushige; Watanabe, Makio; Nakano, Yuji*; Kimura, Shigeru; Fujine, Sachio

Progress in Nuclear Energy, 37(1-4), p.151 - 156, 2000/12

 Times Cited Count:5 Percentile:60.75(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

A Basic study on electrolytic decomposition of butylamine; A Study on decomposition of butylamine solvent washing reagent

Kamei, Kazushige; Hotoku, Shinobu; Asakura, Toshihide; Watanabe, Makio; Uchiyama, Gunzo; Fujine, Sachio

JAERI-Research 2000-021, p.29 - 0, 2000/03

JAERI-Research-2000-021.pdf:1.37MB

no abstracts in English

Journal Articles

Management of minor long-lived nuclides in nuclear fuel reprocessing

Uchiyama, Gunzo; Mineo, Hideaki; Asakura, Toshihide; Hotoku, Shinobu; Kamei, Kazushige; Watanabe, Makio; Fujine, Sachio

Proceedings of 12th Pacific Basin Nuclear Conference (PBNC 2000), Vol.1, p.531 - 538, 2000/00

no abstracts in English

Journal Articles

Reduction of minor nuclides in nuclear fuel reprocessing

Uchiyama, Gunzo; Mineo, Hideaki; Asakura, Toshihide; Hotoku, Shinobu; Kamei, Kazushige; Watanabe, Makio; Fujine, Sachio

Proceedings of 2nd International Conference on Safewaste 2000, Vol.2, p.689 - 700, 2000/00

no abstracts in English

JAEA Reports

Cause finding experiments and environmental analysis on the accident of the fire and explosion in TRP bituminization facility

Fujine, Sachio; Murata, Mikio; Abe, Hitoshi; Takada, Junichi; Tsukamoto, Michio; Miyata, Teijiro*; Ida, Masaaki*; Watanabe, Makio; Uchiyama, Gunzo; Asakura, Toshihide; et al.

JAERI-Research 99-056, p.278 - 0, 1999/09

JAERI-Research-99-056.pdf:22.73MB

no abstracts in English

JAEA Reports

Study on safety of crystallization method applied to dissolver solution in fast breeder reactor reprocessing

; Fujine, Sachio; Asakura, Toshihide; Murazaki, Minoru*; *; *; *

JAERI-Research 99-027, 37 Pages, 1999/03

JAERI-Research-99-027.pdf:1.82MB

no abstracts in English

Journal Articles

Dissolution tests of spent fuel in the NUCEF $$alpha$$$$gamma$$ cell including dissolver off-gas treatment

Mineo, Hideaki; Kihara, Takehiro; *; Kimura, Shigeru; *; ; Uchiyama, Gunzo; Hotoku, Shinobu; Watanabe, Makio; ; et al.

JAERI-Conf 99-004, p.498 - 507, 1999/03

no abstracts in English

Journal Articles

Study on gaseous effluent treatment during dissolusion tests of spent fuel

Mineo, Hideaki; Kihara, Takehiro; *; ; *; Kimura, Shigeru; Uchiyama, Gunzo; Hotoku, Shinobu; ; ; et al.

Proceedings of International Waste Management Symposium '99 (Waste Manegement '99) (CD-ROM), 6 Pages, 1999/03

no abstracts in English

Journal Articles

Development of treatment technology for carbon-14 in dissolver off-gas of spent fuel

Mineo, Hideaki; ; *; Uchiyama, Gunzo; Fujine, Sachio

Proc. of 7th Int. Conf. on Radioactive Waste Mamagement and Environmental Remediation (ICEM '99)(CD-ROM), 3 Pages, 1999/00

no abstracts in English

100 (Records 1-20 displayed on this page)