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Journal Articles

Proposal of laser-induced ultrasonic guided wave for corrosion detection of reinforced concrete structures in Fukushima Daiichi Nuclear Power Plant decommissioning site

Furusawa, Akinori; Takenaka, Yusuke; Nishimura, Akihiko

Applied Sciences (Internet), 9(17), p.3544_1 - 3544_12, 2019/09

 Times Cited Count:6 Percentile:14.2(Chemistry, Multidisciplinary)

Remote-controlled, non-destructive testing is necessary to detect corrosion of the reinforced concrete structures at the Fukushima Daiichi Nuclear Power Plant (NPP) de-commissioning site. This work aims to demonstrate that laser-induced ultrasonic guided wave technology can be applied to achieve this task. Hence, accelerated electrolytic corrosion is performed on a reinforced concrete specimen fabricated by embedding a steel rod into mortar. Waveforms of the laser-induced ultrasonic guided wave on the rod are measured with a previously employed piezoelectric transducer (PZT) probe, for each fixed corrosion time. Based on the results of Fourier and wavelet transforms of the waveforms, issues concerning the detection and extent of rebar corrosion are discussed. It is exhibited that the changes in bonding strength due to corrosion are distinguishable in the frequency domain of the ultrasonic signal.

Journal Articles

Preliminary verification of water radiolysis and ECP calculation models by in-pile ECP measurements

Hanawa, Satoshi; Hata, Kuniki; Chimi, Yasuhiro; Kasahara, Shigeki

Proceedings of 21st International Conference on Water Chemistry in Nuclear Reactor Systems (Internet), 12 Pages, 2019/09

Journal Articles

Effect of re-oxidation rate of additive cations on corrosion rate of stainless steel in boiling nitric acid solution

Irisawa, Eriko; Yamamoto, Masahiro; Kato, Chiaki; Motooka, Takafumi; Ban, Yasutoshi

Journal of Nuclear Science and Technology, 56(4), p.337 - 344, 2019/04

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Journal Articles

Electrochemical measurements in various environments; Corrosion monitoring of carbon steel in deep underground environment

Taniguchi, Naoki; Nakayama, Masashi

Zairyo To Kankyo, 67(12), p.487 - 494, 2018/12

This article describes the current status of corrosion monitoring methods and examples of the measurement under deep underground environments for carbon steel overpacks for high-level radioactive waste disposal. Based on the studies on corrosion monitoring using AC Impedance technique, some of the typical measurement systems such as the electrodes arrangement are introduced. In-situ corrosion monitoring in engineering scale test is also being attempted using a deep underground research facility, and the measurement method and results are presented in this article.

Journal Articles

Corrosion behaviour of FeCrAl-ODS steels in nitric acid solutions with several temperatures

Takahatake, Yoko; Ambai, Hiromu; Sano, Yuichi; Takeuchi, Masayuki; Koizumi, Kenji; Sakamoto, Kan*; Yamashita, Shinichiro

Proceedings of Annual Topical Meeting on Reactor Fuel Performance (TopFuel 2018) (Internet), 9 Pages, 2018/10

The corrosion behaviour of FeCrAl-ODS steels for the accident tolerant fuel cladding of LWRs were investigated in nitric acid solutions for the reprocessing process of spent fuels. The corrosion tests were carried out at 60$$^{circ}$$C, 80$$^{circ}$$C and the boiling point of the solutions, and the specimens were then analysed by XPS. The corrosion remarkably progressed at the boiling point, and the highest corrosion rate was 0.22 mm/y. In the oxide film, the atomic concentration of Fe was lower, than that in the base material, and those of Cr and Al were higher. The results show that the corrosion of FeCrAl-ODS steels in hot nitric acid solution is not severe because of the high corrosion resistance of the oxide film formed on the material; hence, the corrosion resistance of the new cladding materials in the dissolution process of spent fuel is acceptable for reprocessing operations.

Journal Articles

Mass transfer inside narrow crevice of SUS316L in high temperature water

Yamamoto, Masahiro; Soma, Yasutaka; Igarashi, Takahiro; Ueno, Fumiyoshi

Proceedings of Annual Congress of the European Federation of corrosion (EUROCORR 2018) (USB Flash Drive), 7 Pages, 2018/09

In order to clarify the SCC behavior of SUS316L under BWR environment, mass transfer inside crevice of SUS316L in high temperature water using various crevice gap samples was investigated. The samples were prepared by put together two SUS316L sheets. Crevice gap differs from 0.005 mm to 0.1 mm. Corrosion tests were conducted in 8 ppm dissolved oxygen (DO) conditions. Surface oxide film was analysed by laser Raman spectroscopy (LRS) after immersion. Numerical simulations were also conducted by using COMSOL Maltiphysics. Diffusion process of DO and the other chemical species were calculated with connected to electrochemical process. Electrical conductivities inside the crevice were 100 times larger than these of outer water. The reason of high conductivity is existence of Fe$$^{2+}$$ ions at the DO depletion crevice.

Journal Articles

Effects of environmental factors inside the crevice on corrosion of stainless steel in high temperature water

Yamamoto, Masahiro; Sato, Tomonori; Igarashi, Takahiro; Ueno, Fumiyoshi; Soma, Yasutaka

Proceedings of European Corrosion Congress 2017 (EUROCORR 2017) and 20th ICC & Process Safety Congress 2017 (USB Flash Drive), 6 Pages, 2018/09

The authors have studied the differences between outer surface and the crevice-like portion of SUS316L in high pressurized and high temperature water containing dissolved oxygen. We have already introduced that changes in the characteristics of corrosion products along the crevice directions and gap width. It is suggested that the environmental conditions are different with the features of crevice from these results. In this report, we introduce the changes in oxide films with crevice gaps and comparison with the numerical simulation data utilizing of FEM calculation.

JAEA Reports

The In-situ experiment for overpack corrosion at Horonobe Underground Research Laboratory; Production and setting simulated overpack, buffer material blocks and heater

Nakayama, Masashi

JAEA-Technology 2018-006, 43 Pages, 2018/08

JAEA-Technology-2018-006.pdf:5.32MB
JAEA-Technology-2018-006-appendix(CD-ROM).zip:29.19MB

The Horonobe URL Project has being pursued by JAEA to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, Hokkaido. The URL Project proceeds in 3 overlapping phases, "Phase I: Surface-based investigations", "Phase II: Investigations during tunnel excavation" and "Phase III: Investigations in the underground facilities", over a period of around 20 years. The OP corrosion test was prepared from 2013 FY at Niche No.3, and heating by electric heater in simulated overpack started in November, 2014. The objective of the test is acquiring data concerned with corrosion of carbon steel OP. These data will be used in order to confirm the performance of engineered barrier system. In the OP corrosion test, the diameter of simulated OP and buffer material are 100 mm and 300 mm, respectively. Concrete support using low alkaline cement was used in order to investigate the effect of cementitious materials to OP corrosion behavior. We will measure corrosion potential of carbon steel, natural potential, pH in buffer material for several years. In this report, we describe how to make simulated OP and buffer material blocks, and set sensors, and so on.

Journal Articles

Flow-accelerated corrosion of type 316L stainless steel caused by turbulent lead-bismuth eutectic flow

Wan, T.; Saito, Shigeru

Metals, 8(8), p.627_1 - 627_22, 2018/08

 Times Cited Count:3 Percentile:58.46(Materials Science, Multidisciplinary)

Journal Articles

An Empirical model for the corrosion of stainless steel in BWR primary coolant

Uchida, Shunsuke*; Hanawa, Satoshi; Naito, Masanori*; Okada, Hidetoshi*; Lister, D. H.*

Corrosion Engineering, Science and Technology, 52(8), p.587 - 595, 2017/10

 Times Cited Count:1 Percentile:87.67(Materials Science, Multidisciplinary)

Based on the relationship among ECP, metal surface conditions, exposure time and other environmental conditions, a model to evaluate the ECP and corrosion rate of steel was developed by coupling a static electrochemical analysis and a dynamic oxide layer growth analysis. Major conclusion obtained on the model are as follows. The effect of H$$_{2}$$O$$_{2}$$ and O$$_{2}$$ concentrations on ECP were successfully explained as the effects of oxide layer growth. Hysteresis of ECP under changes in water chemistry conditions were successfully explained with the model. Decreases in ECP due to neutron exposure were explained well by radiation-induced diffusion in the oxide layers.

Journal Articles

Effect of chloride ion on corrosion behavior of SUS316L-grade stainless steel in nitric acid solutions containing seawater components under $$gamma$$-ray irradiation

Sano, Yuichi; Ambai, Hiromu; Takeuchi, Masayuki; Iijima, Shizuka; Uchida, Naoki

Journal of Nuclear Materials, 493, p.200 - 206, 2017/09

 Times Cited Count:4 Percentile:39.91(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$$_{3}$$ solution containing seawater components, including under the $$gamma$$-ray irradiation condition. Electrochemical and immersion tests were carried out using a mixture of HNO$$_{3}$$ and artificial seawater (ASW). In the HNO$$_{3}$$ 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$$_{2}$$ and NOCl, generated in the reaction between HNO$$_{3}$$ and Cl$$^{-}$$ ions. The corrosion rate decreased with the immersion time at low concentrations of HNO$$_{3}$$, while it increased at high concentrations. Under the $$gamma$$-ray irradiation condition, the corrosion rate decreased due to the suppression of the cathodic reactions by the reaction between the above oxidants and HNO$$_{2}$$ generated by radiolysis.

Journal Articles

Improving the corrosion resistance of silicon carbide for fuel in BWR environments by using a metal coating

Ishibashi, Ryo*; Tanabe, Shigetada*; Kondo, Takao*; Yamashita, Shinichiro; Nagase, Fumihisa

Proceedings of 2017 Water Reactor Fuel Performance Meeting (WRFPM 2017) (USB Flash Drive), 10 Pages, 2017/09

For improving the corrosion resistance of silicon carbide (SiC) in boiling-water-reactor environments, corrosion-resistant coatings on SiC were evaluated. Due to its hydrogen-generation rate and reaction heat being lower than those of conventional Zircaloy, SiC is expected to be an appropriate material for accident-tolerant fuels. However, there are still many critical issues with the practical application of SiC fuel cladding and fuel channel boxes, one of which is hydrothermal corrosion. Silicon carbide is chemically stable, but silicon oxide formed by oxidation of SiC dissolves in high temperature water. Although the rate of SiC dissolution is very small, the dissolution must be suppressed to comply with regulations for dissolved silica concentration in reactor coolant. In this study, the corrosion behavior of candidate coatings for SiC substrates were evaluated before and after exposure to unirradiated high-purity-water environments.

Journal Articles

Performance degradation of candidate accident-tolerant cladding under corrosive environment

Nagase, Fumihisa; Sakamoto, Kan*; Yamashita, Shinichiro

Corrosion Reviews, 35(3), p.129 - 140, 2017/08

 Times Cited Count:7 Percentile:42.96(Electrochemistry)

As the lessons learnt from the accident at the Fukushima Daiichi Nuclear Power Station, advanced cladding materials are being developed to enhance accident tolerance comparing with conventional zirconium alloys. The present paper reviews the progress of the development and summarizes subjects to be solved for the enhanced accident-tolerance fuel cladding, focusing on performance degradation under various corrosive environmental conditions that should be considered in designing the LWR fuel.

Journal Articles

Status of LBE corrosion test loop "OLLOCHI" and experiments at JAEA

Saito, Shigeru; Okubo, Nariaki; Obayashi, Hironari; Sasa, Toshinobu

NEA/CSNI/R(2017)2 (Internet), p.195 - 200, 2017/06

An ADS (Accelerator Driven System) for waste transmutation investigated in JAEA employs LBE (Lead-Bismuth Eutectic) as spallation target material and core coolant. To realize future ADS and an ADS target experimental facility (TEF-T) planned for construction in J-PARC, there are many technical issues on LBE. In particular, corrosion data of relevant materials like T91 (Mod. 9Cr-1Mo) and SS316L steels at 400-550$$^{circ}$$C under oxygen concentration controlled and flowing condition are indispensable. JAEA has designed and built new LBE corrosion test loop named OLLOCHI (Oxygen-controlled LBE LOop Corrosion tests in HIgh-temperature), to obtain the corrosion data at the higher temperature. The piping of high temperature sections was made by T91 and 2.25Cr-1Mo steel. The maximum temperature of these parts is 550$$^{circ}$$C. At low temperature sections, piping and components were made by SS316L and the maximum temperature is limited to 450$$^{circ}$$C. The status for the OLLOCHI as of March 2016 is that the some modification and the conditioning operation without LBE have already finished. The oxygen sensors and the oxygen control system will be installed soon. After that, the conditioning operation with LBE and oxygen control test will be started. And more, additional flow meters will be installed in each test section until next March. In parallel with these tests, thermal hydraulic analysis of the two test sections will be performed to identify the flow pattern in the specimen holders.

Journal Articles

Development of metal corrosion testing method simulating equipment of reprocessing of spent nuclear fuels

Matsueda, Makoto; Irisawa, Eriko; Kato, Chiaki; Matsui, Hiroki

Proceedings of 54th Annual Meeting of Hot Laboratories and Remote Handling (HOTLAB 2017) (Internet), 4 Pages, 2017/00

In the PUREX method, spent fuels are dissolved with nitric acid media. The reprocessing solution containing Fission Products derived from spent fuels is very corrosive to metal materials, the corrosion problem often appears on the surface stainless steel devices. The oxidizing metal ions such as Ruthenium (Ru) and Neptunium (Np) in the process solution is the key reason for severe corrosion of stainless steel. In order to obtain the corrosion rate of stainless steel, we installed the corrosion test apparatus inside an airtight concrete cell in a hot laboratory (the WAste Safety TEsting Facility (WASTEF) of the Japan Atomic Energy Agency), and performed the corrosion tests of stainless steel in the heated nitric acid solution containing Np. The corrosion tests were performed in the temperature range from room temperature to boiling point for 500 hours per batch. The results show that the presence of Np accelerate the stainless steel corrosion in the nitric acid solution.

Journal Articles

In situ X-ray diffraction study of the oxide formed on alloy 600 in borated and lithiated high-temperature water

Watanabe, Masashi*; Yonezawa, Toshio*; Shobu, Takahisa; Shiro, Ayumi; Shoji, Tetsuo*

Corrosion, 72(9), p.1155 - 1169, 2016/09

 Times Cited Count:0 Percentile:100(Materials Science, Multidisciplinary)

Journal Articles

The Effect of crystal textures on the anodic oxidization of zirconium in a boiling nitric acid solution

Kato, Chiaki; Ishijima, Yasuhiro; Ueno, Fumiyoshi; Yamamoto, Masahiro

Journal of Nuclear Science and Technology, 53(9), p.1371 - 1379, 2016/09

AA2015-0626.pdf:1.2MB

 Times Cited Count:2 Percentile:69.72(Nuclear Science & Technology)

The effects of crystal textures and the potentials in the anodic oxidation of zirconium in a boiling nitric acid solution were investigated to study the stress corrosion cracking of zirconium in nitric acid solutions. The growth of the zirconium oxide film dramatically changed depending on the applied potential at a closed depassivation potential (1.47 V vs. SSE). At 1.5 V, the zirconium oxide film rapidly grows, and its growth exhibits cyclic oxidation kinetics in accordance with a nearly cubic rate law. The zirconium oxide film grows according to the quantity of electric charge, and the growth rate does not depend on the crystal texture in the pretransition region before the cyclic oxidation kinetics. However, the growth and cracking under the thick oxide film depend on the crystal texture in the transition region. On the normal direction side, the oxide film thickness decreases on average since some areas of the thick oxide film are separated from the specimen surface owing to the cracks in the thick oxide. On the rolling direction side, cracks are found under the thick oxide film, which deeply propagate along the RD without an external stress. The cracks under the thick oxide film propagate to the center of the oxide layer. The cracks in the oxide layer propagate in the (0002)Zr plane in the zirconium matrix. The oxide layer consists of string-like zirconium oxide and zirconium hydride. The string-like zirconium oxide contains orthorhombic ZrO$$_{2}$$ in addition to monoclinic ZrO$$_{2}$$. As one assumption for the mechanism of crack initiation and propagation without an external stress, it is considered that the oxidizing zirconium hydrides precipitate in the (0002)Zr and then the phase transformation from orthorhombic ZrO$$_{2}$$ to monoclinic ZrO$$_{2}$$ in the oxide layer causes the crack propagation in the (0002) plane.

Journal Articles

Seawater effects on the soundness of spent fuel cladding tube

Motooka, Takafumi; Ueno, Fumiyoshi; Yamamoto, Masahiro

Proceedings of 2016 EFCOG Nuclear & Facility Safety Workshop (Internet), 6 Pages, 2016/09

At the Fukushima Daiichi nuclear accident, seawater was injected into spent fuel pools of Unit 2-4 for the emergency cooling. Seawater might cause localized corrosion of spent fuel cladding. This would lead to leakage of not only fissile materials but also fission products from fuel cladding. The behavior, however, is not understood well. In this paper, the effects of seawater on corrosion behavior and mechanical property of were studied by using a spent fuel cladding from a BWR. We immersed the spent cladding tubes in diluted artificial seawater for 300h at 353 K, and conducted their visual, cross-sectional and strength examinations. As a localized corrosion index, the pitting potentials of specimens fabricated from the cladding were measured as functions of chloride ion concentration ranging from 20 to 2500 ppm. The visual examination showed that localized corrosion has not occurred, and cross-sectional examination showed no cracks. The strength of immersed tubes was comparable to that of non-immersed tubes. Additionally, pitting potential could not be measured over 1.0 V; pitting corrosion was hardly occurred. These results suggested that the specimens from the spent fuel cladding tube was very resistant to localized corrosion.

Journal Articles

Corrosion property of sheath materials using MI cables at conditions simulated severe accident

Nakano, Hiroko; Shibata, Hiroshi; Takeuchi, Tomoaki; Matsui, Yoshinori; Tsuchiya, Kunihiko

Proceedings of International Conference on Asia-Pacific Conference on Fracture and Strength 2016 (APCFS 2016) (USB Flash Drive), p.283 - 284, 2016/09

no abstracts in English

Journal Articles

Corrosion of 9-12Cr ferritic-martensitic steels in high-temperature CO$$_{2}$$

Rouillard, F.*; Furukawa, Tomohiro

Corrosion Science, 105, p.120 - 132, 2016/04

 Times Cited Count:44 Percentile:3.47(Materials Science, Multidisciplinary)

The high temperature corrosion behavior of two 9Cr and 12Cr ferritic-martensitic steel grades was studied under CO$$_{2}$$ pressure varying from 1 to 250 bar for exposure times up to 8000 h. No breakaway oxidation was observed. 9Cr steel grades suffered from fast parabolic uniform oxidation and fast carburisation. Increasing CO$$_{2}$$ pressure had very little effect on the oxidation rate but increased the carburisation rate. The corrosion behavior of both 12Cr steel grades differed and might be influenced by gas composition, minor elements or surface finish. A corrosion mechanism coupling oxidation and carburisation is proposed.

149 (Records 1-20 displayed on this page)