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Journal Articles

Corrosion behavior of cold-worked austenitic stainless steels in liquid lead-bismuth eutectic

Kurata, Yuji

Journal of Nuclear Materials, 448(1-3), p.239 - 249, 2014/05

 Times Cited Count:38 Percentile:96.28(Materials Science, Multidisciplinary)

The compatibility of steels with lead-bismuth (LBE) is one of critical issues to develop accelerator driven systems. It is expected to use cold-worked austenitic stainless steels as core materials for the improvement of irradiation resistance. The corrosion tests of solution-treated, 20% and 50% cold-worked 316SS and JPCA were conducted in oxygen-controlled LBE. A little ferritization was found at 500$$^{circ}$$C under intermediate oxygen condition(1.4$$times$$10$$^{-7}$$ wt.%). In the corrosion test at 550$$^{circ}$$C for 1000h under low-oxygen condition (4.2$$times$$10$$^{-9}$$ wt.%), the depth of the ferritization increased with increasing the cold work. Whereas only oxidation was found at 550$$^{circ}$$C for 1000h under high-oxygen condition (about 10$$^{-5}$$wt.%), the ferritization accompanied by Pb-Bi penetration was widely observed with oxidation at 550$$^{circ}$$C for 3000h under the high-oxygen condition. The cold work accelerated the ferritization and Pb-Bi penetration notably.

Journal Articles

Corrosion behavior of Si-enriched steels for nuclear applications in liquid lead-bismuth

Kurata, Yuji

Journal of Nuclear Materials, 437(1-3), p.401 - 408, 2013/06

 Times Cited Count:33 Percentile:93.83(Materials Science, Multidisciplinary)

The compatibility of steels with lead-bismuth is one of critical issues to develop accelerator driven systems and lead-bismuth cooled reactors. It is expected that Si-enriched steels have good compatibility with lead-bismuth. Type 316SS with addition of 2.5 wt.% Si and Mod.9Cr-1Mo steel with addition of 1.5 wt.% Si were produced for the purpose of nuclear applications. In this paper, the results of corrosion tests of these steels in liquid lead-bismuth are reported. Corrosion tests were conducted at 550$$^{circ}$$C in lead-bismuth containing 2.5$$times$$10$$^{-5}$$ wt.% of oxygen and in lead-bismuth containing 4.4$$times$$10$$^{-8}$$ wt.% of oxygen. The additions of 2.5 wt.% Si to 316SS and 1.5 wt.% Si to T91 had the effect of reducing oxide film thickness in liquid lead-bismuth where oxygen concentrations were high. However, it was found that the formed oxide films didn't have enough protectiveness to prevent Ni dissolution and the penetration of Pb and Bi in liquid lead-bismuth containing 4.4$$times$$10$$^{-8}$$ wt.% of oxygen.

Journal Articles

Progress review of research and development on accelerator driven system in JAEA

Oigawa, Hiroyuki; Tsujimoto, Kazufumi; Sasa, Toshinobu; Kurata, Yuji; Takei, Hayanori; Saito, Shigeru; Nishihara, Kenji; Obayashi, Hironari; Sugawara, Takanori; Iwamoto, Hiroki

KURRI-KR(CD)-40 (CD-ROM), p.16 - 30, 2013/00

In JAEA, research and development on an Accelerator-Driven System (ADS) have been conducted in order to transmute minor actinides (MA) contained in high-level radioactive wastes. One unit of ADS with thermal power of 800 MW can transmute MA generated in 10 units of light water reactors with electric power of 1 GW. In JAEA, we are studying variety of technical areas such as a superconducting proton accelerator, a spallation target including a beam window and a subcritical core including neutronics design and safety assessment. Moreover, construction of the Transmutation Experimental Facility is being planned as a phase-2 program of the J-PARC project to perform basic experiments for transmutation technology.

Journal Articles

Development of aluminum powder alloy coating for innovative nuclear systems with lead-bismuth

Kurata, Yuji; Sato, Hidetomo*; Yokota, Hitoshi*; Suzuki, Tetsuya*

Proceedings of 2nd International Workshop on Structural Materials for Innovative Nuclear Systems (SMINS-2), p.177 - 188, 2012/12

Liquid lead-bismuth is a candidate material used for innovative nuclear systems such as accelerator driven reactors and fast reactors. Development of corrosion resistant materials in liquid lead-bismuth is one of important research subjects to realize these systems. In this study, improvement of corrosion properties in lead-bismuth by Al alloy coating was investigated. Aluminum alloys were coated on 316SS using sheets made of Al, Ti and Fe powders, and laser heating. Adjustments of chemical composition in sheets and scanning rate of laser beam enabled us to control Al concentration in coating layers. The corrosion tests were conducted at 550$$^{circ}$$C for 1,000 hours or 3,000 hours in oxygen-controlled lead-bismuth. As a result of the corrosion tests, it was found that the coating with Al concentration of 5 to 8 mass% showed good corrosion resistance.

Journal Articles

Development of Al-alloy coating for advanced nuclear systems using lead alloys

Kurata, Yuji; Yokota, Hitoshi*; Suzuki, Tetsuya*

Journal of Engineering for Gas Turbines and Power, 134(6), p.062902_1 - 062902_7, 2012/06

 Times Cited Count:7 Percentile:35.85(Engineering, Mechanical)

Nuclear systems using lead alloys are one of the promising reactor concepts with improved safety. This paper focuses on development of Al-alloy coating for nuclear systems using liquid lead-bismuth eutectic (LBE). It is necessary to improve corrosion resistance of steels because of high corrosiveness of liquid LBE at high temperatures. An Al-alloy coating method using Al, Ti and Fe powders and laser beam heating has been developed. Main defects formed in an Al-powder-alloy coating process are surface defects and cracks. Conditions required to avoid these defects have been studied. According to results of the corrosion tests at 550$$^{circ}$$C in liquid LBE, the Al-alloy coating layers on 316SS prevent severe corrosion attack observed in 316SS without coating. The good corrosion resistance of the Al-alloy coating is based on the thin Al-oxide film regenerated in liquid LBE. It is estimated that the range of the adequate Al concentration in the coating layer is from 4 to 12 wt%.

Journal Articles

Development of aluminum-alloy coating on type 316SS for nuclear systems using liquid lead-bismuth

Kurata, Yuji; Yokota, Hitoshi*; Suzuki, Tetsuya*

Journal of Nuclear Materials, 424(1-3), p.237 - 246, 2012/05

 Times Cited Count:24 Percentile:86.91(Materials Science, Multidisciplinary)

An Al-alloy coating method using Al, Ti and Fe powders and the laser beam heating has been developed for nuclear systems using liquid lead-bismuth eutectic (LBE). The main defects formed in the Al-alloy coating process are surface defects and cracks. Conditions required to avoid such defects have been studied. A static corrosion test was conducted in liquid LBE at the controlled oxygen concentrations of 10$$^{-6}$$ to 10$$^{-3}$$ wt% at 550$$^{circ}$$C for 3000h. The Al-alloy coating layer on 316SS prevents severe corrosion attack such as Ni dissolution, partial loss of grains and LBE penetration observed in the 316SS without Al-alloy coating. The Al-alloy coating layer, which is formed without surface defects and cracks under the optimum condition, exhibits good corrosion resistance in liquid LBE.

Journal Articles

Present status for research and development on accelerator driven system in JAEA

Tsujimoto, Kazufumi; Oigawa, Hiroyuki; Kurata, Yuji; Nishihara, Kenji; Sugawara, Takanori; Takei, Hayanori; Saito, Shigeru; Obayashi, Hironari; Iwamoto, Hiroki

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 8 Pages, 2011/12

To continue the utilization of the nuclear fission energy, the management of the high-level radioactive waste (HLW) is one of the most important issues to be solved. Partitioning and Transmutation technology of HLW is expected to be effective to mitigate the burden of the HLW disposal by reducing the radiological toxicity and heat generation. The Japan Atomic Energy Agency (JAEA) has been conducting the research and development (R&D) on accelerator-driven subcritical system (ADS) as a dedicated system for the transmutation of long-lived radioactive nuclides. The ADS proposed by JAEA is a lead-bismuth eutectic (LBE) cooled fast subcritical reactor with thermal output of 800 MW. For ADS to play important roles in the nuclear fuel cycle, several critical issues have to be resolved. Items of R&D are divided into three technical areas peculiar to the ADS: (1) superconducting linear accelerator (SC-LINAC), (2) LBE as spallation target and core coolant, and (3) subcritical core design and technology. For these technical areas, various R&D activities are progressing in JAEA. In this paper, the present status of the R&D activities in JAEA is reported.

Journal Articles

Application of electromotive force measurement in nuclear systems using lead alloys

Kurata, Yuji

Electromotive Force and Measurement in Several Systems, p.107 - 124, 2011/10

Electromotive force measurement using oxygen sensors with a solid electrolyte of YSZ and a Pt/gas reference electrode is a useful and reliable means to measure oxygen concentration correctly in liquid LBE online. The accuracy of Pt/gas reference sensors was validated in terms of EMF measurements in gas with known oxygen concentration and in oxygen-saturated LBE. The Pt/gas reference sensors can be certainly used to measure oxygen concentration in liquid LBE at least above 450$$^{circ}$$C. It occurs that even the YSZ sensor with the Pt/gas reference electrode exhibits incorrect outputs on account of contamination such as deposition of black soot etc. on the outer surface of the YSZ. It is possible to re-activate the YSZ sensor, which exhibited incorrect outputs, by means of Pt-treatment on the outer YSZ surface. The YSZ sensors with the Pt/gas reference electrode have been used for a long time as a reliable oxygen sensor to monitor oxygen concentration in liquid LBE online.

Journal Articles

Study on the structural integrity of fuel claddings against beam trips for accelerator-driven system

Takei, Hayanori; Nishihara, Kenji; Kurata, Yuji; Tsujimoto, Kazufumi; Oigawa, Hiroyuki

Proceedings of 19th International Conference on Nuclear Engineering (ICONE-19) (CD-ROM), 8 Pages, 2011/10

Japan Atomic Energy Agency (JAEA) has promoted the design study of the Accelerator-Driven System (ADS) cooled by lead-bismuth eutectic (LBE) to transmute minor actinide. The structural integrity of the fuel claddings is one of key issues in designing the ADS. For ADS, frequent beam trips as experienced in existing high power proton accelerators may cause thermal fatigue problems which may lead to degradation of the structural integrity and reduction of the lifetime of the fuel claddings. To estimate the structural integrity of the fuel claddings, the thermal stress of the fuel cladding was evaluated for following two states: the steady state and the transient state. For the steady-state analysis, the thermal stress was divided into two types: the primary stress and the secondary stress, which were caused by the inner pressure and the thermal load, respectively. These stresses were compared with the design stress limits. As a result, it was confirmed that their structural strength was sufficient under the conditions of design temperature and corrosion environment without irradiation. For the transient-state analysis, the number of acceptable beam trips was evaluated based on the total strain range due to the primary and secondary stress of the fuel cladding. As a result, the number of acceptable beam trips was evaluated to be over $$1times10^6$$ times. If the fuel cladding was replaced once every two years, the acceptable beam-trip frequency was estimated to be greater than $$5times10^5$$ times per year. This acceptable frequency was 20 times greater than the expected beam-trip frequency caused by the accelerator for the JAEA's reference ADS.

Journal Articles

Development of aluminum alloy coating for advanced nuclear systems using lead alloys

Kurata, Yuji; Yokota, Hitoshi*; Suzuki, Tetsuya*

Proceedings of ASME 2011 Small Modular Reactors Symposium (SMR 2011) (CD-ROM), 7 Pages, 2011/09

Small and medium reactors using lead alloys as coolant are one of the promising reactor concepts with improved safety. This paper focuses on development of Al-alloy coating for nuclear systems using liquid lead-bismuth eutectic (LBE). Since corrosion attack becomes severe against steels at high temperatures, it is necessary to improve corrosion resistance. An Al-alloy coating method using Al, Ti and Fe powders, and laser beam heating has been developed. Main defects formed in an Al-powder-alloy coating process are surface defects and cracks. Conditions required to avoid these defects were found. According to results of the corrosion tests at 550 $$^{circ}$$C in liquid LBE, the Al-alloy coating layers on 316SS protect severe corrosion attack observed in 316SS without coating. From the viewpoints of the soundness of coating layers and preservation of their corrosion resistance, it is estimated that the range of the adequate Al concentration in the coating layer is from 4 to 12 wt%.

Journal Articles

Corrosion experiments and materials developed for the Japanese HLM systems

Kurata, Yuji

Journal of Nuclear Materials, 415(3), p.254 - 259, 2011/08

 Times Cited Count:25 Percentile:86.63(Materials Science, Multidisciplinary)

Corrosion experiments and study on materials developed for an accelerator-driven system and heavy liquid metal reactors have been conducted in Japan. Temperature dependence, oxygen concentration dependence and effects of alloying elements in steels on corrosion properties have been made clear through corrosion experiments in pots using liquid lead-bismuth. Austenitic stainless steels containing Si of about 5wt% exhibited good corrosion resistance. Si-enriched 316 stainless steel and Si-enriched Mod. 9Cr-1Mo steel were produced and exposed to liquid lead-bismuth. As a result of the corrosion test, it was found that the Si-enriched steels would have corrosion resistance to a certain extent. Since there was a limitation to improvement in corrosion resistance by Si-enrichment, an aluminum alloy coating method was developed. Specimens produced by means of the Al powder alloy coating method exhibited good corrosion resistance at 550$$^{circ}$$C in lead-bismuth.

Journal Articles

Role of ADS in the back-end of the fuel cycle strategies and associated design activities; The Case of Japan

Oigawa, Hiroyuki; Tsujimoto, Kazufumi; Nishihara, Kenji; Sugawara, Takanori; Kurata, Yuji; Takei, Hayanori; Saito, Shigeru; Sasa, Toshinobu; Obayashi, Hironari

Journal of Nuclear Materials, 415(3), p.229 - 236, 2011/08

 Times Cited Count:47 Percentile:95.92(Materials Science, Multidisciplinary)

The Partitioning and Transmutation (P&T) technology provides the possibility to reduce the amount of the radiotoxic inventory of the high-level radioactive waste dramatically and to extend the repository capacity. The accelerator-driven system (ADS) is regarded as a powerful tool to effectively transmute minor actinides. The ADS has a potential to flexibly manage MA in the transient phase from light water reactors to fast breeder reactors (FBRs), and can co-exist with FBR symbiotically and complementarily to enhance the reliability and the safety of the commercial FBR cycle. The concept of ADS in JAEA is a lead-bismuth eutectic (LBE) cooled subcritical reactor. The design study was performed mainly for the subcritical reactor and the spallation target. In Japan, Atomic Energy Commission has implemented the check and review (C&R) on P&T technology from 2008 to 2009, and discussed the benefit of P&T technology, the current status of the R&D, and the way forward to promote it.

Journal Articles

Investigation of safety for accelerator-driven system

Sugawara, Takanori; Nishihara, Kenji; Tsujimoto, Kazufumi; Kurata, Yuji; Oigawa, Hiroyuki

Proceedings of 1st International Workshop on Technology and Components of Accelerator-driven Systems (TCADS-1), p.347 - 357, 2011/06

It is supposed that the Accelerator Driven System (ADS) is safer than other critical systems such as fast reactors since the ADS is driven by the external neutron source in the subcritical state. In this study, the possibility of Core Disruptive Accident (CDA) for the ADS was investigated by detailed safety analyses. Safety analyses for Unprotected Transient Over Power (UTOP) and Unprotected Loss of Flow (ULOF) were carried out by using the SIMMER-III code. The calculation results showed that the maximum temperatures of the nitride fuel and the clad tube (316SS) in the accidents were lower than their melting points (2780$$^{circ}$$C and 1400$$^{circ}$$C, respectively). It was also found by Level 1 PSA that the frequency of those accidents would be exceedingly small. Although the creep rupture of the clad tube might happen in Beam Over Power (BOP), which was a kind of UTOP, and ULOF, it was concluded that the ADS had very little possibility of CDA or the re-criticality accident.

Journal Articles

Applicability of Al-powder-alloy coating to corrosion barriers of 316SS in liquid lead-bismuth eutectic

Kurata, Yuji; Sato, Hidetomo*; Yokota, Hitoshi*; Suzuki, Tetsuya*

Materials Transactions, 52(5), p.1033 - 1040, 2011/05

 Times Cited Count:11 Percentile:54.72(Materials Science, Multidisciplinary)

A new Al-alloy coating method using Al, Ti and Fe powders has been applied to 316SS in order to develop corrosion resistant coating in lead-bismuth eutectic (LBE). The 316SS plates with coating layers of different Al concentrations were tested at 550$$^{circ}$$C for 1000h in liquid LBE with controlled oxygen concentrations of 10$$^{-6}$$$$sim$$10$$^{-4}$$ mass%. While surface oxidation and grain boundary corrosion accompanied by LBE penetration are observed in 316SS without Al-alloy coating, the Al-alloy coating is effective to protect such severe corrosion attacks in LBE. Although the coating layer containing 2.8 mass% Al does not always keep sufficient corrosion resistance, good corrosion resistance is obtained in the coating layer where the average Al concentration is 4.2 mass%. Cracks are found in the coating layer containing 17.8 mass% Al. The Al-powder-alloy coating applied to 316SS is promising as a corrosion resistant coating method in liquid LBE environment.

Journal Articles

Conceptual design study of beam window for accelerator-driven system

Sugawara, Takanori; Nishihara, Kenji; Obayashi, Hironari; Kurata, Yuji; Oigawa, Hiroyuki

Journal of Nuclear Science and Technology, 47(10), p.953 - 962, 2010/10

 Times Cited Count:16 Percentile:74.17(Nuclear Science & Technology)

The conceptual design study for the beam window of the spallation target is one of the critical issues in the R&D of the accelerator driven system (ADS). In this study, the investigation to create a feasible concept of the beam window for the ADS was performed by changing the proton beam profile from the gaussian distribution to the parabolic and the flat distributions. The detailed analyses were performed by considering the particle transport of protons and neutrons in the spallation target region, the thermal hydraulics of lead bismuth eutectic (LBE) around the beam window and the structural strength of the beam window. The calculation results presented the concept with the parabolic distribution would be the most feasible concept in the current ADS design condition.

JAEA Reports

Feasibility study for transmutation system using lead-bismuth cooled accelerator-driven system

Tsujimoto, Kazufumi; Nishihara, Kenji; Takei, Hayanori; Sugawara, Takanori; Kurata, Yuji; Saito, Shigeru; Obayashi, Hironari; Sasa, Toshinobu; Kikuchi, Kenji*; Tezuka, Masao; et al.

JAEA-Research 2010-012, 59 Pages, 2010/07

JAEA-Research-2010-012.pdf:2.0MB

The design of an accelerator-driven system was modified and its feasibility was investigated on the basis of new data and knowledge for corrosion by lead-bismuth eutectic and irradiation behavior of candidate materials. The neutronics and thermal design was carried out and a modified core concept was established. As a result of evaluation for the integrity of fuel cladding tubes and a beam window, it was confirmed that their structural strength was sufficient under the conditions of design temperature and corrosion environment without irradiation. Though irradiation effects on material properties were considered not to be so serious under the practical conditions of the ADS according to existing irradiation data, it was needed to accumulate further experimental data for more detailed evaluation. According to level-1 PSA and dynamic analysis of beyond-design-basis accidents, it was shown that there was little possibility of core disruption and re-criticality accidents for ADS.

Journal Articles

Characterization and re-activation of oxygen sensors for use in liquid lead-bismuth

Kurata, Yuji; Abe, Yuji*; Futakawa, Masatoshi; Oigawa, Hiroyuki

Journal of Nuclear Materials, 398(1-3), p.165 - 171, 2010/03

 Times Cited Count:14 Percentile:70.51(Materials Science, Multidisciplinary)

Liquid lead-bismuth is a candidate material used for accelerator driven systems and fast reactors. Oxygen control in liquid lead-bismuth is essential in this system and oxygen sensors are the critical instruments for the active oxygen control system. In this study, a re-activation treatment was investigated as well as characterization of oxygen sensors for use in liquid lead-bismuth. The oxygen sensor with a solid electrolyte of yttria-stabilized zirconia (YSZ) and a Pt/gas reference electrode showed almost the same electromotive force values as the theoretical ones at temperatures above 400 or 450 $$^{circ}$$C. After use for longer times than 6000 h, the outputs of the sensor became incorrect in liquid lead-bismuth. The state of the sensor showing incorrect outputs was not recovered by cleaning with nitric acid. However, it was found that the oxygen sensor was able to become a correct sensor indicating theoretical values after a re-activation treatment of the surface of the YSZ.

Journal Articles

Investigation of beam window structure for accelerator-driven system

Sugawara, Takanori; Suzuki, Kazuhiko; Nishihara, Kenji; Sasa, Toshinobu; Kurata, Yuji; Kikuchi, Kenji; Oigawa, Hiroyuki

Proceedings of 10th OECD/NEA Information Exchange Meeting on Actinide and Fission Product Partitioning and Transmutation (CD-ROM), 11 Pages, 2010/00

The investigations of the beam window which is one of the most critical components for the Accelerator Driven System (ADS) were performed. In the previous study, it was found that the buckling failure was the most severe failure mode for the beam window. Hence, the shape and the thickness of the beam window were optimized to prevent the buckling failure. The buckling analyses with initial imperfections were also performed to identify the level of the factor of safety (FS). The results showed that FS of 3 was conservative enough to ensure the integrity of the beam window. It was also shown that the ellipse shape concepts with the thickness of 2.0-2.4[mm] at the top and the thickness of 2.0-4.0[mm] at the transient part were acceptable under the current ADS design parameters.

Journal Articles

Results of corrosion tests in liquid Pb-Bi at JAEA; Temperature and oxygen concentration dependence, and corrosion properties of Si-enriched steels

Kurata, Yuji; Saito, Shigeru

Proceedings of 10th OECD/NEA Information Exchange Meeting on Actinide and Fission Product Partitioning and Transmutation (CD-ROM), 11 Pages, 2010/00

Corrosion tests of various steels in liquid Pb-Bi have been conducted using static corrosion apparatus to study corrosion behaviour in liquid Pb-Bi, a promising candidate material of coolants and high-power spallation targets of accelerator driven systems for transmutation of radioactive wastes. Effects of temperature, oxygen concentration in Pb-Bi and elements in steels on corrosion behavior were estimated from test results. Tested temperature range was from 450$$^{circ}$$C to 600$$^{circ}$$C. Temperature increase produced active corrosion and grain boundary corrosion, penetration of Pb-Bi and ferritization became severe above 550$$^{circ}$$C. Effect of oxygen concentration was clearly found in pure iron and 316SS at 450$$^{circ}$$C and corrosion attack became severe under the low oxygen concentration condition at 550$$^{circ}$$C. Mod.9Cr-1Mo with addition of 1.5%Si and 316SS with addition of 2.5%Si showed good corrosion resistance in liquid oxygen-saturated Pb-Bi at 550$$^{circ}$$C.

JAEA Reports

Investigation of safety for accelerator driven system; Investigation for abnormal event and safety analysis for accident event

Sugawara, Takanori; Nishihara, Kenji; Tsujimoto, Kazufumi; Kurata, Yuji; Oigawa, Hiroyuki

JAEA-Research 2009-024, 83 Pages, 2009/09

JAEA-Research-2009-024.pdf:21.99MB

It is supposed that the Accelerator Driven System (ADS) is safer than other critical systems such as Fast Reactors since the ADS is driven by the external neutron source in the subcritical state. In this study, the investigation to confirm the possibility of Core Disruptive Accident (CDA) for the ADS was performed by Level 1 PSA and detailed safety analyses. Abnormal events for the ADS were sorted by Level 1 PSA and calculation cases for the safety analysis were discussed. Based on these results, safety analyses for Unprotected Transient Over Power (UTOP) and Unprotected Loss of Flow (ULOF) were carried out. These results showed that there were hardly possibilities of CDA for the ADS. In the beyond design basis accidents (UTOP and ULOF), it was considered that the creep rupture of the clad tube would happen. However, the frequency of the accidents was exceedingly small. It was concluded that the ADS had very little possibility of CDA or the re-criticality accident.

143 (Records 1-20 displayed on this page)