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Journal Articles

Effect of trace amount tungsten on long-term material properties of high Cr steels

Onizawa, Takashi; Nagae, Yuji; Kikuchi, Kenji*

Tetsu To Hagane, 100(8), p.999 - 1005, 2014/08

 Times Cited Count:2 Percentile:12.31(Metallurgy & Metallurgical Engineering)

The applicability of high chromium (Cr) steel as the main structural material in fast breeder reactors (FBR) has been explored to enhance the safety, the credibility and the economic competitiveness of FBR power plants. Tungsten (W) is believed to improve the high temperature strength of high Cr steels by solid-solution strengthening mechanism, although the long-term effectiveness and stability of such a strengthening mechanism has not fully been understood yet. High Cr steels controlling W content are produced and tensile tests, creep tests, aging tests and charpy impact tests were conducted to investigate the long-term material properties. It was observed that the short-term creep strength could be improved by W. However, there is almost no influence of W on the long-term creep strength. And it was observed that the impact properties after aging could be improved by decreasing of W. It was found that the optimal W content for excellent high Cr steel of FBR grade are $$<$$ 0.1 wt.%, under FBR operating conditions.

Journal Articles

Bend-fatigue properties of JPCA and Alloy800H specimens irradiated in a spallation environment

Saito, Shigeru; Kikuchi, Kenji*; Hamaguchi, Dai; Endo, Shinya; Sakuraba, Naotoshi; Miyai, Hiromitsu; Kawai, Masayoshi*; Dai, Y.*

Journal of Nuclear Materials, 450(1-3), p.27 - 31, 2014/07

 Times Cited Count:0 Percentile:0.01(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

HCM12A Cr-rich oxide layer investigation using 3D atom probe

Kikuchi, Kenji*; Okada, Noriyuki*; Kato, Mikio*; Uchida, Hiroshi*; Saito, Shigeru

Journal of Nuclear Materials, 450(1-3), p.237 - 243, 2014/07

 Times Cited Count:3 Percentile:24.02(Materials Science, Multidisciplinary)

Three-dimensional atom probe techniques were applied to the investigation on the oxide scale in 12Cr ferritic-martensitic steel, HCM12A. A duplex oxide scale was formed in lead bismuth eutectic at 450-500$$^{circ}$$C, during 5500 h. Samples were located 500-700 nm away from the boundary between magnetite and Fe-Cr spinel layers, while the total oxide layer thickness is 18 $$mu$$m. It detected super enrichment of Cr with a size of ten nm roughly, as well as depletion of Fe and enrichment of O at the same site. Surrounding the Cr super enrichment area, enrichment of Si was newly noticed due to the scanned profile of detected atom counts. It is also confirmed that Pb and Bi concentration in the observed spinel region is almost null or less than 0.01 atomic percent, which is possible detecting lowest limit.

Journal Articles

Development of high chromium steel for fast breeder reactors with high-temperature strength, ductility, and microstructural stabilit

Onizawa, Takashi; Asayama, Tai; Kikuchi, Kenji*

ISIJ International, 53(6), p.1081 - 1088, 2013/06

 Times Cited Count:3 Percentile:22.67(Metallurgy & Metallurgical Engineering)

The applicability of high chromium (Cr) steel as the main structural material in fast breeder reactors (FBR) has been explored to enhance the safety, the credibility and the economic competitiveness of FBR power plants. Vanadium (V) and Niobium (Nb) are believed to improve the high-temperature strength of high Cr steels by precipitating as carbides and/or nitrides, namely fine MX particles, although the long-term efficiency and stability of such precipitation strengthening mechanisms resulting from the fine MX particles have not been clarified yet. The effects of V and Nb on degradation of creep properties were investigated under FBR operating conditions, e.g., at 550 $$^{circ}$$C for 500,000 h, and the relationship between the long-term creep properties and microstructural changes was investigated considering the MX particles and the Z-phase. It was found that the optimal V and Nb contents for excellent high Cr steel of FBR grade are 0.2 mass% and $$<$$0.01 mass%, respectively, under FBR operating conditions.

Journal Articles

Corrosion-erosion test of SS316L grain boundary engineering materials (GBEM) in lead bismuth flowing loop

Saito, Shigeru; Kikuchi, Kenji*; Hamaguchi, Dai; Tezuka, Masao*; Miyagi, Masanori*; Kokawa, Hiroyuki*; Watanabe, Seiichi*

Journal of Nuclear Materials, 431(1-3), p.91 - 96, 2012/12

 Times Cited Count:13 Percentile:71.39(Materials Science, Multidisciplinary)

To evaluate lifetime of structural materials for ADS, corrosion tests in LBE have been done at JAEA. The corrosion test was performed by using JAEA lead-bismuth flowing loop (JLBL-1). Experimental condition was as follows; The temperature of high and low temperature parts of the loop were 450$$^{circ}$$C and 350$$^{circ}$$C, respectively. Flowing velocity at the test specimens was about 1m/s. Plate type SS316L-BM and SS316L-GBEM were used as a specimens. After the 3,000 hours operation, the test specimens were cut and macroscopic observation was carried out. The result showed that both materials were intensively eroded. Corrosion depth and LBE penetration through grain boundaries of GBEM were smaller than these of 316SS-BM.

Journal Articles

Tensile mechanical properties of a stainless steel irradiated up to 19 dpa in the Swiss spallation neutron source

Saito, Shigeru; Kikuchi, Kenji*; Hamaguchi, Dai; Usami, Koji; Endo, Shinya; Ono, Katsuto; Matsui, Hiroki; Kawai, Masayoshi*; Dai, Y.*

Journal of Nuclear Materials, 431(1-3), p.44 - 51, 2012/12

 Times Cited Count:2 Percentile:17.83(Materials Science, Multidisciplinary)

To evaluate the lifetime of the beam window of an accelerator-driven transmutation system (ADS), post irradiation examination (PIE) of the STIP (SINQ target irradiation program, SINQ; Swiss spallation neutron source) specimens was carried out. The specimens tested in this study were made from the austenitic steel JPCA (Japan primary candidate alloy). The specimens were irradiated at SINQ Target 4 (STIP-II) with high-energy protons and spallation neutrons. The irradiation conditions were as follows: the proton energy was 580 MeV, irradiation temperatures ranged from 100 to 430$$^{circ}$$C, and displacement damage levels ranged from 7.1 to 19.5 dpa. Tensile tests were performed in air at room temperature (R.T.), 250$$^{circ}$$C and 350$$^{circ}$$C. Fracture surface observation after the tests was done by SEM (Scanning electron microscope). Results of the tensile tests performed at R.T. showed the extra hardening of JPCA at higher dose compared to the fission neutron irradiated data. At the higher temperatures, 250$$^{circ}$$C and 350$$^{circ}$$C, the extra hardening was not observed. Degradation of ductility bottomed around 10 dpa, and specimens kept their ductility until 19.5 dpa. All specimens fractured in ductile manner. The result from a microstructure observation on a specimen irradiated to 19.3 dpa at 420$$^{circ}$$C indicates that some agglomeration of bubbles on grain boundaries was observed in the specimen irradiated to 19.3 dpa at 420$$^{circ}$$C. However the tensile specimen irradiated up to 18.4 dpa at 425$$^{circ}$$C still exhibited little loss of ductility. Since He/dpa was very high on SINQ target irradiations, the formation of highly dense small bubbles in the matrix consequently avoided the accumulation of He on grain boundaries, which might have resulted in avoiding grain boundary embrittlement.

Journal Articles

HCM12A oxide layer investigation using scanning probe microscope

Kikuchi, Kenji*; Rivai, A. K.*; Saito, Shigeru; Bolind, A. M.*; Kogure, Akinori*

Journal of Nuclear Materials, 431(1-3), p.120 - 124, 2012/12

 Times Cited Count:6 Percentile:43.65(Materials Science, Multidisciplinary)

The oxide layer on the 12Cr steel, HCM12A, is investigated using a scanning probe microscope (SPM), which was formed in lead bismuth eutectic (LBE) at 450$$sim$$500$$^{circ}$$C, during 5500 hrs. Hitherto oxide formation mechanisms were studied from viewpoints of the location of original base metal surface, the pass for oxygen travel and Fe diffusion to understand the stability of oxide layer. The new findings in this research are that surface potential measurement detected the boundary between (FeCr)$$_{3}$$O$$_{4}$$ and Fe$$_{3}$$O$$_{4}$$, which is not found at the topographic mode measurement. The spinel layer can be distinguished from the bulk area with lower surface potential profile, but near the boundary between the spinel and magnetite layers the surface potential profile seems to be continuous except for the narrow path corresponding to the boundary line. The band structure penetrating magnetite and spinel layer was found, which was not found at the topography.

Journal Articles

Effect of cold working on the corrosion resistance of JPCA stainless steel in flowing PB-Bi at 450$$^{circ}$$C

Rivai, A. K.*; Saito, Shigeru; Tezuka, Masao*; Kato, Chiaki; Kikuchi, Kenji*

Journal of Nuclear Materials, 431(1-3), p.97 - 104, 2012/12

 Times Cited Count:10 Percentile:60.5(Materials Science, Multidisciplinary)

In the present study, we applied 20% cold work (CW) treatment to JPCA austenitic stainless steel and investigated it from the corrosion behavior viewpoint. The corrosion test of 20% CW JPCA has been carried in the JLBL-1 (JAEA Lead-Bismuth Loop-1) apparatus. The maximum temperature and the exposure time of LBE were 450$$^{circ}$$C and 1000 h, respectively. The results showed a different corrosion behavior between the JPCA without and with CW. As for the JPCA without CW, LBE penetrated into the matrix through a ferrite layer which was formed because of constituent metals dissolution from the matrix into LBE. As for the 20% CW JPCA, dissolution attack occurred only partially and formed localized superficial pitting corrosion. It was found that the different corrosion behavior occurred because the CW induced a structure transformation from $$gamma$$-austenite to $$alpha$$'-martensite and affected the corrosion resistance of the JPCA in flowing LBE at 450$$^{circ}$$C.

Journal Articles

Evaluation of tritium trap effect produced by high energy proton irradiation in SS316

Nakamura, Hirofumi; Kobayashi, Kazuhiro; Yokoyama, Sumi*; Saito, Shigeru; Yamanishi, Toshihiko; Kikuchi, Kenji*

Journal of Plasma and Fusion Research SERIES, Vol.9, p.326 - 331, 2010/08

Based on results of tritium measurement in the SS316 specimens irradiated up to 5.9 dpa in the SINQ target (580 MeV proton) using a thermal desorption (TDS) method, trap site density and trap energy in the materials induced by the high-energy proton irradiation have been evaluated by means of the numerical tritium transport analysis. The results indicate that almost residual tritium in the SS316 specimen exists in the trap site, whose trap density is maximum 238 appm (5.9 dpa) and trap energy is $$>$$ 1.4 eV, and that tritium release by the TDS is mainly attributed to the disappearance of the trap sites by the specimen heating, whose activation energy is about 0.7 eV. The trap site density seems to be almost proportional to the irradiation dose (dpa). Additionally, irradiation conditions such as the dose or irradiation temperature do not affect on the trapping mechanism.

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

Investigation of beam window buckling with consideration of irradiation effects for conceptual ADS design

Sugawara, Takanori; Kikuchi, Kenji; Nishihara, Kenji; Oigawa, Hiroyuki

Journal of Nuclear Materials, 398(1-3), p.246 - 250, 2010/03

 Times Cited Count:3 Percentile:24.16(Materials Science, Multidisciplinary)

The investigation of the beam window which is a key component in the conceptual design of Accelerator Driven System (ADS) has been performed. In the past study, it was found that the buckling failure was the most severe failure mode for the beam window from the simplified assessment. Detail structural analyses were explored to find a solution for avoiding instantaneous buckling. The results showed 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. These investigations, however, did not consider the irradiation effect by neutrons and protons. In this study, investigations based on the latest knowledge for the irradiation effect such as the data obtained in SINQ target irradiation program (STIP) are presented.

Journal Articles

Proton irradiation effects on tensile and bend-fatigue properties of welded F82H specimens

Saito, Shigeru; Kikuchi, Kenji*; Hamaguchi, Dai; Usami, Koji; Ishikawa, Akiyoshi; Nishino, Yasuharu; Endo, Shinya; Kawai, Masayoshi*; Dai, Y.*

Journal of Nuclear Materials, 398(1-3), p.49 - 58, 2010/03

 Times Cited Count:6 Percentile:40.42(Materials Science, Multidisciplinary)

In several institutes, R&D for an ADS have been progressed. Ferritic / martensitic (F/M) steels are the candidate material for the beam window. To obtain the irradiation data, the PIE work of the SINQ target irradiation program (STIP) specimens was carried out at JAEA. In this study, the results of PIE on F/M steel F82H and its welded joint will be reported. The results of tensile tests indicate that the irradiation hardening occurred with increasing dpa up to 10.1 dpa below 320$$^{circ}$$C irradiation. At higher dose (- 11.8 dpa) and higher temperature (- 380$$^{circ}$$C), irradiation hardening and degradation of ductility relaxed. In this study, all specimens kept its ductility after irradiation and fractured in ductile manner. The fatigue life of F82H base metal is almost the same as that of unirradiated specimens. Though the number of specimen is limited, the fatigue life of F82H EB welded joints seems to increase after irradiation. The fracture surfaces of the specimens showed transgranular morphology. While F82H TIG welded specimens were not fractured by 10$$^{7}$$ cycles.

Journal Articles

Mechanical properties of austenitic stainless steels irradiated at SINQ target 4

Saito, Shigeru; Hamaguchi, Dai; Usami, Koji; Endo, Shinya; Ono, Katsuto; Matsui, Hiroki; Kikuchi, Kenji*; Kawai, Masayoshi*; Yong, D.*

Proceedings of 1st International Workshop on Technology and Components of Accelerator-driven Systems (TCADS-1) (Internet), 9 Pages, 2010/03

The research and development for an accelerator-driven system (ADS) to transmute minor actinide (MA) have been progressed. The target beam window of ADS submerged in the reactor will be subjected to high-energy proton and spallation neutron irradiation. To evaluate mechanical properties of irradiated materials, post irradiation examination (PIE) of the STIP (SINQ target irradiation program) specimens was carried out at JAEA. In the present study, PIE on austenitic steels JPCA and Alloy800H irradiated at SINQ target 4 (STIP-II) was conducted. Austenitic steels are preferable as the material for the target beam window of ADS from the view point of DBTT shift, which should be taken into consideration for ferritic / martensitic steels. The irradiation conditions were as follows: proton energy was 580 MeV, irradiation temperatures were ranged from 100 to 450$$^{circ}$$C, and displacement damage levels were ranged from 6.5 to 19.5 dpa. Tensile tests were performed in air at R.T. to 350$$^{circ}$$C. Results of the tensile tests performed at R.T. indicate that irradiation hardening occurred with increasing displacement damage level up to 10 dpa. At higher doses, irradiation hardening seemed to tend to saturate. Degradation of ductility was bottomed around 10 dpa and specimens kept its ductility until 19.5 dpa. All the specimens fractured in ductile manner.

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

Material development in lead-bismuth spallation target system

Kikuchi, Kenji; Saito, Shigeru; Hamaguchi, Dai; Tezuka, Masao; Obayashi, Hironari

Proceedings of 10th OECD/NEA Information Exchange Meeting on Actinide and Fission Product Partitioning and Transmutation (CD-ROM), p.315 - 320, 2010/00

R&Ds to know materials performance and its limit for usage applying to the beam window of ADS are conducted by irradiation material test and lead bismuth flowing loop tests. Proton irradiation experiment showed ductility reduction and off-set stress increase in austenitic steels. Fracture mode change in ferritic-martensitic steels, 8-9 Cr steels. Fatigue test is under way in the hot cell. Microstructure analyses found that many bubbles exist in the materials. The relation between mechanical strength and nano-scale observation results is studied now. Corrosion of the materials under the lead bismuth flows showed local erosion-corrosion. A visualization technique has developed by using ultrasonic Doppler method and surface vitalizing techniques to inspect a local flow condition. Thermal fluid experiment was conducted to know heat transfer performance at the beam window, which will affect thermal loading magnitude. Experimental formula was established for design work.

Journal Articles

Research and development programme on ADS in JAEA

Takei, Hayanori; Ouchi, Nobuo; Sasa, Toshinobu; Hamaguchi, Dai; Kikuchi, Kenji*; Kurata, Yuji; Nishihara, Kenji; Obayashi, Hironari; Saito, Shigeru; Sugawara, Takanori; et al.

Proceedings of International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators (CD-ROM), 11 Pages, 2009/05

JAEA has been promoting 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, tank-type subcritical reactor with a thermal power of 800 MW driven by a superconducting linac. The R&D activities can be divided into two categories: one is the design study and technical development for a future large-scale ADS, and the other is the experimental programme at the Transmutation Experimental Facility (TEF) under the J-PARC (Japan Proton Accelerator Research Complex) project. As for the design study of the future ADS, the reliability of the accelerator is being investigated based on the data analysis of existing linac facilities. As for the technical development of the superconducting linac, fabrication and tests of prototype cryomodule were carried out, and its good performance was demonstrated. As for the TEF development, design study including experimental device to handle minor actinide fuels is being conducted.

Journal Articles

Study on swelling for Austenitic steel irradiated by 580 MeV proton

Kikuchi, Kenji; Hamaguchi, Dai; Saito, Shigeru

Materia, 47(12), P. 635, 2008/12

TEM observation on austenitic stainless steel irradiated by proton beam was reported. Two cases were studied; those are 10 dpa, 623 K and 800 appm, and 20 dpa. 693 K and 1800 appm in irradiation damage, irradiated temperature and Helium gas production, respectively. The results showed that bubbles are formed homogeneously in the matrix and the bubble size is averagely 2.5 nm. Swelling volume is calculated to be less than 0.1% by the bubbles size and the bubble density.

Journal Articles

Experimental study for thermal striping in LBE loop by using UVP with high-temperature ultrasonic transducer

Obayashi, Hironari; Kikuchi, Kenji

Proceedings of 6th International Symposium on Ultrasonic Doppler Methods for Fluid Mechanics and Fluid Engineering (ISUD-6), p.135 - 138, 2008/09

Japan Atomic Energy Agency (JAEA) has been proceeding with the research and development on accelerator-driven system (ADS) for the transmutation of long-lived radioactive nuclides. The ADS proposed by JAEA utilize the Lead-Bismuth Eutectic (LBE) as a spallation target and core coolant. To examine the feasibility and applicability of the LBE to accelerator-driven transmutation systems, JAEA has an experimental lead-bismuth loop for investigate the problems caused by LBE flow. As a result of the experimental surveys, LBE flow is connected closely with a lot of serious problems in development of ADS. Therefore, the development of the high-temperature transducer that can be used at the high temperature condition (over 150 degrees Celsius) is a pressing need because it establishes the velocity measurement techniques for LBE flow. We adopted the wave guide method. And we conducted a survey of the suitable guide material for LBE flow by using the wave equation. As a result, it is forecast that Al and Si are excellent materials in the present situation.

Journal Articles

Corrosion rate of parent and weld materials of F82H and JPCA steels under LBE flow with active oxygen control at 450 and 500 $$^{circ}$$C

Kikuchi, Kenji; Kamata, Kinya*; Ono, Mikinori*; Kitano, Teruaki*; Hayashi, Kenichi*; Oigawa, Hiroyuki

Journal of Nuclear Materials, 377(1), p.232 - 242, 2008/06

 Times Cited Count:17 Percentile:72.99(Materials Science, Multidisciplinary)

Corrosion behavior of F82H and JPCA was studied in the circulating LBE loop. Those are candidate materials of Japanese ADS beam windows. Maximum temperatures were kept to 450 and 500 $$^{circ}$$C with 100 $$^{circ}$$C constant temperature difference. Main flow velocity was 0.4 to 0.6 m/s in every case. Oxygen concentration was controlled to 2$$sim$$4$$times$$10$$^{-5}$$ mass% although there was an exception. Testing time durations were 500 to 3000 hrs. Round bar type specimens were put in the circular tube of the loop. Electron beam welded joint in the middle part of specimens were also studied. Optical micrograph, electron micrograph, X-ray element analyses and X-ray diffraction were investigated. Consequently for a long-term behavior a linear law is recommended to predict corrosion in the ADS beam design.

Journal Articles

Irradiation damage to the beam window in the 800 MWth accelerator-driven system

Nishihara, Kenji; Kikuchi, Kenji

Journal of Nuclear Materials, 377(1), p.298 - 306, 2008/06

 Times Cited Count:8 Percentile:49.21(Materials Science, Multidisciplinary)

Irradiation damage to the beam window in the concept of 800 MWth accelerator-driven system is evaluated. Heat produced in the window is also evaluated. Transport of proton and neutron up to 3.0 GeV is calculated by both PHITS that is the Monte Carlo code for particles and heavy ions and TWODANT that is 2-dimentional deterministic transport code. The beam window is irradiated at the center of the accelerator-driven system with 20 MW proton beam power and neutron from the core during 300 full power days. Heat, displacement per atom, production rate of hydrogen and helium isotopes, and neutron and proton fields are estimated, assuming the Gaussian and flat beam profiles.

194 (Records 1-20 displayed on this page)