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Journal Articles

Void denuded zone formation for Fe-15Cr-15Ni steel and PNC316 stainless steel under neutron and electron irradiations

Sekio, Yoshihiro; Yamashita, Shinichiro; Sakaguchi, Norihito*; Takahashi, Heishichiro*

Journal of Nuclear Materials, 458, p.355 - 360, 2015/03

 Times Cited Count:13 Percentile:81.43(Materials Science, Multidisciplinary)

Irradiation-induced void denuded zone (VDZ) formation near grain boundaries was studied to clarify the effects of minor alloying elements on vacancy diffusivity during irradiation in PNC316 steel. The test materials were Fe-15Cr-15Ni steel without additives and PNC316 stainless steel, which contains minor alloying elements. These steels were neutron-irradiated in the experimental fast reactor JOYO and electron-irradiation was also carried out using 1 MeV high voltage electron microscopy. VDZ formation was analyzed from the TEM microstructural observations after irradiation. VDZs were formed near random grain boundaries in both Fe-15Cr-15Ni and PNC316 steels. The VDZ widths in the PNC316 steel were narrower than those for the Fe-15Cr-15Ni steel for all neutron and electron irradiations. The VDZ width analysis implied that the vacancy diffusivity was reduced in PNC316 steel as a result of interaction of vacancies with minor alloying elements.

Journal Articles

Effect of additional minor elements on accumulation behavior of point defects under electron irradiation in austenitic stainless steels

Sekio, Yoshihiro; Yamashita, Shinichiro; Sakaguchi, Norihito*; Takahashi, Heishichiro

Materials Transactions, 55(3), p.438 - 442, 2014/03

 Times Cited Count:8 Percentile:46.14(Materials Science, Multidisciplinary)

In order to perform the comparative evaluations for vacancy diffusivity and flux between a base alloy and modified alloys, the void denuded zones (VDZ) widths were measured from the TEM in-situ observation during electron irradiation in the SUS316L, SUS316L-V and SUS316L-Zr steels. As a result, VDZs with given widths were formed near GBs. Then, the VDZ widths were different depending on steels, and the width was narrower due to addition of minor alloying elements which strongly interact with vacancies. Furthermore, from the analyses of measured VDZ widths in the SUS316L and SUS316L-V steels, the changes of vacancy diffusivity, vacancy flux and excess vacancy concentration were estimated as 0.50, 0.71 and 1.41, respectively. The decreases of vacancy diffusivity and flux during electron irradiation would be due to the interaction of vacancies with added minor elements, while the enhancement of the excess vacancy concentration would be caused by trapping effects due to alloying elements.

Journal Articles

Mechanical properties and microstructural stability of 11Cr-ferritic/martensitic steel cladding under irradiation

Yano, Yasuhide; Yamashita, Shinichiro; Otsuka, Satoshi; Kaito, Takeji; Akasaka, Naoaki; Shibayama, Tamaki*; Watanabe, Seiichi*; Takahashi, Heishichiro

Journal of Nuclear Materials, 398(1-3), p.59 - 63, 2010/03

 Times Cited Count:9 Percentile:56.9(Materials Science, Multidisciplinary)

The in-reactor creep rupture tests of 11Cr-0.5Mo-2W, V, Nb F/M steel were carried out in the temperature range from 823 to 943 K using Materials Open Test Assembly in the Fast Flux Test Facility and tensile and temperature-transient-to-burst specimens were irradiated in the experimental fast reactor JOYO at temperatures between 693 to 1013 K to fast neutron doses ranging from 3.5 to 102 dpa. The results of post irradiation mechanical tests showed that there was no significant degradation in tensile and transient burst strengths even after neutron irradiation below 873 K, but that there was significant degradation in both strengths at neutron irradiation above 903 K. On the other hand, the in-reactor creep rupture times were equal or greater than those of out-reactor creep even after neutron irradiation at all temperatures. This creep rupture behavior was different from that of tensile and transient burst specimens.

Journal Articles

Effects of microstructural evolution on mechanical properties of 11Cr ferritic/martensitic steel after neutron irradiation

Yano, Yasuhide; Yamashita, Shinichiro; Yoshitake, Tsunemitsu; Akasaka, Naoaki; Takahashi, Heishichiro

Materia, 47(12), P. 625, 2008/12

no abstracts in English

Journal Articles

Effects of fast reactor irradiation conditions on tensile and transient burst properties of ferritic/martensitic steel claddings

Yano, Yasuhide; Yoshitake, Tsunemitsu; Yamashita, Shinichiro; Akasaka, Naoaki; Onose, Shoji; Watanabe, Seiichi*; Takahashi, Heishichiro

Journal of Nuclear Science and Technology, 44(12), p.1535 - 1542, 2007/12

 Times Cited Count:11 Percentile:63.76(Nuclear Science & Technology)

The effects of fast neutron irradiation have been investigated on the mechanical properties of 11Cr-0.5Mo-2W, Nb, V ferritic/martensitic (F/M) stainless steel (PNC-FMS) and 10.5Cr-1.5Mo, Nb, V F/M stainless steel (HT9M) claddings, especially tensile and transient burst properties. These two F/M claddings were irradiated in the experimental fast reactor JOYO using the PFB090 fuel test assembly. Post irradiation tensile and temperature-transient-to-burst tests were carried out for defueled cladding specimens. The results of mechanical tests for PNC-FMS cladding showed that there was no significant degradation in tensile and transient burst strengths even after fast neutron irradiation. However, these strengths for HT9M cladding tended to shift to lower values than those of as-received specimens. This different behavior of tensile and transient burst strengths was attributed to martensite structural stability which was related to the stable solid solution elements.

Journal Articles

Mechanical properties and microstructural stability of advanced ferritic/martensitic steel under irradiation

Yano, Yasuhide; Yamashita, Shinichiro; Akasaka, Naoaki; Watanabe, Seiichi*; Takahashi, Heishichiro

Proceedings of 9th China-Japan Symposium on Materials for Advanced Energy Systems and Fission & Fusion Engineering jointed with CAS-JSPS Core-university Program Seminar on Fusion Materials, System and Design Integration, p.2 - 5, 2007/10

Ferritic/martensitic (F/M) steels are expected to be prospective not only for the long life core material of fast reactors but also for the blanket materials of fusion reactor because of their superior swelling resistance. Japan Atomic Energy Agency has developed a 11Cr-0.5Mo-2W-V, Nb F/M steel (PNC-FMS) for core materials of next fast reactor. In order to evaluate the effect of structural change due to irradiation on mechanical properties of PNC-FMS, neutron irradiations were carried out between 773 and 1013 K to doses of from 11 to 102 dpa in JOYO reactor. Post irradiation tensile tests were performed at 773-1013 K with a strain rate of 0.5$$times$$10$$^{-4}$$/s. The stability of microstructures under irradiation was also compared with those of electron irradiation using HVEM.

Journal Articles

Tensile and transient burst properties of advanced ferritic/martensitic steel claddings after neutron irradiation

Yano, Yasuhide; Yoshitake, Tsunemitsu; Yamashita, Shinichiro; Akasaka, Naoaki; Onose, Shoji; Takahashi, Heishichiro*

Journal of Nuclear Materials, 367-370(1), p.127 - 131, 2007/08

 Times Cited Count:10 Percentile:60.87(Materials Science, Multidisciplinary)

The effects of fast neutron irradiation on tensile and transient burst properties of advanced ferritic/martensitic steel claddings were investigated. Specimens were irradiated in the experimental fast reactor JOYO using the material irradiation rig at temperatures between 773 and 1013 K to fast neutron doses ranging from 11 to 102 dpa. The post-irradiation tensile and temperature-transient-to-burst tests were carried out. The results of mechanical tests showed that there was no significant degradation in tensile and transient burst strengths after neutron irradiation below 873 K. This was attributed to grain boundary strengthening caused by precipitates that preferentially formed on prior-austenite grain boundaries. Both strengths at neutron irradiation above about 903 K up to 102 dpa decreased due to recovery of lath martensite structures and recrystallization.

Journal Articles

Present status of beryllide R&D as neutron multiplier

Kawamura, Hiroshi; Takahashi, Heishichiro*; Yoshida, Naoaki*; Mishima, Yoshinao*; Ishida, Kiyohito*; Iwadachi, Takaharu*; Cardella, A.*; Van der Laan, J. G.*; Uchida, Munenori*; Munakata, Kenzo*; et al.

Journal of Nuclear Materials, 329-333(1), p.112 - 118, 2004/08

 Times Cited Count:29 Percentile:86.95(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Effects of He/Electron irradiation on microstructure evolution in Be$$_{12}$$Ti

Shibayama, Tamaki*; Nakamichi, Masaru*; Uchida, Munenori*; Kawamura, Hiroshi; Kinoshita, Hiroshi*; Kiyanagi, Yoshiaki*; Takahashi, Heishichiro*; Nomura, Naoyuki*

JAERI-Conf 2004-006, p.216 - 219, 2004/03

no abstracts in English

Journal Articles

Development of advanced blanket materials for a solid breeder blanket of a fusion reactor

Kawamura, Hiroshi; Ishitsuka, Etsuo; Tsuchiya, Kunihiko; Nakamichi, Masaru; Uchida, Munenori*; Yamada, Hirokazu*; Nakamura, Kazuyuki; Ito, Haruhiko; Nakazawa, Tetsuya; Takahashi, Heishichiro*; et al.

Nuclear Fusion, 43(8), p.675 - 680, 2003/08

 Times Cited Count:26 Percentile:63.92(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Detection of Radiation-Enhanced Diffusion by Means of Neutron Irradiated Diffusion Couples of Fe-Cr-Ni System

Akasaka, Naoaki; Tanaka, Kosuke; Onuki, Somei*; Takahashi, Heishichiro*; Watanabe, Seiichi*

Effects of Radiation on Materials (ASTM STP 1447), 516- Pages, 2003/00

Radiation-enhanced diffusion is one of the most important parameters for the understanding and modeling the effect of radiation on materials. In this study, the average effective interdiffusion coefficients of Ni and Cr in pure iron, an Fe-15Cr-15ni model

Journal Articles

Application of beryllium intermetallic compounds to neutron multiplier of fusion blanket

Kawamura, Hiroshi; Takahashi, Heishichiro*; Yoshida, Naoaki*; Shestakov, V.*; Ito, Yoshio*; Uchida, Munenori*; Yamada, Hirokazu*; Nakamichi, Masaru; Ishitsuka, Etsuo

Fusion Engineering and Design, 61-62, p.391 - 397, 2002/11

 Times Cited Count:28 Percentile:84.91(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Evaluation of properties of low activation Mn-Cr steel, 3; Evaluation of corrosion resistnace

Saito, Shigeru; Fukaya, Kiyoshi*; Ishiyama, Shintaro; Sato, Ikuo*; Kusuhashi, Mikio*; Hatakeyama, Tsuyoshi*; Takahashi, Heishichiro*; Kikuchi, Mitsuru

JAERI-Tech 2002-047, 51 Pages, 2002/05

JAERI-Tech-2002-047.pdf:3.42MB

no abstracts in English

Journal Articles

Characterization of non-magnetic Mn-Cr steel as a low induced activation material for vacuum vessels

Saito, Shigeru; Fukaya, Kiyoshi; Ishiyama, Shintaro; Eto, Motokuni; Sato, Ikuo*; Kusuhashi, Mikio*; Hatakeyama, Tsuyoshi*; Takahashi, Heishichiro*; Kikuchi, Mitsuru

Journal of Nuclear Materials, 283-287(Part1), p.593 - 596, 2000/12

 Times Cited Count:1 Percentile:12.53(Materials Science, Multidisciplinary)

no abstracts in English

JAEA Reports

Evaluation of properties of low activation Mn-Cr steel, 2; Physical properties an aging properties

Saito, Shigeru; Fukaya, Kiyoshi; Ishiyama, Shintaro; Sato, Ikuo*; Kusuhashi, Mikio*; Hatakeyama, Tsuyoshi*; Takahashi, Heishichiro*; Kikuchi, Mitsuru

JAERI-Tech 2000-047, 64 Pages, 2000/08

JAERI-Tech-2000-047.pdf:6.05MB

no abstracts in English

Journal Articles

R&D of low activated Fe-Mn-Cr high strength non-magnetic steel, 1; Screening test for constituent optimization and fundamental characterization test

Ishiyama, Shintaro; Fukaya, Kiyoshi; Eto, Motokuni; Kikuchi, Mitsuru; Sato, Ikuo*; Kusuhashi, Mikio*; Hatakeyama, Tsuyoshi*; Takahashi, Heishichiro*

Nihon Genshiryoku Gakkai-Shi, 42(2), p.116 - 123, 2000/02

 Times Cited Count:1 Percentile:12.53(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Evaluation of properties of low activation Mn-Cr steel, 1; Mechanical properties and weldability

Saito, Shigeru; Fukaya, Kiyoshi; Ishiyama, Shintaro; Eto, Motokuni; Sato, Ikuo*; Kusuhashi, Mikio*; Hatakeyama, Tsuyoshi*; Takahashi, Heishichiro*; Kikuchi, Mitsuru

JAERI-Tech 99-076, p.53 - 0, 1999/10

JAERI-Tech-99-076.pdf:8.86MB

no abstracts in English

Journal Articles

Void formation and microstructural development in oxide dispersion strengthened ferritic steels during electron-irradiation

Saito, J.*; Suda, Takanori*; Yamashita, Shinichiro*; Onuki, Somei*; Takahashi, Heishichiro*; Akasaka, Naoaki; Nishida, M.; Ukai, Shigeharu

Journal of Nuclear Materials, 258-263(Part.2), p.1264 - 1268, 1998/10

 Times Cited Count:37 Percentile:92.69(Materials Science, Multidisciplinary)

None

Oral presentation

Irradiation effect on microstructure of modified SUS316 stainless steel cladding irradiated at elevated temperature to high dose

Yamashita, Shinichiro; Akasaka, Naoaki; Nishinoiri, Kenji; Takahashi, Heishichiro

no journal, , 

A modified SUS316 stainless steel (PNC316) for high burn-up fast reactor core application has been successfully developed. The material has a typical composition of 16Cr-14Ni-2.5Mo-0.25P-0.004B-0.1Ti-0.1Nb and is used in the 20% cold-worked condition. To demonstrate irradiation performance of PNC316 cladding irradiation experiments has been successively carried out at the temperature ranging from 775 K to 905 K up to a maximum dose of 125 dpa. In this study, the microstructures of the irradiated specimens were carefully examined. Low-magnification image including some of needle-like precipitates indicates many helium bubbles attaching at the precipitate interface. On the other hand, a representative high-resolution image of the needle-like precipitate with the sizes of a few tens of nanometers long and a few nanometers wide shows a distinct interface structure between FCC matrix and the precipitate. As the results of diffraction pattern and image analyses this characteristic precipitate was identified as Fe$$_{2}$$P phase. Based on the numerous results of TEM examination, it is found that a significant improvement in the swelling resistance of PNC316 was mainly derived from the formation of a stable phosphide that traps helium bubbles and retards the conversion of bubbles to voids.

Oral presentation

Effect of fine precipitate on swelling behavior of heavily-irradiated PNC316 stainless steel

Yamashita, Shinichiro; Sekine, Manabu*; Tachi, Yoshiaki; Akasaka, Naoaki; Nishinoiri, Kenji; Takahashi, Heishichiro

no journal, , 

no abstracts in English

25 (Records 1-20 displayed on this page)