Evaluation of deformation behavior of In grains and grain boundaries of L-grade austenitic stainless steel 316L

Nagashima, Nobuo*; Hayakawa, Masao*; Tsukada, Takashi; Kaji, Yoshiyuki; Miwa, Yukio*; Ando, Masami*; Nakata, Kiyotomo*

Atsuryoku Gijutsu, 47(4), p.236 - 244, 2009/07

http://joi.jlc.jst.go.jp/JST.JSTAGE/hpi/47.236

In this study, micro-hardness tests and AFM observations were performed on SUS316L low-carbon austenitic stainless steel pre-strained by cold rolling to investigate its deformation behavior. The following results were obtained. Despite the fact that the same plastic strain was applied, post-tensile test AFM showed narrower slip-band spacing in a reduction in area of 30% cold-rolled specimen than the unrolled specimen. Concentrated slip bands were observed near grain boundaries. Micro-hardness exceeding 300 was found to occur frequently in after tensile test specimens with a reduction in area of 30% or more, particularly at grain boundaries. It is suggested that the nonuniformity of deformation at grain boundaries plays an important role of IGSCC crack propagation mechanism of low-carbon austenitic stainless steel.

Parameter dependence on the lower hybrid driven current in tokamaks

Uehara, Kazuya; Nagashima, Takashi*

JAEA-Research 2008-051, 20 Pages, 2008/03

JAEA-Research-2008-051.pdf:6.3MB
JAEA-Research-2008-051(errata).pdf:0.14MB

An optimum efficiency and the current profile on the lower-hybrid driven current in tokamaks are estimated in half-experimental by the modified quasi-linear theory including the mode conversion effect, the accessibility condition and the non-linear effect of the parametric instability so as to predict the experimentally obtained flowing current. The spectrum gap is bridged by the gap parameter depending on the electron temperature and the rf power density. It is shown that for the JT-60 parameter an optimum N parallel of the rf wave must be less smaller for the higher electron temperature not to destroy the accessibility condition and the driving efficiency depends on the electron temperature. The survey is also performed for the LHCD of the ITER parameter.

Deformation behavior around grain boundaries for SCC propagation in hardened low-carbon austenitic stainless steel by micro hardness test

Nagashima, Nobuo*; Hayakawa, Masao*; Tsukada, Takashi; Kaji, Yoshiyuki; Miwa, Yukio; Ando, Masami*; Nakata, Kiyotomo*

Proceedings of 13th International Conference on Environmental Degradation of Materials in Nuclear Power Systems (CD-ROM), 15 Pages, 2007/00

Stress corrosion cracking (SCC) was found in shroud and PLR piping made of low-carbon austenitic stainless steels in Japanese BWR plants. The intergranular type (IG) SCC propagated in hardened heat affected zones (HAZ) around welds. Strength behavior and local plastic deformation for a low-carbon austenitic stainless steel 316L, cold-rolled at the reductions in area of 10, 30% at room temperature to simulate the hardened HAZ, were measured by a micro-hardness test machine and observed by atomic force microscopy (AFM), respectively. The tensile deformation at yield point (0.2% plastic strain) had given to the work-hardened 316L to simulate the plastic zone at the crack tip. It is suggested that one of the IGSCC propagation mechanisms for 316L was related with the intergranular strength behavior and local plastic deformation around grain boundaries.

Current profiles and major disruptions in a lower-hybrid current drive tokamak

Uehara, Kazuya; Nagashima, Takashi*

JAEA-Research 2006-002, 15 Pages, 2006/02

JAEA-Research-2006-002.pdf:0.69MB

The radial rf current profile of the lower-hybrid current drive tokamak is estimated using an rf power damping model for various Gaussian type nz spectrum, and the stability of the major disruption is examined using the criterion of the tearing mode instability. The value of nzc determines the spatial damping of the rf power and in resultant the rf current profile. The value of hz determine the extent of the damping of the rf power and in resultant the absolute value of the rf current. The peaking and flattening rf current profile to be free from the disruption are obtained when the rf power does not damp at the boundary region and when the extent of damping is relatively small even if the rf power begins to damp at relatively boundary region, whose rf spectrum must be having relatively large phase velocity and must be not so broad.

Post irradiation examination of (U,Pu)C and (U,Pu)N fuels for fast reactors; Destructive examination result of the fuel pins (Joint research)

Iwai, Takashi; Nakajima, Kunihisa; Kikuchi, Hironobu; Nagashima, Hisao; Kimura, Yasuhiko; Matsui, Hiroki; Arai, Yasuo

JAERI-Research 2002-038, 69 Pages, 2003/01

JAERI-Research-2002-038.pdf:12.46MB

Uranium-plutonium mixed carbide and nitiride fuel pins were fabricated in JAERI and irradiated at fast test rector JOYO based on the JAERI-JNC joint research program. The results of non-destructive and destructive post irradiation examinations cariied out at JNC were reported elsewhere. This report summarizes the results of destructive post irradiation examinations of (U,Pu)C and (U,Pu)N fuel pins carried out at JAERI.

Diagnostics system of JT-60U

Sugie, Tatsuo; Hatae, Takaki; Koide, Yoshihiko; Fujita, Takaaki; Kusama, Yoshinori; Nishitani, Takeo; Isayama, Akihiko; Sato, Masayasu; Shinohara, Koji; Asakura, Nobuyuki; et al.

Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.482 - 511, 2002/09

https://doi.org/10.13182/FST02-A242

The diagnostic system of JT-60U (JT-60upgrade) is composed of about 50 individual diagnostic devices. Recently, the detailed radial profile measurements of plasma parameters have been improved, so that the internal structure of plasmas has been explored. The understanding of plasma confinement has been enhanced by density and temperature fluctuation measurements using a mm-wave reflectometer and electron cyclotron emission measurements respectively. In addition, the real-time control experiments of electron density, neutron yield, radiated power and electron temperature gradient have been carried out successfully by corresponding diagnostic devices. These measurements and the real time control contribute to improving plasma performance. Diagnostic devices for next generation fusion devices such as a CO2 laser interferometer/polarimeter and a CO2 laser collective Thomson scattering system have been developed.

Post-irradiation examinations of uranium-plutonium mixed nitride fuel irradiated in JMTR; 89F-3A capsule

Iwai, Takashi; Nakajima, Kunihisa; Kikuchi, Hironobu; Kimura, Yasuhiko; Nagashima, Hisao; Sekita, Noriaki; Arai, Yasuo

JAERI-Research 2000-010, p.110 - 0, 2000/03

JAERI-Research-2000-010.pdf:20.61MB

no abstracts in English

Development of a tritium fuel processing systems using an electrolytic reactor for ITER

Yamanishi, Toshihiko; Kawamura, Yoshinori; Iwai, Yasunori; Arita, Tadaaki*; Maruyama, T.*; Kakuta, Toshiya*; Konishi, Satoshi; Enoeda, Mikio; Ohira, Shigeru; Hayashi, Takumi; et al.

Nuclear Fusion, 40(3Y), p.515 - 518, 2000/03

https://doi.org/10.1088/0029-5515/40/3Y/311

no abstracts in English

YAG laser Thomson scattering diagnostics on the JT-60U

Hatae, Takaki; Nagashima, Akira; Kitamura, Shigeru; ; Yoshida, Hidetoshi*; Naito, Osamu; Yamashita, Osamu; Shimizu, Kazuaki; ; Kondoh, Takashi

Review of Scientific Instruments, 70(1), p.772 - 775, 1999/01

https://doi.org/10.1063/1.1149392

no abstracts in English

Improvement of tritium accountancy technology for the ITER fuel cycle safety enhancement

Ohira, Shigeru; Hayashi, Takumi; Nakamura, Hirofumi; Kobayashi, Kazuhiro; Tadokoro, Takahiro*; Nakamura, H.*; Ito, Takeshi*; Yamanishi, Toshihiko; Kawamura, Yoshinori; Iwai, Yasunori; et al.

Fusion Energy 1998, 3, p.1069 - 1072, 1998/10

no abstracts in English