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Journal Articles

Annealing effect of thermal conductivity on thermal stress induced fracture of nuclear graphite

Sumita, Junya; Shibata, Taiju; Ishihara, Masahiro; Iyoku, Tatsuo; Tsuji, Nobumasa*

Key Engineering Materials, 297-300, p.1698 - 1703, 2005/11

no abstracts in English

JAEA Reports

An Irradiation test of heat-resistant ceramic composite materials, 2; Interim report on post-irradiation examinations of the second and third preliminary test, 98M-41A, 99M-30A

Baba, Shinichi; Nemoto, Makoto*; Sozawa, Shizuo; Yamaji, Masatoshi*; Ishihara, Masahiro; Sawa, Kazuhiro

JAERI-Tech 2005-055, 157 Pages, 2005/09


The Japan Atomic Energy Research Institute (JAERI) has been carrying out the research on radiation damage mechanism of heat-resistant ceramics composite materials, as one of the subjects of the innovative basic research on high temperature engineering using the High Temperature Engineering Test Reactor (HTTR). A series of preliminary irradiation tests is being made using the Japan Materials Testing Reactor (JMTR). The present report describes results of post-irradiation examinations so far on specimens irradiated in the second and third capsule, designated 98M-41A and 99M-30A, to fast neutron fluences of 1.0$$times$$10$$^{25}$$m$$^{-2}$$(E$$>$$1MeV) at temperatures of 973K-1173K and 1273K-1473K. The PIE were conducted as the fundamental statistics index of the diametral dimensions for irradiated specimen, irradiation induced dimensional change rate and thermal expansion rate.

Journal Articles

Temperature evaluation of core components of HTGR at depressurization accident considering annealing recovery on thermal conductivity of graphite

Sumita, Junya; Shibata, Taiju; Nakagawa, Shigeaki; Hanawa, Satoshi; Iyoku, Tatsuo; Ishihara, Masahiro

Transactions of 18th International Conference on Structural Mechanics in Reactor Technology (SMiRT-18), p.4822 - 4828, 2005/08

Graphite materials are used for structural components in High Temperature Gas-Cooled Reactor (HTGR) core because of their excellent thermo/mechanical properties. Thermal conductivity of graphite components is reduced by neutron irradiation in reactor operation. The reduced conductivity is expected to be recovered by thermal annealing effect when irradiated graphite component is heated above irradiated temperature. In the present study, temperature analyses considering the annealing effect of the HTGR core at a depressurization accident were carried out and influence of annealing effect on maximum fuel temperature was investigated. The analyses show that the annealing effect can reduce the fuel temperature about 100$$^{circ}$$C at the maximum, and it is possible to evaluate the maximum fuel temperature more appropriately. It was also shown that the core-temperature of High Temperature Engineering Test Reactor (HTTR) at the safety demonstration tests can be analyzed with the developed evaluation method considering annealing effect.

Journal Articles

Synchrotron radiation photoabsorption and photoemission spectroscopy for thermal-induced reoriented Si polymer

Nath, K. G.; Shimoyama, Iwao; Sekiguchi, Tetsuhiro; Baba, Yuji

Journal of Electron Spectroscopy and Related Phenomena, 144-147, p.323 - 326, 2005/06

 Times Cited Count:5 Percentile:28.59(Spectroscopy)

The effect of laser annealing on electronic atructures and molecular orientation for poly(dimethylsilane), {PDMS, [Si(CH$$_{3}$$)$$_{2}$$]$$_{n}$$} has been studied by synchrotron radiation photoemission and photoabsorption spectroscopy. Prior to annealing, PDMS powder was mounted on the basal plane of highly oriented pyrolytic graphite. Both Si 1s X-ray photoemission spectroscopy and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at Si 1s edge show that electronic structures have been modified due to annealing. Furthermore, the angle-dependent NEXAFS spectra clearly indicate that the annealed products maintain a specific orientation. Interestingly, no such kind of orientation is present in as-received PDMS powder as no angle-dependency is observed before annealing.

Journal Articles

Growth of ZnO nanorods on Cu implanted substrates

Takeyama, Akinori; Yamamoto, Shunya; Yoshikawa, Masahito; Ito, Hiroshi

Japanese Journal of Applied Physics, Part 1, 44(1B), p.750 - 753, 2005/01

 Times Cited Count:0 Percentile:0(Physics, Applied)

Pyramid shaped Cu precipitates were formed on Si (100) surface as a result of 200 keV Cu ion implantation and subsequent annealing. Then, ZnO nanorods were successfully synthesized on the Cu implanted substrates by chemical vapor transport (CVT). Hexagonal shaped nanorods with a diameter of 200 nm were grown nearly perpendicular to the Cu implanted substrate and their average density was increased as increasing that of Cu precipitates. The facts strongly indicate the Cu precipitates served as the catalytic particles for the growth of ZnO rods.

Journal Articles

Ion beam surface modification of Y-TZP and effects of subsequent annealing

Motohashi, Yoshinobu*; Shibata, Taiju; Harjo, S.*; Sakuma, Takaaki*; Ishihara, Masahiro; Baba, Shinichi; Sawa, Kazuhiro

Proceedings of 14th International Federation for Heat Treatment and Surface Engineering Congress Transactions of Materials and Heat Treatment Vol.25 No.5, p.1032 - 1036, 2004/10

no abstracts in English

JAEA Reports

Preliminary investigation of annealing effect on thermal conductivity of graphite and investigation of annealing test method (Contract research)

Sumita, Junya; Nakano, Masaaki*; Tsuji, Nobumasa*; Shibata, Taiju; Ishihara, Masahiro

JAERI-Tech 2004-055, 25 Pages, 2004/08


Neutron irradiation remarkably reduces the thermal conductivity of graphite, and the reduced thermal conductivity is recovered by annealing effect if the graphite is heated above the irradiation temperature. Therefore, it is expected that the reduced thermal conductivity of graphite components in the HTGR could be recovered by the annealing effect in accidents, such as a depressurization accident. Then, an analytical investigation of the annealing effect on thermal performance of a HTGR core was carried. The analysis showed that the annealing effect reduces the maximum fuel temperature about 70$$^{circ}$$C, and it is important to introduce the annealing effect appropriately in the temperature analysis of the core components and reactor internals. In addition, an annealing test method was investigated to evaluate the effect quantitatively, and the test plan was made.

Journal Articles

Annealing effect of thermal conductivity on thermal stress of nuclear graphite

Sumita, Junya; Shibata, Taiju; Baba, Shinichi; Ishihara, Masahiro; Iyoku, Tatsuo

Nihon Kikai Gakkai M&M 2004 Zairyo Rikigaku Kanfarensu Koen Rombunshu, p.141 - 142, 2004/07

Neutron irradiation reduces the thermal conductivity of graphite, but the reduced thermal conductivity is recovered by annealing effect if the graphite is heated above the irradiation temperature. In this research, annealing effect of thermal conductivity on thermal stress of graphite is investigated. In addition, effect of recovered thermal conductivity on membrane, point and peak stress is also investigated.

Journal Articles

Recent Japanese PFM researches related to failure probability of aged RPV

Shibata, Katsuyuki; Kanto, Yasuhiro*; Yoshimura, Shinobu*; Yagawa, Genki*

Proceedings of 5th International Workshop on the Integrity of Nuclear Components, p.99 - 117, 2004/00

no abstracts in English

Journal Articles

Fabrication of TiO$$_{2}$$ photocatalysts by oxidative annealing of TiC

Choi, Y.; Umebayashi, Tsutomu; Yamamoto, Shunya; Tanaka, Shigeru

Journal of Materials Science Letters, 22(17), p.1209 - 1211, 2003/09

 Times Cited Count:45 Percentile:79.28(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Defect production and radiation annealing in platinum irradiated with high-energy heavy ions

Chimi, Yasuhiro; Iwase, Akihiro; Iwata, Tadao*

Nuclear Instruments and Methods in Physics Research B, 209, p.159 - 164, 2003/08

 Times Cited Count:2 Percentile:21.84(Instruments & Instrumentation)

Accumulation of defects during energetic ion irradiation below $$sim$$10K in platinum thin films is studied by electrical resistivity measurements. Experimental results are analyzed by using a model which describes the production and selective radiation annealing of defects. For high-energy ($$sim$$100MeV) heavy ion irradiations, radiation annealing process due to electronic excitation is found mainly at the initial stage of irradiation. From the defect accumulation curve and defect recovery spectra, the effective temperature corresponding to the lattice agitation induced by electronic excitation is estimated.

Journal Articles

Structure and optical properties of germanium implanted with carbon ions

Wei, P.; Xu, Y.; Nagata, Shinji*; Narumi, Kazumasa; Naramoto, Hiroshi

Nuclear Instruments and Methods in Physics Research B, 206(1-4), p.233 - 236, 2003/05

 Times Cited Count:5 Percentile:39.95(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Effects of 293-1573K annealing on some properties of 3Y-TZP irradiated with Zr ions

Sakuma, Takaaki*; Motohashi, Yoshinobu*; Kobayashi, Tomokazu*; Harjo, S.*; Shibata, Taiju; Ishihara, Masahiro; Baba, Shinichi; Hoshiya, Taiji

Nihon Kikai Gakkai Kanto Shibu Ibaraki Koenkai (2002) Koen Rombunshu (No.020-3), p.125 - 126, 2002/09

no abstracts in English

Journal Articles

Post-irradiation annealing and re-irradiation technique for LWR reactor pressure vessel material

Matsui, Yoshinori; Ide, Hiroshi; Itabashi, Yukio; Kikuchi, Taiji; Ishikawa, Kazuyoshi; Abe, Shinichi; Inoue, Shuichi; Shimizu, Michio; Iwamatsu, Shigemi; Watanabe, Naoki*; et al.

KAERI/GP-195/2002, p.33 - 40, 2002/00

Studies on the irradiation damage of the material of the RPV are inevitable for the LWR. Recently, the researches of annealing effect on the irradiation damage of RPV material were extensively carried out using specimens irradiated in the JMTR of the JAERI. As the next step, an annealing test of irradiated specimens and re-irradiation of annealed specimens were planned. The aim of the test is to evaluate the effect of annealing by comparing the damage of irradiated specimen, its recovery by annealing and the damage after re-irradiation. For the re-irradiation test of this study, JAERI developed a new capsule in which the specimens can be exchanged before and after annealing, and, re-irradiated afterward. The development of the capsule consisted of the design and fabrication of airtight connector for thermocouples and mechanical seal device which was fit to remote handling. Remote operation procedures for handling the radioactive capsule and for exchanging specimens were carefully performed. The results of the re-irradiation proved that the development was technically successful.

JAEA Reports

Development of probabilistic fracture mechanics code PASCAL and user's manual

Shibata, Katsuyuki; Onizawa, Kunio; Li, Y.*; Kato, Daisuke*

JAERI-Data/Code 2001-011, 233 Pages, 2001/03


no abstracts in English

Journal Articles

Formation of TiO$$_{2-x}$$F$$_{x}$$ compounds in fluorine-implanted TiO$$_{2}$$

Yamaki, Tetsuya; Sumita, Taishi; Yamamoto, Shunya

Journal of Materials Science Letters, 21(1), p.33 - 35, 2001/01

 Times Cited Count:88 Percentile:91.82(Materials Science, Multidisciplinary)

We showed the effects of 200 keV F$$^{+}$$ implantation in TiO$$_{2}$$ rutile single crystals followed by the thermal annealing. The isochronal annealing at 573 and 873 K for 5 h for each step led to the formation of an F-doped TiO$$_{2}$$ phase, along with the recovery of the radiation damage and the simultaneous impurity diffusion. This phase was identified to be a TiO$$_{2-x}$$F$$_{x}$$ compound with x = 0.0039 in the outmost region as determined by X-ray photoelectron spectroscopy (probably the first few atomic layers). The fluorination of TiO$$_{2}$$ leads to interesting characteristics and opens avenues towards photoelectronic films with various applications. In addition, our method enabled dopants to be introduced in a controlled manner at specific locations to realize impurity concentration gradients in TiO$$_{2}$$.

Journal Articles

Steam annealing effects on CV characteristics of MOS structures on (11$$bar{2}$$0) face of 4H-SiC

Yoshikawa, Masahito; Oshima, Takeshi; Ito, Hisayoshi; Takahashi, Kunimasa*; Kitabatake, Makoto*

Materials Science Forum, 353-356, p.635 - 638, 2001/00

no abstracts in English

Journal Articles

Change in superconducting properties of Bi$$_{2}$$Sr$$_{2}$$CaCu$$_{2}$$O$$_{8+x}$$ single crystals by Kr$$^{20+}$$-ion irradiation followed by thermal annealing

Ogikubo, Koji*; Uchida, Yukihiro*; Terai, Takayuki*; Yamaguchi, Kenji*; Yamawaki, Michio*; Hayashi, Kimio

Tokyo Daigaku Kogakubu Sogo Shikenjo Nempo, 59, p.91 - 95, 2000/12

no abstracts in English

Journal Articles

Effects of primary recoil (PKA) energy spectrum on radiation damage in FCC metals

Iwata, Tadao; Iwase, Akihiro

Radiat. Eff. Defect Solids, 144(1-4), p.27 - 61, 1998/00

no abstracts in English

Journal Articles

Thermal annealing of interface traps and trapped charges induced by irradiation in oxides of 3C-SiC metal-oxide-semiconductor structures

Yoshikawa, Masahito; Nemoto, N.*; Ito, Hisayoshi; Okumura, Hajime*; *; Yoshida, Sadafumi*; Nashiyama, Isamu

Mater. Sci. Eng., B, 47(3), p.218 - 223, 1997/00

 Times Cited Count:1 Percentile:12.05(Materials Science, Multidisciplinary)

no abstracts in English

56 (Records 1-20 displayed on this page)