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Journal Articles

The Laser and optical system for the RIBF-PALIS experiment

Sonoda, Tetsu*; Iimura, Hideki; Reponen, M.*; Wada, Michiharu*; Katayama, Ichiro*; Sonnenschein, V.*; Takamatsu, Takahide*; Tomita, Hideki*; Kojima, Takao*

Nuclear Instruments and Methods in Physics Research A, 877, p.118 - 123, 2018/01

 Times Cited Count:2 Percentile:16.17(Instruments & Instrumentation)

In order to produce low-energy RI beams at RIKEN RIBF, a laser ion source, PALIS, is under construction. This ion source is based on resonance ionization of RI atoms captured in Ar gas. Because the ion source is located 70m away from lasers, we have developed an optical system for laser beam transport. This system can be controlled remotely when the ion source is not accessible because of high radiation level. The position of laser beam after transport is reasonably stable, and the transport efficiency is about 50%.

Journal Articles

Radiolysis of mixed solutions of Cl$$^{-}$$ and Br$$^{-}$$ and its effect on corrosion of a low-alloy steel

Hata, Kuniki; Inoue, Hiroyuki*; Kojima, Takao*; Kasahara, Shigeki; Hanawa, Satoshi; Ueno, Fumiyoshi; Tsukada, Takashi; Iwase, Akihiro*

Proceedings of Symposium on Water Chemistry and Corrosion in Nuclear Power Plants in Asia 2017 (AWC 2017) (USB Flash Drive), p.304 - 314, 2017/09

A model simulation of $$gamma$$ radiolysis of mixed solutions of NaCl and NaBr was carried out. The simulation result agreed well with the experimental result, and Br$$^{-}$$ played an important role in determining the amounts of products from water radiolysis. The simulation result also showed that, in highly pure NaCl solutions, the steady-state concentration of a radolytic product, H$$_{2}$$O$$_{2}$$, was mainly controlled by three reactions (Cl$$^{-}$$ + $$^{.}$$OH $$rightarrow$$ ClOH$$^{.-}$$, ClOH$$^{.-}$$ $$rightarrow$$ Cl$$^{-}$$ + $$^{.}$$OH, and ClOH$$^{.-}$$ + H$$^{+}$$ $$rightarrow$$ Cl$$^{.}$$ + H$$_{2}$$O), which indicated that accurate evaluation of the rate constants of these reactions was very important in improving the radiolysis simulation of solutions containing Cl$$^{-}$$. An immersion test using a low-alloy steel, SQV2A, in the mixed solutions was also carried out under irradiation. The corrosion rate increased or decreased depending on the pH or the concentrations of the halide ions in a similar way to the change in concentration of H$$_{2}$$O$$_{2}$$ produced from water radiolysis, which is affected by the presence of Cl$$^{-}$$ and Br$$^{-}$$. However, at high pH values ($$>$$12), the corrosion rate was almost zero even though the concentration of H$$_{2}$$O$$_{2}$$ was high. This could be attributed to enhancement of the passivity of test specimens at higher pH values.

Journal Articles

Corrosion behavior of pure titanium in high pH solution under $$gamma$$ irradiation

Yukawa, Takuji*; Inoue, Hiroyuki*; Kojima, Takao*; Iwase, Akihiro*; Taniguchi, Naoki; Tachikawa, Hirokazu*

Zairyo To Kankyo 2016 Koenshu (CD-ROM), p.359 - 362, 2016/05

The immersion tests of pure titanium were carried out in aqueous solution containing carbonate/bicarbonate with 50 mM-chloride ion under gamma irradiation. The effect of pH on general corrosion rate of titanium were studied. The experimental results showed that the concentration of hydrogen preoxide was increased with pH, and the corrosion rate increased with the hydrogen preoxide concentration. The corrosion rate in pH12 and 13 were 5 to10 times larger than those under unirradiated conditions.

Journal Articles

Hydrogen peroxide production by $$gamma$$ radiolysis of sodium chloride solutions containing a small amount of bromide ion

Hata, Kuniki; Inoue, Hiroyuki*; Kojima, Takao*; Iwase, Akihiro*; Kasahara, Shigeki; Hanawa, Satoshi; Ueno, Fumiyoshi; Tsukada, Takashi

Nuclear Technology, 193(3), p.434 - 443, 2016/03

 Times Cited Count:2 Percentile:57.25(Nuclear Science & Technology)

Journal Articles

Effect of hydrogenation on the electronic state of metallic La hydrides probed by X-ray absorption sectroscopy at the La $$L$$-edges

Ishimatsu, Naoki*; Sasada, Ryohei*; Maruyama, Hiroshi*; Ichikawa, Takayuki*; Miyaoka, Hiroki*; Kimura, Toru*; Tsubota, Masami*; Kojima, Yoshitsugu*; Tsumuraya, Takao*; Oguchi, Tamio*; et al.

Journal of Physics; Conference Series, 190, p.012070_1 - 012070_4, 2009/11

 Times Cited Count:2 Percentile:35.79

We have investigated the effect of hydrogenation on La $$5d$$ and $$6p$$ electronic states in metallic LaH$$_x$$ by X-ray absorption near edge structure at the La $$L$$-edges. As the hydrogen content $$x$$ increases from 0 to 2.6, white-line intensity at the La $$L_{2,3}$$-edges shows a remarkable increase in the range of $$x$$ $$>$$ 2.0. This is interpreted as the increase in La $$5d$$ hole induced by interstitial H atoms on the octahedral sites. On the other hand, the shoulder structure at the La $$L_1$$-edge disappears in the process of $$x$$ = 0.0 $$rightarrow$$ 2.0, indicating that the $$p$$-$$ d$$ hybridization is weakened by H atoms on the tetrahedral sites. This study demonstrates that H atoms on the two interstitial H sites provide different contribution to the modification of the electronic states.

JAEA Reports

Technical data on electron beam and $$gamma$$-ray irradiation facilities; Electron accelerator and $$^{60}$$Co irradiation facility

Seito, Hajime; Haruyama, Yasuyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Kanazawa, Takao; Kaneko, Hirohisa; Kojima, Takuji

JAEA-Technology 2008-071, 29 Pages, 2008/11

JAEA-Technology-2008-071.pdf:17.71MB

This report outlines useful data for users in electron beam and $$^{60}$$Co $$gamma$$-ray irradiation facilities at JAEA, TARRI. The contents include fundamental data such as characteristics of irradiation field, mechanism of irradiator and dose measurement in irradiated materials.

Journal Articles

Operation of the electron accelerators and $$gamma$$-ray irradiation facilities

Kaneko, Hirohisa; Haruyama, Yasuyuki; Haneda, Noriyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Kanazawa, Takao; Kojima, Takuji; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; et al.

JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 192, 2008/11

The accelerator served mainly for graft-polymerization for new material development, radiation effect study on semiconductors and various experiments of visiting users. The annual operation time of the electron accelerator is 706.3h. The Co-60 $$gamma$$-ray irradiation facilities consist of three buildings (8 rooms) and cover a wide dose-rate range from 0.04 Gy/h to 20 kGy/h with eight irradiation cells. The annual operation time for the first, second cobalt irradiation facilities and food irradiation facility is 23,433h, 9,010h and 10,631h.

Journal Articles

Utilization of the electron accelerator and $$gamma$$-ray irradiation facilities

Kaneko, Hirohisa; Haruyama, Yasuyuki; Haneda, Noriyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Kanazawa, Takao; Kojima, Takuji; Yamaguchi, Toshiyuki*; Yagi, Norihiko*; et al.

JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 193, 2008/11

An electron accelerator and three $$gamma$$-ray irradiation facilities were operated for various research subjects as operation plan in FY 2007 without serious trouble. The number of research subjects for the electron accelerator and $$gamma$$-ray irradiation facilities is 505 and 1174, respectively. The number of experiment subject at the electron accelerator increased in the research fields of environment and nuclear facilities, and decreased in the field of heat resist. Also, the number at $$gamma$$-ray irradiation facilities increased in the field of resource & bio-technology, and decreased in the field of nuclear facilities.

Journal Articles

Operation of the electron accelerators and $$gamma$$-ray irradiation facilities

Kaneko, Hirohisa; Hanaya, Hiroaki; Haneda, Noriyuki; Yamagata, Ryohei; Seito, Hajime; Kanazawa, Takao; Kojima, Takuji; Koyama, Shigeru*; Yamaguchi, Toshiyuki*; Kawashima, Ikuo*; et al.

JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 209, 2008/03

The accelerator served mainly for graft-polymerization for new material development, radiation effect study on semiconductors, and various experiments of outside users. The annual operation time for the electron accelerator is 597.4h(517h for vertical beams, 80.4h for horizontal beams) The Co-60 $$gamma$$-ray irradiation facilities consist of three buildings (8 rooms) and cover a wide dose-rate range from 0.04Gy/h to 20kGy/h with eight irradiation cells. The annual operation time for the cobalt first, second irradiation facilities and food irradiation facility is 20,844 h, 6,335 h and 3,150 h.

Journal Articles

Utilization of the electron accelerator and $$gamma$$-ray irradiation facilities

Kojima, Takuji; Kaneko, Hirohisa; Haneda, Noriyuki; Hanaya, Hiroaki; Yamagata, Ryohei; Seito, Hajime; Kanazawa, Takao; Koyama, Shigeru*; Yamaguchi, Toshiyuki*; Kawashima, Ikuo*; et al.

JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 208, 2008/03

An electron accelerator and three $$gamma$$ ray irradiation facilities were operated for various research subjects as operation plan in FY 2006 without serious trouble. The number of research subjects for the No.1 accelerator, the Cobalt No.1 facility, the Cobalt No.2 facility, and the Food irradiation facility, is 544, 159, 622, and 357, respectively.

JAEA Reports

Development of the carbon fiber reinforced carbon-carbon composite for High Temperature Gas-cooled Reactors

Sogabe, Toshiaki; Ishihara, Masahiro; Baba, Shinichi; Kojima, Takao; Tachibana, Yukio; Iyoku, Tatsuo; Hoshiya, Taiji; Hiraoka, Toshiharu*; Yamaji, Masatoshi*

JAERI-Research 2002-026, 22 Pages, 2002/11

JAERI-Research-2002-026.pdf:2.41MB

Carbon Fiber Reinforced Carbon-carbon Composites, C/C composites, have been developed and extensively studied their characteristics. C/C composites are considered to be promising materials for the application of a control rod in the next high performance high temperature gas-cooled reactors. In the present paper, details of the development of the candidate C/C composite are described. In the course of the development of the material, especially, feasibility of the production, stableness of the supply and cost are much taken into consideration. As the physical properties of the material, high mechanical strength such as tensile and bending, high fracture strain and fracture toughness and low dimensional change by neutron irradiation have to be met. The developed 2D-C/C composite consists of plain-weave PAN-based carbon fiber cloth and pitch derived matrix. Also, high purification up to the level of nuclear grade was successfully attained in the composite.

JAEA Reports

Rise-to-power test in High Temperature Engineering Test Reactor; Test progress and summary of test results up to 30MW of reactor thermal power

Nakagawa, Shigeaki; Fujimoto, Nozomu; Shimakawa, Satoshi; Nojiri, Naoki; Takeda, Takeshi; Saikusa, Akio; Ueta, Shohei; Kojima, Takao; Takada, Eiji*; Saito, Kenji; et al.

JAERI-Tech 2002-069, 87 Pages, 2002/08

JAERI-Tech-2002-069.pdf:10.12MB

Rise-to-power test in the HTTR has been performed from April 23rd to June 6th in 2000 as phase 1 test up to 10MW, from January 29th to March 1st in 2001 as phase 2 test up to 20MW in the rated operation mode and from April 14th to June 8th in 2001 as phase 3 test up to 20MW in the high temperature test operation mode. Phase 4 test to achieve the thermal reactor power of 30MW started from October 23rd in 2001. On December 7th it was confirmed that the thermal reactor power reached to 30MW and the reactor outlet coolant temperature reached to 850$$^{circ}$$C. JAERI obtained the certificate of pre-operation test from MEXT because all the pre-operation tests by MEXT were passed successfully. From the test results of rise-up-power test up to 30MW, the performance of reactor and cooling system were confirmed, and it was confirmed that an operation of reactor facility could be performed safely. Some problems to be solved were found through tests. By means of solving them, the reactor operation with the reactor outlet coolant temperature of 950$$^{circ}$$C will be achievable.

JAEA Reports

Evaluation of thermal displacement behavior of high temperature piping system in power-up test of HTTR, 1; Results up to 20MW operation

Hanawa, Satoshi; Kojima, Takao; Sumita, Junya; Tachibana, Yukio

JAERI-Tech 2002-024, 46 Pages, 2002/03

JAERI-Tech-2002-024.pdf:3.29MB

no abstracts in English

JAEA Reports

Cause and countermeasure for heat up of HTTR core support plate at power rise tests

Fujimoto, Nozomu; Takada, Eiji*; Nakagawa, Shigeaki; Tachibana, Yukio; Kawasaki, Kozo; Saikusa, Akio; Kojima, Takao; Iyoku, Tatsuo

JAERI-Tech 2001-090, 69 Pages, 2002/01

JAERI-Tech-2001-090.pdf:7.88MB

HTTR has carried out many kinds of tests as power rise tests in which reactor power rises step by step after attained the first criticality. In the tests, temperature of a core support plate showed higher results than expected value at each power level, the temperature was expected to be higher than the maximum working temperature at 100% power level. Therefore, tests under the high temperature test operation mode, in which the core flow rate was different, were carried out to predict the temperature at 100% power precisely, and investigate the cause of the temperature rise. From the investigation, it was clear that the cause was gap flow in a core support structure. Furthermore, it was estimated that the temperature of the core support plate rose locally due to change in gap width between the core support plate and a seal plate due to change in core pressure drop. The maximum working temperature of the core support plate was revised. The integrity of core support plate under the revised maximum working temperature condition was confirmed by stress analyses.

Journal Articles

Bending failure assessment of C/C composite by competing risk theory

Ishihara, Masahiro; Kojima, Takao; Hoshiya, Taiji

Proceedings of International Conference on Carbon in 2002 (Carbon2002) (CD-ROM), 6 Pages, 2002/00

Bending failure of two-dimensional C/C composite was studied by both experimental and analytical approaches. In the experiment, a bending test and observation of failure surfaces were performed. From the surface observation, three kinds of fundamental fracture modes were observed; these were tensile, compressive and shear fracture modes. In the analysis, the risk-based statistical fracture theory, so-called the competing risk theory was applied to clarify the bending failure taking account of the competition of these fracture modes. Parameters used in the theory on these fundamental fracture modes were determined by additional experiments, and the theory was applied to the bending failure prediction. As a result of this study, it is concluded that the bending failure was well predicted by the theory, and that the theory would be possible to predict the strength under stress gradient condition. Furthermore, a new strength prediction method combined with FEM code, which is applicable to arbitrary shaped structures with stress gradient, was proposed in this paper.

JAEA Reports

Measurement of $$gamma$$ ray from fuel of High Temperature Engineering Test Reactor; Method of measurement and results

Fujimoto, Nozomu; Nojiri, Naoki; Takada, Eiji*; Yamashita, Kiyonobu; Kikuchi, Takayuki; Nakagawa, Shigeaki; Kojima, Takao; Umeta, Masayuki; Hoshino, Osamu; Kaneda, Makoto*; et al.

JAERI-Tech 2001-002, 64 Pages, 2001/02

JAERI-Tech-2001-002.pdf:3.64MB

no abstracts in English

Journal Articles

Effect of interlaminar fracture on mechanical strength of C/C composites

Kojima, Takao; Tachibana, Yukio; Fujimoto, Nozomu; Ishihara, Masahiro

Proceedings of 8th Annual International Conference on Composites Engineering (ICCE/8), p.479 - 480, 2001/00

no abstracts in English

JAEA Reports

Countermeasure to prevent temperature rise of primary upper shield in HTTR; Performance test of countermeasures under actural core configuration

Tachibana, Yukio; Hontani, Koji*; Kojima, Takao; Takeda, Takeshi; Emori, Koichi; Saruta, Toru; Iyoku, Tatsuo; Kunitomi, Kazuhiko

JAERI-Tech 2000-026, p.61 - 0, 2000/03

JAERI-Tech-2000-026.pdf:2.18MB

no abstracts in English

Journal Articles

Tensile and bending properties of C/C composite for future HTGR control rod

Tachibana, Yukio; Kojima, Takao; Hanawa, Satoshi; Ishihara, Masahiro

Proceedings of 7th Annual International Conference on Composites Engineering (ICCE-7), p.841 - 842, 2000/00

no abstracts in English

Oral presentation

High-dose dosimetry in radiation processing

Seito, Hajime; Kojima, Takuji; Kaneko, Hirohisa; Haneda, Noriyuki; Haruyama, Yasuyuki; Kanazawa, Takao

no journal, , 

no abstracts in English

27 (Records 1-20 displayed on this page)