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Journal Articles

Optimum temperature for HIP bonding invar alloy and stainless steel

Wakui, Takashi; Ishii, Hideaki*; Naoe, Takashi; Kogawa, Hiroyuki; Haga, Katsuhiro; Wakai, Eiichi; Takada, Hiroshi; Futakawa, Masatoshi

Materials Transactions, 60(6), p.1026 - 1033, 2019/06

 Times Cited Count:1 Percentile:17.37(Materials Science, Multidisciplinary)

The mercury target has large size as 1.3$$times$$1.3$$times$$2.5 m$$^{3}$$. In view of reducing the amount of wastes, we studied the structure so that the fore part could be separated. The flange is required to have high seal performance less than 1$$times$$10$$^{-6}$$ Pa m$$^{3}$$/s. Invar with low thermal expansion is a candidate. Due to its low stiffness, however, the flange may deform when it is fastened by bolts. Practically invar is reinforced with stainless steel where all interface between them has to be bonded completely with the HIP bonding. In this study, we made specimens at four temperatures and conducted tensile tests. The specimen bonded at 973 K had little diffusion layer, and so fractured at the interface. The tensile strength reduced with increasing the temperature, and the reduced amount was about 10% at 1473 K. The analyzed residual stresses near the interface increased by 50% at maximum. Then, we concluded that the optimum temperature was 1173 K.

Journal Articles

Technical investigation on small water leakage incident occurrence in mercury target of J-PARC

Haga, Katsuhiro; Kogawa, Hiroyuki; Wakui, Takashi; Naoe, Takashi; Takada, Hiroshi

Journal of Nuclear Science and Technology, 55(2), p.160 - 168, 2018/02

 Times Cited Count:4 Percentile:60.9(Nuclear Science & Technology)

The mercury target vessel used for the spallation neutron source in J-PARC has multi-walled structure made of stainless steel type 316L, which comprises a mercury vessel and a water shroud. In 2015, water leak incidents from the water shroud occurred while the mercury target was operated with a proton beam power of 500 kW. Several investigations were conducted to identify the cause of failure. The results of the visual inspections, mockup tests, and analytical evaluations suggested that the water leak was caused by the combination of two factors. One was the diffusion bonding failure due to the large thermal stress induced by welding of the bolt head, which fixes the mercury vessel and the water shroud, during the fabrication process. The other was the thermal fatigue failure of the seal weld due to the repetitive beam trip during the operating period. These target failures point to the importance of eliminating initial defects from welding lines and to secure the rigidity and reliability of welded structures. The next mercury target was fabricated with an improved design which adopted parts of monolithic structure machined by wire EDM to reduce welding lines, and intensified inspections to eliminate the initial defects. The operation with the improved target is planned to be started in October 2017.

Journal Articles

Stability of montmorillonite edge faces studied using first-principles calculations

Sakuma, Hiroshi*; Tachi, Yukio; Yotsuji, Kenji; Suehara, Shigeru*; Arima, Tatsumi*; Fujii, Naoki*; Kawamura, Katsuyuki*; Honda, Akira

Clays and Clay Minerals, 65(4), p.252 - 272, 2017/08

 Times Cited Count:1 Percentile:15.66(Chemistry, Physical)

Structure and stability of montmorillonite edge faces (110), (010), (100), and (130) of the layer charges y = 0.5 and 0.33 are investigated by the first-principles electronic calculations based on the density functional theory. Stacking and single layer models are tested for understanding the effect of stacking on the stability of montmorillonite edge faces. Most stacking layers stabilize the edge faces by making hydrogen bonds between the layers; therefore, the surface energy of stacking layers is reduced rather than the single layer model. This indicates that the surface energy of edge faces should be estimated depending on the swelling conditions. Lowest surface energies of (010) and (130) edge faces were realized by the presence of Mg ions on the edge faces. These edge faces have a strong adsorption site for cations due to local negative charge of the edges.

Journal Articles

Progress of ITER full tungsten divertor technology qualification in Japan

Ezato, Koichiro; Suzuki, Satoshi; Seki, Yohji; Mori, Kensuke; Yokoyama, Kenji; Escourbiac, F.*; Hirai, Takeshi*; Kuznetsov, V.*

Fusion Engineering and Design, 98-99, p.1281 - 1284, 2015/10

 Times Cited Count:24 Percentile:94.92(Nuclear Science & Technology)

Japan Atomic Energy Agency (JAEA) is now devoting to development of Full-W ITER divertor outer vertical target (OVT), especially, PFU that needs to withstand the repetitive heat load as high as 20MW/m$$^{2}$$. JAEA have succeeded in demonstrating that the soundness of a bonding technology is sufficient for the full-W ITER divertor. For the development of bonding technology, the load carrying capability test on the W monoblock with a leg attachment to an OVT support structure was carried out and shows that the attachment can withstand against the uniaxial load more than 20 kN which is three times higher than the IO requirement. JAEA manufactured 6 small-scale mock-ups and tested under the repetitive heat load of 10 and 20 MW/m$$^{2}$$ to examine the durability of the divertor structure including W tile bonding and the cooling tube. All of the mock-ups could survived 5000 cycles at 10 MW/m$$^{2}$$ and 1000 cycles 20 MW/m$$^{2}$$ with no failure such as debonding of the W tile and water leak from the cooling tube. The number of cycles at 20 MW/m$$^{2}$$ is three times longer than the requirement of ITER divertor.

Journal Articles

Cladding technique for development of Ag-In-Cd decoupler

Teshigawara, Makoto; Harada, Masahide; Saito, Shigeru; Kikuchi, Kenji; Kogawa, Hiroyuki; Ikeda, Yujiro; Kawai, Masayoshi*; Kurishita, Hiroaki*; Konashi, Kenji*

Journal of Nuclear Materials, 343(1-3), p.154 - 162, 2005/08

 Times Cited Count:10 Percentile:59.51(Materials Science, Multidisciplinary)

For decoupled and poisoned moderator, a thermal neutron absorber, i.e., decoupler, is located around the moderator to give neutron beam with a short decay time. A B4C decoupler is already utilized, however, it is difficult to use in a MW class source because of He void swelling and local heating by (n,a) reaction. Therefore, a Ag-In-Cd (AIC) alloy which gives energy-dependence of macroscopic neutron cross section like that of B$$_{4}$$C was chosen. However, from heat removal and corrosion protection points of view, AIC is needed to bond between an Al alloy (A6061-T6), which is the structural material of a moderator. An AIC plate is divided into a Ag-In (15wt%) and Ag-Cd (35wt%) plate to extend the life time, shorten by burn up of Cd. We performed bonding tests by HIP (Hot Isostatic Pressing). We found out that a better HIP condition was holding at 803 K, 100 MPa for 1 h for small test pieces (f20mm). Though a hardened layer is found in the bonding layer, the rupture strength of the bonding layer is more than 20 MPa, which is less than that of the design stress.

Journal Articles

Improved direct bonding method of Nd:YVO$$_{4}$$ and YVO$$_{4}$$ laser crystals

Sugiyama, Akira; Nara, Yasunaga

Ceramics International, 31(8), p.1085 - 1090, 2005/00

 Times Cited Count:15 Percentile:77.37(Materials Science, Ceramics)

We succeeded in the fabrication of bonded laser crystals composed of a neodymium-doped YVO$$_{4}$$ laser crystal (Nd:YVO$$_{4}$$) and its host crystals YVO$$_{4}$$ by a newly developed dry etching technique using an argon ion beam. The optical distortion caused by the bonded interface of size 5 mm $$times$$ 6 mm was estimated to be 0.05-wave at 633 nm. From the comparison of laser performance pumped by a laser diode, the bonded crystals could increase the laser output power by nearly twice that of the non-bonded crystals with the same degree of polarization of 99.2 %. To analyze the mechanism of the enhanced reduction of the thermal load in the bonded crystals, numerical simulations with a finite-element method were also performed.

Journal Articles

Analysis on lift-off experiment in Halden reactor by FEMAXI-6 code

Suzuki, Motoe; Kusagaya, Kazuyuki*; Saito, Hiroaki*; Fuketa, Toyoshi

Journal of Nuclear Materials, 335(3), p.417 - 424, 2004/12

 Times Cited Count:5 Percentile:37.37(Materials Science, Multidisciplinary)

Experimental analysis was conducted on the Lift-Off experiment IFA-610.1 in Halden reactor by the FEMAXI-6 code using the detailed measured conditions of test-irradiation. Calculated fuel center temperatures on the two assumptions, i.e., (1) an enhanced thermal conductance across the pellet-clad bonding layer is maintained during the cladding creep-out by over-pressurization, and (2) the bonding layer is broken by the cladding creep-out, were compared with the measured data to analyze the effect of the creep-out by over-pressure inside the test pin. The measured center temperature rise was higher by a few tens of K than the prediction performed on the assumption (1), though this difference was much smaller than the predicted rise on the assumption (2). Therefore, it is appropriate to attribute the measured center temperature rise to the decrease of effective thermal conductance by irregular re-location of pellet fragments, etc. which was caused by cladding creep-out.

Journal Articles

Interfacial properties of a direct bonded Nd-doped YVO$$_{4}$$ and YVO$$_{4}$$ single crystal

Sugiyama, Akira; Nara, Yasunaga; Wada, Kengo*; Fukuyama, Hiroyasu

Journal of Materials Science; Materials in Electronics, 15(9), p.607 - 612, 2004/09

Laser crystal bonding of a neodymium-doped yttrium orthovanadate (Nd: YVO$$_{4}$$) and a non-doped yttrium orthovanadate (YVO$$_{4}$$) crystal as a cold finger has been demonstrated. Instead of a traditional chemical treatment, a newly developed dry etching process was applied to the preparation for contact of mechanically polished surfaces. In the subsequent heat treatment process, stable heating at 873 K was required to prevent precipitation at the bonded interface. The bonded interface of 3 mm $$times$$ 3 mm was investigated by optical scattering and wavefront distortion measurements. The scattering density around the bonded interface was less than 4.6$$times$$10$$^{6}$$ /cm$$^{3}$$ and the wavefront distortion caused by the bonded region was assumed to be around 0.04-wave at 633 nm. Additional magnified inspection showed that atoms in the bonded region were well arranged with the same regularity as the bulk crystal. The diffusion coefficient of Nd$$^{3+}$$ ions in the YVO$$_{4}$$ crystal was estimated at 2.3$$times$$10$$^{-23}$$ m$$^{2}$$/sec at 873 K.

Journal Articles

High temperature bending characteristics of Al$$_{2}$$O$$_{3}$$ joints bonded using superplastic ceramics as interlayer

Sato, Takashi*; Motohashi, Yoshinobu*; Sakuma, Takaaki*; Waseda, Kazuyoshi*; Shibata, Taiju; Ishihara, Masahiro; Sawa, Kazuhiro

Nihon Kikai Gakkai Kanto Shibu Ibaraki Koenkai (2004) Koen Rombunshu (No.040-3), p.55 - 56, 2004/09

no abstracts in English

JAEA Reports

Feasibility study of a direct bonding method for laser crystals; Evaluations of YVO$$_{4}$$ yttrium orthovanadate bonded laser crystals

Sugiyama, Akira; Nara, Yasunaga

JAERI-Research 2003-023, 14 Pages, 2003/11

JAERI-Research-2003-023.pdf:2.09MB

We succeeded in fabrication of an integrated laser crystal with good heat conductivity by bonding two kinds of crystals; one is neodymium-doped YVO$$_{4}$$ crystal (Nd: YVO$$_{4}$$) which is used for high peak power lasers and another is its host crystal YVO$$_{4}$$. Instead of conventional chemical etching, dry etching technique using an argon ion beam has been newly developed for the bonding of these crystals. It is essential for the heat treatment of this bonding to optimize the processing temperature for preventing vanadic acid precipitation due to thermo-chemical reaction. Optical characteristics of the bonded crystals were investigated. Bonded interface of the crystal was also observed with a transmission electron microscope (TEM). Through this experimental study, we made it clear that thermal conductivity of the integrated Nd: YVO$$_{4}$$/YVO$$_{4}$$ crystal is much improved and the crystal possesses good lasing capability of increasing laser output without destruction of crystals due to thermal stress.

Journal Articles

Development of fuel performance code FEMAXI-6 and analysis of mechanical loading on cladding during power ramp for high burn-up fuel rod

Suzuki, Motoe; Uetsuka, Hiroshi

IAEA-TECDOC-CD-1345 (CD-ROM), p.217 - 238, 2003/03

A fuel performance code FEMAXI-6 has been developed for the analysis of LWR fuel rod behaviors. The code uses FEM analysis, and has incorporated thermal and mechanical models of phenomena anticipated in high burn-up fuel rods. In the present study, PCMI induced by swelling in a high burn-up BWR type fuel rod has been analyzed. During a power ramp for the high burn-up fuel, instantaneous pellet swelling been simulated by a new swelling model which has been installed in the code to take into account the FP gas bubble growth, and the new model can give satisfactory predictions on cladding diametral expansion. In addition, a pellet-clad bonding model in the code, which assumes firm mechanical coupling between pellet outer surface and cladding inner surface, predicts an increased tensile stress in the axial direction of cladding during the power ramp, indicating the generation of bi-axial stress state in the cladding.

Journal Articles

Nd:YVO$$_{4}$$ and YVO$$_{4}$$ laser crystal integration by a direct bonding technique

Sugiyama, Akira; Fukuyama, Hiroyasu; Katsumata, Masaki*; Okada, Yukikatsu*

Integrated Optical Devices: Fabrication and Testing (Proceedings of SPIE Vol.4944), p.361 - 368, 2003/00

We report recent progress in bonding of crystals used in microchip lasers, Nd:YVO$$_{4}$$ and non-doped YVO$$_{4}$$ crystal that functions as a cold finger. The bonding technique consists of a dry etching process for polished crystal surfaces to be bonded and a successive transformation from hydrogen bonding to oxygen-bridged bonding at temperature below half of the melting point of crystal. Roughness of the surfaces was less than 0.2-lambda at 633 nm. After the etching of around 30 nm by an argon ion beam, the surfaces were contacted in the clean ambient, then heat treatment was done for 50 hours in a vacuum furnace. To evaluate the bonded region, we made optical scattering measurements, and laser oscillation tests pumped by a laser diode with the output power of 20 W. From these experiments, it was clear that the number of defects on the bonded surface is much smaller than that of the intrinsic defects, and the integrated crystal, improving thermal conductivity, can produce twice of laser output power compared with a usual one.

JAEA Reports

Development of HIP technique for bonding of CuCrZr with stainless steel and beryllium for application to the ITER first wall

Hatano, Toshihisa; Enoeda, Mikio; Kuroda, Toshimasa*; Akiba, Masato

JAERI-Tech 2002-075, 59 Pages, 2002/10

JAERI-Tech-2002-075.pdf:17.38MB

no abstracts in English

JAEA Reports

Development of the fabrication technology for the superconducting coils in the ITER magnet system and its achievements

Hamada, Kazuya; Nakajima, Hideo; Okuno, Kiyoshi; Endo, Sakaru*; Kikuchi, Kenichi*; Kubo, Yoshio*; Aoki, Nobuo*; Yamada, Yuichi*; Osaki, Osamu*; Sasaki, Takashi*; et al.

JAERI-Tech 2002-027, 23 Pages, 2002/03

JAERI-Tech-2002-027.pdf:2.94MB

The Engineering Design Activities (EDA) for the International Thermonuclear Experimental Reactor (ITER) was performed under the collaboration of Japan, EU, Russia and the US. The EDA was successfully completed in July 2001, in which the development of fabrication technology for advanced components, such as superconducting coils, was conducted. The ITER magnet system consists of Toroidal Field coils, a Central Solenoid (CS), Poloidal Field coils and Correction coils. The construction of these coils requires advanced technologies that fairly exceeded those available at the start of the EDA. Therefore, CS Model Coil and TF Model Coil projects were implemented. To fabricate the CS Model Coil, the fabrication technologies for high performance strand, large cable, winding, heat treatment, joint and insulation are indispensable. This report describes the above detailed fabrication technologies successfully developed in the CS Model Coil Project.

Journal Articles

Feasibility study of a direct bonding technique for laser crystals

Sugiyama, Akira; Fukuyama, Hiroyasu*; Kataoka, Yohei*; Nishimura, Akihiko; Okada, Yukikatsu*

Advanced Optical Manufacturing and Testing Technology 2000 (Proceedings of SPIE Vol.4231), p.261 - 268, 2000/11

no abstracts in English

Journal Articles

Optics developments for CPA lasers in JAERI

Sugiyama, Akira; Fukuyama, Hiroyasu*; Katsurayama, Masamichi*; Anzai, Yutaka*

Denki Gakkai Hikari, Ryoshi Debaisu Kenkyukai OQD-00-50, p.23 - 28, 2000/10

no abstracts in English

Journal Articles

Development of 46-kA Nb$$_{3}$$Sn conductor joint for ITER model coils

Takahashi, Yoshikazu; Nunoya, Yoshihiko; Nishijima, Gen; Koizumi, Norikiyo; Matsui, Kunihiro; Ando, Toshinari; Hiyama, Tadao; Nakajima, Hideo; Kato, Takashi; Isono, Takaaki; et al.

IEEE Transactions on Applied Superconductivity, 10(1), p.580 - 583, 2000/03

 Times Cited Count:20 Percentile:70.33(Engineering, Electrical & Electronic)

no abstracts in English

JAEA Reports

Fission gas release from rock-like fuels, PuO$$_{2}$$-ZrO$$_{2}$$(Y){or ThO$$_{2}$$}-Al$$_{2}$$O$$_{3}$$-MgO at burn-up of 20 MWd/kg

Yanagisawa, Kazuaki; Omichi, Toshihiko; Kanazawa, Hiroyuki; Amano, Hidetoshi; Yamahara, Takeshi

JAERI-Research 97-085, 31 Pages, 1997/11

JAERI-Research-97-085.pdf:2.38MB

no abstracts in English

Journal Articles

Mechanical properties of HIP bonded joints of austenitic stainless steel and Cu-alloy for fusion experimental reactor blanket

Sato, Satoshi; Takatsu, Hideyuki; Hashimoto, T.*; Kurasawa, Toshimasa; Furuya, Kazuyuki; *; Osaki, Toshio*; Kuroda, Toshimasa*

Journal of Nuclear Materials, 233-237(PT.B), p.940 - 944, 1996/00

 Times Cited Count:33 Percentile:92.51(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Consideration of the thermodynamic and magnetic properties of NaCl-type uranium, neptunium, and plutonium compounds

Arai, Yasuo; Omichi, Toshihiko

Journal of Solid State Chemistry, 115(1), p.66 - 70, 1995/02

 Times Cited Count:1 Percentile:6.99(Chemistry, Inorganic & Nuclear)

no abstracts in English

29 (Records 1-20 displayed on this page)