Development of high-grade VPS-tungsten coatings on F82H reduced activation steel

Tokunaga, Tomonori*; Watanabe, Hideo*; Yoshida, Naoaki*; Nagasaka, Takuya*; Kasada, Ryuta*; Lee, Y.-J.*; Kimura, Akihiko*; Tokitani, Masayuki*; Mitsuhara, Masatoshi*; Hinoki, Tatsuya*; et al.

Journal of Nuclear Materials, 442(1-3), p.S287 - S291, 2013/11

https://doi.org/10.1016/j.jnucmat.2012.11.004

Effect of sweep gas species on tritium release behavior from lithium titanate packed bed during 14MeV neutron irradiation

Kawamura, Yoshinori; Ochiai, Kentaro; Hoshino, Tsuyoshi; Kondo, Keitaro*; Iwai, Yasunori; Kobayashi, Kazuhiro; Nakamichi, Masaru; Konno, Chikara; Yamanishi, Toshihiko; Hayashi, Takumi; et al.

Fusion Engineering and Design, 87(7-8), p.1253 - 1257, 2012/08

https://doi.org/10.1016/j.fusengdes.2012.02.125

Tritium generation and recovery study on lithium ceramic packed bed was started by use of FNS in JAEA. Lithium titanate was selected as tritium breeding material. In this work, the effect of sweep gas species on tritium release behavior was investigated. In case of sweep by helium with 1% of hydrogen, tritium in water form was released sensitively corresponding to the irradiation. This is due to existence of the water vapor in the sweep gas. On the other hand, in case of sweep by dry helium, tritium in gaseous form was released first, and release of tritium in water form was delayed and was gradually increased.

Recent status of fabrication technology development of water cooled ceramic breeder test blanket module in Japan

Hirose, Takanori; Tanigawa, Hisashi; Yoshikawa, Akira; Seki, Yohji; Tsuru, Daigo; Yokoyama, Kenji; Ezato, Koichiro; Suzuki, Satoshi; Enoeda, Mikio; Akiba, Masato

Fusion Engineering and Design, 86(9-11), p.2265 - 2268, 2011/10

https://doi.org/10.1016/j.fusengdes.2011.02.024

As one of the most important fabrication technologies of the WCCB TBM, Hot Isostatic Pressing (HIP) joining technology was selected to fabricate the first wall with built-in cooling channel structure made of reduced activation martensitic/ferritic steel, F82H. By using developed HIP technology, a real scale TBM first wall mockup was successfully fabricated. High heat flux test of the fabricated mockup showed the feasibility to with the equivalent conditions of the WCCB TBM operation. The breeder pebble box was successfully fabricated with thin wall cooling pipes and thin plate sleds by Laser welding. With respect to the side walls with built in cooling channels were also fabricated using drilling technology. Assembling of the first wall and side walls is one of the critical fabrication processes of the fabrication of the TBM structure. By using a F82H first wall mockup and side wall mockups, assembling process was demonstrated successfully by Electron Beam welding.

Application of tritium tracer techniques to observation of hydrogen on surface and in bulk of F82H

Otsuka, Teppei*; Tanabe, Tetsuo*; Tokunaga, Kazutoshi*; Yoshida, Naoaki*; Ezato, Koichiro; Suzuki, Satoshi; Akiba, Masato

Journal of Nuclear Materials, 417(1-3), p.1135 - 1138, 2011/10

https://doi.org/10.1016/j.jnucmat.2010.12.101

Deuterium retention in F82H after low energy hydrogen ion irradiation

Ito, Tatsuya*; Yamauchi, Yuji*; Hino, Tomoaki*; Shibayama, Tamaki*; Nobuta, Yuji*; Ezato, Koichiro; Suzuki, Satoshi; Akiba, Masato

Journal of Nuclear Materials, 417(1-3), p.1147 - 1149, 2011/10

https://doi.org/10.1016/j.jnucmat.2010.12.206

Interfacial properties of HIP joints between beryllium and reduced activation ferritic/martensitic steel

Hirose, Takanori; Ando, Masami; Ogiwara, Hiroyuki*; Tanigawa, Hiroyasu; Enoeda, Mikio; Akiba, Masato

Fusion Engineering and Design, 85(5), p.809 - 812, 2010/08

https://doi.org/10.1016/j.fusengdes.2010.06.002

In this work, the interfacial properties of Be-reduced activation ferritic/martensitic steel (RAFMs) joints were investigated for the first wall of an ITER test blanket module (TBM). The joints were produced by the solid state hot isostatic pressing (HIP) method. Chromium (Cr) was used as a diffusion barrier with a thickness of 1 micron or 10 microns, formed by plasma vapor deposition on the Be surface. The HIPping was conducted at 1023 K and 1233 K. The temperatures are standard normalizing and tempering temperatures of F82H. EPMA showed the Cr layer effectively worked as a diffusion barrier at 1023 K. However, for the F82H/Be interface which underwent HIP at 1233 K followed by tempering a Be rich layer was formed. Bend tests revealed that a thin Cr layer and low temperature HIP is preferable.

Thermal conductivity measurement with silica-coated hot wire for LiSiO pebble bed

Tanigawa, Hisashi; Tanaka, Yuichiro*; Enoeda, Mikio; Akiba, Masato

Journal of Nuclear Science and Technology, 46(6), p.553 - 556, 2009/06

https://doi.org/10.3327/jnst.46.553

Effective thermal conductivity of a LiSiO pebble bed was measured by the hot wire method. The bare and the silica-coated Nichrome heaters were used as the hot wire. At 975 K, the effective thermal conductivity was not measured correctly by the bare hot wire. This is caused by that the electrical signal of the bare thermocouple is distorted due to electrical conductivity of LiSiO. Using the silica-coated hot wire, the effective thermal conductivity can be measured at temperatures ranging from room temperature to 975 K. The effect of the coating layer on the measured effective thermal conductivity was estimated to be small and corresponded to the experimental data. The hot wire method with silica-coating can be applied to the other ceramic breeder materials.

R&Ds of a LiTiO pebble bed for a test blanket module in JAEA

Tanigawa, Hisashi; Hoshino, Tsuyoshi; Kawamura, Yoshinori; Nakamichi, Masaru; Ochiai, Kentaro; Akiba, Masato; Ando, Masami; Enoeda, Mikio; Ezato, Koichiro; Hayashi, Kimio; et al.

Nuclear Fusion, 49(5), p.055021_1 - 055021_6, 2009/05

https://doi.org/10.1088/0029-5515/49/5/055021

This paper presents recent achievements of the research activities for the TBM being developed in JAEA, focusing on the pebble bed of the tritium breeder materials and tritium behaviour. For the breeder material, the chemical stability of LiTiO has been improved by LiO additives. In order to analyze the pebble bed behaviour, thermo-mechanical properties of the LiTiO pebble bed has been experimentally obtained. In order to verify nuclear properties of the pebble bed, the activation foil method has been proposed and a preliminary experiment has been conducted. For the tritium behaviour, the chemical densified coating method has been well developed and tritium recovery system has been modified taking account of the design change of the TBM.

Heatup event analyses of the water cooled solid breeder test blanket module

Tsuru, Daigo; Enoeda, Mikio; Akiba, Masato

Fusion Engineering and Design, 83(7-9), p.1238 - 1243, 2008/12

https://doi.org/10.1016/j.fusengdes.2008.07.008

One-dimensional analyses are carried out for the three representative event sequences about heatup of WCSB TBM. For the event sequence of loss of cooling of the TBM during plasma operation, the requirement to the TBM design becomes apparent that no cooling pipe rupture can be guaranteed under the predicted highest temperature condition to prevent the activation of the Be-HO chemical reaction under the high temperature condition. For the event sequence of ingress of coolant into the TBM during plasma operation, the requirement for the cooling system of TBM becomes apparent that the cooling system for the TBM should be designed to continue its operation against partial loss of coolant due to the ingress of coolant. For the loss of off-site power after the ingress of coolant, it is confirmed that the event converges.

Critical heat flux experiments using a screw tube under DEMO divertor-relevant cooling conditions

Ezato, Koichiro; Suzuki, Satoshi; Dairaku, Masayuki; Akiba, Masato

Fusion Engineering and Design, 83(7-9), p.1097 - 1101, 2008/12

https://doi.org/10.1016/j.fusengdes.2008.07.036

As part of development of Plasma-Facing Components (PFCs) for fusion machines, JAEA has been developing high performance cooling tubes with pressurized water flow. Along this line, a cooling tube with a helical triangular fin on its inner surface has been proposed recently for application to a fusion DEMO to enhance heat removal. Since the fin can be machined by a simple mechanical threading, this tube is called as a screw tube. Divertor cooling conditions in the DEMO design in JAEA are envisaged at the pressure of 4 MPa and the outlet temperature of 200C to improve thermal efficiency of power generation. In the this study, effect of subcooling on critical heat flux (CHF) of the screw tube has been investigated under DEMO-relevant condition with the local pressure of 4 MPa and the inlet coolant temperature up to 180C. A test sample is the screw tube made of pure Cu instead of F82H, a candidate material of the DEMO divertor. The results show that the ICHF values of the screw tube remains more than double values of the smooth at the inlet coolant temperature of 180C, although temperature rise of the cooling water with 140 K leads to reduction of ICHF by almost half compared with those values at room temperature.