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gas-cooled reactorsNakamura, Hirofumi; Isobe, Kanetsugu; Nakamichi, Masaru
Fusion Science and Technology, 54(2), p.341 - 345, 2008/08
Times Cited Count：2 Percentile：16.95(Nuclear Science & Technology)Super critical carbon dioxide (SCCO) cooled reactor is attractive because of its higher thermal efficiency and low reactivity with the primary coolant. But, tritium permeation from primary coolant to the secondary coolant (SCCO) through the heat exchanger tubes will increase in this system, it is important to control tritium in the secondary coolant. JAEA has been investigated a research on the tritium control method in the SCCO cooling reactor. This program consists of two activities; those are development of the tritium permeation reduction coating through the heat exchanger tubes and development of tritium removal method from the SCCO. As to the permeation reduction, the glassy coating developed by JAEA as the tritium permeation reduction barrier for the water cooled fusion reactors are applied to the SCCO cooling system. As a result of experiment, physical and chemical stability of the coating under 100 hours soaking in the SCCO has been demonstrated. As to the tritium control in the coolant, it is essential to identify the chemical state of tritium in the SCCO in order to remove tritium from the SCCO system. In this viewpoint, self-radio chemical reaction study between tritium and CO has been initiated. Based on these results, effective tritium control method in the SCCO system will be proposed. In the presentation, detail of this program and experimental results will be reported.
Yamanishi, Toshihiko; Iwai, Yasunori
Fusion Science and Technology, 54(2), p.454 - 457, 2008/08
Times Cited Count：1 Percentile：10.01(Nuclear Science & Technology)In a fusion reactor, a large amount of tritiated water is expected to be produced. A CECE (Combined Electrolysis Catalytic Exchange) column is applied to process this water. The CECE column of a water processing system of a demo fusion plant design by JAEA is chosen for a reference case. The height and inner diameter of the columns are 22 and 0.7 m. A main feed stream to the column is 20 kg/h, and its atomic ratio of tritium is 5.0
10
. We have developed a simulation code of the CECE column, and have analyzed its dynamic characteristics. In the case where the column is filled with natural water, it takes about 3 hours to reach the steady state of the column. If the column has the recombiner, only a hour is needed to reach the steady state after the total reflux operation. The effect of the reflux has thus been indicated. The control characteristics of the CECE column are also reported by using the developed code with a series of calculated results.
Isobe, Kanetsugu; Hayashi, Takumi; Nakamura, Hirofumi; Kobayashi, Kazuhiro; Yamanishi, Toshihiko; Okuno, Kenji*
Fusion Science and Technology, 54(2), p.533 - 536, 2008/08
Times Cited Count：7 Percentile：44.46(Nuclear Science & Technology)Tritium permeation is one of key issues from the viewpoint of safety and tritium cycle. The oxide formed on metal surface was reported to act as barrier for hydrogen permeation due to its characters, such as low diffusivity and low solubility of hydrogen. On the other hand, the tritium behavior in the oxide as well as the interface of oxide (oxide-metal, oxide-water) is not clarified. The tritium permeation through pure iron, which was coated with its oxide, into water has been studied. Although some characteristics of tritium permeation through the oxide were found, the permeation mechanism through the oxide has not been clarified yet. The tritium distribution in the oxide can give us useful information of tritium behavior in the oxide / oxide-interface and help to understand the mechanism of tritium permeation through the oxide. In the present study, tritium distribution in the iron oxide is observed with tritium micro autoradiography.
O separation and dehydration characteristics of Y-type zeolite adsorbentIwai, Yasunori; Uzawa, Masayuki*; Yamanishi, Toshihiko
Fusion Science and Technology, 54(2), p.462 - 465, 2008/08
Times Cited Count：4 Percentile：29.44(Nuclear Science & Technology)Adsorber has been studied to apply in the first stage of water detritiation system processing more than 100 kg/h of high-level tritiated water generated in a future fusion plant. Zeolite is a suitable adsorbent since it is an inorganic matter having a large water capacity. Rapid dehydration characteristic as well as large HTO/HO separation factor is necessary for adsorber to minimize its size. Present experiments were focused on the effect of cation on HTO/HO separation and dehydration characteristics of Y-type zeolites. It was found that the isotope separation factors are around 1.1-1.2 under static conditions. As for dehydration, operating temperature fixs the movable water capacity of the zeolites and the capacity at room temperature is NaY 
CaY KY. HTO dehydration characteristics depend on the accumulated purge gas amount and the purge gas rate is less influential. It is found that pressure swing is an effective method for HTO dehydration.
Iwai, Yasunori; Yamanishi, Toshihiko; Hiroki, Akihiro; Yagi, Toshiaki*; Tamada, Masao
Fusion Science and Technology, 54(2), p.458 - 461, 2008/08
Times Cited Count：6 Percentile：39.98(Nuclear Science & Technology)A solid-polymer-electrolyte (SPE) water electrolyzer for high-level tritiated water was designed for the Water Detritiation System (WDS). Polymeric materials were selected from a main viewpoint of radiation durability to keep their functions beyond ITER-WDS requirement (530 kGy). Our selection was Pt + Ir applied Nafion N117 ion exchange membrane, VITON O-ring seal and polyimide insulator. A g-ray irradiation test of the SPE cell demonstrated the durability of the cell against 530 kGy. The detritiation of the polymeric materials is a critical problem for the maintenance or for the disposal of the electrolyzer. As for the Nafion membrane, most of tritiated water in the membrane was rapidly removed by such as vacuum dehydration. It was difficult, by contrast, to remove bound tritiated water in the membrane. An effective method to remove tritiated water in the bound water is to promote an isotope exchange.
Yamanishi, Toshihiko; Hayashi, Takumi; Shu, Wataru; Kawamura, Yoshinori; Nakamura, Hirofumi; Iwai, Yasunori; Kobayashi, Kazuhiro; Isobe, Kanetsugu
Fusion Science and Technology, 54(1), p.45 - 50, 2008/07
Times Cited Count：4 Percentile：29.44(Nuclear Science & Technology)The R&D for tritium technologies towards to the DEMO plants are carried out in Broader Approach (BA) program in Japan: (1) tritium accountancy technology; (2) basic tritium safety research; and (3) tritium durability test. A multi-purpose facility is constructed at Rokkasho in Japan to carry out the above R&Ds. Beta 
radioisotopes as well as tritium (370 TBq/year) can be handled in the facility. At TPL (Tritium Process Laboratory) of JAEA, a series of R&Ds for the tritium technologies relevant to the above BA program have been started. A series of basic studies for the tritium-materials has also been carried out. The main R&D activities in this field are the tritium behavior in a confinement; monitoring; detritiation; and decontamination. In this paper, the results of above recent activities at TPL of JAEA are also summarized from viewpoint of future fusion DEMO reactors.
Yamanishi, Toshihiko; Yamada, Masayuki; Suzuki, Takumi; Shu, Wataru; Kawamura, Yoshinori; Nakamura, Hirofumi; Iwai, Yasunori; Kobayashi, Kazuhiro; Isobe, Kanetsugu; Hoshi, Shuichi; et al.
Fusion Science and Technology, 54(1), p.315 - 318, 2008/07
Times Cited Count：11 Percentile：59.06(Nuclear Science & Technology)The construction of the building and safety systems of the TPL was completed until 1985. The operations of the safety systems with tritium have been started from March 1988. The amount of tritium held at the TPL was 13 PBq at March 2007. The average tritium concentration in a stream from a stack of the TPL to environment was 6.010
Bq/cm
; and is 1/100 smaller than that of the regulation value for the concentration of HTO in the air in Japan. The safety operation results with tritium have thus been obtained. A set of failure data of several main components of the TPL was also obtained as the valuable data for fusion tritium facilities.
Kobayashi, Kazuhiro; Hayashi, Takumi; Iwai, Yasunori; Yamanishi, Toshihiko; Willms, R. S.*; Carlson, R. V.*
Fusion Science and Technology, 54(1), p.311 - 314, 2008/07
Times Cited Count：2 Percentile：16.95(Nuclear Science & Technology)In order to obtain the data for actual tritium behavior in the room and/or building, a series of intentional tritium release experiments were planed and carried out within a radiological controlled area at Tritium System Test Assembly (TSTA) in Los Alamos National Laboratory (LANL) under US-JAPAN collaboration program. In these experiments, influence of a difference of the release point and a difference of the amount of hydrogen isotope were suggested. In this report, the results of intentional tritium release experiments at TSTA in LANL are summarized. The released tritium was reached a uniform value about 30 
40 minutes in all the experiments. The influence of the difference of the release point and the difference of the amount of hydrogen isotope were not seen in these experiments drastically. The initial tritium behavior in the room is also discussed by comparing calculated values with experimental results.
Hayashi, Takumi; Kobayashi, Kazuhiro; Iwai, Yasunori; Isobe, Kanetsugu; Nakamura, Hirofumi; Kawamura, Yoshinori; Shu, Wataru; Suzuki, Takumi; Yamada, Masayuki; Yamanishi, Toshihiko
Fusion Science and Technology, 54(1), p.319 - 322, 2008/07
Times Cited Count：2 Percentile：16.95(Nuclear Science & Technology)Murdoch, D.*; Beloglazov, S.*; Boucquey, P.*; Chung, H.*; Glugla, M.*; Hayashi, Takumi; Perevezentsev, A.*; Sessions, K.*; Taylor, C.*
Fusion Science and Technology, 54(1), p.3 - 8, 2008/07
Times Cited Count：21 Percentile：78.77(Nuclear Science & Technology)Takata, Hiroki*; Furuichi, Kazuya*; Nishikawa, Masabumi*; Fukada, Satoshi*; Katayama, Kazunari*; Takeishi, Toshiharu*; Kobayashi, Kazuhiro; Hayashi, Takumi; Namba, Haruyuki*
Fusion Science and Technology, 54(1), p.223 - 226, 2008/07
Times Cited Count：9 Percentile：52.68(Nuclear Science & Technology)Concentration profiles of tritium penetrated into cement paste, mortar and concrete were measured by using samples with a shape of column. Tritium penetrated until a location of about 5 cm from the exposed surface after 6 months' exposure. The amount of tritium penetrated into mortar and concrete were less than 70% and half that into cement paste.
Glugla, M.*; Beloglazov, S.*; Carlson, B.*; Cho, S.*; Cristescu, I.*; Cristecu, I.*; Chung, H.*; Girard, J.-P.*; Hayashi, Takumi; Mardoch, D.*; et al.
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