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Nakamichi, Masaru; Kim, Jae-Hwan; Munakata, Kenzo*; Shibayama, Tamaki*; Miyamoto, Mitsutaka*
Journal of Nuclear Materials, 442(1-3), p.S465 - S471, 2013/11
Times Cited Count：11 Percentile：64.2(Materials Science, Multidisciplinary)Iwata, Yoshihiro*; Ishii, Keizo*; Kamiya, Tomihiro; Sato, Takahiro
JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 90, 2012/01
Naganawa, Akihiro*; Oka, Kiyoshi
Tateishi Kagaku Gijutsu Shinko Zaidan Josei Kenkyu Seikashu, 21, p.74 - 77, 2012/00
no abstracts in English
Munakata, Kenzo*; Kawamura, Yoshinori
Fusion Science and Technology, 60(1), p.426 - 430, 2011/07
Times Cited Count：3 Percentile：26.02(Nuclear Science & Technology)Cryogenic adsorption is effective for the recovery of hydrogen isotopes of small concentrations from the bulk helium gas. Thus, the cryogenic adsorption method is considered to be applied to the recovery of tritium from the blanket sweep gas which recovers tritium from ceramic breeder materials. The authors performed a screening test to find more suitable adsorbents for the recovery of hydrogen isotopes from the bulk helium gas at 77K. The screening test indicates that a natural mordenite adsorbent has a quite high adsorption capacity for hydrogen under the helium atmosphere. The adsorption rate of hydrogen isotopes was quantified by analyzing breakthrough curves obtained in the experiments. Evaluated effective pore diffusivities of hydrogen isotopes in the mordenite adsorbents are comparable to that in MS5A adsorbents. Thus, it can be said that mordenite adsorbents are also suitable for adsorption of hydrogen isotopes from the viewpoint of adsorption rates.
Seki, Takeshi*; Naganawa, Akihiro*; Oka, Kiyoshi; Yoshino, Junji*
Keisoku Jido Seigyo Gakkai Sangyo Rombunshu, 10(2), p.7 - 16, 2011/05
Enteroscopy was usually performed by the double balloon or capsule endoscopes. However, it is difficult to use these endoscopes in patients who suffer from intestinal obstruction and adhesion. We have developed a new endoscope that can be used in patients who suffer from these problems; the instrument consists of an ileus tube and an optical fiberscope (diameter 1.1 mm). The entire small intestine can be observed by controlling the internal pressure of the balloon in the ileus tube and by pulling the tube out at a constant speed. In our previous study, we developed an internal pressure control device that consists of a balloon attached to an ileus tube and a medical syringe. We also verified the control performance of this device. In this study, we have designed a new two-degrees-of-freedom control system having self-tuning capabilities that enhances the control performance for various types of syringes doctors use usually. The effects of the proposed method are illustrated by the experiment. The obtained results show that balloon pressure in the reference response satisfactorily tracks the output of the reference model and can be settled within 
2% in steady state. In addition, the disturbance rejection properties of the PID control method were affected by the changes in balloon pressure, but this problem can be solved by using the proposed control system.
Amamoto, Ippei; Mitamura, Naoki*; Tsuzuki, Tatsuya*; Takasaki, Yasushi*; Shibayama, Atsushi*; Yano, Tetsuji*; Nakada, Masami; Okamoto, Yoshihiro
Proceedings of 13th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM 2010) (CD-ROM), p.503 - 508, 2010/10
The main objective of this development is to recycle the purified eutectic medium of the pyroreprocessing, delaying its disposal for as long as possible. We have introduced the simple filtration method to remove the rare earth element (REE) particles which were formed due to the conversion of REE chlorides to phosphates. Here, the iron phosphate glass is used as a filtration medium for the removal of FP particles. However, some soluble FP such as compounds of alkali-metals, alkaline-earth metals, etc. still remain in the eutectic medium. This time around, on an experimental basis, the iron phosphate glass has been used as a sorbent instead, to remove the soluble FP. We have obtained some positive results and have intention to incorporate it into the spent electrolyte recycle process as a part of the FP separation and immobilization system.
Amamoto, Ippei; Kofuji, Hirohide; Myochin, Munetaka; Takasaki, Yasushi*; Yano, Tetsuji*; Terai, Takayuki*
Nuclear Technology, 171(3), p.316 - 324, 2010/09
Times Cited Count：11 Percentile：59.22(Nuclear Science & Technology)The separation technique by phosphate conversion of FP from NaCl-KCl or NaCl-2CsCl as the medium of the spent electrolyte of pyroprocessing is being developed at RIAR in Russia. To ascertain the technical feasibility of applying this RIAR's method for recycling of spent electrolyte which composed of FP such as AL, ALE, and REE and 3LiCl-2KCl as the medium, preliminary study was undertaken at JAEA. This study occupies an auxiliary role which is forwarded as a part of FaCT Project of Japan. As a first approach, the thermodynamic analysis to understand the behaviours of FP in the electrolyte was carried out after literature research and acquisition of required thermodynamic properties. Preliminary experiment was then undertaken to observe the conversion behaviours of chlorides to phosphate. In this paper, these results are shown and are evaluated to discern the feasibility of the phosphate conversion method.
Seki, Takeshi; Naganawa, Akihiro*; Oka, Kiyoshi; Ishikawa, Shinji*; Yoshino, Junji*
Nihon Kikai Gakkai Rombunshu, C, 76(766), p.1645 - 1647, 2010/06
Recently, by development of double balloon and capsule endoscopes, small intestinal whole area observation was enabled. However, it is difficult to use these endoscopes in patients with intestinal obstruction and adhesion. We developed a new endoscope that can be used in patients with intestinal obstruction and adhesion; this instrument consists of an ileus tube and an optical fiberscope (diameter, 1.1 mm). The complete observation of small intestinal is to be planned by controlling internal pressure of balloon in ileus tube, and pulling the tube out at constant speed. In our previous study, we have developed an internal pressure control device which consists of a balloon of ileus and an industrial cylinder, and we confirmed the utility. In this study, we developed a new control device combined with a general medical syringe, which enables to be sterilized easily and also to give less anxiety to patients. As the results of performance experiment of the device, the control accuracy was within 0.5% error. Furthermore, in a disturbance response, the pressure fluctuation was limited down to 12%, compared with a case without any control.
Seki, Takeshi*; Naganawa, Akihiro*; Oka, Kiyoshi; Chiba, Toshio*
Keisoku Jido Seigyo Gakkai Sangyo Rombunshu, 9(10), p.70 - 75, 2010/04
The fetoscopic laser photocoagulation of chorionic plate anastomosing vessels is main treatment for the twin-twin transfusion syndrome. However, in this treatment, it is required highly endoscopic technologies, for example, blood flow measurement, estimation of distance between placental vessels and irradiation fiber tip and so on. We research and develop a composite-type optical fiberscope (2.2 mm in diameter), which has centrally-located cautery laser fiber and surrounding located fiberglasses for viewing. The laser transmitting efficiency of our fiberscope was very high (84.7%), and certain degree of cauterization was performed with from 20 to 40W laser power, when the distance between irradiated area and fiber tip was 10 mm. In addition, we emitted the laser to porcine liver for laser power control using a thermocouple as a basic research for intercepting placental blood flow, and we controlled the temperature of irradiation spot within 0.3
C error in previous paper. In this study, we emitted the laser to in vivo porcine mesenteric vessel with blood flow for laser power control under temperature measurement. From the experimental result, the target temperature of 60 and 70C with feedback control system using thermocouple was controlled low power of about 17W maintain target temperature within 2.0C error. Moreover, we measured the blood flow before and after laser irradiation by a laser Doppler blood-flow meter, and confirmed quantitatively the blood flow blocking.
Seki, Takeshi*; Naganawa, Akihiro*; Oka, Kiyoshi; Yoshino, Junji*
Nihon Kompyuta Geka Gakkai-Shi, 12(1), p.33 - 42, 2010/03
no abstracts in English
Seki, Takeshi*; Oka, Kiyoshi; Naganawa, Akihiro*; Yamashita, Hiromasa*; Kim, K.*; Chiba, Toshio*
Minimally Invasive Therapy and Allied Technologies, 18(6), p.350 - 355, 2009/12
Times Cited Count：3 Percentile：16.09(Surgery)Fetoscopic laser photocoagulation of chorionic plate anastomosing vessels (FLPC) applies to the treatment of previable fetuses with severe twin-twin transfusion syndrome (TTTS). However, there has not been an established method to confirm that the blood flow is blocked. For this issue, we have developed a composite-type optical fiberscope (2.2 mm in diameter). This fiberscope enables transmission of 50 W Yb fiber laser which can be focused to 10 mm focal length using two lenses on the fiberscope tip. In this study, we combined the fiberscope and a laser blood-flow meter, and irradiated cautery laser to porcine mesenteric vein with measuring blood flow at the same time. From the experimental results, we could quantitatively measure the blood flow before and after laser irradiation, and confirm the blood flow blocking with our system.
Amamoto, Ippei; Kofuji, Hirohide; Myochin, Munetaka; Tsuzuki, Tatsuya*; Takasaki, Yasushi*; Yano, Tetsuji*; Terai, Takayuki*
Proceedings of 12th International Conference on Environmental Remediation and Radioactive Waste Management (ICEM '09/DECOM '09) (CD-ROM), 9 Pages, 2009/10
This study is carried out to make the pyroprocessing hold a competitive advantage. As one of the measures is to reduce the volume of HLW, the phosphate conversion method is applied for removal of FP from the spent electrolyte in this paper. Though the removing target elements in the electrolyte are alkali metals, alkaline earth metals and lanthanoid elements, only lanthanoid elements and lithium form the insoluble phosphates by reaction with Li
PO
. Therefore, as the first step, the precipitation experiment was carried out to observe the behaviours of elements which form the insoluble precipitates. Then the filtration was experimented to remove precipitates in the spent electrolyte using Fe
O-PO
glass system as a filtlation medium which is compatible material with the glassification. The result of separation of precipitates by filtration was effective and attained almost 100
.
Kofuji, Hirohide; Amamoto, Ippei; Sasaki, Kazuya*; Yasumoto, Masaru*; Takasaki, Yasushi*; Myochin, Munetaka; Terai, Takayuki*
Denki Kagaku Oyobi Kogyo Butsuri Kagaku, 77(8), p.597 - 600, 2009/08
Times Cited Count：0 Percentile：0.01(Electrochemistry)The process flow of the phosphate conversion technique has been developed for the reduction of high-level radioactive waste (HLW) generated from the metal-electrorefining process. In this study, the results of thermodynamic calculations for the phosphate conversion reactions were examined by the basic experiments. The chlorides of rare earth elements (REE) turned out to be converted into phosphates easily. Furthermore, as the additive for the phosphate conversion reaction, high temperature behavior of lithium phosphate was evaluated to elucidate the thermodynamic property.
Ishikawa, Noriko; Oka, Kiyoshi; Naganawa, Akihiro*; Yoshino, Junji*; Wakabayashi, Takao*; Watanabe, Shinya*; Naito, Takehito*
Nihon Kikai Gakkai Rombunshu, C, 75(756), p.2359 - 2361, 2009/08
Instruments for measuring the internal pressure of digestive organs are used for diagnosing functional diseases, judging how critical the condition is, and deciding the treatment method or determining the degree of alleviation. However, the technique wherein the internal pressure of the small intestine is measured is highly invasive and painful for patients, and the insertion of the catheter via transducers is not preferred because it involves the insertion of an electric instrument in the body. In this study, we developed a system that measures the pressure of the small intestine with an ileus tube, which is generally used for the treatment of ileus. The main feature of our system is that can be used to measure internal pressure without the insertion of electric instruments such as transducers into the body, allowing the assessment of ileus without causing pain to the patient being treated. In this note, we present a brief description of the structure and function of this instrument used to measure the internal pressure of the small intestine.
Amamoto, Ippei; Kofuji, Hirohide; Myochin, Munetaka; Takasaki, Yasushi*; Terai, Takayuki*
Journal of Nuclear Materials, 389(1), p.142 - 148, 2009/05
Times Cited Count：15 Percentile：68.94(Materials Science, Multidisciplinary)The spent electrolyte of the pyroprocessing by metal electrorefining method should be considered for recycling after removal of FP, such as AL (alkali metals), ALE (alkaline earth metals), and/or REE (rare-earth elements), to reduce the volume of HLW. Authors have been carrying out theoretical analysis and experiment showing the behaviours of phosphate precipitates so as to estimate the feasibility of the phosphate conversion method. From hitherto results, it was found that AL except Li, and ALE are unlikely formed phosphate precipitates. However, their conversion behaviours including REE were compatible with former presented theoretical analysis; in the case of lanthanum precipitate as one of REE, submicron-size particles could be observed while that of LiPO was larger; under different conversion temperatures, the precipitates were apt to grow larger at higher temperature; etc..
Oka, Kiyoshi; Nakamura, Tetsuya*; Ueda, Hirohisa*; Toriya, Tomoaki*; Tsumanuma, Koji*; Naganawa, Akihiro*; Watanabe, Shinsuke*; Ishiyama, Akihiko*; Yamashita, Hiromasa*; Chiba, Toshio*
no journal, ,
no abstracts in English
Kofuji, Hirohide; Amamoto, Ippei; Yasumoto, Masaru*; Takasaki, Yasushi*; Sasaki, Kazuya*; Myochin, Munetaka; Terai, Takayuki*
no journal, ,
Phosphate conversion process for recycling spent electrolyte originated from pyrochemical reprocessing has been studied. Feasibility of the process has been evaluated thermodynamically based on basic experiments. Current situation of phosphate conversion experiments and the estimations of thermodynamic properties will be introduced in this presentation.
Iwata, Yoshihiro*; Ishii, Keizo*; Yokota, Wataru; Kamiya, Tomihiro; Sato, Takahiro; Oikawa, Masakazu*
no journal, ,
no abstracts in English
Seki, Takeshi*; Naganawa, Akihiro*; Oka, Kiyoshi; Yamashita, Hiromasa*; Chiba, Toshio*
no journal, ,
We developed a new laser device using the composite-type optical fiberscope for laser surgery for twin-twin transfusion syndrome. A composite-type optical fiberscope (2.2 mm in diameter) consists of a centrally located single fiber for laser treatment and its surrounding fibers for diagnosis. This fiberscope enables transmission of 50-W Yb fiber laser. The Yb fiber laser can focus laser to 10 mm focal length using two lenses on tip of the fiberscope. In this paper, we describe the experimental results of temperature control during blood-flow interception of porcine mesenteric venous flow and measure blood flow before and after laser irradiation for evaluation blood flow interception.
Amamoto, Ippei
no journal, ,
no abstracts in English
