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Iwai, Hiroki; Nakamura, Yasuyuki; Mizui, Hiroyuki; Sano, Kazuya; Morishita, Yoshitsugu
Proceedings of 7th International Congress on Laser Advanced Materials Processing (LAMP 2015) (Internet), 4 Pages, 2015/08
The reactor of FUGEN is characterized by its tube-cluster construction that contains 224 channels arranging both the pressure and the calandria tubes coaxially in each channel. And the periphery part of the core has the laminated structure of up to 150 mm thickness of carbon steel for radiation shielding. Method for dismantling the reactor core is also being studied with considering processes of dismantlement by remote-handling devices under the water for the radiation shielding. In order to shorten the term of the reactor dismantlement work and reduce the secondary waste, some cutting tests and literature research for various cutting methods had been carried out. As the result, the laser cutting method, which has feature of the narrow cutting kerf and the fast cutting velocity, was mainly selected for dismantling the reactor. In this presentation, current activities of FUGEN decommissioning and R&D of laser cutting tests are introduced.
Nakamura, Yasuyuki; Sano, Kazuya; Morishita, Yoshitsugu; Maruyama, Shinichiro*; Tezuka, Shinichi*; Ogane, Daisuke*; Takashima, Yuji*
Journal of Engineering for Gas Turbines and Power, 133(6), p.064501_1 - 064501_3, 2011/06
Times Cited Count：1 Percentile：11.98(Engineering, Mechanical)Abrasive water jet (AWJ), is to shoot the abrasive mixed with high-pressure water to the material for cutting, can cut most materials like metals and concretes in water with long stand-off means the length from the cutting head to the material for cutting. On the other hand, AWJ is required to reduce an amount of the abrasive because it becomes the waste. It is also difficult to monitor the cutting condition by any visual methods like a TV camera in the water becoming cloudy by both used abrasive and cut metal grit. For solving these issues, some cutting tests were conducted and (1) It was possible to predict an optimal supply rate of abrasive by considering the conservation of momentum between the water jet and the abrasive. (2) It was also possible to judge whether the material could be cut successfully or not by detecting the change in the frequency characteristics of vibration or sound caused during the cutting process.
Yanagie, Hironobu*; Kumada, Hiroaki*; Nakamura, Takemi; Higashi, Shushi*; Ikushima, Ichiro*; Morishita, Yasuyuki*; Shinohara, Atsuko*; Fujiwara, Mitsuteru*; Suzuki, Minoru*; Sakurai, Yoshinori*; et al.
Proceedings of 14th International Congress on Neutron Capture Therapy (ICNCT-14) (CD-ROM), p.157 - 160, 2010/10
Hasegawa, Shin; Sato, Ken*; Narita, Tadashi*; Suzuki, Yasuyuki; Takahashi, Shuichi; Morishita, Norio; Maekawa, Yasunari
Journal of Membrane Science, 345(1-2), p.74 - 80, 2009/12
Times Cited Count：33 Percentile：70.33(Engineering, Chemical)Radiation-induced graft polymerization of styrene into poly(ether ether ketone) (PEEK) with 32% crystallinity was investigated with DSC, TGA, XRD, and ESR. Endothermic heats of melting of the original and styrene-grafted PEEK (grafted PEEK) films were similar, indicating the crystallinity was almost completely maintained up to a grafting degree of 51%. Lower glass transition temperature of the grafted PEEK film in the DSC, and the absence of an extra halo originating from amorphous polystyrene grafts in the XRD strongly indicate the grafting of styrene to crystalline PEEK films proceeded in the amorphous region of PEEK. This is probably because polystyrene grafts have hydrocarbon structures similar to a base PEEK polymer, resulting in compatibility to the amorphous phase of the PEEK films. The grafted PEEK films can be converted to PEEK-based electrolyte membranes by subsequent sulfonation, and had conductivity of more than 0.01 S/cm and exhibited higher water content above 100%.
Tezuka, Masashi; Mizui, Hiroyuki; Matsushima, Akira; Nakamura, Yasuyuki; Hayashi, Hirokazu; Sano, Kazuya; Nanko, Takashi; Morishita, Yoshitsugu
Proceedings of International Conference on Advanced Nuclear Fuel Cycle; Sustainable Options & Industrial Perspectives (Global 2009) (CD-ROM), p.2815 - 2821, 2009/09
FUGEN is a proto-type heavy water moderated, boiling light water cooled, pressure tube type reactor with 165MWe and has been shut downed on Mar. 2003. Following the approval of decommissioning program in 2008, stage of FUGEN was changed to the decommissioning of the facilities. The program consists of following four periods; (1) Spent fuel transportation, (2) Periphery facilities dismantlement, (3) Reactor dismantlement and (4) Building demolition. It is expected that the whole decommissioning will be completed until 2028. As a part of the work in the spent fuel transportation period, the main steam system and the feeder water system etc. are being dismantled in the turbine building. The remaining tritium in the heavy water system is also being removed for facilitating the dismantlement of the heavy water system. Moreover, method on dismantlement of the reactor core is being studied with considering the process under the water for the radiation shielding and the dust suppression.
Nakamura, Yasuyuki; Iwai, Hiroki; Sano, Kazuya; Morishita, Yoshitsugu; Maruyama, Shinichiro*; Tezuka, Shinichi*; Ogane, Daisuke*; Takashima, Yuji*
Dekomisshoningu Giho, (38), p.43 - 52, 2008/11
The advanced thermal reactor (Fugen) at Fugen Decommissioning Engineering Center is characterized by its tube-cluster construction. As a part of the study of dismantling, we are considering the abrasive water jet (AWJ) technique that could be used for the dismantlement techniques of double-tubes (pressure tube and calandria tube) as one of possible methods. As a part of tests, we confirmed the possibility of abrasive recycle for cutting and the applicability of cutting monitoring technique for reducing the volume of secondary wastes and developing the cutting monitoring technique in the water.
Nakamura, Yasuyuki; Kikuchi, Koichi; Morishita, Yoshitsugu; Usui, Tatsuo*; Ogane, Daisuke*
Proceedings of 14th International Conference on Nuclear Engineering (ICONE-14) (CD-ROM), 9 Pages, 2006/07
It is necessary to clarify the dismantlement method of 224 double tubes arranging both pressure and calandria tubes concentrically in the reactor as a peculiar problem of Fugen, in the case of phased dismantlement of the reactor. The machine type cutting is desirable, considering the influence on the atmospheres because the double tubes consist of the zirconium alloy and zircalloy material radio activated highly. Besides, Cutting method has long standoff to cut the double tubes at a time for to be short the term of dismantlement. is desirable. Therefore, it was examined to confirm the applicability to the double tubes cutting by abrasive water jet (hereinafter referred to as AWJ) as the machine type cutting method that can take the standoff comparatively longer. As a result, We confirmed for possibility of cutting the double tubes at a time from inside and outside tube, and cutting thick slab by abrasive water jet. Besides, We confirmed for relationship of abrasive supply and cutting velocity, properties of secondly waste.
Nakamura, Yasuyuki; Kikuchi, Koichi; Morishita, Yoshitsugu; Ogane, Daisuke*; Usui, Tatsuo*
no journal, ,
no abstracts in English
Nakamura, Yasuyuki; Morishita, Yoshitsugu; Kikuchi, Koichi; Usui, Tatsuo*; Ogane, Daisuke*
no journal, ,
As a peculiar issue of the decommissioning of FUGEN, it is necessary to establish a dismantlement method for the reactor having a 224 double-tubes structure arranged with pressure and calandria tubes concentrically. Mechanical cutting method will be desirable considering the influence on the atmospheres because the double-tubes consist of highly activated zirconium alloy and zircalloy material. Therefore, the abrasive water jet method was tested and examined as a mechanical double-tube cutting method that needs the standoff comparatively longer. We confirmed the applicability of the abrasive water jet method to the dismantlement of FUGEN's reactor. According to this cutting test, it is possible to cut slab at ca. 0.3-0.6kg/min of abrasive supply. (abrasive supply of AWJ is generally ca. 1.5-2.0kg/min.) And, 150mm thick of SUS were able to cut in the water by once.
Nakamura, Yasuyuki; Iwai, Hiroki; Sano, Kazuya; Morishita, Yoshitsugu
no journal, ,
no abstracts in English
Sano, Kazuya; Morishita, Yoshitsugu; Mori, Naoto; Nakamura, Yasuyuki; Ogawa, Takemitsu; Shamoto, Hideyasu*; Ozawa, Kenji*; Minehara, Eisuke*; Ida, Toshio*
no journal, ,
no abstracts in English
Sano, Kazuya; Nakamura, Yasuyuki; Mori, Naoto; Iwai, Hiroki; Morishita, Yoshitsugu
no journal, ,
Laser cutting method, is that the metal melted by laser power is removed by assist gas, has some advantages which are high speedcutting and narrow line-width cutting for the thin metal. We has conducted the joint research with the relevant organizations on the R&D of the laser cutting technology for cutting stainless and carbon steel of over the 150mm thickness which is maximum thickness of core structure in Fugen. We report the R&D plan and the current status of the laser cutting test.
