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Journal Articles

Establishment of Fukui Smart Decommissioning Technology Demonstration Base; Decommissioning Technology Demonstration Test Center (tentative name)

Muramatsu, Toshiharu; Sano, Kazuya; Terauchi, Makoto

Dekomisshoningu Giho, (57), p.65 - 74, 2018/03

The Decommissioning Technology Demonstration Test Center (tentative name) is established as a central facility of "Fukui Smart Decommissioning Technology Demonstration Base" which was adopted by the support policy "Regional Science and Technology Demonstration Base Establishment Project" of the Ministry of Education, Culture, Sports, Science and Technology in FY 2016 supplementary budget. This facility is a base to train local companies about technology concerning the decommissioning of nuclear power plants and for the industry, academia and government to contribute to the development of the regional economy and solving the problem of decommissioning under one roof, and consists of decommissioning dismantling technology verification field, laser processing advanced field and decommissioning mock-up test field. The papers introduce the outline of the facilities in each of these fields.

Journal Articles

Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12

The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.

Journal Articles

Technology development on reactor dismantling and investigation of contamination in FUGEN

Soejima, Goro; Iwai, Hiroki; Nakamura, Yasuyuki; Hayashi, Hirokazu; Kadowaki, Haruhiko; Mizui, Hiroyuki; Sano, Kazuya

Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 5 Pages, 2017/07

no abstracts in English

JAEA Reports

Applicability test of abrasive water jet cutting technology for dismantling of the core internals of Fukushima Daiichi NPS

Nakamura, Yasuyuki; Iwai, Hiroki; Tezuka, Masashi; Sano, Kazuya

JAEA-Technology 2015-055, 89 Pages, 2016/03

JAEA-Technology-2015-055.pdf:17.54MB

It was reported that Fukushima Daiichi Nuclear Power Station (1F) had lost the cooling function of the reactor by the Tohoku Earthquake. It is assumed that the core internals became narrow and complicated debris structure mixed with the molten fuel. In consideration of the above situations, the AWJ cutting method, which has features of the long work distance and little heat effect for a material, has been developed for the removal of the molten core internals through cutting tests for 3 years since FY 2012. And it was confirmed that AWJ cutting method is useful for the removal of the core internals etc. The results in FY 2012 were reported in "R&D of the fuel debris removal technologies by abrasive water jet cutting technology (JAEA-Technology 2013-041)" and this report summarizes the results of FY 2012, 2013 and 2014 in this report. It was confirmed the possibility to apply the removal work of the fuel debris and the core internals.

JAEA Reports

Applicability test of plasma cutting technology for dismantling of the core internals of Fukushima Daiichi NPS

Tezuka, Masashi; Nakamura, Yasuyuki; Iwai, Hiroki; Sano, Kazuya

JAEA-Technology 2015-047, 114 Pages, 2016/03

JAEA-Technology-2015-047.pdf:46.17MB

It was reported that Fukushima Daiichi Nuclear Power Plant had been lost the function of cooling the reactor by the Tohoku Earthquake. It is assumed that the original shapes of the internal core are not kept and the inside of the reactor makes so narrow in the space, however the fuel debris and the molten internal core will have to be removed for the decommissioning of 1F. We concerned the suppression of dross by optimization of cutting conditions, in using some moderated test pieces. And we can improve the cutting capability by heating the objects in advance. Moreover, it's possible that plasma arc cutting can cut off the mixed material the fuel debris and the molten internal core by using the cooperation cutting technique both the plasma arc and the plasma jet cutting. From these results, we have got the prospect that plasma cutting method can apply the removal of the fuel debris and the molten internal core.

JAEA Reports

The Development of the basic dismantling procedure of the reactor of FUGEN

Iwai, Hiroki; Nakamura, Yasuyuki; Mizui, Hiroyuki; Sano, Kazuya

JAEA-Technology 2015-046, 110 Pages, 2016/03

JAEA-Technology-2015-046.pdf:85.22MB

Advanced Thermal Reactor (ATR) FUGEN is a proto-type heavy water moderated, boiling light water cooled, pressure tube-type reactor with the thermal power of 557 MW and the electrical power of 165 MW. The reactor of FUGEN is classified into the core region and the shielding region. The core region is highly activated owing to the long term operation, and characterized by its tube-cluster construction that contains 224 fuel channels arranging both the pressure and the calandria tubes coaxially in each channel closely. And the shielding region surrounding the core region has the laminated structure composed of up to 150 mm thickness of carbon steel. The reactor is planning to be dismantled under water remotely in order to shield the radiation around the core and prevent airborne dust generated by the cutting, and firing of zirconium material. This paper reports on the result of development of the basic dismantling procedure of the reactor of FUGEN.

JAEA Reports

The Selection of the cutting technologies for dismantling the FUGEN reactor

Nakamura, Yasuyuki; Iwai, Hiroki; Mizui, Hiroyuki; Sano, Kazuya

JAEA-Technology 2015-045, 137 Pages, 2016/03

JAEA-Technology-2015-045.pdf:27.77MB

FUGEN is 9 m outer-diameter and 7m height, and characterized by its tube-cluster construction that contains 224 fuel channels arranging both the pressure and the calandria tubes coaxially in each channel. And the periphery part of the core has the laminated structure composed of up to 150 mm thickness of carbon steel for radiation shielding. The structure of the reactor, which is made of various materials such as stainless steel, carbon steel, zirconium alloy and aluminum. The reactor is planning to be dismantled under water in order to shield the radiation ray around the core and prevent airborne dust generated by the cutting, the temporary pool structure and the remote-operated dismantling machines needs to be installed on the top of reactor. In consideration of above the structure of Fugen reactor, the cutting method was selected for dismantling the reactor core in order to shorten the dismantling term and reduce the secondary waste.

Journal Articles

The Study on application of laser technology for the reactor core dismantling

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.

Journal Articles

Application of measurement and evaluation method on the clearance system of the Fugen NPP for dismantled equipment of turbine system

Hayashi, Hirokazu; Soejima, Goro; Mizui, Hiroyuki; Sano, Kazuya

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05

In the Fugen Nuclear Power Plant, we are going to conduct appropriate classification of the waste according to the contamination level of the material of the plant, to reduce the amount of radioactive waste and to promote dismantling work rationally and efficiently. For this reason, we are going to apply the clearance system to the dismantled material generated from dismantling work of the turbine system, and to reduce the radioactive waste amount as much as possible. In order to operate the clearance system properly, the target nuclides need to be selected accurately, and the evaluation method of them should be established. The assessment was conducted as follows.

Journal Articles

Relaxation behavior of laser-peening residual stress under tensile loading investigated by X-ray and neutron diffraction

Akita, Koichi; Hayashi, Kengo*; Takeda, Kazuya*; Sano, Yuji*; Suzuki, Hiroshi; Moriai, Atsushi; Oya, Shinichi*

Mechanical Engineering Journal (Internet), 1(4), p.SMM0029_1 - SMM0029_8, 2014/08

Compressive residual stresses induced by peening techniques improve the strength properties of steels, such as fatigue and stress corrosion cracking. However, the compressive residual stress might be reduced owing to thermal and mechanical loading in-service. In this study, the behavior of surface and internal residual stresses of a laser-peened ferritic steel under quasi-static tensile loading was investigated by X-ray and neutron diffraction. The complementary use of these diffraction techniques provided decisive experimental evidence for elucidating the relaxation process. The critical applied stress of peened samples subjected to a tensile loading can be estimated from the von Misses yield criterion with the maximum tensile residual stress inside the sample.

Journal Articles

The Development of thermal and mechanical cutting technology for the dismantlement of the internal core of Fukushima Daiichi NPS

Tezuka, Masashi; Nakamura, Yasuyuki; Iwai, Hiroki; Sano, Kazuya; Fukui, Yasutaka

Journal of Nuclear Science and Technology, 51(7-8), p.1054 - 1058, 2014/07

 Times Cited Count:5 Percentile:51.05(Nuclear Science & Technology)

The cutting technologies for removing the fuel debris and the internal core structure in 1F are needed in consideration of the situation in the core and so on. On the other hand, JAEA has been carrying out the decommissioning of the nuclear facilities ending the R&D, has several technologies and knowledge to dismantle the nuclear facilities. In particular, the cutting technologies of the plasma arc, the laser, and the abrasive water jet (AWJ) and the plasma jet have been developed. Therefore, based on the above, JAEA has carried out the cutting test for investigating the applicability of those cutting technologies to propose the method for removing the fuel debris and the internal core structure to the national project. In this paper, it is outlined on the test results of the plasma arc and the AWJ cutting technologies, and the future plan of the test of those technologies and the plasma jet cutting technology.

JAEA Reports

R&D of the fuel debris removal technologies by abrasive water jet cutting technology

Iwai, Hiroki; Nakamura, Yasuyuki; Tezuka, Masashi; Sano, Kazuya

JAEA-Technology 2013-041, 57 Pages, 2014/02

JAEA-Technology-2013-041.pdf:7.01MB

It was reported that Fukushima Daiichi Nuclear Power Plant (1F) had been lost the function of cooling the reactor by the Tohoku Earthquake. It is assumed that the original shapes of the internal core are not kept and the inside of the reactor makes so narrow in the space, however the fuel debris and the molten internal core will have to be removed for the decommissioning of 1F. The cutting methods for those removal works will have to be selected depending on the situation of the inside of the reactor. In consideration of above situations, the abrasive water jet cutting method, Fugen has much data of underwater cutting for the reactor dismantling and there are experiences of the reactor maintenance and dismantling in both domestic and international, will be being developed for the fuel debris removal works and so on. In the fiscal year 2012, in order to confirm the cutting performance of the cutting machine, the cutting tests were carried out to acquire the fundamental data.

JAEA Reports

R&D of the fuel debris removal technologies by plasma arc cutting technology

Nakamura, Yasuyuki; Tezuka, Masashi; Iwai, Hiroki; Sano, Kazuya

JAEA-Technology 2013-040, 80 Pages, 2014/02

JAEA-Technology-2013-040.pdf:4.29MB

It was reported that Fukushima Daiichi Nuclear Power Plant (1F) had been lost the function of cooling the reactor by the Tohoku Earthquake. It is assumed that the original shapes of the internal core are not be kept and the inside of the reactor make so narrow in the space, however the fuel debris and the molten internal core will have to be removed for the decommissioning of 1F. The cutting methods for those removal works will have to be selected depending on the situation of the inside of the reactor. In consideration of above situations, the plasma-arc cutting method, Fugen has much data of underwater cutting for the reactor dismantling and there are experiences of the reactor dismantling in both domestic and international, will be being developed for the fuel debris removal works and so on.

Journal Articles

Counter-anion effect on the properties of anion-conducting polymer electrolyte membranes prepared by radiation-induced graft polymerization

Koshikawa, Hiroshi; Yoshimura, Kimio; Sinnananchi, W.; Yamaki, Tetsuya; Asano, Masaharu; Yamamoto, Kazuya*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Maekawa, Yasunari

Macromolecular Chemistry and Physics, 214(15), p.1756 - 1762, 2013/08

 Times Cited Count:11 Percentile:54.91(Polymer Science)

Graft-type anion-conducting polymer electrolyte membranes were prepared by the radiation-induced graft polymerization of chloromethylstyrene into poly(ethylene-co-tetrafluoroethylene) (ETFE) films and subsequent quaternization with trimethylamine to evaluate the counter anion effects on fuel cell properties. The hydroxide form was maintained in -saturated water to prevent the bicarbonate formation. The hydroxide form showed conductivity and water uptake four and two times higher than the chloride and bicarbonate forms. The hydroxide form is thermally and chemically less stable, resulting in the tendency to absorb water and to convert to the bicarbonate form.

Journal Articles

Radwaste reduction technology for spent resins

Aizawa, Hideyuki*; Katagiri, Genichi*; Sano, Kazuya; Higashiura, Norikazu

Fuji Denki Homu Peji and Fuji Denki America Sha Homu Peji (Internet), 11 Pages, 2012/04

In a nuclear power plant, spent IXR (hereafter called SR), low-level radioactive waste, is produced from water purification systems in association with the operation of the plant. These SR are different in a radioactive concentration depending on purification systems, and SR which is relatively higher in the radioactivity concentration is stored in the nuclear power plant. Stored amounts continue to increase year after year. In Japan, it is planned that SR will be buried in the ground in the future as a "waste solid" which is solidified in a specific metal container. In terms of securing long-term soundness of the waste solids, it is said the solidification of the SR is required after stabilization treatment is performed. Moreover, SR with high radioactivity concentration requires higher disposal expenses; therefore, the reduction of the disposal volume is required in terms of cost-cutting. To realize these requirements, processing technologies are required which satisfy both the volume reduction and stabilization of the SR at once. Fuji Electric is continuing to develop LPOP technology and the equipment (FRR: Fuji Resin Reducer) as technologies to respond to these requirements. LPOP treatment is a technology enabling realization of both volume reduction and stabilization of SR which is low-level radioactive waste. Fuji Electric post the overview of LPOP technology and the results of mineralization of ion exchange resin and solidification tests executed for the purpose of evaluating the effect of LPOP treatment aiming the burial disposal on our website.

Journal Articles

Development of laser cutting technology for reactor decommissioning process

Kobayashi, Kojiro*; Ida, Toshio*; Yamaguchi, Takeshi*; Daido, Hiroyuki; Muramatsu, Toshiharu; Sano, Kazuya; Tsuboi, Akihiko*; Shamoto, Hideyasu*; Ikeda, Takeshi*

Reza Kako Gakkai-Shi, 19(1), p.63 - 67, 2012/03

Laser cutting method, is that the metal melted by laser power is removed by assist gas, has some advantages which are high speed cutting 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 150 mm 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.

Journal Articles

Laser cutting technologies under water for the nuclear reacter dismantlement

Kobayashi, Kojiro*; Ida, Toshio*; Yamaguchi, Takeshi*; Daido, Hiroyuki; Muramatsu, Toshiharu; Sano, Kazuya; Tsuboi, Akihiko*; Shamoto, Hideyasu*; Ikeda, Takeshi*

Yosetsu Gijutsu, 59(7), p.64 - 69, 2011/07

no abstracts in English

Journal Articles

Relaxation behaviour of laser peening residual stress due to mechanical loading on aluminum alloy

Miyashita, Daisuke*; Takeda, Kazuya*; Oya, Shinichi*; Sano, Yuji*; Saito, Toshiyuki*; Akita, Koichi

Zairyo, 60(7), p.617 - 623, 2011/07

The surface residual stress relaxation under tensile loading occurred when the plastic-deformation started at the inside of material where the balancing tensile residual stress existed. Under the compressive loading, the surface residual stress relaxation started due to the plastic deformation beneath the surface where the maximum compressive residual stress existed. The plastic deformation at the inside of material caused the redistribution of the residual stress and resulted in the relaxation of the surface residual stress. For both tensile and compressive loading, the surface compressive residual stress relaxation occurred before the total stress (= (residual stress) + (applied stress)) at the surface reached to the yield condition. The conclusions of this study are thought to be able to apply to the behavior of the residual stress under the mechanical loading on metallic materials treated by any mechanical surface treatment.

Journal Articles

The Study on abrasive water jet for predicting the cutting performance and monitoring the cutting situation in the water

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:0 Percentile:100(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.

Journal Articles

Preparation of anion-exchange membranes for fuel cell applications by $$gamma$$-ray pre-irradiation grafting

Koshikawa, Hiroshi; Yamaki, Tetsuya; Asano, Masaharu; Maekawa, Yasunari; Yamaguchi, Susumu*; Yamamoto, Kazuya*; Asazawa, Koichiro*; Yamada, Koji*; Tanaka, Hirohisa*

Proceedings of 12th International Conference on Radiation Curing in Asia (RadTech Asia 2011) (Internet), p.240 - 241, 2011/06

The anion-exchange membranes (AEM) for fuel cells were prepared by the radiation-induced graft polymerization of chloromethylstyrene into poly(ethylene-co-tetrafluoroethylene) (ETFE) films and subsequent quaternization of the grafts with trimethylamine. When the AEM were treated in 1M-KOH and washed with N$$_{2}$$-saturated water, the membranes with chloride form can be converted quantitatively to hydroxide form. However, the hydroxide form was easily converted to the bicarbonate form by the treatment in non-bubbled (CO$$_{2}$$ dissolved) water. When we introduced the crosslinkers in polymer grafts, which is proved to be very effective in the proton conducting PEM having a poly(styrenesulfonic acid) grafts, the grafted AEM with both chloride and hydroxide forms showed only slight decrease of water uptake. It should be noted that AEM with hydroxide form showed very high tendency to absorb water.

111 (Records 1-20 displayed on this page)