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Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.
Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09
Times Cited Count：6 Percentile：84.97(Nuclear Science & Technology)In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.
Fujihara, Masayoshi*; Morita, Katsuhiro*; Mole, R.*; Mitsuda, Setsuo*; Toyama, Takami*; Yano, Shinichiro*; Yu, D.*; Sota, Shigetoshi*; Kuwai, Tomohiko*; Koda, Akihiro*; et al.
Nature Communications (Internet), 11, p.3429_1 - 3429_7, 2020/07
Times Cited Count：37 Percentile：90.63(Multidisciplinary Sciences)Tamura, Koji*; Toyama, Shinichi
Nihon Genshiryoku Gakkai-Shi ATOMO
, 62(5), p.268 - 271, 2020/05
The laser cutting technology is expected to be a promising candidate for the decommissioning measure of nuclear facilities, because it has a lot of advantage such as its high controllability and excellent suitability to remote handling by robot arm, etcetera. This report describes the recent result from laser cutting technology development for thick steel materials summarizing the cutting demonstration of 300 mm thick steels and dummy pressure vessel, the analysis of cutting condition of thick steel cutting, the observation of cutting process, remote controlled cutting system, the cutting in pile of steels by the system, and countermeasure for fume produce by cutting process.
Tamura, Koji*; Toyama, Shinichi
Nihon Genshiryoku Gakkai-Shi ATOMO, 61(5), p.413 - 415, 2019/05
In decommissioning of nuclear reactors, it is necessary to disassemble the nuclear reactor structure. In addition to the conventional cutting method, the laser method has many advantages such as remote controllability and no need for replacement parts such as blades, which can be a powerful choice. Nuclear reactor structure such as a pressure vessel are made of steel materials with a thickness exceeding 100 mm, and the laser method has poor knowledge and experience in cutting such thick steel materials. Therefore, as a result of trial cutting of steel materials under various cutting conditions with the high power fiber laser which is progressively available nowadays, it has been demonstrated that laser cutting is also possible for thick plates such as those used in nuclear reactors, and cutting of thick steel plates. We also developed the cutting technology using remote control using a robot in order to apply it to the decommissioning of thick steel cutting on the spot.
Toyama, Shinichi; Minehara, Eisuke*
Dekomisshoningu Giho, (56), p.55 - 65, 2017/09
Development of the steel cutting technology which employs high power fiber laser for the industrial applicability of the laser technology has been carried out at The Wakasa Wan Energy Research Center (WERC). At present, the laser technologies for dismantling and decontamination are concurrently being developed to the application measure of nuclear dismantling for domestic nuclear power plants in the future. Dismantling of nuclear facilities is now under the development in the world. The necessity of the technology is increasing and the development is strongly expected. Beside the relative easiness to handle compared with other laser system, suppression of production of secondary radioactive waste and dose exposure can be realized by the dramatic improvement by excelled thermal density of fiber laser. This paper provides recent results from cutting technology for thick steels aiming disassembling nuclear pressure vessel, and decontamination machine technology which works under high radiation dose, explaining the results from cutting experiment of steels and the actual equipment and from the radiation resistance experiment for component devices.
Takebe, Shinichi; Kimura, Hideo; Matsuzuru, Hideo; Takahashi, Tomoyuki*; Yasuda, Hiroshi*; Uchida, Shigeo*; Mahara, Yasunori*; Saeki, Akiyoshi*; Sasaki, Noriyuki*; Ashikawa, Nobuo*; et al.
JAERI-Review 2001-015, 81 Pages, 2001/05
JAERI-Review-2001-015.pdf:5.94MB
no abstracts in English
; Hasegawa, Makoto; Toyama, Shinichi; Nomura, Masahiro; ; Hirano, Koichiro
Saikuru Kiko Giho, (9), p.29 - 39, 2000/12
None
Nomura, Masahiro; Toyama, Shinichi; ; ; Yamazaki, Yoshio; Hirano, Koichiro; Omura, Akiko
JNC TN9410 2000-007, 376 Pages, 2000/03
JNC-TN9410-2000-007.pdf:15.51MB
According to the Long-Term Program for Partitioning and Transmutation which was published by the Atomic Energy Commission in 1988, study on the transmutation using an electron accelerator, which was a part of the program, has been carried out in the O-arai Engineering Center. It is the study on converting radioactive fission products for example Strontium and Cesium to stable nuclides by photonuclear reaction caused by high energy gamma-ray made by an electron accelerator. It was thought that a 100mA-100MeV (10MW output power) accelerator would be needed in order to carry out the transmutation study in engineering phase. Therefore, development of the High-Current Electron Accelerator whose target had been 20mA-10MeV (200 kW output power) accelerator was carried out as development of elemental technologies on beam stabilization. The conceptual design of the accelerator was started in 1989. In March 1997, the main facility of this accelerator was completed. The test operation was carried out to confiim the performance of the accelerator from January, 1999 to December. As the result, an output of about 14 kW was achieved. In addition, the electron beam of 40 kW could be to accelerate in short time. In this report, the design, fabrication and evalution of performance of the facilities are presented.
; ; Toyama, Shinichi; Hasegawa, Makoto
JNC TN9410 2000-005, 182 Pages, 2000/03
JNC-TN9410-2000-005.pdf:5.73MB
According to the Long-term Program for Partitioning and Transmutation which was published by the Atomic Energy Commission in 1988, study on the transmutation using an electron accelerator, which was a part of the program, has been carried out in the O-arai Engineering Center. It is the study on converting radioactive fission products for example Strontium and Cesium to stable nuclides by photonuclear reaction caused by high energy gamma-ray made by an electron accelerator. It was thought that a 100mA-100Mev (10MW output power) accelerator would be needed in order to carry out the transmutation study in engineering phase. Therefore, development of the High-Current Electron Accelerator whose target had been 20mA-10Mev (200kW output power) accelerator was carried out as development of elemental technologies on beam stabilization. Construction of the accelerator was completed in March, 1997, afler development of the elemental devices. After the facility assessment, the full-scale experiment of the accelerator was started in January, 1999. However, the reform of the Power Reactor and Nuclear Fuel Development Corporation caused by the fire and explosion accident in the Asphalt Bitumenizing Facility was hardly discussed between the completion and the starting the experiment. It was decided that development of the accelerator would be terminated until the fiscal year 1999, results of the development would be summarized, and the developed accelerator would be planed to utilize as a beam utilization facility, in the Medium-Long-term Project Program of the Japan Nuclear Fuel Cycle Development Institute which was in March, 1999. It showed the direction that research and development for transmutation would be terminated. According to the Medium-Long-Term Project Program, the utilization of the accelerator was discussed, and research themes of the utilization of the accelerator in the various fields as well as nuclear field were investigated.
Takahashi, Tomoyuki*; Takebe, Shinichi; Kimura, Hideo; Matsuzuru, Hideo; Yasuda, Hiroshi*; Uchida, Shigeo*; Saeki, Akiyoshi*; Mahara, Yasunori*; Sasaki, Noriyuki*; Ashikawa, Nobuo*; et al.
KURRI-KR-44, p.169 - 176, 2000/02
no abstracts in English
; Toyama, Shinichi; Nomura, Masahiro; Hirano, Koichiro; Yamazaki, Yoshio; Sato, Isamu
JNC TN9400 99-073, 18 Pages, 1999/08
A short traveling wave accelerator with a traveling wave resonant ring is proposed for high beam current accelerators (including the linear accelerator, circular accelerator and storage ring). It is a normal conducting accelerator. The CW beam current can be as high as 10A. Such kind of accelerator unit has large beam holes for damping all of the cavity high order modes in order to avoid the resonant buildup of the fields that would cause multibunch instabilities at high currents. It has high efficiency, high power input capability and low K
. It is called "single mode" type. Even though beams are accelerated off the crest for phase stability in circular accelerator, the cavities do not need detuning.
Nomura, Masahiro; Toyama, Shinichi; ; ; Yamazaki, Yoshio; Hirano, Koichiro
JNC TN9410 99-009, 22 Pages, 1999/05
Design and construction of a high power CW electron linac was started in 1989 at PNC. The construction of the linac was completed in March 1997 and the beam commissioning was started in November 1998. After the beam commissioning, we have been successful to produce 420 
sec width electron beam with 74 mA peak and energy 8 Mev. In the beam test, we measured the radiation level in an electron gun room and pressure at chopper slits on the condition of 2 msec width electron beams. The preliminary results show those are going to be problems more than 100 kW high power operation . In those measurements, a vacuum leak was occurred at a ceramic duct. Now we are investigating the cause of this trouble. It is necessary to prepare beam monitors and interlock systems for long pulse beams and also high quality beams are required.
Toyama, Shinichi
JNC TN9400 99-039, 39 Pages, 1999/04
In Japan Nuclear Cycle Development Institute, the development of high current CW electron linear accelerator is in progress. It is possible for an accelerator to produce neutrons by means of a spallation and photo nuclear reactions. Application of neutron beam produced by bremsstrahlung is one of ways of the utilization for high current electron accelerator. It is actual that many electron linear accelerators which maximum energy is higher than a few hundreds MeV are used as neutron sources. In this report, an estimate of neutron production is evaluated for high current CW electron linear accelerator. The estimate is carried out by 10 MeV beam which is maximum energy limited from the regulation and rather low for neutron production. Therefore, the estimate is also done by 17 and 35 MeV beam which is possible to be accelerated. Beryllium is considered as a target for lower electron energy in addition to Lead target for higher energy, because Beryllium has low threshold energy for neutron production. The evaluation is carried out in account of the target thickness optimized by the radiation length and neutron cross section reducing the energy loss for both of electron and neutron, so as to get the maximum number of neutrons. The result of the calculations shows neutron numbers 1.9 
10
, 6.1 10
and 4.8 10 (n/s), respectively, for 10, 17,and 35 MeV with low duty. The thermal removal from the target is one of critical points. The additional shielding and cooling system is necessary in order to endure radiation. A comparison with other facilities are also carried out. The estimate of neutron numbers suggests the possibility to be applied for neutron radiography and measurement of nuclear data by means of Lead spectrometer, for example.
Omura, Akiko; Toyama, Shinichi; Hasegawa, Makoto; Tani, Satoshi
JNC TN9410 99-011, 92 Pages, 1999/03
JNC is investingating the best way to treat high-level radioactive nuclear waste from reactors. For basic research into the transmutation of fission products, JNC developed a high-power CW electron linac. Shielding of the radiation which leaks from beam dump and accelerating tube, it is necessary to establish the technology which can deal with the current enlargement as well as other accelerator element. In this report, shielding evaluation injector test of high-power CW electron linac is reported. As a result of the shielding evaluation, it was obtained that the management of the radiation was possible in the injector test under the dose equivalent limit. And, it was possible that problems such as operation and maintenance.
Toyama, Shinichi
PNC TN9410 98-075, 24 Pages, 1998/07
It is important for high current accelerators to estimate the contribution of the space charge effect to keep the beam off its beak up (BBU). The CW electron linac is designed in order to study BBU experimentally. The design is primary on the consideration which type of accelerator structure is suitable to reduce the BBU threshold, and how to observe and control BBU when it appears. The contribution of beam charge for the acceleration characteristics is surveyed by means of the comparison between traveling wave and standing wave structures in this report. At first, the characteristics of both traveling wave and standing wave structures are calculated analytically and the conversion efficiency and accelerator gain are presented. The merits and drawbacks are also mentioned concerning with unit accelerator length. Next, the choice of RF frequency on energy conversion is mentioned as independent matter of the types of accelerator structure. After that, the characteristics of TWRR are described as the advanced accelerator structure compared with above structures. The effect of longitudinal induced field is estimated by means of the loss parameter. The result from the analysis shows that the unit accelerator length is 1 m to get high conversion ratio from RF to beam power and that the BBU for transverse component is small. Therefore, total BBU is expected small in the accelerator, for transverse BBU is already expected small in previous reports.
; ; Toyama, Shinichi; Nomura, Masahiro; ; Hirano, Koichiro
Journal of Pressure Vessel Technology, -(-), - Pages, 1998/00
None
; ; Nomura, Masahiro; Yamazaki, Yoshio; Toyama, Shinichi; Hirano, Koichiro
Proceedings of The First Asian Particle Accelerator Conference (APAC98), 0 Pages, 1998/00
None
Emoto, Takashi; Wang, Y.; Toyama, Shinichi; Nomura, Masahiro; Takei, Hayanori; Hirano, Koichiro; Yamazaki, Yoshio; Omura, Akiko; Tanimoto, Yasunori*; Tani, Satoshi
PNC TN9410 98-010, 51 Pages, 1997/12
Design and construction of a high power CW (Continuous Wave) electron linac for studying feasibility of nuclear waste transmutation was started in l989 at PNC. The transmutation by photonuclear reaction using a electron accelerator has advantages of the small production for secondary radioactive waste and broad base of accelerator technology. The PNC accelerator (10 MeV, 20 mA average current, 20% duty) has been pre-commissioned. We have been very successful to produce 3 ms pulse width electron beam with 100 mA peak and energy about 2.9 MeV at present. The rest of the accelerating section was installed by March 1997. Studies are continued towards the designed goal of 100 mA beam with 4 msec pulse width and 50 Hz pulse repetition.
Takahashi, Tomoyuki; Takebe, Shinichi; Kimura, Hideo; Matsuzuru, Hideo; Yasuda, Hiroshi*; Uchida, Shigeo*; Saeki, Akiyoshi*; Mahara, Yasunori*; Sasaki, Noriyuki*; *; et al.
JAERI-Research 97-089, 25 Pages, 1997/12
JAERI-Research-97-089.pdf:1.11MB
no abstracts in English
Toyama, Shinichi
PNC TN9410 97-056, 46 Pages, 1997/09
It is important for high current accelerators to estimate the contribution of the space charge effect to keep the beam of its beak up, The application of an envelope equation is examined in previous report in which the beam is just coasting beam (non accelerating). The analysis of space charge effect is necessary for the comparison in coming accelerator test in PNC. In order to evaluate the beam behavior in high current, the beam dynamics and beam parameters which are input to the equation for the evaluation are developed and make it ready to estimate the beam transverse dynamics by the space charge. The estimate needs to have enough accuracy for advanced code calculation. After the preparation of the analytic expression of transverse motion, the non-linear differential equation of beam dynamics is solved by a numerical method on a personal computer. The beam envelope fFom the equation is estimated by means of the beam emittance, current and energy. The result from the analysis shows that the transverse beam broadening is scaresely small around the beam current value of PNC design. The contribution to the beam broadening of PNC linac comes from its beam emittance. The beam broadening in 100 MeV case is almost negligible in the view of transverse space charge effect. Therefore, the electron beam is stable up to 10 A order in PNC linac design. Of course, the problem for RF supply is out of consideration here. It is important to estimate other longitudinal effect such as beam bunch effect which is lasting unevaluated.
