Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Takei, Hayanori
Journal of Nuclear Science and Technology, 45 Pages, 2025/06
Times Cited Count：0 Percentile：0.00The Japan Atomic Energy Agency is working on the research and development of an accelerator-driven nuclear transmutation system (ADS) for transmuting minor actinides. This system combines a subcritical nuclear reactor with a high-power superconducting proton linear accelerator (JADS-linac). One of the factors limiting the advancement of the JADS-linac is beam trips, which often induce thermal cycle fatigue, thereby damaging the components in the subcritical core. The average beam current of the JADS-linac is 32 times higher than that of the linear accelerator (linac) of the Japan Proton Accelerator Research Complex (J-PARC). Therefore, according to the development stage, comparing the beam trip frequency of the JADS-linac with the allowable beam trip frequency (ABTF) is necessary. Herein the beam trip frequency of the JADS-linac was estimated through a Monte Carlo program using the reliability functions based on the operational data of the J-PARC linac. The Monte Carlo program afforded the distribution of the beam trip duration, which cannot be obtained using traditional analytical methods. Results show that the frequency of the beam trips with a duration exceeding 5 min must be reduced to 27% of the current J-PARC linac level to be below the ABTF.
Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Maekawa, Fujio; Meigo, Shinichiro
Proceedings of 32nd Linear Accelerator Conference (LINAC 2024) (Internet), p.488 - 491, 2024/10
The Japan Atomic Energy Agency (JAEA) is designing a 30-MW CW proton linear accelerator (linac) for nuclear waste transmutation. Space-charge is the primary challenge in achieving low losses and high beam quality for high-power accelerators, especially at low energy levels where space-charge forces are greater. To counteract the space-charge effects, the low-energy beam transport (LEBT) uses a magnetostatic design to enable the neutralization of the beam charge, the so-called space charge compensation. The neutralization is an accumulation process that reaches a charge balance between the main beam and the opposite ionized particles. However, this equilibrium is destroyed by the chopper system used during beam ramping. During those transient regimes, the beam optics conditions are not optimal for the beam, producing considerable degradation that can end in serious damage to the accelerator. Thus, analysis of beam behavior at these periods is essential to develop a robust design and an efficient operation of the JAEA-ADS linac. This study presents the beam dynamics of neutralization build-up and chopper operation for the JAEA-ADS LEBT.
Jameson, R. A.*; Yee-Rendon, B.
Journal of Instrumentation (Internet), 17(12), p.P12011_1 - P12011_11, 2022/12
Times Cited Count：1 Percentile：5.86(Instruments & Instrumentation)A new application of vane modulation variation in a Radio Frequency Quadrupole (RFQ) cell has been applied that significantly improves beam bunching and longitudinal emittance control to achieve lower longitudinal rms emittance at the RFQ output. This procedure occurs in the individual cells, is independent of the overall design, and therefore is general, affording an extra parameter for beam manipulation. It can be applied besides the usual goals of vane modulation variation, e.g., to achieve higher acceleration efficiency. Examples of the cumulative effects on the overall design are provided to point out further exploration avenues for the designer.
Maekawa, Fujio
JAEA-Conf 2022-001, p.7 - 13, 2022/11
The partitioning and transmutation (P-T) technology has promising potential for volume reduction and mitigation of degree of harmfulness of high-level radioactive waste. JAEA is developing the P-T technology combined with accelerator driven systems (ADS). One of critical issues affecting the feasibility of ADS is the proton beam window (PBW) which functions as a boundary between the accelerator and the sub-critical reactor core. The PBW is damaged by a high-intensity proton beam and spallation neutrons produced in the target, and also by flowing high-temperature liquid lead bismuth eutectic alloy which is corrosive to steel materials. To study the materials damage under the ADS environment, J-PARC is proposing a plan of proton irradiation facility which equips with a liquid lead-bismuth spallation target bombarded by a 400 MeV - 250 kW proton beam. The facility is also open for versatile purposes such as soft error testing of semi-conductor devises, RI production, materials irradiation for fission and fusion reactors, and so on. Application to nuclear data research with using the proton beam and spallation neutrons is also one of such versatile purposes, and we welcome unique ideas from the nuclear data community.
Yee-Rendon, B.; Meigo, Shinichiro; Kondo, Yasuhiro; Tamura, Jun; Nakano, Keita; Maekawa, Fujio; Iwamoto, Hiroki; Sugawara, Takanori; Nishihara, Kenji
Journal of Instrumentation (Internet), 17(10), p.P10005_1 - P10005_21, 2022/10
Times Cited Count：0 Percentile：0.00(Instruments & Instrumentation)To reduce the hazard of minor actinides in nuclear waste, JAEA proposed an accelerator-driven subcritical system (JAEA-ADS). The JAEA-ADS drives a subcritical reactor 800-MWth by 30-MW proton linac delivering the beam to the spallation neutron target inside the reactor. The beam transport to the target (BTT) is required for high-beam power stability and low peak density to ensure the integrity of the beam window. Additionally, the design should have compatible with the reactor design for the maintenance and replacement of the fuel and the beam window. A robust-compact BTT design was developed through massive multiparticle simulations. The beam optics was optimized to guarantee beam window feasibility requirements by providing a low peak density of less than 0.3 
A/mm
. Beam stability was evaluated and improved by simultaneously applying the linac's input beam and element errors. The input beam errors to the reactor were based on the beam degradation obtained by implementing fast fault compensation in the linac. Those results show that the BTT fulfills the requirements for JAEA-ADS.
Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Nakano, Keita; Maekawa, Fujio; Meigo, Shinichiro
Physical Review Accelerators and Beams (Internet), 25(8), p.080101_1 - 080101_17, 2022/08
Times Cited Count：5 Percentile：54.12(Physics, Nuclear)High reliability and availability are primary goals for the operation of particle accelerators, especially for accelerator-driven subcritical systems (ADS). ADSs employ high-power beams for the transmutation of minor actinide; as a result, the amount and the radiotoxicity of the nuclear waste are considerably reduced. To this end, the Japan Atomic Energy Agency is designing a 30-MW continuous wave (cw) super-conducting proton linear accelerator (linac) that supplies neutrons to an 800-MW subcritical reactor by a spallation process. The major challenge for an ADS linac is the strict control of the beam trip duration and its frequency to avoid thermal stress in the subcritical reactor structures. The maximum allowed beam trips for failures longer than a few seconds are estimated to be far below the rate achieved in current accelerators. Thus, we implemented a combination of hot standby and local compensation that enables a fast beam recovery. This work comprehensively investigated the tolerance of our linac lattice for the local compensations for failures in superconducting cavities and magnets. This scheme includes simultaneous compensation of multiple cavities in independent and same cryomodules that significantly enhance the reliability of the linac. The returned schemes present acceptable beam performance to guarantee the integrity of the linac and the beam transport to the target; moreover, they satisfy the beam stability in the beam window. In addition, the readjusted elements are subjected to moderate stress to ensure a sustainable operation. This manuscript reports the beam dynamics results toward fulfilling the high reliability demanded by an ADS linac.
Maekawa, Fujio; Takei, Hayanori
Purazuma, Kaku Yugo Gakkai-Shi, 98(5), p.206 - 210, 2022/05
In developing an accelerator-driven nuclear transmutation system (ADS), it is necessary to solve technical issues related to proton beams, such as the development of materials that can withstand high-intensity proton beams and the characterization of subcritical cores driven by proton beams. Therefore, at the high-intensity proton accelerator facility J-PARC, a transmutation experimental facility that actually conducts various tests using a high-intensity proton beam is being planned. This paper introduces the outline and future direction of the transmutation experimental facility.
Nakano, Keita; Matsuda, Hiroki*; Meigo, Shinichiro; Iwamoto, Hiroki; Takeshita, Hayato*; Maekawa, Fujio
JAEA-Research 2021-014, 25 Pages, 2022/03
JAEA-Research-2021-014.pdf:2.1MB
For the development of accelerator-driven transmutation system (ADS), measurement of nuclide production cross-sections in proton-induced reactions on 
Be, C, 
Al, 
Sc, and V have been performed. The measured data are compared with the calculations by the latest nuclear reaction models and with the nuclear data library to investigate the reproducibilities.
Yee-Rendon, B.; Kondo, Yasuhiro; Maekawa, Fujio; Meigo, Shinichiro; Tamura, Jun
Physical Review Accelerators and Beams (Internet), 24(12), p.120101_1 - 120101_17, 2021/12
Times Cited Count：8 Percentile：63.12(Physics, Nuclear)The Japan Atomic Energy Agency (JAEA) is working on the research and development of a 30-MW continuous wave (CW) proton linear accelerator (linac) for the JAEA accelerator-driven subcritical system (ADS) proposal. The linac will accelerate a 20 mA proton beam to 1.5 GeV, using mainly superconducting cavities. The main challenge for an ADS accelerator is the high reliability required to prevent thermal stress in the subcritical reactor; thus, we pursue a robust lattice to achieve stable operation. To this end, the beam optics design reduces the emittance growth and the beam halo through the superconducting part of the linac. First, we simulated an ideal machine without any errors to establish the operation conditions of the beam. Second, we applied element errors and input beam errors to estimate the tolerance of the linac design. Finally, we implemented a correction scheme to increase the lattice tolerance by reducing the beam centroid offset on the transverse plane. Massive multiparticle simulations and a cumulative statistic of 1
10
macroparticles have shown that the JAEA-ADS linac can operate with less than 1 W/m beam losses in error scenarios.
Yoshimoto, Masahiro; Nakanoya, Takamitsu; Yamazaki, Yoshio; Saha, P. K.; Kinsho, Michikazu; Yamamoto, Shunya*; Okazaki, Hiroyuki*; Taguchi, Tomitsugu*; Yamada, Naoto*; Yamagata, Ryohei*
Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.850 - 854, 2021/10
no abstracts in English
Yee-Rendon, B.; Kondo, Yasuhiro; Maekawa, Fujio; Meigo, Shinichiro; Tamura, Jun
Proceedings of 12th International Particle Accelerator Conference (IPAC 21) (Internet), p.790 - 792, 2021/08
The Medium Energy Beam Transport (MEBT) will transport a CW proton beam with a current of 20 mA and energy of 2.5 MeV from the exit of the normal conducting Radiofrequency Quadrupole (RFQ) to the superconducting Half-Wave resonator (HWR) section. The MEBT must provide a good matching between the RFQ and HWR, effective control of the emittance growth and the halo formation, enough space for all the beam diagnostics devices, among others. This work reports the first lattice design and the beam dynamics studies for the MEBT of the JAEA-ADS.
for a mercury target induced by 3-GeV protonsMatsuda, Hiroki; Iwamoto, Hiroki; Meigo, Shinichiro; Takeshita, Hayato*; Maekawa, Fujio
Nuclear Instruments and Methods in Physics Research B, 483, p.33 - 40, 2020/11
Times Cited Count：3 Percentile：27.13(Instruments & Instrumentation)A thick target neutron yield for a mercury target at an angle of 180 from the incident beam direction is measured with the time-of-flight method using a 3-GeV proton beam at the Japan Proton Accelerator Research Complex (J-PARC). Comparing the experimental result with a Monte Carlo particle transport simulation by the Particle and Heavy Ion Transport code System (PHITS) shows that there are apparent discrepancies. We find that this trend is consistent with an experimental result of neutron-induced re- action rates obtained using indium and niobium activation foils. Comparing proton-induced neutron-production double-differential cross-sections for a lead target at backward directions between the PHITS calculation and experimental data suggests that the dis- crepancies for our experiments would be linked to the neutron production calculation around 3 GeV by the PHITS spallation model and/or the calculation of nonelastic cross-sections around 3 GeV in the particle transport simulation.
Matsuda, Hiroki; Meigo, Shinichiro; Iwamoto, Yosuke; Yoshida, Makoto*; Hasegawa, Shoichi; Maekawa, Fujio; Iwamoto, Hiroki; Nakamoto, Tatsushi*; Ishida, Taku*; Makimura, Shunsuke*
Journal of Nuclear Science and Technology, 57(10), p.1141 - 1151, 2020/10
Times Cited Count：15 Percentile：78.66(Nuclear Science & Technology)To estimate the structural damages of materials in accelerator facilities, displacement per atom (dpa) is widely employed as a damage index, calculated based on the displacement cross-section obtained using a calculation model. Although dpa is applied as standard, the experimental data of the displacement cross-section for a proton in the energy region above 20 MeV are scarce. Among the calculation models, difference of about factor 8 exist, so that the experimental data of the cross-section are crucial to validate the model. To obtain the displacement cross-section, we conducted experiments at J-PARC. The displacement cross-section of copper and iron was successfully obtained for a proton projectile with the kinetic energies, 0.4 - 3 GeV. The results were compared with those obtained using the widely utilized Norgertt-Robinson-Torrens (NRT) model and the athermal-recombination-corrected (arc) model based on molecular dynamics. It was found that the NRT model overestimates the present displacement cross-section by 3.5 times. The calculation results obtained using with the arc model based on the Nordlund parameter show remarkable agreement with the experimental data. It can be concluded that the arc model must be employed for the dpa calculation for the damage estimation of copper and iron.
Yee-Rendon, B.; Tamura, Jun; Kondo, Yasuhiro; Hasegawa, Kazuo; Maekawa, Fujio; Meigo, Shinichiro; Oguri, Hidetomo
Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.107 - 111, 2019/07
J-PARC Center
JAEA-Evaluation 2019-003, 52 Pages, 2019/06
JAEA-Evaluation-2019-003.pdf:6.61MB
Evaluation Committee of Research Activities for J-PARC for interim assessment of Japan Proton Accelerator Research Complex evaluated the management and research activities of J-PARC center on the explanatory documents and oral presentations during the period from April 2015 to December 2018. This report summarizes the results of the assessment by the Committee with the Committee report attached.
Hotchi, Hideaki; Watanabe, Yasuhiro; Harada, Hiroyuki; Okabe, Kota; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Yoshimoto, Masahiro
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.1041 - 1044, 2018/06
Hasegawa, Kazuo; Hayashi, Naoki; Oguri, Hidetomo; Yamamoto, Kazami; Kinsho, Michikazu; Yamazaki, Yoshio; Naito, Fujio*; Koseki, Tadashi*; Yamamoto, Noboru*; Hori, Yoichiro*
Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.2290 - 2293, 2017/06
The J-PARC is a high intensity proton facility and the accelerator consists of a 400 MeV linac, a 3 GeV Rapid Cycling Synchrotron (RCS) and a 30 GeV Main Ring Synchrotron (MR). We have taken many hardware upgrades such as front end replacement and energy upgrade at the linac, vacuum improvement, collimator upgrade, etc. The beam powers for the neutrino experiment and hadron experiment from the MR have been steadily increased by tuning and reducing beam losses. The designed 1 MW equivalent beam was demonstrated and user program was performed at 500 kW from the RCS to the neutron and muon experiments. We have experienced many failures and troubles, however, to impede full potential and high availability. In this report, operational performance and status of the J-PARC accelerators are presented.
Yamamoto, Kazami; Kamiya, Junichiro; Saha, P. K.; Takayanagi, Tomohiro; Yoshimoto, Masahiro; Hotchi, Hideaki; Harada, Hiroyuki; Takeda, Osamu*; Miki, Nobuharu*
Proceedings of 8th International Particle Accelerator Conference (IPAC '17) (Internet), p.579 - 581, 2017/05
The 3-GeV Rapid Cycling Synchrotron of Japan Proton Accelerator Research Complex aims to deliver 1-MW proton beam to the neutron target and Main Ring synchrotron. Present beam power of the Rapid Cycling Synchrotron is up to 500-kW and the higher radiation doses were concentrated in the injection area. These activations were caused by the interaction between the foil and the beam. To reduce the worker dose near the injection point, we have studied a new design of the injection scheme to secure enough space for radiation shielding and bellows. In the new system, two of four injection pulse bump magnets are replaced and we are able to ensure the additional space around the injection foil chamber. So far, new injection system seems not impossible. However, preliminary study result indicated that temperature of the duct and shielding metals would be slightly higher. The eddy current due to the shift bump magnet field generates heat. Thus we have to study details of above effect.
Iwamoto, Hiroki; Nishihara, Kenji; Iwamoto, Yosuke; Hashimoto, Shintaro; Matsuda, Norihiro; Sato, Tatsuhiko; Harada, Masahide; Maekawa, Fujio
Journal of Nuclear Science and Technology, 53(10), p.1585 - 1594, 2016/10
Times Cited Count：19 Percentile：82.12(Nuclear Science & Technology)Nishimura, Arata*; Muroga, Takeo*; Takeuchi, Takao*; Nishitani, Takeo; Morioka, Atsuhiko
Fusion Engineering and Design, 81(8-14), p.1675 - 1681, 2006/02
Times Cited Count：3 Percentile：23.21(Nuclear Science & Technology)In a fusion reactor plant, a neutral beam injector (NBI) will be operated for a long time, and it will allow neutron streaming from NBI ports to outside of the plasma vacuum vessel. It requires the superconducting magnet to develop nuclear technology to produce stable magnetic field and to reduce activation of the magnet components. In this report, the back ground of the necessity and the contents of the nuclear technology of the superconducting magnets for fusion application are discussed and some typical investigation results are presented, which are the neutron irradiation effect on Nb
Sn wire, the development of low activation superconducting wire, and the design concept to reduce nuclear heating and nuclear transformation by streaming. In addition, recent activities in high energy particle physics are introduced and potential ripple effect of the technology of the superconducting magnets is described briefly.
