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Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Meigo, Shinichiro; Maekawa, Fujio
JPS Conference Proceedings (Internet), 45, p.011174_1 - 011174_10, 2026/06
A 30 MW continuous wave proton linac is devised by the Japan Atomic Energy Agency (JAEA) for the use of Accelerator Driven Subcritical System (ADS) technology. The efficiency of the accelerator is crucial for the realization of ADS in terms of minor actinides management. Therefore, it is necessary to assess the overall efficiency of the different components to ensure the accelerator's feasibility. This study estimated the power required to operate RF cavities, considering effects such as beam loading and microphonics. Additionally, the contribution of cryogenics was considered by calculating the heat load generated by the cryomodules, as well as the power consumption of auxiliary systems such as magnets. In this analysis, we will present the efficiency estimations of the JAEA-ADS linac, as well as the methodology used to obtain the results.
Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Meigo, Shinichiro; Maekawa, Fujio
JPS Conference Proceedings (Internet), 45, p.011173_1 - 011173_7, 2026/06
The Japan Atomic Energy Agency (JAEA) is carrying out research and development on an Accelerator Driven Subcritical System (ADS) for nuclear transmutation. The JAEA-ADS consists of a CW superconducting proton linac of 30 MW coupling with a subcritical core reactor. The linac will accelerate a 20-mA proton beam to a final energy of 1.5 GeV, starting with a Normal Conducting section up to 2.5 MeV, and followed by a Superconducting part. More than 300 LLRF systems will control longitudinal parameters of the RF structures that compose the linac. In addition to ensuring stability on RF settings for efficient linac performance, the JAEA-ADS LLRF system will also enable fault-tolerance compensations to increase the availability of the linac, which is a major challenge for ADS operation. In this work, we will discuss the necessity of the ADS LLRF and present a proposed model that satisfies these demands.
Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Meigo, Shinichiro; Maekawa, Fujio; Miyamoto, Ryoichi*; Milas, N.*; Eshraqi, M.*
Proceedings of 22nd International Conference on RF Superconductivity (SRF2025) (Internet), p.58 - 62, 2026/04
The European Spallation Source (ESS) superconducting proton linac is currently undergoing commissioning. During the initial operation phase, the final beam energy will be about 800 MeV, reaching a 2 MW power. High reliability and availability are crucial for the success of the ESS science programs and thus operations will be maintained even with failures of main linac components such as cavities and quadrupoles, as long as ~50 percent of the intended power can be achieved. To this end, we developed beam optics strategies to address failures in the cavities of the superconducting linac. Due to the constraints in the RF cavity amplitudes, we implemented a modified version of standard cavity compensation techniques. The results indicated that this strategy enables beam recovery that meets the beam quality specifications, thereby enhancing the availability of the ESS linac.
Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Meigo, Shinichiro; Maekawa, Fujio; Pla
ais, A.*; Bouly, F.*
Proceedings of 22nd International Conference on RF Superconductivity (SRF2025) (Internet), p.316 - 320, 2026/04
High-intensity accelerators, particularly Accelerator-Driven Systems (ADS), require high availability and reliability for proper operation. For superconducting linear accelerators, the ability to continue operating even when one of the RF cavities fails is key to achieving the required availability, known as cavity compensation. Beam dynamics studies of the JAEA-ADS linear accelerator have demonstrated the possibility of operating with multiple RF cavities disabled with acceptable beam quality. Several other superconducting linear accelerator laboratories have adopted similar methods and developed their procedures. Among these efforts, the LightWin tool has proven to be an effective tool for automatically and systematically identifying compensation settings for each cavity failure in any linear accelerator. This software has been successfully utilized on the MINERVA linac, as well as on the high-energy part of the JAEA-ADS linac. It has currently been tested and improved to ease SPIRAL2 operation. This work presents an analysis of cavity compensation in the JAEA-ADS superconducting linear accelerator using the LightWin tool and compares the results with previous studies.
Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Meigo, Shinichiro; Maekawa, Fujio
Proceedings of 22nd Annual Meeting of Particle Accelerator Society of Japan (Internet), p.130 - 134, 2026/03
Accelerator-Driven Systems (ADS) represent an efficient solution to the challenge of nuclear waste disposal. Therefore, the Japan Atomic Energy Agency (JAEA) is designing a 30-MW proton linac as a key element of its proposal for the use of ADS technology. A key feature of ADS accelerators is their extremely high availability and reliability that is required to avoid thermal stress on reactor structures. To this end, JAEA-ADS adopted a combined strategy of hot standby in the front part of the linac and standby element compensation as a fast and efficient way to reduce the downtime due to an element failure. The JAEA-ADS injector is mainly composed of a normal conducting section and ends with the first section of superconducting cavities (Half Wave Resonator). This paper presents the details of the optics design of the JAEA-ADS injector and the results of beam dynamics simulations.
Takei, Hayanori
Journal of Nuclear Science and Technology, 62(11), p.1051 - 1070, 2025/11
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)The 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 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.205 - 209, 2024/10
The Japan Atomic Energy Agency (JAEA) designs a 30-MW CW proton linear accelerator (linac) as a key component for the accelerator-driven subcritical system (ADS) project, aimed at nuclear waste management. The low energy beam transport (LEBT) in JAEA-ADS uses charge neutralization to minimize space-charge effects, which are the primary cause of beam loss in high-power accelerators. During commissioning and power ramp-up, precise control of the duty cycle is required for safety and machine protection; thus, a chopper system will be installed to manage the beam power. The chopper is located at the LEBT, to facilitate the disposal of the excess beam power, but its operation will affect the charge neutralization producing beam transients that could lead to beam loss. To shed light on this, we created a beam optics model for the chopper using an analytic approach to determine the required characteristics like voltage and dimensions, which was confirmed through TraceWin simulations. Subsequently, we analyzed the chopper's impact on space-charge compensation to evaluate the beam transients in the LEBT. This study reports the design of the chopper and its effects on beam performance for the JAEA-ADS LEBT.
Yee-Rendon, B.; Kondo, Yasuhiro; Tamura, Jun; Maekawa, Fujio; Meigo, Shinichiro
Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.545 - 549, 2023/11
The Japan Atomic Energy Agency (JAEA) is proposing a 30-MW proton linear accelerator (linac) for the application of accelerator-driven subcritical system (ADS) technology to achieve nuclear waste transmutation. A major challenge for the JAEA-ADS linac is the efficient transport of a 35 keV proton beam from the ion source to the radio-frequency quadrupole. In order to achieve this goal, we have optimized a magnetostatic low energy beam transport (LEBT) consisting of two solenoids to reduce the transmission of high-charge ions generated by the source and minimize the growth of proton emittance, while taking into account various space-charge compensation scenarios. In this report, we present the optical design and discuss the multiparticle tracking results of 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：4.66(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.
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：6 Percentile：54.61(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.
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：58.99(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.
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.
Hasegawa, Kazuo; Hayashi, Naoki; Oguri, Hidetomo; Yamamoto, Kazami; Kinsho, Michikazu; Yamazaki, Yoshio; Naito, Fujio; Koseki, Tadashi; Yamamoto, Noboru; Yoshii, Masahito
Proceedings of 9th International Particle Accelerator Conference (IPAC '18) (Internet), p.1038 - 1040, 2018/06
Tsujimoto, Kazufumi; Oigawa, Hiroyuki; Ouchi, Nobuo; Kikuchi, Kenji; Kurata, Yuji; Mizumoto, Motoharu; Sasa, Toshinobu; Nishihara, Kenji; Saito, Shigeru; Umeno, Makoto*; et al.
Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 6 Pages, 2005/10
The Japan Atomic Energy Research Institute (JAERI) has been proceeding with the research and development (R&D) on accelerator-driven subcritical system (ADS). The ADS proposed by JAERI is a lead-bismuth (Pb-Bi) eutectic cooled fast subcritical core with 800 MWth. To realize such an ADS, some technical issues should be studied, developed and demonstrated. JAERI has started a comprehensive R&D program since the fiscal year of 2002 to acquire knowledge and elemental technology that are necessary for the validation of engineering feasibility of the ADS. The first stage of the program had been continued for three years. The program is conducted by JAERI, and many institutes, universities and private companies were involved. Items of R&D are concentrated on three technical areas peculiar to the ADS: (1) superconducting linear accelerator (SC-LINAC), (2) Pb-Bi eutectic as spallation target and core coolant, and (3) subcritical core design and technology. In the present work, the outline and the results in the first stage of the program are reported.
Yamazaki, Yoshishige
Proceedings of 9th European Particle Accelerator Conference (EPAC 2004), p.1351 - 1353, 2004/00
The J-PARC (Japan Proton Accelerator Research Complex) is under construction in JAERI Tokai site. The beam commissioning will start there by the end of 2006. Prior to this, the front end of the linac was beam-commissioned in 2003 at KEK. The negative hydrogen beam with a peak current of 30 mA was accelerated up to 20 MeV by the first tank of the three DTL's following the 3-MeV RFQ linac. The 324-MHz DTL contains the electro quadrupole magnets with water-cooling channels specially fabricated by means of electroforming and wire-cutting technologies. The construction status of the J-PARC accelerator is also presented.
Yamazaki, Yoshishige
Proceedings of 2003 Particle Accelerator Conference (PAC 2003) (CD-ROM), p.576 - 580, 2003/00
The JAERI-KEK Joint Project for the High Intensity Proton Accelerator, now referred to as the J-PARC Project (Japan Proton Accelerator Research Complex), comprises a 400-MeV linac, a 3-GeV, 25-Hz Rapid-Cycling Synchrotron (RCS), and a 50-GeV Main Synchrotron (MR). In contrast to the SNS or the ESS, the J-PARC makes use of the RCS in order to produce MW-class pulsed spallation neutrons rather than a combination of the full-energy linac and the compressor ring.
Ao, Hiroyuki; Hayashizaki, Noriyosu*; Paramonov, V.*
Proceedings of 2003 Particle Accelerator Conference (PAC 2003) (CD-ROM), p.2826 - 2828, 2003/00
An Annular Coupled Structure (ACS) has been developed for upgrade of a J-PARC (Japan Proton Accelerator Research Complex) linac from 180 MeV to 400 MeV. Although install area is prepared for the ACS cavities at an initial construction, it will be used as a beam-transport line temporarily. Aluminum and copper models were fabricated for RF properties confirmation based on an initial design, and for final optimization. RF measurement procedure of the ACS structure was also studied thorough the R&D process. Many items should be considered for mass production; schedule, handling parts, utilities, and so on. The measurement results of models and some fabrication status are presented.
Oigawa, Hiroyuki; Ouchi, Nobuo; Kikuchi, Kenji; Tsujimoto, Kazufumi; Kurata, Yuji; Sasa, Toshinobu; Takano, Hideki; Nishihara, Kenji; Saito, Shigeru; Futakawa, Masatoshi; et al.
Proceedings of GLOBAL2003 Atoms for Prosperity; Updating Eisenhower's Global Vision for Nuclear Energy (CD-ROM), p.1374 - 1379, 2003/00
JAERI is developing an Accelerator Driven System (ADS) for transmutation of nuclear waste such as minor actinide and long-lived fission product. To acquire the knowledge and the elemental technology that are necessary for the validation of engineering feasibility of ADS, JAERI has started a comprehensive research and development (R&D) program since 2002. The first stage of the program will be continued for three years. The program is conducted by JAERI with many institutes, universities and private companies. Items of R&D are concentrated on three technical areas peculiar to ADS: (1) a superconducting linear accelerator, (2) lead-bismuth eutectic as spallation target and core coolant, and (3) subcritical core design and physics. The outline and the preliminary results of the program are summarized in the present report.
Oigawa, Hiroyuki; Sasa, Toshinobu; Takano, Hideki; Tsujimoto, Kazufumi; Nishihara, Kenji; Kikuchi, Kenji; Kurata, Yuji; Saito, Shigeru; Futakawa, Masatoshi; Umeno, Makoto*; et al.
Proceedings of 13th Pacific Basin Nuclear Conference (PBNC 2002) (CD-ROM), 8 Pages, 2002/10
To reduce the burden on the final disposal of the nuclear waste, the Acclelerator-Driven System (ADS) which can transmute minor actinides efficiently has been studied in JAERI. The proposed ADS design is an 800MWth subcritical core with lead-bismuth coolant and minor-actinide nitride fuel driven by a neutron source of a superconductivity linear accelerator with 30MW and a lead-bismuth spallation target. To realize the ADS, many research and development are under way in the fields of the accelerator, the spallation target and the nitride fuel. Moreover, a new experimental facility, the Transmutation Experimental Facility, is proposed under a framework of the High-Intensity Proton Accelerator Project to study the feasibility of the ADS from physics and engineering aspects.
