New research programme of JAEA/CLADS to reduce the knowledge gaps revealed after an accident at Fukushima-1; Introduction of boiling water reactor mock-up assembly degradation test programme

Pshenichnikov, A.; Kurata, Masaki; Bottomley, D.; Sato, Ikken; Nagae, Yuji; Yamazaki, Saishun

Journal of Nuclear Science and Technology, 57(4), p.370 - 379, 2020/04

https://doi.org/10.1080/00223131.2019.1691070

Heterogeneity of BWR control blade degradation under steam-starved conditions

Pshenichnikov, A.; Yamazaki, Saishun; Nagae, Yuji; Kurata, Masaki

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05

High temperature oxidation test of simulated BWR fuel bundle in steam-starved conditions

Yamazaki, Saishun; Pshenichnikov, A.; Pham, V. H.; Nagae, Yuji; Kurata, Masaki; Tokushima, Kazuyuki*; Aomi, Masaki*; Sakamoto, Kan*

Proceedings of Annual Topical Meeting on Reactor Fuel Performance (TopFuel 2018) (Internet), 8 Pages, 2018/10

It is predictively evaluated that degradation of fuel assembly proceeded in a certain steam-starved condition at the early stage of a SA at 1F unit 2 (BWR). As for PWR fuel assembly, effective steam flow rate was properly indicated by normalizing to a unit of g-HO/sec/rod which is used as an important parameter for evaluating fuel degradation progression. Due to the inhomogeneous configuration of BWR fuel assembly, the difference of Zry oxidation and hydrogen uptake between the inside and outside of the channel box cannot be properly evaluated by this normalization. Instead of g-HO/sec/rod, proper evaluation unit for BWR configuration is necessary. To accumulate Zry oxidation and hydrogen uptake data for steam-starved conditions, high temperature oxidation tests were performed using a simulated BWR fuel bundle sample. The use of equivalent diameter of the cross section of BWR fuel assembly was proposed for normalization of effective steam flow rate.

Rod-filter-field optimization of the J-PARC RF-driven H ion source

Ueno, Akira; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Yamazaki, Saishun; Oguri, Hidetomo

AIP Conference Proceedings 1655, p.030010_1 - 030010_7, 2015/04

https://doi.org/10.1063/1.4916437

The J-PARC cesiated rf-driven H ion source was successfully developed to satisfy the J-PARC second stage requirements of an H ion beam of 60mA within normalized emittances of 1.5mmmrad both horizontally and vertically, a flat top beam duty factor of 1.25 and a life-time of longer than 1 month. In the source, the rod-filter-field effect was successfully tuned to produce the necessary beam with about 20 lower 2MHz rf-power by a newly devised method of the center-gapped rod-filter-magnets last year. In this paper, the rod-filter-filed optimization by using the trippel-gaps (TG) and two different cross-sections (RFM1:4.75mm10mm and RFM2:5mm10mm) of rod-filter-magnets are presented. With both of RFM1 and RFM2, the optimum rod-filter effect was produced with the gaps of around 2mm. However, it takes 5 times longer period to condition the source to produce the necessary beam with RFM2 compared with RFM1.

Beam test of a new radio frequency quadrupole linac for the Japan Proton Accelerator Research Complex

Kondo, Yasuhiro; Morishita, Takatoshi; Yamazaki, Saishun; Hori, Toshihiko; Sawabe, Yuki; Chishiro, Etsuji; Fukuda, Shimpei; Hasegawa, Kazuo; Hirano, Koichiro; Kikuzawa, Nobuhiro; et al.

Physical Review Special Topics; Accelerators and Beams, 17(12), p.120101_1 - 120101_8, 2014/12

https://doi.org/10.1103/PhysRevSTAB.17.120101

We performed a beam test of a new radio frequency quadrupole linac (RFQ III) for the beam current upgrade of the Japan Proton Accelerator Research Complex. First, the conditioning of RFQ III was conducted, and after 20 h of conditioning, RFQ III became very stable with a nominal peak power and duty factor of 400 kW and 1.5%, respectively. An off-line beam test was subsequently conducted before installation in the accelerator tunnel. The transmission, transverse emittance, and energy spread of the 50-mA negative hydrogen beam from RFQ III were measured and compared with simulation results. The experiment and simulation results showed good agreement; therefore, we conclude that the performance of RFQ III conforms to its design.

Present status of J-PARC linac

Oguri, Hidetomo; Hasegawa, Kazuo; Ito, Takashi; Chishiro, Etsuji; Hirano, Koichiro; Morishita, Takatoshi; Shinozaki, Shinichi; Ao, Hiroyuki; Okoshi, Kiyonori; Kondo, Yasuhiro; et al.

Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.389 - 393, 2014/10

http://www.pasj.jp/web_publish/pasj2014/proceedings/PDF/FSP0/FSP021.pdf

no abstracts in English

Operation status of the J-PARC ion source

Okoshi, Kiyonori; Ikegami, Kiyoshi*; Koizumi, Isao; Ueno, Akira; Takagi, Akira*; Yamazaki, Saishun; Oguri, Hidetomo

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.946 - 949, 2014/06

http://www.pasj.jp/web_publish/pasj10/proceedings/PDF/SUP0/SUP038.pdf

A J-PARC ion source driven with a LaB6 filament is being operated without any serious trouble since the restoration from the earthquake. The H ion current from the source is routinely restricted 19 mA for the filament lifetime. In order to increase the beam power at the linac beam operation, the beam current from the ion source was increased to 22 mA. At this operation, the filament lifetime was estimated by the reduction in the filament current. According to the steep reduction in the filament current, the break of the filament was predicted. Although the filament has broken after 10 h from the steep current reduction, the beam operation was restarted 8 h later by the preparation for the exchange of new filament. At the study time for the 3 GeV synchrotron, the ion source was operated at 30 mA for 8 days.

Development of a Cs-seeded RF-driven H ion source for the J-PARC

Yamazaki, Saishun; Ueno, Akira; Namekawa, Yuya*; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Koizumi, Isao; Oguri, Hidetomo

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.260 - 264, 2013/08

http://www.pasj.jp/web_publish/pasj9/proceedings/PDF/FRLR/FRLR08.pdf

A cesium (Cs) seeded RF-driven H ion source using an internal-antenna developed at the SNS (Spallation Neutron Source) is under development for the J-PARC (Japan Proton Accelerator Research Complex). The axial magnetic field optimization by using an axial magnetic field compensation (AMFC) coil significantly enhances the H ion beam by typically 10%. An H ion beam with a flat top duty factor of 2.5% (1 ms 25 Hz) of 77 mA, whose about 90% (corresponding to about 70 mA) of emittance of each direction is within 1.5 mmmrad, is successfully extracted. During a demonstration operation over 100-hours, an H ion beam over 66 mA was successfully produced with a relatively low RF power of about 40 kW by seeding Cs for 4-minutes a day.

Operation status of the J-PARC negative hydrogen-ion source

Oguri, Hidetomo; Ikegami, Kiyoshi*; Okoshi, Kiyonori; Koizumi, Isao; Namekawa, Yuya*; Ueno, Akira; Takagi, Akira*; Yamazaki, Saishun

AIP Conference Proceedings 1515, p.379 - 385, 2013/02

https://doi.org/10.1063/1.4792806

The J-PARC was extensively damaged by the earthquake in March 2011. The ion source had some damages such as dew condensation on the ion source surface due to the flooding in the accelerator tunnel, vacuum leakage due to the breaking of the viewing port and vacuum pump failure due to the strong quake. The restoration work was accomplished on schedule, and the linac beam operation was restarted in December 9th. The ion source supplies the beam to the accelerator without serious aftereffects of the earthquake. Availability of the ion source is one of the important issues because it is directly related to the operation time of the J-PARC. To evaluate the lifetime of the present ion source, we started 2 months beam operation. The results of recent four beam runs show the ion source is capable of continuous operation for approximately 1,200 hours with the beam current of 17 mA. For another attempt to enhance the ion source availability, we tried to decrease the time for maintenance to replace consumable elements. By unitizing the replacement elements and keeping them under the vacuum condition until just before the installing, the maintenance is completed within 24 hours without any beam performance degradation of the ion source.

Perfectly matched pulsed 2MHz RF network and CW 30MHz RF matching network for the J-PARC RF-driven H ion source

Ueno, Akira; Namekawa, Yuya*; Yamazaki, Saishun; Okoshi, Kiyonori; Koizumi, Isao; Ikegami, Kiyoshi*; Takagi, Akira*; Oguri, Hidetomo

AIP Conference Proceedings 1515, p.409 - 416, 2013/00

https://doi.org/10.1063/1.4792810

In order to satisfy the J-PARC second stage requirements a cesiated RF-driven H ion source using a internal-antenna developed at the Spallation Neutron Source (SNS) was developed. As similar as the SNS ion source, two matching networks for pulsed high-temperature 2MHz-RF plasma and CW low-temperature 30MHz-RF plasma are used. Each of them is composed of two vacuum variable condensers (VVCs). In order to supply pulsed 60kW - 2MHz-RF power from the power supply (PS) on the ground level, a one-turn isolation transformer using FINEMET cores is installed between the PS and the J-PARC ion source. Up to 46kW of pulsed 2MHz-RF power is successfully input to the plasma stably and with almost no reflected power.