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Journal Articles

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

 Times Cited Count:6 Percentile:71.03(Nuclear Science & Technology)

Journal Articles

Features of a control blade degradation observed ${it in situ}$ during severe accidents in boiling water reactors

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

Journal of Nuclear Science and Technology, 56(5), p.440 - 453, 2019/05

 Times Cited Count:7 Percentile:85.54(Nuclear Science & Technology)

Journal Articles

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

Journal Articles

The Behaviour of materials in case of solidified absorber melt - oxidized BWR channel box interaction revealed after CLADS-MADE-01 test

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

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05

Journal Articles

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-H$$_{2}$$O/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-H$$_{2}$$O/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.

Journal Articles

Operation status of the J-PARC ion source

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

JPS Conference Proceedings (Internet), 8, p.011009_1 - 011009_6, 2015/09

Journal Articles

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

 Times Cited Count:6 Percentile:47.51(Physics, Nuclear)

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.

Journal Articles

Beam test of a new RFQ for the J-PARC linac

Kondo, Yasuhiro; Morishita, Takatoshi; Yamazaki, Saishun; Hori, Toshihiko; Sawabe, Yuki; Takagi, Akira*

Proceedings of 27th International Linear Accelerator Conference (LINAC 2014) (Internet), p.267 - 269, 2014/12

We performed a beam test of a new 324-MHz 3-MeV H$$^{-}$$ RFQ (RFQ III) for the beam-current upgrade of the J-PARC linac. RFQ III is the first RFQ developed to meet the requirement of the J-PARC linac. The peak beam current is 50 mA, pulse length is 500 micro-sec, and the repetition is 25 Hz. Prior to the installation to the accelerator tunnel in summer of 2014, we constructed a test stand for off line testing of the new ion source and RFQ. Basic performances of RFQ III such as transmission and emittances were measured. In this paper, the beam test results are presented.

Journal Articles

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

no abstracts in English

Journal Articles

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

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.

Journal Articles

Development of a Cs-ceeded Rf-driven H$$^{-}$$ ion source for the J-PARC

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

Proceedings of 10th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.920 - 923, 2014/06

In order to satisfy the J-PARC (Japan Proton Accelerator Research Complex) 2nd stage requirements the J-PARC rf-driven H$$^{-}$$ ion source is under development. The source plasma is produced by an about 50 W CW 30 MHz-rf and an about 40 kW pulsed 2 MHz-rf. The Cs is installed into the plasma chamber by opening the Cs-valve between the plasma chamber and the Cs oven, which is heated to 200$$sim$$240 $$^{circ}$$C. The H$$^{-}$$ ion beam current is maximized by optimizing the Cs quantity depending upon the Cs-valve opening time, the PE temperature depending upon the flow rate of the air through the PE cooling plate, the AMFC by the AMFC coil current, and so on. The experimental results using the plasma chamber made of copper, which satisfied the above requirements, were reported last year. The experimental results using the plasma chamber made of stainless steel are presented in this paper. The observed several interesting differences between the two plasma chambers are also presented.

Journal Articles

Dependence of beam emittance on plasma electrode temperature and rf-power, and filter-field tuning with center-gapped rod-filter magnets in J-PARC rf-driven H$$^{-}$$ ion source

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

Review of Scientific Instruments, 85(2), p.02B133_1 - 02B133_5, 2014/02

 Times Cited Count:6 Percentile:33.97(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Operation status of the J-PARC ion source

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

Proceedings of 9th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1081 - 1083, 2013/08

no abstracts in English

Journal Articles

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

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 $$times$$ 25 Hz) of 77 mA, whose about 90% (corresponding to about 70 mA) of emittance of each direction is within 1.5 $$pi$$mm$$cdot$$mrad, 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.

Oral presentation

Development of RF-driven negative hydrogen ion source for J-PARC

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

no journal, , 

In order to achieve the design beam power of 1MW, a negative hydrogen ion source with a peak beam current of 60 mA is under development. The status of an rf-driven source using an rf-antenna developed at SNS of ORNL (Oak Ridge National Laboratory) is reported. The beam extraction system is the same with the J-PARC ion source, which is using a lanthanum hexaboride (LaB6) filament. The inner diameter of the plasma chamber is enlarged form 100 mm to 120 mm in order to install a water cooled plate attached to the plasma electrode (PE) and a cesium (Cs) oven. The end flange is modified to install the rf-antenna. A rod-filter flange is installed to produce a low-temperature plasma around the PE. In the conditions of the pulsed rf duty of 2.5%(1ms$$times$$25Hz), Cs oven temperature of 175 $$^{circ}$$C and the water cooled PE (PE temperature of 33 $$^{circ}$$C), a negative hydrogen ion beam with a peak beam current of 60 mA is successfully produced.

Oral presentation

Axial magnetic field effect for the J-PARC RF-driven ion source

Yamazaki, Saishun

no journal, , 

A cesium (Cs) seeded RF-driven H$$^{-}$$ ion source using an internal-antenna is under development for the Japan Proton Accelerator Research Complex (J-PARC). The J-PARC second stage requirements are an H$$^{-}$$ ion beam of 60 mA within normalized emittances of 1.5 $$pi$$mm$$cdot$$mrad both horizontally and vertically, and a flat top beam duty factor of 1.25% (500 $$mu$$s $$times$$ 25 Hz). An H$$^{-}$$ ion beam current of 77.5 mA with a flat top duty factor of 2% (800 $$mu$$s $$times$$ 25 Hz), whose approximately 90% (corresponding to approximately 70 mA) of each emittance is within 1.5 $$pi$$mm$$cdot$$mrad, is successfully extracted from it. The experimental results of axial magnetic field (AMF) optimization with an axial magnetic field correction (AMFC) coil, which significantly enhances the H$$^{-}$$ ion beam current by 10% typically, are presented in this meeting.

Oral presentation

Operation and development status of The J-PARC ion source

Yamazaki, Saishun

no journal, , 

A cesium-free H$$^{-}$$ ion source driven with a LaB$$_{6}$$ filament is being operated at the Japan Proton Accelerator Research Complex (J-PARC) without any serious trouble since the restoration from the March 2011 earthquake. The beam current from the source is routinely restricted approximately 19 mA for the lifetime of the filament. To increase the beam power at the linac beam operation, the beam current from the source was increased to 22 mA. At this operation, the lifetime of the filament 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. As a part of the beam current upgrade plan, the front end test stand consisting of the rf-driven H$$^{-}$$ ion source developed for the J-PARC 2nd stage requirements and the RFQ is under preparation.

Oral presentation

Specifications of CLADS test facilities for fuel degradation simulation

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

no journal, , 

Oral presentation

CLADS test facilities on BWR core material degradation

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

no journal, , 

Oral presentation

Focusing the test strategy of CLADS-MADE-01 and first results of the BWR control blade degradation test

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

no journal, , 

27 (Records 1-20 displayed on this page)