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Yamaguchi, Akinori*; Yokotsuka, Muneyuki*; Furuta, Masayo*; Kubota, Kazuo*; Fujine, Sachio*; Mori, Kenji*; Yoshida, Naoki; Amano, Yuki; Abe, Hitoshi
Nihon Genshiryoku Gakkai Wabun Rombunshi (Internet), 21(4), p.173 - 182, 2022/09
Risk information obtained from probabilistic risk assessment (PRA) can be used to evaluate the effectiveness of measures against severe accidents in nuclear facilities. The PRA methods used for reprocessing facilities are considered immature compared to those for nuclear power plants, and to make the methods mature, reducing the uncertainty of accident scenarios becomes crucial. In this paper, we summarized the results of literature survey on the event progression of evaporation to dryness caused by boiling of high-level liquid waste (HLLW) which is a severe accident in reprocessing facilities and migration behavior of associated radioactive materials. Since one of the important characteristics of Ru is its tendency to form volatile compounds over the course of the event progression, the migration behavior of Ru is categorized into four stages based on temperature. Although no Ru has been released in the waste in the high temperature region, other volatile elements such as Cs could be released. Sufficient experimental data, however, have not been obtained yet. It is, therefore, necessary to further clarify the migration behavior of radioactive materials that predominantly depends on temperature in this region.
Osaka, Masahiko; Konashi, Kenji*; Hayashi, Hirokazu; Li, D.*; Homma, Yoshiya*; Yamamura, Tomoo*; Sato, Isamu; Miwa, Shuhei; Sekimoto, Shun*; Kubota, Takumi*; et al.
Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 5 Pages, 2011/12
Summer schools for future experts have successfully been completed under Japan Actinide Network (J-ACTINET) for the purpose of development of human resources who are expected to be engaged in every areas of actinide-research/engineering. The first summer school was held in Ibaraki-area in August 2009, followed by the second one in Kansai-area in August 2010. Two summer schools have focused on actual experiences of actinides in actinide-research fields for university students and young researchers/engineers as an introductory course of actinide-researches. Several quasi actinide-handling experiences at the actinide-research fields have attracted attentions of participants at the first school in Ibaraki-area. The actual experiments using actinides-containing solutions have been carried out at the second school in Kansai-area. Future summer schools will be held every year for the sustainable human resource development in various actinide-research fields.
Fang, Z.*; Michizono, Shinichiro*; Anami, Shozo*; Yamaguchi, Seiya*; Naito, Fujio*; Fukui, Yuji*; Kawamura, Masato*; Kubota, Chikashi*; Nammo, Kesao*; Kobayashi, Tetsuya; et al.
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.1434 - 1436, 2010/05
The output energy of the J-PARC proton linac will be upgraded from 181 to 400 MeV in the next two years by adding high-b acceleration sections. The upgrade of the FPGA-based digital LLRF controller for the 400 MeV linac will be presented in this paper. This new LLRF controller works for both the 324-MHz low-b and 972-MHz high-b sections. Many functions have been added into the LLRF controller, such as (1) working for different RF systems, (2) gradually increasing the feedback gains in the feedback loop instead of fixed ones, (3) automatic chopped beam compensation, (4) automatically switching the beam loading compensation in accordance with different beam operation mode, (5) input RF-frequency tuning to match the RF cavities during RF start-up, and (6) auto-tuning of the RF cavity tuner by detecting the phase curve of the RF cavity during the field decay instead of the phase difference between the cavity input and output signals.
Hasegawa, Kazuo; Kobayashi, Tetsuya; Kondo, Yasuhiro; Morishita, Takatoshi; Oguri, Hidetomo; Hori, Yoichiro*; Kubota, Chikashi*; Matsumoto, Hiroshi*; Naito, Fujio*; Yoshioka, Masakazu*
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.621 - 623, 2010/05
The J-PARC RFQ accelerates a negative hydrogen beam from 50 keV to 3 MeV. Beam commissioning of the J-PARC linac started in November 2006 and the linac has delivered beams to the 3 GeV synchrotron since September 2007. Trip rates of the RFQ, however, unexpectedly increased in September 2008. We tried to recover by tender conditioning, improvement of vacuum properties, etc. User operations for the Material and Life Experimental Facilities were successfully carried out at 20 kW in June 2009, and the beam power was increased to 120 kW in November. The high power operation at 300 kW for one hour was also demonstrated. Status and improvement of the J-PARC RFQ are presented.
Hasegawa, Kazuo; Morishita, Takatoshi; Kondo, Yasuhiro; Oguri, Hidetomo; Kobayashi, Tetsuya; Naito, Fujio*; Yoshioka, Masakazu*; Matsumoto, Hiroshi*; Kawamata, Hiroshi*; Hori, Yoichiro*; et al.
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.693 - 695, 2010/03
The J-PARC RFQ (length 3.1m, 4-vane type, 324 MHz) accelerates a beam from the ion source to the DTL. The beam test of the linac was started in November 2006 and 181 MeV beam was successfully accelerated in January 2007. Since then, the linac has been delivered beams for commissioning of the linac itself, downstream accelerators and facilities. Trip rates of the RFQ, however, suddenly increased in Autumn 2008, and we are suffering from this issue for user run operation. We tried to recover by tender conditioning, modification of RF control, improvement of vacuum and so on. We manage to have beam operation. In this report, we describe the status of the RFQ.
Morishita, Takatoshi; Ao, Hiroyuki; Ito, Takashi; Ueno, Akira; Hasegawa, Kazuo; Ikegami, Masanori*; Kubota, Chikashi*; Takasaki, Eiichi*; Tanaka, Hirokazu*; Naito, Fujio*; et al.
Proceedings of 2nd Annual Meeting of Particle Accelerator Society of Japan and 30th Linear Accelerator Meeting in Japan, p.266 - 268, 2005/07
J-PARC linear accelerator components are now being installed in the accelerator tunnel. Markings are placed on the floor, which act as a reference for the initial alignment at the installation. A planned and ongoing alignment schemes for the installation of linac components and watching the long term motion of the building are described.
Morishita, Takatoshi; Ao, Hiroyuki; Ito, Takashi; Ueno, Akira; Hasegawa, Kazuo; Ikegami, Masanori*; Kubota, Chikashi*; Naito, Fujio*; Takasaki, Eiichi*; Tanaka, Hirokazu*; et al.
Proceedings of 2005 Particle Accelerator Conference (PAC '05) (CD-ROM), p.2851 - 2853, 2005/00
In J-PARC linac, a precise alignment of accelerator components is essential for high quality beam acceleration. Markings have been placed on the floor, which act as a reference for the initial alignment at the installation. For a straight line alignment, the wire position sensor is placed on the offset position with respect to the beam center by a target holder. The hydrostatic levering system is used for watching the floor elevation over the long period.
Morishita, Takatoshi; Ao, Hiroyuki; Ito, Takashi; Ueno, Akira; Hasegawa, Kazuo; Ikegami, Masanori*; Kubota, Chikashi*; Takasaki, Eiichi*; Tanaka, Hirokazu*; Naito, Fujio*; et al.
Proceedings of 1st Annual Meeting of Particle Accelerator Society of Japan and 29th Linear Accelerator Meeting in Japan, p.671 - 673, 2004/08
A precise alignment of accelerator components is essential for the J-PARC linear accelerator. The wire position sensor is applied to measure the accelerator component positioning and the ground motion of the building is measured by the hydrostatic leveling sensors. In this paper, the scheme of the alignment system is presented.
Kondo, Yasuhiro; Akikawa, Hisashi; Anami, Shozo*; Asano, Hiroyuki*; Fukui, Yuji*; Igarashi, Zenei*; Ikegami, Kiyoshi*; Ikegami, Masanori*; Ito, Takashi; Kawamura, Masato*; et al.
Proceedings of 1st Annual Meeting of Particle Accelerator Society of Japan and 29th Linear Accelerator Meeting in Japan, p.156 - 158, 2004/08
A commissioning of the J-PARC linac DTL1 is now under way at KEK. A 30mA H
beam was accelerated to 19.7-MeV, and 100% transmission was obtained with a 20-msec-pulse-width and 12.5-Hz-repetition beam. In this paper, present status of the DTL1 commissioning and preliminary results of the commissioning, such as emittance measurements, are presented.
Sato, Susumu; Tomisawa, Tetsuo; Hiroki, Fumio; Lee, S.*; Igarashi, Zenei*; Ikegami, Masanori*; Ueno, Akira; Kondo, Yasuhiro; Hasegawa, Kazuo; Toyama, Takeshi*; et al.
Proceedings of 1st Annual Meeting of Particle Accelerator Society of Japan and 29th Linear Accelerator Meeting in Japan, p.467 - 469, 2004/08
As a joint project of KEK and JAERI, a MW class of high intensity proton accelerator (J-PARC), consisting of Linac, 3 GeV-RCS, 50 GeV-MR, is under construction. For this accelerator, it is required to minimize the beam loss (typically, lower than0.1
1 W/m at the linac). To achieve the requirement, beam trajectory needs to be controlled with accuracy of some 100 
m. The first stage of the acceleration (up to 181 MeV during the first stage of construction) is done by linac. The beam position monitor (BPM) in the linac utilizes 4 stripline pickups (50 ohm) on the beam transportation chamber. In this paper, systematic calibration of the BPM is described.
Sato, Susumu; Igarashi, Zenei*; Lee, S.*; Tomisawa, Tetsuo; Hiroki, Fumio; Kishiro, Junichi; Ikegami, Masanori*; Kondo, Yasuhiro; Hasegawa, Kazuo; Ueno, Akira; et al.
Proceedings of 22nd International Linear Accelerator Conference (LINAC 2004), p.429 - 431, 2004/00
As a joint project of KEK and JAERI, a MW class of high intensity proton accelerator (J-PARC), consisting of Linac, 3 GeV-RCS, 50 GeV-MR, is under construction at Tokai, Japan. For this accelerator, it is required to minimize the beam loss (typically, lower than 0.11 W/m at the linac). To achieve the requirement, beam trajectory needs to be controlled with accuracy of some 100 micro-meter. The first stage of the acceleration (up to 181 MeV during the first stage of construction) is done by linac. The beam position monitor (BPM) in the linac utilizes 4 strip-line pickups (50 ohm) on the beam transportation chamber. In this paper, systematic calibration of the BPM is described.
Kubota, Shigeru*; ; Okutsu, Kazuo*; Horita, M.*; Amemiya, Kiyoshi*
PNC TJ1449 98-001, 1944 Pages, 1998/02
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Aoki, Kenji*; Hibiya, Keisuke*; Shiogama, Yukihiro*; Toida, Masaru*; Yamamoto, T.*; Yoshida, Hiroshi*; Banno, K.*; Kubota, T.*; Shimizu, Y.*; Okutsu, Kazuo*; et al.
PNC TJ1100 94-001, 69 Pages, 1994/02
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