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Oikawa, Kenichi; Kiyanagi, Yoshiaki*; Sato, Hirotaka*; Omae, Kazuma*; Pham, A.*; Watanabe, Kenichi*; Matsumoto, Yoshihiro*; Shinohara, Takenao; Kai, Tetsuya; Harjo, S.; et al.
Materials Research Proceedings, Vol.15, p.207 - 213, 2020/02
Kondo, Yasuhiro; Hasegawa, Kazuo; Higashi, Yasuo*; Sugawara, Hirotaka*; Yoshioka, Masakazu*; Kumada, Hiroaki*; Matsumoto, Hiroshi*; Naito, Fujio*; Kurokawa, Shinichi*
Proceedings of 7th International Particle Accelerator Conference (IPAC '16) (Internet), p.906 - 909, 2016/06
An accelerator based boron neutron capture therapy (BNCT) facility is being planned at Okinawa institute of science and technology (OIST). The proton accelerator consists of a radio frequency quadrupole (RFQ) linac and a drift tube linac (DTL). The required beam power is 60 kW. The present beam energy and current are 10 MeV and 30 mA, respectively. The pulse length is 3.3 ms and the repetition rate is 60 Hz, therefore, the duty factor is 20%. In this paper, present design of this compact, medium current, high duty proton linac is presented.
Kondo, Yasuhiro; Hasegawa, Kazuo; Higashi, Yasuo*; Kumada, Hiroaki*; Kurokawa, Shinichi*; Matsumoto, Hiroshi*; Naito, Fujio*; Yoshioka, Masakazu*
Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.948 - 950, 2015/09
An accelerator based boron neutron capture therapy (BNCT) facility is being planned at Okinawa institute of science and technology (OIST). The proton accelerator consists of a radio frequency quadrupole (RFQ) linac and a drift tube linac (DTL). The reqired beam power is 60 kW. The present beam energy and current are 10 MeV and 30 mA, respectively. The pulse length is 3.3 ms and the repetition rate is 60 Hz, therefore, the duty factor is 20%. In this paper, present designof this compact, midium current, high duty proton linac is presented.
Morishita, Takatoshi; Kondo, Yasuhiro; Hasegawa, Kazuo; Naito, Fujio*; Yoshioka, Masakazu*; Matsumoto, Hiroshi*; Hori, Yoichiro*; Kawamata, Hiroshi*; Saito, Yoshio*; Baba, Hiroshi*
Proceedings of 25th International Linear Accelerator Conference (LINAC 2010) (CD-ROM), p.521 - 523, 2010/09
The fabrication of a new RFQ has been started as a backup machine for the J-PARC linac. The RFQ cavity is divided by three unit tanks in the longitudinal direction. The unit tank consists of two major vanes and two minor vanes, those are brazed together. A one-step vacuum brazing of a unit tank was adopted to unite these four vanes together with the flanges and ports. At the first tank brazing, the vacuum leak has been occurred due to the non-uniform temperature rise during the heating. Repair of this leakage and the results of the improved brazing of the second tank are reported.
Morishita, Takatoshi; Kondo, Yasuhiro; Hasegawa, Kazuo; Kawamata, Hiroshi*; Naito, Fujio*; Yoshioka, Masakazu*; Matsumoto, Hiroshi*; Hori, Yoichiro*; Saito, Yoshio*; Baba, Hiroshi*
Proceedings of 25th International Linear Accelerator Conference (LINAC 2010) (CD-ROM), p.518 - 520, 2010/09
The fabrication of a new RFQ has been started in the J-PARC linac. The RFQ cavity is divided by three unit tanks in the longitudinal direction. The unit tank consists of two major vanes and two minor vanes, those will be brazed together. To reduce the costs and periods to develop the special formed bite for the modulation machining, a numerical controlled machining using a conventional ball-end-mill was adopted for the vane modulation cutting instead of the wheel shape cutter. The dimension accuracy was confirmed by cutting test pieces. Moreover, the obtained surface seems smooth enough for the operation. Results of the ball-end-mill machining for the vanes are described.
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.
Morishita, Takatoshi; Kondo, Yasuhiro; Hasegawa, Kazuo; Naito, Fujio*; Yoshioka, Masakazu*; Matsumoto, Hiroshi*; Hori, Yoichiro*; Kawamata, Hiroshi*; Saito, Yoshio*; Baba, Hiroshi*
Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.783 - 785, 2010/05
The J-PARC RFQ (length 3.1 m, 4-vane type, 324 MHz) accelerates a negative hydrogen beam from 0.05 MeV to 3 MeV toward the following DTL. The stability of the operating RFQ decreased for a few months at the end of 2008, then, we started a preparation of a new RFQ as a backup machine in the case of RFQ problem. The beam dynamics design of the new RFQ is the same as the current cavity for a quick resumption of operation, however, the engineering and RF designs are changed to improve stability. The processes of the vane machining and the surface treatments have been carefully considered to reduce the discharge problem. The vacuum brazing technique has been chosen for vane jointing. The design of the new RFQ and the fabrication progress is descried in this proceeding.
Morishita, Takatoshi; Kondo, Yasuhiro; Hasegawa, Kazuo; Naito, Fujio*; Yoshioka, Masakazu*; Matsumoto, Hiroshi*; Hori, Yoichiro*; Kawamata, Hiroshi*; Saito, Yoshio*; Baba, Hiroshi*; et al.
Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.1047 - 1049, 2010/03
The beam commissioning of J-PARC linac has been started since November 2006. After the scheduled shutdown in summer 2007, the beam is successfully delivered from the linac to the RCS. Since then, a stable beam provision was emphasized. However, the trip in the RFQ was increased at the end of Sept. 2008, then, the stability of the beam operation decreased. To improve this situation, we started to prepare a new RFQ cavity as a backup machine. The basic concept of the engineering design is the simplicity and the effective vacuum pumping aiming at the stable operation. A 3m long cavity is divided into 3 modules longitudinally. A numerical control machining with ball-end mill is chosen for a vane machining. Four vanes are vacuum brazed each other after machining. Each modules are aligned on the platform using a linear motion guide. A basic design of the key components on machining and brazing are described in this proceeding.
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.
Taniguchi, Wataru; Suzuki, Hideaki*; Sugino, Hiroyuki*; Matsumoto, Kazuhiro*; Chijimatsu, Masakazu*; Shibata, Masahiro
JNC TN8400 99-052, 73 Pages, 1999/12
For the buffer of geological disposal of High-level radioactive waste (HLW) in Japan, it is expected to maintain its low water permeability, self-sealing properties, radionuclides adsorption retardation properties, thermal conductivity, etc. It is considered that compacted bentonite or a compacted sand-mixtured bentonite that satisfy many of the expected properties mentioned above are superior. JNC (Japan Nuclear Fuel Development Corporation) has studied the measurement method for the properties of buffer and measured to use the measurement results for the design and performance assessment analysis. Also, we have conducted the design of engineered barrier and underground facility based on assuming geological condition. For the design of engineered barrier and underground facility, high thermal conductivity of buffer is design requirement to avoid mineralogical alternation. Also, the design is not conducted using the density of buffer less than the bulk density (powder-mass density). Therefore, the bulk density (powder-mass density) is one of the design requirements. In this report, the thermal properties and the bulk density (powder-mass density) of the buffer material is measured. Then thermal analysis in the near field is conducted using the measurement results, and we studied the relationships between the dry density, sand-mixtured ratio, water content and thickness of the buffer to satisfy the design requirement from the view point of thermal condition, based on the temperature constraint of the buffer.
Chijimatsu, Masakazu*; Matsumoto, Kazuhiro*; *; Sugita, Yutaka; Kikuchi, Hirohito*; Saito, Toshiaki*
PNC TN8410 98-058, 46 Pages, 1998/04
None
Fujita, Tomoo; Chijimatsu, Masakazu; Suzuki, Hideaki*; Matsumoto, Kazuhiro*; Ishikawa, Hirohisa
PNC TN8410 97-071, 29 Pages, 1997/02
It is an important part of the near field performance assessment of nuclear waste disposal to evaluate coupled thermo-hydro-mechanical (T-H-M) phenomena, e.g., thermal effects on groundwater flow through rock matrix and water seepage into the buffer material, the generation of swelling pressure of the buffer material, and thermal stresses potentially affecting porosity and fracture apertures of the rock. An in-situ T-H-M experiment named 'Engineered Barrier Experiment' has been conducted at the Kamaishi Mine, of which host rock is granodiorite, in order to establish conceptual models of the coupled T-H-M processes and to build confidence in mathermatical models and computer codes. We used the BENTONITE OT-9607 as a buffer material. This is the special order goods for this experiment and the granulated bentonite before final crush of KUNIGEL V1. This note describes the reason for using this material and the fundamental properties.
Chijimatsu, Masakazu*; Matsumoto, Kazuhiro*; Kanno, Takeshi; Ishiguro, Katsuhiko; Sugita, Yutaka; Moro, Yoshiji*; Ishikawa, Hirohisa
PNC TN8410 97-025, 57 Pages, 1997/01
None
Water leak alarm systemShirato, Seiichi*; Kaneko, Yoshihisa*; Nishikimi, Masakazu*; Morimoto, Makoto*; Matsumoto, Shigeharu*; Motonaga, Tsutsuji*; Imai, Hiroshi*; Fukuda, Toru
PNC TN941 85-23, 193 Pages, 1985/02
To develop the small leak sodium-water reaction detection system in the steam generator for Fast Breeder Reactor, the series studies on system evaluation tests have been carried out at the 50MW Steam Generator Test Facility. This report deals with hydrogen and injection tests into the sodium outlet pipe from the superheater, test plans and test equipments for hydrogen injection tests into the evaporator, the response performances for the hydrogen meter and oxygen meter, detection ratio for hydrogen and oxygen and the water leak alarm system etc. The test results are summarized as follows: (1)Hydrogen injection tests & water injection tests into the sodium outlet pipe from the superheater were done and the hydrogen & oxygen behaviors were understood. (2)Hydrogen injection tests at the annulus, down-comer and cover-gas region in the evaporator were done and hydrogen behaviors were understood. (3)Hydrogen detection rates depending on hydrogen injection tests & water injection tests were arranged and factors giving the effect on the rate were evaluated. Also, hydrogen transfer times were evaluated. (4)Hydrogen detection rates at the water leakage in the evaporator were evaluated by the comparison of hydrogen injection test results & water injection test results into the sodium out1et pipe from the superheater and hydrogen injection test results into the evaporator. (5)The water leak alarm system by the computor was completed and the validity was confirmed.
Kikuchi, Tatsuya; Matsumoto, Masakazu*; Yamamuro, Osamu*
no journal, ,
We are studying the formation mechanism of gas hydrates currently attracting much attention in the research field of clathrate hydrates. The largest difficulty for this study is that guest gas molecules hardly dissolve into water under ambient pressure. In order to overcome this difficulty, we prepared aqueous solutions with high solubility (2% at maximum) of guest gases by applying gas high-pressure to water. The quasi-elastic neutron scatterings (QENS) of these samples have been measured to investigate the dynamics of water molecules affected by the guest molecules. The measurements were carried out on AGNES spectrometer installed at JRR-3 (JAEA, Tokai) and maintained by ISSP, University of Tokyo. The guest molecules taken in this study were Ar, Xe, N
, and CO which have simple molecular structures. The pressure and temperature ranges were 0-100 MPa and 263-363 K, respectively. We analyzed the QENS spectra 
based on the jump diffusion model. The diffusion coefficient 
is smaller than of pure water especially below the hydrate-formation temperature 
and for the guest molecules with high solubility. These experimental results were reproduced well by MD simulations. It was also found that the gas molecules get closer to each other and the diffusion of water molecules near gas molecules is suppressed, resulting in the smaller diffusion coefficient below .
Kobayashi, Hitoshi*; Kurihara, Toshikazu*; Matsumoto, Hiroshi*; Yoshioka, Masakazu*; Matsumoto, Noriyuki*; Kumada, Hiroaki*; Matsumura, Akira*; Sakurai, Hideyuki*; Hiraga, Fujio*; Kiyanagi, Yoshiaki*; et al.
no journal, ,
no abstracts in English
Mikami, Satoshi; Shimada, Kiyotaka; Nakano, Masakazu; Sato, Tetsuro; Sato, Akane; Uno, Kiichiro; Seki, Akiyuki; Matsumoto, Shinichiro; Saito, Kimiaki
no journal, ,
We conducted a monitoring and mapping of the radioactive substances distribution around the Fukushima Daiichi Nuclear Power Plant. In the area of 80 km radius from Fukushima Daiichi Nuclear Power Plant, 
measurements with portable Germanium detectors were conducted at approximately 380 points, and measurements with sureveymeters were done at approximately 6500 points. Newly acquired data were compared to the results obtained by the first or second investigation campaign in 2011.
Mikami, Satoshi; Nakano, Masakazu; Sato, Tetsuro; Uno, Kiichiro; Sato, Akane; Matsumoto, Shinichiro; Saito, Kimiaki
no journal, ,
The results of air dose rates measured by survey meters and 
spectrometry implemented as a fourth distribution investigation campaign in 2013 are to be introduced. In addition, spatial distribution of ratio of deposited Cs-134 and Cs-137 based on results of second campaign in 2011-2012 will be discussed.
Sato, Tetsuro*; Ando, Masaki; Uno, Kiichiro; Nakano, Masakazu; Kanno, Takashi; Yamamoto, Hideaki; Matsumoto, Shinichiro; Saito, Kimiaki
no journal, ,
The distribution of radioactive cesium were examined by man borne survey method by using KURAMA-II monitoring system. The correlation between the air dose rate measured by man borne survey method and the air dose rate measured by survey meters at 1 m above ground were examined. The correlation between the air dose rate measured by man borne survey method and the air dose rate measured by car borne survey were examined.
Mikami, Satoshi; Ishikawa, Daisuke; Nakano, Masakazu; Matsuda, Norihiro; Uno, Kiichiro; Sato, Akane; Matsumoto, Shinichiro; Yamamoto, Hideaki; Saito, Kimiaki
no journal, ,
Distributions of air dose rate and inventory of radioactive cesium deposited on ground were investigated in 2013, within 80-km radial area centered around the Fukushima Daiichi Nuclear Power Plant. We revealed the characteristics of the time-dependent change of the air dose rate and the inventory by comparison with the measurement results of the past investigations.
