Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 182

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Radiochemical research for the advancement of $$^{99}$$Mo/$$^{99m}$$Tc generator by (n,$$gamma$$) method

Fujita, Yoshitaka; Seki, Misaki; Namekawa, Yoji*; Nishikata, Kaori; Kimura, Akihiro; Shibata, Akira; Sayato, Natsuki; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; et al.

KURNS Progress Report 2018, P. 155, 2019/08

no abstracts in English

Journal Articles

Progress of the J-PARC cesiated rf-driven negative hydrogen ion source

Shinto, Katsuhiro; Okoshi, Kiyonori; Shibata, Takanori*; Nammo, Kesao*; Ikegami, Kiyoshi*; Takagi, Akira*; Namekawa, Yuya*; Ueno, Akira; Oguri, Hidetomo

AIP Conference Proceedings 2052, p.050002_1 - 050002_7, 2018/12

 Times Cited Count:0 Percentile:100

In the 2017/2018 campaign, the J-PARC cesiated rf-driven negative hydrogen (H$$^-$$) ion source producing H$$^-$$ beam with the beam current of 47 mA accomplished three long-term operations more than 2,000 hours without any serious issues. On the final day of this campaign, the ion source produced an H$$^-$$ beam current of 72 mA so that the linac commissioning group could demonstrate the beam current of 60 mA at the linac exit. We are also conducting an endurance test of a J-PARC-made antenna at a test bench. The antenna achieved the operation time approximately 1,400 hours.

Journal Articles

Status of development on LaB$$_6$$ filament arc-driven multi-cusp ion source for iBNCT

Shibata, Takanori*; Takagi, Akira*; Ikegami, Kiyoshi*; Sugimura, Takashi*; Nammo, Kesao*; Naito, Fujio*; Kobayashi, Hitoshi*; Kurihara, Toshikazu*; Honda, Yosuke*; Sato, Masaharu*; et al.

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.385 - 387, 2018/10

Journal Articles

Present status of the J-PARC cesiated rf-driven H$$^-$$ ion source

Shinto, Katsuhiro; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Shibata, Takanori*; Nammo, Kesao*; Namekawa, Yuya*; Ueno, Akira; Oguri, Hidetomo

AIP Conference Proceedings 2011, p.050018_1 - 050018_3, 2018/09

 Times Cited Count:1 Percentile:12.98

Journal Articles

Observation of plasma density oscillation with doubled value of RF frequency in J-PARC RF ion source

Shibata, Takanori*; Shinto, Katsuhiro; Takagi, Akira*; Oguri, Hidetomo; Ikegami, Kiyoshi*; Okoshi, Kiyonori; Nammo, Kesao*; Naito, Fujio*

AIP Conference Proceedings 2011, p.020008_1 - 020008_3, 2018/09

 Times Cited Count:1 Percentile:12.98

Journal Articles

Numerical and experimental study of H$$^{-}$$ beam dynamics in J-PARC LEBT

Shibata, Takanori*; Ikegami, Kiyoshi*; Liu, Y.*; Miura, Akihiko; Naito, Fujio*; Nammo, Kesao*; Oguri, Hidetomo; Okoshi, Kiyonori; Otani, Masashi*; Shinto, Katsuhiro; et al.

Proceedings of 29th International Linear Accelerator Conference (LINAC 2018) (Internet), p.519 - 521, 2018/09

Transport process of negative hydrogen ion (H$$^{-}$$) in LEBT (Low Energy Beam Transport) is investigated by comparison of experimental and numerical results. A three dimensional Particle-In-Cell (PIC) particle transport model has been developed in order to take into account (i) axial magnetic field by two solenoids in J-PARC LEBT and (ii) radial electric field by space charge (SC) effect. Ratio of H$$^-$$ beam particles inside the RFQ (Radio Frequency Quadrupole) acceptance to the total particles at the RFQ entrance is calculated for different current conditions in LEBT solenoid 1 and 2. The results are compared with RFQ transmission rate measured in the J-PARC linac commissioning. The double peak of RFQ transmission rate to the solenoid applied current seen in the measurement is explained by the calculation results. The results indicate that presence of the LEBT orifice for differential pumping plays a role as a collimator to reduce emittance at RFQ entrance.

Journal Articles

Neutron irradiation effect of high-density MoO$$_{3}$$ pellets for Mo-99 production

Fujita, Yoshitaka; Nishikata, Kaori; Namekawa, Yoji*; Kimura, Akihiro; Shibata, Akira; Sayato, Natsuki; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; Zhang, J.*

KURRI Progress Report 2017, P. 126, 2018/08

no abstracts in English

Journal Articles

Operation status of the J-PARC H$$^{-}$$ ion source

Okoshi, Kiyonori; Shinto, Katsuhiro; Nammo, Kesao*; Shibata, Takanori*; Ikegami, Kiyoshi*; Takagi, Akira*; Ueno, Akira; Namekawa, Yuya*; Oguri, Hidetomo

Proceedings of 15th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.889 - 892, 2018/08

In 2017-2018 campaign, three times of long-time operation more than 2,000 hours of the J-PARC rf-driven negative hydrogen (H$$^{-}$$) ion source producing H$$^{-}$$ beam with the beam current of 47 mA were successfully achieved without any serious problems. At the final day of this campaign, the ion source produced an H$$^{-}$$ beam with the current of 72 mA in order to demonstrate the beam current of 60 mA at the linac exit. We are also conducting an endurance test of a J-PARC-made antenna at a test bench. Approximately 1,400-hour operation with the antenna was successfully performed.

JAEA Reports

Study on degradation phenomenon of nuclear reactor materials (Thesis)

Shibata, Akira

JAEA-Review 2017-035, 184 Pages, 2018/03

JAEA-Review-2017-035.pdf:21.07MB

The degradation of materials, the exposing to high-dose neutron and gamma irradiation, the high temperature and the high pressure water environment are important issues for nuclear reactors. Due to the public concern, plants will inevitably be used for a long term, thereby facing problems of degradation materials due to ageing. In addition, "high burn-up" is being promoted. This prolongs period of operation cycles. The major objective of the thesis is to understand the degradation phenomenon of reactor materials and to improve the evaluation test techniques. Zirconium alloys have been used as fuel cladding material. Advanced Zr-Nb alloys gradually replaced Zircaloy-4 in PWR. Corrosion tests under simulated PWR water conditions were conducted on those materials and formation of oxide layers was studied via EIS. Mechanical properties of oxide layers on Zircaloy-4 and M5 were evaluated by Nano indentation with FEM analysis. Stainless steel is widely used as structure material of nuclear reactors. Tensile tests and SSRTs were conducted on specimens irradiated to higher than threshold fluence of IASCC. The integrity and the IASCC susceptibility were evaluated.

Journal Articles

Operation status of the J-PARC H$$^{-}$$ ion source

Okoshi, Kiyonori; Shinto, Katsuhiro; Ikegami, Kiyoshi*; Shibata, Takanori*; Takagi, Akira*; Nammo, Kesao*; Ueno, Akira; Oguri, Hidetomo

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.651 - 654, 2017/12

Operation of a cesiated rf-driven negative hydrogen ion source was initiated in September 2014 in response to the requirements of beam current upgrade in J-PARC linac. Delivery of the required beam current from the ion source to the J-PARC accelerators has been successfully performed. In 2016-2017 campaign, continuous operation of the ion source for approximately 1,845 hours (from April to July 2017) was achieved with beam current of 47 mA.

Journal Articles

Status of the JENDL project

Iwamoto, Osamu; Shibata, Keiichi; Iwamoto, Nobuyuki; Kunieda, Satoshi; Minato, Futoshi; Ichihara, Akira; Nakayama, Shinsuke

EPJ Web of Conferences (Internet), 146, p.02005_1 - 02005_6, 2017/09

 Times Cited Count:0 Percentile:100

Journal Articles

Operation status of the J-PARC RF-driven H$$^{-}$$ ion source

Oguri, Hidetomo; Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Asano, Hiroyuki; Shibata, Takanori*; Nammo, Kesao*; Ueno, Akira; Shinto, Katsuhiro

AIP Conference Proceedings 1869, p.030053_1 - 030053_7, 2017/08

 Times Cited Count:3 Percentile:4.32

A cesiated RF-driven negative hydrogen ion source was started to operate in September, 2014 in response to the need for upgrading J-PARC's linac beam current. The ion source mainly comprises a stainless-steel plasma chamber, a beam extractor, and a large vacuum chamber with two turbo molecular pumps of 1500 L/s for differential pumping. The ion source has been successfully providing the required beam current to the accelerator without any significant issues other than a single-incident antenna failure occurred in October, 2014. Continuous operation for approximately 1,000 h was achieved with a beam current and duty factor of 45 mA and 1.25 % (0.5 msec and 25 Hz), respectively. In this paper, we will present the some operation parameters and the beam stability through the long-term user operation.

Journal Articles

High density plasma calculation of J-PARC RF negative ion source

Shibata, Takanori*; Asano, Hiroyuki; Ikegami, Kiyoshi*; Naito, Fujio*; Nammo, Kesao*; Oguri, Hidetomo; Okoshi, Kiyonori; Shinto, Katsuhiro; Takagi, Akira*; Ueno, Akira

AIP Conference Proceedings 1869, p.030017_1 - 030017_11, 2017/08

 Times Cited Count:3 Percentile:4.32

From September 2014, operation of Cs-seeded, multi-cusp, Radio Frequency (RF), hydrogen negative ion source (J-PARC source) has been started. The operation for 1,000 hours of J-PARC source has been achieved with H$$^{-}$$ beam current 45 mA and duty factor of 1.25 % (0.5 msec and 25 Hz). In the present study, mechanisms of hydrogen plasma ramp-up and H$$^{-}$$ production/transport processes in the steady state (which lasts for few 100 us) are investigated by numerical modeling for RF plasma. In the simulation, charged particle (e, H$$^{+}$$, H$$_2^{+}$$, and Cs$$^{+}$$) transport, time variations of inductive and capacitive electromagnetic field, collision processes between charged and neutral (H, H$$_{2}$$) particles are solved simultaneously. The model is applied to KEK parallel computation System-A with 32 nodes and 256 GB memory in order to solve high density RF plasma up to around 10$$^{18}$$ m$$^{-3}$$ with adequate statisticity. In the presentation, time variations of plasma density distributions and average energy are shown with electromagnetic field variations.

Journal Articles

LEBT commissioning of the J-PARC LINAC

Shibata, Takanori*; Ikegami, Kiyoshi*; Liu, Y.*; Maruta, Tomofumi*; Naito, Fujio*; Takagi, Akira*; Asano, Hiroyuki; Kondo, Yasuhiro; Miura, Akihiko; Oguri, Hidetomo; et al.

Proceedings of 28th International Linear Accelerator Conference (LINAC 2016) (Internet), p.251 - 253, 2017/05

After upgrade of J-PARC Linac in 2014, Low Energy Beam Transport (LEBT) beam commissioning of the J-PARC LINAC has been made for improving H$$^{-}$$ beam intensity extracted from Linac. Currents of two solenoid coils and steering magnets in LEBT are optimized with extraction and acceleration voltages for static acceleration in ion source (IS) which decides on an initial emittance diagram of H$$^{-}$$ beam. As a result of LEBT and IS parameter optimization, beam transmission rate of RFQ has been reached up to 96% in 50 mA H$$^{-}$$ current operation. Moreover, PIC-MC (Particle-In-Cell Monte-Carlo) simulation models developed for H$$^{-}$$ transport in LEBT. Comparison between experimental and numerical results are presented to clarify beam physics from IS exit to RFQ entrance.

Journal Articles

Integrity evaluation for welding of irradiated and un-irradiated type 316 stainless steels

Shibata, Akira; Nakamura, Natsuki; Futakawa, Masatoshi; Maekawa, Katsuhiro*

Zairyo Shiken Gijutsu, 62(1), p.35 - 40, 2017/01

Welding between irradiated and un-irradiated type 316 stainless steel is demanded for in-pile IASCC tests in Japan Materials Testing Reactor. Specimens were made from type 316 stainless steel which was irradiated up to 6$$times$$10$$^{25}$$ n/m$$^{2}$$($$>$$ 1 MeV) in Reactor and welding tests of irradiated and un-irradiated type 316 stainless steels were performed to confirm integrity of the welding. Relationship between heat input and amount of Helium bubbles in welding bead was evaluated and hardness test was performed. It appeared that there is threshold value of heat input for welding without problem.

Journal Articles

Evaluation of mechanical properties of oxide layers of fuel cladding material Zircaloy-4 and M5 oxidized under PWR condition using Nano indentation with spherical indenter

Shibata, Akira; Wakui, Takashi; Nakamura, Natsuki; Futakawa, Masatoshi; Maekawa, Katsuhiro*; Naka, Michihiro

Zairyo Shiken Gijutsu, 62(1), p.41 - 47, 2017/01

Nuclear reactor fuel cladding material has been gradually replaced from Zircaloy-4 to Zr-Nb alloys such as M5. To reveal the origin of good corrosion resistance of Zr-Nb alloys, evaluation on oxide layer of fuel cladding tube Zircaloy-4 and M5 was performed. Nano-indentation with spherical indenter was performed on oxide layer of those materials. Test results of the indentation were evaluated by the inverse analysis using Kalman filter and Finite Element Method. The results analysis shows that the oxide layer of M5 has more ductility compare from that of Zircaloy 4. Thus, oxide layer of Zircaloy4 could be injured by smaller strain compare from that of M5.

Journal Articles

Damage on the JMTR hot laboratory by the 2011 Great East Japan Earthquake

Shibata, Akira; Nakamura, Natsuki; Naka, Michihiro

Proceedings of 54th Annual Meeting of Hot Laboratories and Remote Handling (HOTLAB 2017) (Internet), 11 Pages, 2017/00

An earthquake with magnitude 9.0 hit eastern Japan on 11th March 2011. It is known as "The 2011 Great East Japan Earthquake". The JMTR hot laboratory was damaged by the earthquake. This paper describes various damages on the JMTR hot laboratory caused by the earthquake. In the concrete cell, an electric lock of the shielding door of a hot cell was broken by the earth quake. Cracks were found in the walls of hot laboratory building. The exhaust stack of JMTR Hot laboratory is a part of gaseous waste treatment system. Thinning was found at anchor bolts on base of the stack in 2015. When thinning of anchor bolts were investigated, gaps between anchor bolt nuts and flange plate were found. It was concluded that the thinning was caused by water infiltration over a long period of time and the gaps were caused by elongation of thinning part of anchor bolts by series of earthquakes start from the 2011 Great East Japan Earthquake.

Journal Articles

Management of JMTR hot laboratory without operation of system of air supply and exhaust

Nakamura, Natsuki; Shibata, Akira; Naka, Michihiro

Proceedings of 54th Annual Meeting of Hot Laboratories and Remote Handling (HOTLAB 2017) (Internet), 4 Pages, 2017/00

no abstracts in English

Journal Articles

Progress in the geological disposal program in Japan

Deguchi, Akira*; Umeki, Hiroyuki*; Ueda, Hiroyoshi*; Miyamoto, Yoichi; Shibata, Masahiro; Naito, Morimasa; Tanaka, Toshihiko*

LBNL-1006984 (Internet), p.12_1 - 12_22, 2016/12

The H12 report demonstrated the feasibility of safe and technically reliable geological disposal in 1999. The Government of Japan re-evaluated the geological disposal program in terms of technical feasibility based on state-of-the-art geosciences and implementation process, because more than 10 years have passed from H12 and the Great Earthquake and nuclear accident have increased public concern regarding nuclear issues and natural hazards to cause accidents at nuclear facilities. Following the re-evaluation, the Government concluded further to promote geological disposal program, and thus the Basic Policy for Final Disposal was revised in 2015 including a new approach to siting process with identification of "Scientifically Preferable Areas". NUMO and relevant research organizations such as JAEA have been carrying out R and D activities to increase technical reliability for geological disposal. NUMO has started to develop a generic safety case.

Journal Articles

Status of the J-PARC RF ion source

Okoshi, Kiyonori; Ikegami, Kiyoshi*; Takagi, Akira*; Asano, Hiroyuki; Ueno, Akira; Shibata, Takanori*; Nammo, Kesao*; Shinto, Katsuhiro; Oguri, Hidetomo

Proceedings of 13th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.940 - 943, 2016/11

In 2014 October, operation of cesium-seeded Radio Frequency (RF)-driven negative hydrogen ion (H$$^{-}$$) source was started in J-PARC LINAC. Due to the skillful RF antenna screening and the proper pre-conditioning process, long term unscheduled beam stop due to the antenna failure did not occur for more than 1 year. The continuous operation of 1,350 hours with a peak beam current of 45 mA was achieved in the recent beam run. Moreover, the fluctuation of beam current in a low energy beam transport (LEBT) is kept within $$pm$$2% of target value by application of three feedback systems. An ion source test-stand was assembled to investigate the ion source beam characteristic, for example, the emittance at the position of the RFQ entrance. In the presentation, we will report the recent status of the ion source operation and some experimental results obtained at the ion source test-stand.

182 (Records 1-20 displayed on this page)