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Tanabe, Kosuke*; Komeda, Masao; Toh, Yosuke; Kitamura, Yasunori*; Misawa, Tsuyoshi*
Nihon Genshiryoku Gakkai-Shi ATOMO
, 67(3), p.198 - 202, 2025/03
no abstracts in English
Yoshida, Masato; Iguchi, Satoshi; Hirano, Hiroshi*; Kitamura, Akihiro
Nuclear Engineering and Design, 431, p.113691_1 - 113691_16, 2025/01
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)The Plutonium Fuel Fabrication Facility is currently in the decommissioning phase, with glovebox dismantling operations ongoing since 2010. During conventional glovebox dismantling operations, the glovebox to be dismantled is enclosed within plastic tents to contain contamination. The glovebox is then dismantled by workers wearing air-fed suits with thermal or mechanical cutting tools, which typically generate dross or sparks in the form of radioactive aerosols during cutting. Despite the longevity and meticulous organization of this manual method, the workload remains considerable, while the allowable working time is limited. In addition, the potential for inhalation exposure to plutonium is elevated in the event of an accident given the contamination of the work area. To overcome disadvantages associated with conventional glovebox dismantling methods, new methods are currently being developed. The primary objective is to reduce the reliance on operation based on air-fed suits and enhance worker safety by introducing remote equipment and a new floor-reinforcing panel. Another objective is to suppress waste generation by reusing all equipment on multiple occasions which is achieved by developing a containment system that have a large open port with a pallet for the storage and reuse of equipment for successive operations. Furthermore, a glove operation compartment is designed and tested for the manual handling of dismantled materials as an additional strategy to reduce work based on air-fed suits and mitigate secondary waste generation.
Kitamura, Yoshimasa; Oka, Toshitaka; Seito, Hajime*; Yokozuka, Eri*; Nagasawa, Naotsugu*; Kitatsuji, Yoshihiro
Radiation Protection Dosimetry, 200(16-18), p.1660 - 1665, 2024/11
Times Cited Count：0 Percentile：0.00(Environmental Sciences)In this work, we evaluated the applicability of hydroxyapatite, which is a main component of tooth enamel, as individual dosimeters that can detect from less than 1 Gy to several tens Gy. Commercially available hydroxyapatite was irradiated by 
Co gamma-ray up to 75 Gy and ESR spectrum of the irradiated sample was observed. The relationship between the intensity of produced carbonated radical and the absorbed dose shows a good linearity (
) from 0 to 75 Gy. The detection limit of this samples was estimated to be 99.7 mGy, and the radical intensity do not change for eight month from the irradiation. These results suggest that this sample can be used as a candidate of the individual dosimeter.
Kitamura, Ryo; Fuwa, Yasuhiro; Kuriyama, Yasutoshi*; Miyao, Tomoaki*
Proceedings of 21st Annual Meeting of Particle Accelerator Society of Japan (Internet), p.233 - 234, 2024/10
Cf rotation method with a water Cherenkov neutron detectorTanabe, Kosuke*; Komeda, Masao; Toh, Yosuke; Kitamura, Yasunori*; Misawa, Tsuyoshi*; Tsuchiya, Kenichi*; Sagara, Hiroshi*
Scientific Reports (Internet), 14, p.18828_1 - 18828_10, 2024/08
Times Cited Count：0 Percentile：0.00(Multidisciplinary Sciences)Kimuro, Shingo; Taneichi, Yayoi; Iwata, Hajime; Ishidera, Takamitsu; Kitamura, Akira; Tachi, Yukio; Tanaka, Takeru*; Hirano, Kana*; Hieda, Manami*; Miyabe, Shunsuke*; et al.
Journal of Solution Chemistry, 53(6), p.854 - 868, 2024/06
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)Kitamura, Ryo; Hayashi, Naoki; Hirano, Koichiro; Kosaka, Satoshi*; Miyao, Tomoaki*; Morishita, Takatoshi; Nemoto, Yasuo*
Journal of Physics; Conference Series, 2687(7), p.072006_1 - 072006_6, 2024/01
Times Cited Count：0 Percentile：0.00(Physics, Atomic, Molecular & Chemical)The mitigation of heat loading is one of the important issues for beam instrumentation to measure the high-power proton beam. Recently, the highly-oriented pyrolytic graphite (HOPG) material was used for the target probe of the bunch-shape monitor at the front-end in the Japan Proton Accelerator Research Complex (J-PARC). Since the thermal conductivity of the HOPG is high, it is suitable to measure the beam profile under the condition of high heat loading. As an application of the HOPG, for example, the thin HOPG may be used as a substitutive material of the target wire for the transverse profile monitor such as the wire scanner monitor. The possibility of the HOPG target for the beam profile monitor is discussed from some results of the test experiment using the 3-MeV negative hydrogen ion beam at the test stand.
Be ground-state molecular structure using Be(
)
He triple differential reaction cross-section measurementsLi, P. J.*; Beaumel, D.*; Lee, J.*; Assi
, M.*; Chen, S.*; Franchoo, S.*; Gibelin, J.*; Hammache, F.*; Harada, T.*; Kanada-En'yo, Yoshiko*; et al.
Physical Review Letters, 131(21), p.212501_1 - 212501_7, 2023/11
Times Cited Count：18 Percentile：91.30(Physics, Multidisciplinary)The cluster structure of the neutron-rich isotope Be has been probed via the () reaction. The triple differential cross-section was extracted and compared to distorted-wave impulse approximation reaction calculations performed in a microscopic framework using the Tohsaki-Horiuchi-Schuck-R
pke wave function and the wave function deduced from Antisymmetrized Molecular Dynamics calculations. The remarkable agreement between calculated and measured cross-sections in both shape and magnitude validates the description of the Be ground-state as a rather compact nuclear molecule.
Kitamura, Ryo; Fuwa, Yasuhiro; Ito, Daito*
Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.280 - 281, 2023/11
In the J-PARC linac, an RF chopper produces a characteristic time structure in the beam bunch at the injection into the 3-GeV synchrotron. Incomplete chopped beam derived from the transient response of the RF chopper results in the beam loss. The investigation of the particle tracking and the countermeasure for the beam loss are reported using the particle-in-cell simulation.
Fuwa, Yasuhiro; Kitamura, Ryo
Proceedings of 20th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.531 - 534, 2023/11
In the J-PARC LINAC, the beam current and pulse width are being upgraded in order to increase the beam output power for the next decade. MEBT1 (Medium Energy Beam Transport 1) is located between the RFQ and the DTL to form an intermediate bunch structure for matching the transverse and longitudinal beams and for injection into the rapid cycling synchrotron in the later stage. Since the beam energy in MEBT1 section is low (3 MeV), the space-charge effect is expected to increase as the beam intensity increases. In this study, a new magnet has been designed and fabricated to suppress the beam loss caused by the space-charge effect. The new magnet is a combined-function magnet that can generate superimposed multipole components for beam focusing and space-charge effect compensation in a small space, and a permanent magnet is used to reduce the power consumption and the size of the equipment. In this presentation, the design of the magnet and its effect on beam dynamics will be discussed.
Kitamura, Akihiro; Hirano, Hiroshi*; Yoshida, Masato
Nuclear Engineering and Design, 411, p.112435_1 - 112435_14, 2023/09
Times Cited Count：1 Percentile：27.70(Nuclear Science & Technology)This study presents the features and brief history of the glovebox dismantling facility and the primary dismantlement results. Subsequently, we evaluate the novelties of the facility from operational experiences in manual and remote glovebox dismantlement methods and discuss their characteristics. Furthermore, we evaluate the worker exposure dose based on the obtained data. Finally, we show how these experiences are effectively fed back to the technological dismantlement development for our decommissioning project.
Shibanuma, Tomohiro; Hirano, Hiroshi*; Kimura, Yasuhisa; Aita, Takahiro; Yoshida, Masato; Nagai, Yuya; Kitamura, Akihiro
Hoken Butsuri (Internet), 58(2), p.91 - 98, 2023/08
We developed new containment tents that are more easily assembled and effectively functioned, by improving and refurbishing the shortcomings of the conventional tents. The new tents have been already tested in the real airborne contamination situation occurred at the plutonium fuel fabricating facility. The tents appropriately functioned for intended use but other shortcomings emerged and therefore we had modified the structure of the tents further.
Kitamura, Akihiro; Hirano, Hiroshi*; Yoshida, Masato; Takeuchi, Kentaro
Hoken Butsuri (Internet), 58(2), p.76 - 90, 2023/08
The alpha contaminated gloveboxes have been dismantled for over 20 years in Plutonium Fuel Fabrication Facility. The so called wet recovery equipment gloveboxes, which recover plutonium and uranium from scrap fuel by dissolving and extracting processes, were chosen as the priority gloveboxes to be dismantled. These gloveboxes and other gloveboxes in the same room were size reduced and removed up until 2022. Also, non-radioactive ancillary facility and non-radioactive giant glovebox were removed from 2007 to 2010 for ease of glovebox dismantling activities that follows and for making waste storage spaces. Several incidents were occurred and recidivism prevention measures were implemented on each occasion. In this report, glovebox dismantling activities we conducted in the past 20 years are reviewed and lessons we have learned are summarized.
(cr) at 318 K in the presence of ironYoshida, Yasushi*; Kitamura, Akira; Shibutani, Sanae*
Journal of Nuclear Science and Technology, 60(8), p.900 - 910, 2023/08
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Arai, Sora; Kosaka, Satoshi*; Nemoto, Yasuo*; Kitamura, Ryo
JAEA-Technology 2023-009, 18 Pages, 2023/05
JAEA-Technology-2023-009.pdf:1.89MB
The linac located at the head of the J-PARC accelerators and required to provide the stable and high-quality beam. One of the accelerating cavities in the linac is the Separated-type Drift Tube Linac (SDTL). It is important to appropriately apply the RF power into the cavity for the stable operation. However, after the recovery from the Great East Japan Earthquake, the RF power could not be applied into the cavities for several SDTL cavities because the voltage standing wave ratio increased around the designed operating power. The investigation revealed that the inner surface of the cavity was exposed to high humidity and the backflow of oil from the rotary pump for a long period of time after the earthquake. It was suggested that the residue on the inner surface caused the multipactor resulted in the failure when the power was applied. The residue was wiped out with organic solvents and acids, resulted in solving the failure. This report describes the method and results of the cleaning for the cavity in 2021.
Kosaka, Satoshi*; Arai, Sora; Nemoto, Yasuo*; Kitamura, Ryo
JAEA-Technology 2023-003, 34 Pages, 2023/05
JAEA-Technology-2023-003.pdf:3.79MB
The negative hydrogen (H
) ion beam is accelerated with a peak current of 50 mA in the J-PARC linac. The linac consists of the H ion source and four kinds of accelerating cavities; a radio-frequency quadrupole linac (RFQ), a drift-tube linac (DTL), a separated-DTL (SDTL), and an annular-ring coupled structure linac (ACS). The accelerating electric field exists between the drift-tubes in the tank of the DTL. The quadrupole magnet for the beam focusing (DTQ) is installed in the drift-tube. The DTQ at J-PARC employs electromagnets to generate the magnetic field. It is important to set correctly the polarity of the magnetic field of the DTQ for tuning the beam. In this paper, we report the method of confirming the magnetic field polarity of DTQ, that is, the current wiring polarity by measuring DC current using a clamp meter on the power supply side and visually confirming the cable wiring connection on the electromagnet side.
Kitamura, Ryo; Kawamura, Naritoshi; Shibata, Takanori*
Proceedings of 14th International Particle Accelerator Conference (IPAC 23) (Internet), p.1432 - 1433, 2023/05
The muonium is the bound state of the positive muon and the electron. The muoium can be ionized using a dedicated laser to produce the ultra-slow muon beam. It is one idea that the dense electrons may be used as a substitute of the ionization laser for the muonium. The preliminary study is reported for the ionization of the muonium using the electron.
Kitamura, Ryo; Futatsukawa, Kenta*; Hayashi, Naoki; Hirano, Koichiro; Kondo, Yasuhiro; Kosaka, Satoshi*; Miyao, Tomoaki*; Morishita, Takatoshi; Nemoto, Yasuo*; Oguri, Hidetomo
Physical Review Accelerators and Beams (Internet), 26(3), p.032802_1 - 032802_12, 2023/03
Times Cited Count：3 Percentile：48.20(Physics, Nuclear)A bunch-shape monitor (BSM) is a useful device for performing longitudinal beam tuning using the pointwise longitudinal phase distribution measured at selected points in the beam transportation. To measure the longitudinal phase distribution of a low-energy negative hydrogen (H) ion beam, highly oriented pyrolytic graphite (HOPG) was adopted for the secondary-electron-emission target to mitigate the thermal damage due to the high-intensity beam loading. The HOPG target enabled the measurement of the longitudinal phase distribution at the center of a 3-MeV H ion beam with a high peak current of about 50 mA. The longitudinal bunch width was measured using HOPG-BSM at the test stand, which was consistent with the beam simulation. The correlation measurement between the beam transverse and longitudinal planes was demonstrated using HOPG-BSM. The longitudinal Twiss and emittance measurement with the longitudinal Q-scan method was conducted using HOPG-BSM.
Kitamura, Ryo; Hayashi, Naoki; Hirano, Koichiro; Miyao, Tomoaki*; Miura, Akihiko; Morishita, Takatoshi
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.212 - 214, 2023/01
In the J-PARC linac, the bunch-shape monitor (BSM) is developed to precisely and rapidly measure the longitudinal beam profile at the front-end, towards the improvement of the beam matching. The graphite target having the good strength to the high-power beam, has been introduced in order to resist the heat loading of the high-intensity beam. The resolution and other uncertainties were evaluated for the BSM. The longitudinal Twiss parameters and emittance were measured using the BSM and the IMPACT, which was the 3D particle-in-cell simulation code. The precision of the longitudinal emittance measurement was improved, by implementing uncertainties related to the BSM into the calculation. In this presentation, we will report a series of the measurement result, the method of the beam diagnostics with the BSM at the front-end, and the comparison between the measurement and the beam simulation.
beamKitamura, Ryo; Hayashi, Naoki; Hirano, Koichiro; Kosaka, Satoshi*; Miyao, Tomoaki*; Nemoto, Yasuo*; Morishita, Takatoshi
Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.330 - 332, 2023/01
In the J-PARC linac, a new bunch-shape monitor (BSM) is developed to stably measure the high-intensity and low-energy H beam by improving the strength of the target probe for the heat loading. The new target probe is made of the graphite. The first measurement of the longitudinal beam profile has been realized with the BSM at the core region of the high-intensity beam. Since the beam profile can be measured with the new BSM at any transverse position thanks to the new target probe, we propose the advanced application of the beam diagnostics with the BSM. In this presentation, some new approaches of the beam diagnostics with the BSM; the transverse profile measurement using the secondary electrons and the beam current evaluation from the transverse profile measurement, are discussed beyond the original usage of the BSM.
