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Journal Articles

Cavitation damage in double-walled mercury target vessel

Naoe, Takashi; Wakui, Takashi; Kinoshita, Hidetaka; Kogawa, Hiroyuki; Haga, Katsuhiro; Harada, Masahide; Takada, Hiroshi; Futakawa, Masatoshi

Journal of Nuclear Materials, 506, p.35 - 42, 2018/08

 Percentile:100(Materials Science, Multidisciplinary)

A mercury target vessel made of 316L SS is damaged due to the cavitation caused by the pressure waves in mercury. Cavitation damage reduces the structural integrity of the target front, called "beam window", being major factor to determine the lifetime of target vessel. Aiming at mitigating the cavitation damage by faster mercury flow in narrow channel, we employed a target vessel with a double-walled structure at the beam window along with a gas microbubbles injection. After operating the double-walled target vessel with a beam power of 300 to 500 kW, we cut out the beam window using an annular cutter to examine the damage inside it, and found that damages with maximum pit depth of approximately 25 $$mu$$m distributed in a belt on the specimen facing narrow channel. Furthermore, numerical simulation result showed that the distribution of negative pressure period from beam injection to 1 ms was correlated with the damage distribution in the narrow channel. It was suggested that the cavitation induced by relatively short negative pressure period contributed to the damage formation.

Journal Articles

Off-gas processing system operations for mercury target vessel replacement at J-PARC

Kai, Tetsuya; Uchida, Toshitsugu; Kinoshita, Hidetaka; Seki, Masakazu; Oi, Motoki; Wakui, Takashi; Haga, Katsuhiro; Kasugai, Yoshimi; Takada, Hiroshi

Journal of Physics; Conference Series, 1021(1), p.012042_1 - 012042_4, 2018/06

Journal Articles

Cavitation damage prediction for the JSNS mercury target vessel

Naoe, Takashi; Kogawa, Hiroyuki; Wakui, Takashi; Haga, Katsuhiro; Teshigawara, Makoto; Kinoshita, Hidetaka; Takada, Hiroshi; Futakawa, Masatoshi

Journal of Nuclear Materials, 468, p.313 - 320, 2016/01

BB2014-2665.pdf:3.4MB

 Times Cited Count:2 Percentile:57.25(Materials Science, Multidisciplinary)

Mercury target vessel in the JSNS, which is made of 316L SS, is damaged owing to the pressure wave-induced cavitation resulting from the proton beam bombardment. The cavitation damage decreases the structural integrity of the target vessel and is currently a dominant factor to decide the service life in compared with the radiation damage. Injecting microbubbles into mercury is one of the prospective techniques to mitigate the pressure waves and cavitation damage. In the JSNS, a microbubble generator with a gas circulation system was installed and has been operated since October 2012. The effects of microbubble injection into mercury on pressure wave mitigation were studied using a laser Doppler vibrometer. The result showed that the vibrational velocity of the target vessel is clearly reduced according to the increase of void fraction. An average peak vibrational velocity under 340 kW operation with the void fraction of 0.1% was reduced to 1/4 of that without injecting microbubbles.

Journal Articles

Research and development of high intensity beam transport to the target facilities at J-PARC

Meigo, Shinichiro; Oi, Motoki; Ikezaki, Kiyomi*; Kawasaki, Tomoyuki; Kinoshita, Hidetaka; Akutsu, Atsushi*; Nishikawa, Masaaki*; Fukuda, Shimpei

Proceedings of 12th International Topical Meeting on Nuclear Applications of Accelerators (AccApp '15), p.255 - 260, 2016/00

Journal Articles

Development of microbubble generator for suppression of pressure waves in mercury target of spallation source

Kogawa, Hiroyuki; Naoe, Takashi; Kyoto, Harumichi*; Haga, Katsuhiro; Kinoshita, Hidetaka; Futakawa, Masatoshi

Journal of Nuclear Science and Technology, 52(12), p.1461 - 1469, 2015/12

 Times Cited Count:4 Percentile:43.49(Nuclear Science & Technology)JP, 2010-015204   Patent publication (In Japanese)

MW-class mercury target for the spallation neutron source is subjected to the pressure waves. Propagation of the pressure wave causes negative pressure which causes cavitation erosion and degrades the vessel. Microbubbles injection into mercury is an effective technique to suppress the pressure waves and cavitation erosion. The bubble-generator utilizing swirl flow of liquid (swirl-type bubble-generator) is suitable for a mercury target system. However, when the single generator was used, swirl flow remains at downstream. The remaining swirl flow causes the coalescence of bubbles which results in ineffective suppression of pressure waves. To solve this concern, a multi swirl-type bubble-generator, which consists of several single generators arraying in the plane perpendicular to mercury flow direction, was invented. The multi swirl-type bubble-generator generated the microbubbles with the sufficient size to suppress the pressure waves.

Journal Articles

Damage inspection of the first mercury target vessel of JSNS

Naoe, Takashi; Teshigawara, Makoto; Wakui, Takashi; Kinoshita, Hidetaka; Kogawa, Hiroyuki; Haga, Katsuhiro; Futakawa, Masatoshi

Journal of Nuclear Materials, 450(1-3), p.123 - 129, 2014/07

 Times Cited Count:5 Percentile:43.1(Materials Science, Multidisciplinary)

A JSNS mercury target vessel composed of type 316L stainless steel suffers radiation damage in the proton and neutron environment. In addition to this damage, the inner wall of the target vessel in contact with mercury is damaged as a result of the cavitation. The target vessel was replaced with a new target in November 2011, because the pneumatic bellows were damaged during the earthquake. Before replacing the target, disk specimens were cut from the beam window of the target vessel in order to investigate the cavitation damage inside the target vessel and to evaluate the change in the mechanical properties due to radiation damage. As a result, it was confirmed that flow-induced erosion damage was not observed on the flow guide. The cavitation damage was concentrated at the center and around both sides approximately 15 mm from the center of the beam window. Based on the detailed measurements, it was concluded that the eroded damage depth of the beam window was 250 $$mu$$m.

Journal Articles

Experimental study on heat transfer and pressure drop in mercury flow system for spallation neutron source

Kinoshita, Hidetaka; Kaminaga, Masanori; Haga, Katsuhiro; Terada, Atsuhiko; Hino, Ryutaro

Journal of Nuclear Science and Technology, 50(4), p.400 - 408, 2013/04

 Times Cited Count:3 Percentile:62.81(Nuclear Science & Technology)

In the design of MW-class spallation target system using mercury to produce a practical neutron applications, keeping the highest level of safety is vitally important. To establish the safety of spallation target system, it is essential to understand the thermal-hydraulic properties of mercury. Through thermal-hydraulic experiments using a mercury experimental loop, which flows 1.2 m$$^{3}$$/h maximum, the following facts were experimentally confirmed. The wall friction factor was relatively larger than the Blasius correlation due to the effects of wall roughness. The heat transfer coefficients agreed well with the Subbotin correlation. Furthermore, for validation of the design analysis code, thermal hydraulic analyses were conducted by using the STAR-CD code under the same conditions as the experiments. Analytical results showed good agreements with the experimental results, using optimized turbulent Prandtl number and mesh size.

JAEA Reports

Maintenance of used components in spallation neutron source; Moderator $$cdot$$ reflector and proton beam window

Teshigawara, Makoto; Kinoshita, Hidetaka; Wakui, Takashi; Meigo, Shinichiro; Seki, Masakazu; Harada, Masahide; Ito, Manabu; Suzuki, Toru; Ikezaki, Kiyomi; Maekawa, Fujio; et al.

JAEA-Technology 2012-024, 303 Pages, 2012/07

JAEA-Technology-2012-024.pdf:46.04MB

3 GeV Protons with 1 MW beam power are irradiated to mercury target of spallation neutron source in Materials and Life science Facility (MLF), which is one of facilities of J-PARC. Irradiated components, such as target container, moderator, reflector and proton beam window, are needed to replace periodically due to irradiation damage of high energy protons and neutrons. These used components are replaced remotely because of highly activated. Maintenance scenario was settled so as to handle these components. Required remote handling machines were designed and installed in hot cell and other room of the MLF. We performed remote handling tests by using actual components to confirm the design. We report results, such as replacement procedure, trouble and its solution, etc., for moderator, reflector and proton beam window in order to provide the handling of actual used components.

JAEA Reports

Result of study on storage plan for irradiated components generated at MLF in J-PARC

Kinoshita, Hidetaka; Wakui, Takashi; Matsui, Hiroki; Maekawa, Fujio; Kasugai, Yoshimi; Haga, Katsuhiro; Teshigawara, Makoto; Meigo, Shinichiro; Seki, Masakazu; Sakamoto, Shinichi; et al.

JAEA-Technology 2011-040, 154 Pages, 2012/03

JAEA-Technology-2011-040.pdf:8.08MB

In the MLF, relatively high level irradiated components will be generated. Therefore, these components can not be kept in standard facilities. For the irradiated components at the MLF, the storage plan using the facilities in the Nuclear Science Research Institute has been studied, but the concrete plan is not decided yet. In this report, outline of the components, prehistory of the studying for storage, schedule of the component generation and status of the possible facility, which is a hot laboratory, are described. Resulting from the comparison between the generation schedule and the plan of the hot laboratory, the difference is very large. Present status of the hot laboratory and the cost estimation of the modification to use for storage of the MLF components were studied. Using the hot laboratory seems not to have advantage from the view point of cost and modification method. Therefore, the study on a new storage facility construction will be started as soon as possible.

JAEA Reports

Influence of Great East Japan Earthquake on neutron source station in J-PARC

Sakai, Kenji; Sakamoto, Shinichi; Kinoshita, Hidetaka; Seki, Masakazu; Haga, Katsuhiro; Kogawa, Hiroyuki; Wakui, Takashi; Naoe, Takashi; Kasugai, Yoshimi; Tatsumoto, Hideki; et al.

JAEA-Technology 2011-039, 121 Pages, 2012/03

JAEA-Technology-2011-039.pdf:10.87MB

This report investigates the behavior, damage and restoration of a neutron source station of the MLF at the Great East Japan Earthquake and verified the safety design for emergency accidents in the neutron source station. In the MLF, after an occurrence of the Earthquake, strong quakes were detected at the instruments, the external power supply was lost, all of the circulators shut down automatically, and the hydrogen gas was released. The leakages of mercury, hydrogen and radio-activation gases did not occur. While, the quakes made gaps between the shield blocks and ruptured external pipe lines by subsidence around the building. But significant damages to the components were not found though the pressure drop of compressed air lines influenced on a target trolley lock system and so on. These results substantiated the validity of the safety design for emergency accidents in the source station, and suggested several points of improvement.

Journal Articles

Influence of Great East Japan Earthquake on neutron target station in J-PARC

Sakai, Kenji; Futakawa, Masatoshi; Takada, Hiroshi; Sakamoto, Shinichi; Maekawa, Fujio; Kinoshita, Hidetaka; Seki, Masakazu; Haga, Katsuhiro; Kogawa, Hiroyuki; Wakui, Takashi; et al.

Proceedings of 20th Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-20) (USB Flash Drive), 6 Pages, 2012/03

This report investigates behaviors and damages of each component in a neutron target station of the MLF at the J-PARC at the time of the Great East Japan Earthquake (GEJE). At the date of the GEJE, in the MLF, strong quakes were detected at several instruments, an external power supply were lost, all of the circulation systems were shut down automatically, and a hydrogen gas was released as planned. Leakage of activation liquids and gases did not occur. While, the quakes made gaps between shield blocks and ruptured external pipe lines for air and water by subsidence. But significant damages on the components of the target station were not found though a loss of compressed air supply affected lock systems with air cylinders and pneumatic operation values. These results substantiated a validity of safety design on the target station for emergency accidents.

Journal Articles

Distribution of microbubble sizes and behavior of large bubbles in mercury flow in a mockup target model of J-PARC

Haga, Katsuhiro; Naoe, Takashi; Kogawa, Hiroyuki; Kinoshita, Hidetaka; Ida, Masato; Futakawa, Masatoshi; Riemer, B.*; Wendel, M.*; Felde, D.*; Abdou, A.*

Journal of Nuclear Science and Technology, 47(10), p.849 - 852, 2010/10

Microbubble injection into mercury is one of the prospective technologies to mitigate the pressure wave which causes the cavitation damage on the mercury target vessel wall of J-PARC. As one of the studies for the mercury target design with bubbling system, we carried out the mercury loop tests using a mockup model of the target vessel. Injected microbubbles in contact with the transparent top wall were observed to know the bubble size and distribution. As a result, bubbles in the range of radius from 10 to 150 microns, which are the ideal size for our purpose to suppress the pressure wave were transported to the beam window, where the bubbles should be distributed. It was found that the bubbles larger than 150 micron in radius were removed from the distribution by bubble buoyancy, and only the smaller bubbles could be transported downstream. The attention to the effect of bubbles on the cooling performance of the target vessel was raised by the experiment.

JAEA Reports

Design, construction and operation of general control system of Materials and Life Science Experimental Facility (MLF-GCS) in J-PARC

Sakai, Kenji; Oi, Motoki; Kai, Tetsuya; Watanabe, Akihiko; Nakatani, Takeshi; Higemoto, Wataru; Shimomura, Koichiro*; Kinoshita, Hidetaka; Kaminaga, Masanori

JAEA-Technology 2009-042, 44 Pages, 2009/08

JAEA-Technology-2009-042.pdf:35.33MB

A general control system for the Materials and Life Science Experimental Facility (MLF-GCS) at J-PARC has an advanced and independent system for control of the mercury target, including a large amount of mercury, three moderators with supercritical hydrogen, and cooling systems with radioactive water. Although the MLF-GCS is an independent system, it works closely with the accelerator and other facility control systems within J-PARC. The MLF have succeeded in the first proton beam injection and neutron beam generation in May 2008, and succeeded the muon beams generation in September 2008. The design and construction of the MLF-GCS has finished before the first proton beam injection. It has been operated stably and efficiently in the off- and on- beam commissioning. This paper reports on the design, construction and operation of the MLF-GCS.

Journal Articles

Developmental status of a server system for the MLF general control system

Oi, Motoki; Kai, Tetsuya; Kinoshita, Hidetaka; Sakai, Kenji; Kaminaga, Masanori; Futakawa, Masatoshi

Nuclear Instruments and Methods in Physics Research A, 600(1), p.120 - 122, 2009/02

 Percentile:100(Instruments & Instrumentation)

The Materials and Life Science Experimental Facility (MLF) of J-PARC has the general control system (MLF-GCS) that controls all subsystems of the MLFAccording to classifying into each function, the MLF-GCS consists of three layers of a PLC (programmable logic controller) link layer, server layer and external network layer. The PLC link layer is an inner layer and core part of the MLF-GCS. The server layer acquires various data from the inner and outer layer. The server systems also protect the core part of the MLF-GCS from network troubles of external LANs by mediating between the inner and outer layer. The server systems play an important role for realizing advanced and independent control in the MLF. A modeling and construction of the server systems have been almost finished, and an improvement and optimization of them are now in progress. This paper gives an overview of the server systems for the MLF-GCS and reports on their development status.

Journal Articles

Construction status of a general control system for the Materials and Life Science Experimental Facility (MLF) at J-PARC

Sakai, Kenji; Oi, Motoki; Kai, Tetsuya; Kinoshita, Hidetaka; Kawasaki, Susumu; Watanabe, Akihiko; Kaminaga, Masanori; Futakawa, Masatoshi

Nuclear Instruments and Methods in Physics Research A, 600(1), p.75 - 77, 2009/02

 Percentile:100(Instruments & Instrumentation)

In order to operate all equipment of the Materials and Life Science Experimental Facility (MLF) safely and efficiently, the MLF general control system (MLF-GCS) is designed to have several subsystems such as the facility control system centering on the control of the targets, interlock systems for protecting personnel, machine and the neutron target, and so on. Although it is an independent system, the MLF-GCS should also be as a part of the control system of the whole J-PARC operated from the central control room (CCR). The construction of MLF-GCS has been almost finished, and its performance test is in progress to check and adjust remote operations and integral interlocks from the control room of MLF. This paper gives an overview of the MLF-GCS and reports its construction status.

Journal Articles

Development status of the general control system of the Material and Life Science Experimental Facility (MLF) of J-PARC

Sakai, Kenji; Kinoshita, Hidetaka; Kai, Tetsuya; Oi, Motoki; Kaminaga, Masanori; Kato, Takashi; Furusaka, Michihiro*

Physica B; Condensed Matter, 385-386(2), p.1324 - 1326, 2006/11

 Times Cited Count:2 Percentile:85.21(Physics, Condensed Matter)

A general control system of MLF (MLF-GCS) is required to control all the subsystems of MLF including in the muon and neutron target, moderator, target station, experimental hall, and so on. It is an independent system, but it has to work closely with the control systems of accelerator and other facilities in J-PARC. A conceptual design of MLF-GCS has already been conducted and detailed designs are now in progress. This paper reports an overview and the development status of MLF-GCS.

JAEA Reports

Remote handling design for moderator-reflector maintenance in JSNS

Teshigawara, Makoto; Aizawa, Hideyuki; Harada, Masahide; Kinoshita, Hidetaka; Meigo, Shinichiro; Maekawa, Fujio; Kaminaga, Masanori; Kato, Takashi; Ikeda, Yujiro

JAERI-Tech 2005-029, 24 Pages, 2005/05

JAERI-Tech-2005-029.pdf:3.38MB

This report introduces the present design status of remote-handling devices for activated and used components such as moderator and reflector in a spallation neutron source of the Material and Life Science Facility (MLF) at J-PARC. The design concept and maintenance scenario are also mentioned. A key maintenance scenario adopts that the used components should be taken out from the MLF to the other storage facility after the volume reduction of them. Almost full remote handling is available to the maintenance work except for the connection/disconnection pipes of the cooling water. Total six remote handling devices are used for moderator-reflector maintenance. They are also available to the proton beam window and muon target maintenance. Maintenance scenario is separated into two works. One is to replace used components to new ones during beam-stop and the other is dispose used components during beam operation. Required period of replacement work is estimated to be $$sim$$15 days, on the other hand, the disposal work is $$sim$$26 days after dry up work ($$sim$$30 days), respectively.

Journal Articles

Development of beam monitor DAQ system for 3NBT at J-PARC

Oi, Motoki; Kai, Tetsuya; Meigo, Shinichiro; Kinoshita, Hidetaka; Sakai, Kenji; Sakamoto, Shinichi; Kaminaga, Masanori; Kato, Takashi; Kato, Tadahiko*

Europhysics Conference Abstracts, 29J, 6 Pages, 2005/00

The 3GeV proton beam transport facility (3NBT) is a high-intensity proton beam line from the 3GeV Rapid Cycling Synchrotron (RCS) to the Material and Life science Facility (MLF) at Japan Proton Accelerator Research Complex (J-PARC). In order to allow hands-on maintenance, a design criterion has been that the average beam loss at 3NBT be less than 1W/m. The systems for beam monitoring and magnet power control play an important role. In J-PARC, the Experimental Physics and Industrial Control System (EPICS) [1] will be used for the main control system. For the proton beam monitor system of 3NBT, EPICS is used and it has to work at 25Hz. In this study, a data acquisition system for the proton beam monitors is presented that has been developed with EPICS. Its performance has been investigated under 25Hz frequency condition.

Journal Articles

Experiments on mercury circulation system for spallation neutron target

Kinoshita, Hidetaka; Haga, Katsuhiro; Kaminaga, Masanori; Hino, Ryutaro

Journal of Nuclear Science and Technology, 41(3), p.376 - 384, 2004/03

 Times Cited Count:2 Percentile:80.25(Nuclear Science & Technology)

A construction of the spallation neutron source is being promoted under the Japan Proton Accelerator Research Complex (J-PARC) Project. A mercury circulation system has been designed to supply mercury to the target stably. It was necessary to make clear a mercury pump performance, erosion rate under the mercury flowing condition and an amount of remaining mercury after draining from the viewpoints of evaluating lifetime of piping and establishing remote handling scenario of mercury components. The mercury pump performance, the erosion rates and the amount of remained mercury were investigated by using a mercury experimental loop with an experimental gear pump. The discharged flow rates of the experimental gear pump are sufficient and it is increased linearly with the rotation speed. Erosion rates were found to be so small that decrease of piping wall thickness would be estimated 660 $$mu$$m after 30-year operation under the rated velocity of 0.7 m/s. For the amount of remaining mercury, remaining rates of weight was estimated at 50.7 g/m$$^{2}$$.

Journal Articles

Mercury target and its peripheral devices for 1MW spallation neutron source

Haga, Katsuhiro; Kaminaga, Masanori; Kinoshita, Hidetaka; Kogawa, Hiroyuki; Sato, Hiroshi; Ishikura, Shuichi*; Torii, Yoshikatsu; Hino, Ryutaro

Proceedings of 12th International Conference on Nuclear Engineering (ICONE-12) (CD-ROM), 8 Pages, 2004/00

In the Material and Life Science Facility, which will be constructed in the J-PARC project, the spallation mercury target station will be installed. Once the target system operation starts, mercury, the target vessel and the surrounding components are highly irradiated, so that all the replacement and maintenance operations of the target vessel and its peripheral devices have to be done with remote handling. In order to meet the requirements, we designed the target system such that the target vessel and the mercury circulation system are mounted on a target trolley, which is the system carriage. The target vessel is carried with the mercury circulation system together and inserted into the target center by the target trolley during the on-beam operation. During the system maintenance period, the target trolley is withdrawn to the maintenance room of hot cell, and the component exchange or repairing work will be done using a power manipulator and some master-slave manipulators. In this paper, the present design of the mercury target and its peripheral devices for 1MW spallation neutron source including the target vessel, a mercury circulation system, and a target trolley will be reported.

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