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JAEA Reports

Improvement of accumulator in cryogenic hydrogen system used for 1-MW pulsed spallation neutron source

Aso, Tomokazu; Tatsumoto, Hideki*; Otsu, Kiichi*; Kawakami, Yoshihiko*; Komori, Shinji*; Muto, Hideki*; Takada, Hiroshi

JAEA-Technology 2019-013, 77 Pages, 2019/09

JAEA-Technology-2019-013.pdf:5.59MB

At Materials and Life Science experimental Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), a 1-MW pulsed spallation neutron source is equipped with a cryogenic hydrogen system which circulates liquid hydrogen (20 K and 1.5 MPa) to convert high energy neutrons generated at a mercury target to cold neutrons at three moderators with removing nuclear heat of 3.8 kW deposited there. The cryogenic system includes an accumulator with a bellows structure in order to absorb pressure fluctuations generated by the nuclear heat deposition in the system. Welded inner bellows of the first accumulator was failured during operation, forcing us to improve the accumulator to have sufficient pressure resistance and longer life-time. We have developed elemental technologies for manufacturing welded bellows of the accumulator by a thick plate with high pressure resistance, succeeding to find optimum welding conditions. We fabricated a prototype bellows block and carried out an endurance test by adding a pressure change of 2 MPa repeatedly. As a result, the prototype bellows was successfully in use exceeding the design life of 10,000 times. Since distortions given during welding and assembling affect functionality and lifetime of the bellows, we set the levelness of each element of the bellows as within 0.1$$^{circ}$$. The improved accumulator has already been in operation for about 25,000 hours as of January 2019, resulting that the number of strokes reached to 16,000. In July 2018, we demonstrated that the accumulator could suppress the pressure fluctuation generated by the 932 kW beam injection as designed. As current operational beam power is 500 kW, the current cryogenic hydrogen system could be applicable for stable operation at higher power in the future.

Journal Articles

Development of an experimental system for characterization of high-temperature superconductors cooled by liquid hydrogen under the external magnetic field

Tatsumoto, Hideki; Shirai, Yasuyuki*; Shiotsu, Masahiro*; Naruo, Yoshihiro*; Kobayashi, Hiroaki*; Inatani, Yoshifumi*

Journal of Physics; Conference Series, 507(2), p.022042_1 - 022042_4, 2014/05

 Times Cited Count:1 Percentile:55.09

An experimental system has been developed to investigate electro-magnetic properties of high-Tc superconductors cooled by liquid hydrogen under the external magnetic field of up to 7 T. A LH$$_{2}$$ cryostat with a LH$$_{2}$$ inventory of 61 L is concentrically mounted on the inside of a LHe cryostat to cool a NbTi superconducting magnet. The experimental system is installed in an explosion-proof room and explosion proof electrical devices are used. The current leads are covered with an enclosure filled with nitrogen gas. A remote control system has been developed to maintain safety distance. Furthermore, the effects of stray magnetic field on the existing and the new devices are investigated and electro-magnetic shielding panels and enclosure made of iron were designed using ANSYS analysis. It is confirmed through the cryogenic test that the experimental system meets the design requirements.

Journal Articles

Recent progress of pulsed spallation neutron source in J-PARC

Takada, Hiroshi; Haga, Katsuhiro; Meigo, Shinichiro; Tatsumoto, Hideki; Kasugai, Yoshimi; Futakawa, Masatoshi

Proceedings of 11th International Topical Meeting on Nuclear Applications of Accelerators (AccApp '13), p.154 - 158, 2014/05

Remarkable progresses were achieved at a pulsed spallation neutron source in J-PARC. One is to mitigate high-pressure waves which are generated in a mercury target and a source of serious damage on the wall of target vessel by injecting gas micro-bubbles into mercury. It was confirmed with a novel in-situ diagnostic system using a laser Doppler vibrometer that the pressure waves were certainly attenuated with the gas micro-bubbles. Secondly, the supercritical cryogenic hydrogen system has been improved to remove impurity remained in the helium circulation loop by installing a purification system. As a result, the pressure drop at the heat exchanger was suppressed successfully down to several kPa even after operating for 95 days. Furthermore, we have succeeded in sampling hydrogen gas from the cryogenic hydrogen loop during operation and verified with a Raman spectroscopy that the para-hydrogen fraction was 100%, proving the neutronic performance at the moderator is kept unchanged.

Journal Articles

Operational characteristics of the J-PARC cryogenic hydrogen system for a spallation neutron source

Tatsumoto, Hideki; Otsu, Kiichi; Aso, Tomokazu; Kawakami, Yoshihiko; Teshigawara, Makoto

AIP Conference Proceedings 1573, p.66 - 73, 2014/01

 Times Cited Count:6 Percentile:94.98

The J-PARC cryogenic hydrogen system provides supercritical hydrogen provides to three moderators. A heater for the thermal compensation and a cryogenic accumulator are prepared to mitigate a pressure fluctuation. A feed temperature should be lower than 20 K and its fluctuation should be within 0.25 K to provide cold pulsed neutron beams of a higher neutronic performance. An ortho-para hydrogen convertor is installed to maintain the para-hydrogen concentration of more than 99.0%. In this study, it is confirmed that para-hydrogen always exists in the equilibrium concentration during the cool-down process. Propagation characteristics of temperature fluctuation caused by sudden heater power variations were studied. An allowable temperature fluctuation caused by the heater control approach is determined to be 1.05 K. It is found that the heater control would be applicable for the 1-MW proton beam operation by extrapolating from the experimental data for on-beam commissioning.

Journal Articles

Forced convection heat transfer of saturated liquid hydrogen in vertically-mounted heated pipes

Tatsumoto, Hideki; Shirai, Yasuyuki*; Shiotsu, Masahiro*; Hata, Koichi*; Naruo, Yoshihiro*; Kobayashi, Hiroaki*; Inatani, Yoshifumi*

AIP Conference Proceedings 1573, p.44 - 51, 2014/01

 Times Cited Count:7 Percentile:94.98

Heat transfers from the inner side of vertically-mounted heated pipes to forced flow of saturated liquid hydrogen were measured with a quasi-steady increase of a heat generation rate for wide ranges of flow rate and saturated pressure. The tube heaters have lengths L of 100 mm and 167 mm with the diameter D of 4 mm and lengths of 150 mm and 250 mm with the diameter of 6 mm. The heat fluxes at departure from nucleate boiling (DNB) were higher for higher flow velocity, lower pressures and shorter L/D. The effect of L/D on the DNB heat flux was clarified. It is confirmed that our DNB correlation can describe the experimental data.

Journal Articles

Effect of a heated pipe length on DNB heat flux in forced flow of liquid hydrogen

Tatsumoto, Hideki; Shirai, Yasuyuki*; Shiotsu, Masahiro*; Hata, Koichi*; Naruo, Yoshihiro*; Kobayashi, Hiroaki*; Inatani, Yoshifumi*; Narita, Norihiko*

Proceedings of 24th International Cryogenic Engineering Conference (ICEC 24) and International Cryogenic Materials Conference 2012 (ICMC 2012) (CD-ROM), p.157 - 160, 2012/05

The heat transfer in a forced flow of saturated liquid hydrogen was measured using vertically-mounted heated pipes with an inner diameter d of 6.0 mm and lengths L of 50, 100, 200 and 250 mm for wide ranges of flow velocity and pressure. The heat fluxes at departure from nucleate boiling were higher for higher flow velocities, lower pressures and shorter L. The effect of L on the DNB heat flux was clarified and could be described by the modified authors' DNB correlation.

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

Development of a thermal-hydraulics experimental system for high Tc superconductors cooled by liquid hydrogen

Tatsumoto, Hideki; Shirai, Yasuyuki*; Shiotsu, Masahiro*; Hata, Koichi*; Kobayashi, Hiroaki*; Naruo, Yoshihiro*; Inatani, Yoshifumi*; Kato, Takashi; Futakawa, Masatoshi; Kinoshita, Katsuhiro*

Journal of Physics; Conference Series, 234, p.032056_1 - 032056_9, 2010/07

 Times Cited Count:15 Percentile:96.77

A thermal-hydraulics experimental system of liquid hydrogen was developed in order to investigate the forced flow heat transfer characteristics in the various cooling channels for wide ranges of subcoolings, flow velocities, and pressures up to supercritical. Forced flow through the channel is produced by adjusting the pressure difference between the tanks and the valve opening. The mass flow rate is measured from the weight change of the main tank. For the explosion protection, electrical equipments are covered with a nitrogen gas blanket layer and a remote control system has been established. The first cryogenic performance tests have confirmed that the experimental system has satisfied with the required performances. The forced convection heat transfer characteristics have been successfully measured at the pressure of 0.7 MPa for various flow velocities.

Journal Articles

Forced convection heat transfer of subcooled liquid nitrogen in a vertical tube

Tatsumoto, Hideki; Shirai, Yasuyuki*; Hata, Koichi*; Kato, Takashi; Futakawa, Masatoshi; Shiotsu, Masahiro*

Journal of Physics; Conference Series, 234, p.032057_1 - 032057_8, 2010/07

 Times Cited Count:3 Percentile:60.61

Experimental research on forced convection heat transfer of subcooled liquid nitrogen ranging from the pressures of 0.3 MPa to its supercritical pressure is carried out for wide ranges of inlet temperature and flow velocity. The heat transfer coefficients in non-boiling region and the DNB heat fluxes are higher for higher flow velocity and higher subcooling. The heat transfer coefficients in the non-boiling region agree well with those by the Dittus-Boelter correlation, although they are unaffected by the flow velocity for $$Re$$ $$<$$ 8000. The lowest limits agree with those obtained for no forced flow. The correlation of DNB heat flux that can describe the experimental data is presented. The heat transfer characteristics of supercritical nitrogen can be predicted by authors'correlation.

Journal Articles

Commissioning results on the cryogenic hydrogen system for moderators in JSNS

Aso, Tomokazu; Tatsumoto, Hideki; Otsu, Kiichi; Uehara, Toshiaki; Kawakami, Yoshihiko; Sakurayama, Hisashi; Futakawa, Masatoshi

Proceedings of 19th Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-19) (CD-ROM), 8 Pages, 2010/07

In the J-PARC, the cryogenic hydrogen system for the 1MW pulsed spallation neutron source (JSNS) plays a role in supplying supercritical hydrogen at a temperature of 18 K and pressure of 1.5 MPa to three moderators in which spallation neutrons generated in a mercury target are slowed down to cold neutrons. Through the off-beam commissioning until April 2008, we confirmed that the specifications of the cryogenic system were satisfied as expected, and we could succeed in circulating supercritical hydrogen with the maximum flow rate of about 190 g/s. We have succeeded in generating first neutrons in the mercury target and providing moderated neutrons through the hydrogen moderators without any problems in May 2008. We also confirmed characteristics of the cryogenic hydrogen system with accepting the proton beam on the mercury target as on-beam commissioning.

Journal Articles

Forced convection heat transfer of subcooled liquid hydrogen in a small tube

Tatsumoto, Hideki; Shirai, Yasuyuki*; Shiotsu, Masahiro*; Hata, Koichi*; Kobayashi, Hiroaki*; Naruo, Yoshihiro*; Inatani, Yoshifumi*; Kato, Takashi; Futakawa, Masatoshi; Kinoshita, Katsuhiro*

Proceedings of International Cryogenic Engineering Conference 23 (ICEC-23) and International Cryogenic Materials Conference 2010 (ICMC 2010), p.491 - 496, 2010/07

Forced flow heat transfers of liquid hydrogen through a vertical tube with the diameter, d, of 3.0 mm were measured at the pressure of 0.7 MPa for various inlet temperatures and flow velocities. The non-boiling heat transfer coefficients agreed with those by the Dittus-Boelter correlation. The heat fluxes at the inception of boiling and the departure from nucleate boiling (DNB) heat fluxes were higher for higher flow velocity and subcooling. The DNB heat fluxes were higher for larger diameter, compared with those for $$d$$ = 6.0 mm. The effect of tube diameter and subcooling on the DNB heat flux was clarified.

Journal Articles

Pressure control characteristics of the cryogenic hydrogen system for a 300-kW proton beam operation

Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Uehara, Toshiaki; Sakurayama, Hisashi; Kawakami, Yoshihiko; Kato, Takashi; Futakawa, Masatoshi

Proceedings of International Cryogenic Engineering Conference 23 (ICEC-23) and International Cryogenic Materials Conference 2010 (ICMC 2010), p.1009 - 1014, 2010/07

The cryogenic hydrogen system provides supercritical hydrogen to three hydrogen moderators and removes the nuclear heating of 3.75 kW for a 1-MW proton beam operation at the J-PARC. A pressure control system that used a heater and an accumulator was designed to mitigate a pressure fluctuation caused by the sudden heat load of kW-order. The temperature and pressure behaviors were studied for a 300-kW beam operation. It was confirmed that the pressure control system made it possible to reduce the pressure fluctuation below 13.5 kPa. A simulation model was derived and could describe the experimental results within 15% errors.

Journal Articles

Performance test of a centrifugal supercritical hydrogen pump

Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Uehara, Toshiaki; Sakurayama, Hisashi; Kawakami, Yoshihiko; Kato, Takashi; Futakawa, Masatoshi; Yoshinaga, Seiichiro*

Proceedings of International Cryogenic Engineering Conference 23 (ICEC-23) and International Cryogenic Materials Conference 2010 (ICMC 2010), p.377 - 382, 2010/07

A dynamic gas bearing centrifugal pump that circulated supercritical hydrogen with a large flow rate of more than 0.16 kg/s was developed to minimize the hydrogen density change at the moderator. The two pumps were simultaneously operated in parallel for redundancy. The performance test results indicated that the dimensionless characteristics for the single and the parallel operations existed on an identical curve. An outstanding peak adiabatic efficiency exited at the flow coefficient of 0.046, independently of the revolution. It was verified that the developed hydrogen pump satisfied the design requirement.

Journal Articles

Safety interlock of the cryogenic hydrogen system at J-PARC

Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Uehara, Toshiaki; Sakurayama, Hisashi; Kawakami, Yoshihiko; Kato, Takashi; Futakawa, Masatoshi

Proceedings of International Cryogenic Engineering Conference 23 (ICEC-23) and International Cryogenic Materials Conference 2010 (ICMC 2010), p.601 - 606, 2010/07

At the J-PARC, the cryogenic hydrogen system provides supercritical hydrogen to three hydrogen moderators and removes the nuclear heating evolved by converting high energy neutrons into cold neutrons. As safety countermeasure, fail-safe devices such as relief valves and rupture disks are installed and a hydrogen explosion-proof structure is adopted. Additionally, the safety interlock system that is divided into 7 categories based on the trouble events is established to protect the equipments and to ensure the safety at the occurrence of a trouble. It is confirmed that the interlock system can be operated without any problems. The recovery procedures are also established.

Journal Articles

Development of the cryogenic hydrogen system for a spallation neutron source in J-PARC

Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Uehara, Toshiaki; Sakurayama, Hisashi; Kawakami, Yoshihiko; Kato, Takashi; Futakawa, Masatoshi

AIP Conference Proceedings 1218, p.297 - 304, 2010/04

 Times Cited Count:2 Percentile:77.16

In JSNS, supercritical hydrogen at around 20 K and 1.5 MPa was selected as a moderator material. Three kinds of hydrogen moderators are installed to provide pulsed neutron beam with higher neutronic performance. A cryogenic hydrogen system, in which a hydrogen circulation system is cooled by a helium refrigerator system with the refrigerator capacity of 6.45 kW at 15.6 K, provides the supercritical hydrogen to the moderators and absorbs nuclear heating in the moderators. Through the off-beam commissioning, we have confirmed that the cryogenic hydrogen system can be cooled down to 18 K within 19 hours. The supercritical hydrogen with the mass flow rate of 190 g/s can be circulated at the rated condition. It is verified that the cryogenic hydrogen system is satisfied with the performance requirements. In May 2008, we have succeeded in providing the first cold neutron beam cooled by the cryogenic hydrogen system.

Journal Articles

Development of a simulation code for a cool-down process of the cryogenic hydrogen system

Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Kato, Takashi; Futakawa, Masatoshi

AIP Conference Proceedings 1218, p.1154 - 1161, 2010/04

 Times Cited Count:1 Percentile:60.69

Supercritical hydrogen with a pressure of 1.5 MPa and a temperature of 20 K has been selected as a moderator material in an intense spallation neutron source (JSNS), which is one of main experimental facilities in J-PARC. The cryogenic hydrogen system, in which a hydrogen circulation system is cooled by a helium refrigerator with the refrigeration power of 6.45 kW at 15.5 K, has been designed to provide the supercritical hydrogen to the moderator and to remove the nuclear heating generated there. In this study, we have developed a simulation code that predicts temperature behaviors in the hydrogen circulation system during its cool-down process. A cool-down process analyses have been performed, and an operational method for the cool-down process has been studied. The analytical results indicate that the hydrogen circulation system would be able to be cooled down to 18 K within 19 hours.

Journal Articles

Pressure drop evaluation of the hydrogen circulation system for JSNS

Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Kato, Takashi; Futakawa, Masatoshi

AIP Conference Proceedings 1218, p.1162 - 1169, 2010/04

 Times Cited Count:0 Percentile:0.04

In J-PARC, an intense spallation neutron source (JSNS) driven by a proton beam of 1 MW has selected supercritical hydrogen with a temperature of around 20 K and the pressure of 1.5 MPa as a moderator material. A hydrogen circulation system has been designed to provide supercritical hydrogen to the moderators and remove the nuclear heating there. It is important for the cooling design of the hydrogen circulation system to understand the pressure drops through the equipments. In this work, the pressure drop through each component was analyzed by using a CFD code, STAR-CD. The correlation of the pressure drops through the components that can describe the analytical results within 14 % differences has been derived. It is confirmed that the pressure drop in the hydrogen circulation system would be estimated to be 37 kPa for the circulation flow rate of 160 g/s by using the correlations derived here, and is sufficiently lower than the allowable pump head of 100 kPa.

Journal Articles

Pressure fluctuation behavior in the cryogenic hydrogen system caused by a 100 kW proton beam injection

Tatsumoto, Hideki; Aso, Tomokazu; Otsu, Kiichi; Uehara, Toshiaki; Sakurayama, Hisashi; Kawakami, Yoshihiko; Kato, Takashi; Hasegawa, Shoichi; Futakawa, Masatoshi

AIP Conference Proceedings 1218, p.289 - 296, 2010/04

 Times Cited Count:2 Percentile:77.16

A cryogenic hydrogen system provides the supercritical hydrogen to the moderators and removes the nuclear heating at the moderators, which is estimated to 3.8 kW for a proton beam power of 1 MW. In order to mitigate pressure fluctuation caused by suddenly turning a proton beam on and off, we should design a pressure control system, which is composed of a heater as an active controller for thermal compensation and an accumulator as a passive volume controller. In December 2007, a 109 kW proton beam was injected to the JSNS. The pressure fluctuation behaviors have been studied for the 109 kW proton beam operation. As soon as the proton beam is injected, the accumulator starts to spontaneously constrict. The heater control can succeed in maintaining a constant heat load applied to the cryogenic hydrogen system. The pressure control system can reduce the pressure fluctuation below 5 kPa. We have confirmed that the pressure control system should be effective.

Journal Articles

Dynamic characteristics of the cryogenic hydrogen system for a spallation neutron source at J-PARC

Tatsumoto, Hideki; Aso, Tomokazu; Kato, Takashi; Otsu, Kiichi

Teion Kogaku, 45(4), p.181 - 190, 2010/04

To mitigate pressure fluctuation caused by the load, a pressure control system is a necessary requirement. Accordingly, a control system was designed and installed, using a heater and an accumulator. Changes in pressure caused by operation of a 120-kW and a 302-kW proton beam were studied. It was confirmed that the pressure control system was effective in mitigating the pressure fluctuation caused by the load. A simulation code was also developed and the pressure rise behavior and the accumulator variation were studied. The simulation results indicated good agreement with the experimental data within 10%. The pressure fluctuation for a 1-MW proton beam was predicted to be 33.9 kPa, which is lower than the allowable pressure rise of 0.1 MPa, and produced an accumulator variation of 11.35 mm. We believe that the pressure control system is effective for use with the operation of a 1-MW proton beam.

63 (Records 1-20 displayed on this page)