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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

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

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

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

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

Commissioning of the cryogenic hydrogen system in J-PARC; Preliminary operation by helium gas

Aso, Tomokazu; Tatsumoto, Hideki; Hasegawa, Shoichi; Otsu, Kiichi; Uehara, Toshiaki; Kawakami, Yoshihiko; Sakurayama, Hisashi; Maekawa, Fujio; Futakawa, Masatoshi; Ushijima, Isamu*

Proceedings of International Cryogenic Engineering Conference 22 (ICEC-22) and International Cryogenic Materials Conference 20 (ICMC 2008), p.741 - 746, 2009/00

no abstracts in English

Journal Articles

Observation of direct electron heating by the fast waves in the low-hybrid range of frequencies in the JFT-2M tokamak

Yamamoto, Takumi; Uesugi, Yoshihiko; Kawashima, Hisato; Hoshino, Katsumichi; ; Kasai, Satoshi; Kawakami, Tomohide; Kondoh, Takashi; Maeda, Hikosuke; Matsuda, Toshiaki; et al.

Physical Review Letters, 63(11), p.1148 - 1151, 1989/09

 Times Cited Count:17 Percentile:75.33(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

H mode observed in the JFT-2M tokamak with edge heating by electron cyclotron waves

Hoshino, Katsumichi; Yamamoto, Takumi; Kawashima, Hisato; Suzuki, Norio; Uesugi, Yoshihiko; Mori, Masahiro; ; Kasai, Satoshi; Kawakami, Tomohide; Matsuda, Toshiaki; et al.

Physical Review Letters, 63(7), p.770 - 773, 1989/08

 Times Cited Count:24 Percentile:80.58(Physics, Multidisciplinary)

no abstracts in English

JAEA Reports

Observation of H-mode by edge heating solely by electron cyclotron heating in a divertor configuration of JFT-2M tokamak

Hoshino, Katsumichi; Yamamoto, Takumi; Kawashima, Hisato; Suzuki, Norio; Uesugi, Yoshihiko; ; Kasai, Satoshi; Kawakami, Tomohide; Matsuda, Toshiaki; Miura, Yukitoshi; et al.

JAERI-M 89-038, 7 Pages, 1989/03

JAERI-M-89-038.pdf:0.29MB

no abstracts in English

Journal Articles

H-mode by edge ECH in JFT-2M

Hoshino, Katsumichi; Yamamoto, Takumi; Kawashima, Hisato; Tamai, Hiroshi; Ogawa, Toshihide; Odajima, Kazuo; Suzuki, Norio; Uesugi, Yoshihiko; Mori, Masahiro; ; et al.

Radio-Frequency Power in Plasmas, 4 Pages, 1989/00

no abstracts in English

Journal Articles

A New mode of improved confinement in discharges with stationary density in JEF-2M

Mori, Masahiro; Suzuki, Norio; Uesugi, Yoshihiko; Ogawa, Toshihide; Ogawa, Hiroaki; Otsuka, Hideo; Odajima, Kazuo; Kasai, Satoshi; Kawakami, Tomohide; Kawashima, Hisato; et al.

Nuclear Fusion, 28(10), p.1892 - 1897, 1988/10

 Times Cited Count:22 Percentile:73.49(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Particle accumulation at the edge observed in n$$_{e}$$ and T$$_{e}$$ profiles of H-mode JFT-2M plasma

Yamauchi, Toshihiko; Odajima, Kazuo; Uesugi, Yoshihiko; ; D.Dimock*; Kawashima, Hisato; Kasai, Satoshi; Kawakami, Tomohide; Maeda, Hikosuke; Matsuda, Toshiaki; et al.

Physics Letters A, 131(4-5), p.301 - 309, 1988/08

 Times Cited Count:2 Percentile:34.86(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Steep gradient and pedestal of electron profiles in H-mode JFT-2M plasma

Yamauchi, Toshihiko; Hoshino, Katsumichi; Uesugi, Yoshihiko; ; Kawashima, Hisato; Kasai, Satoshi; Kawakami, Tomohide; Maeda, Hikosuke; Matoba, Toru; Matsuda, Toshiaki; et al.

Japanese Journal of Applied Physics, 27(5), p.L924 - L926, 1988/05

 Times Cited Count:1 Percentile:9.88(Physics, Applied)

no abstracts in English

JAEA Reports

Requirements in the edge for H-mode transitions

Matsumoto, Hiroshi; ; Hoshino, Katsumichi; Kawashima, Hisato; Kawakami, Tomohide; Maeda, Hikosuke; Matoba, Toru; Matsuda, Toshiaki; Miura, Yukitoshi; Mori, Masahiro; et al.

JAERI-M 88-033, 15 Pages, 1988/02

JAERI-M-88-033.pdf:0.59MB

no abstracts in English

Journal Articles

Enhancement of wall fueling and improvement in n$$tau$$ of a beam-heated H-mode discharge by electron cyclotron wave in the JFT-2M Tokamak

Sengoku, Seio; ; Hasegawa, Mitsuru*; Hoshino, Katsumichi; Kasai, Satoshi; Kawakami, Tomohide; Kawashima, Hisato; Matoba, Toru; Matsuda, Toshiaki; Matsumoto, Hiroshi; et al.

Journal of the Physical Society of Japan, 57(3), p.903 - 908, 1988/00

 Times Cited Count:4 Percentile:48.11(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Transition from the L-mode to the H-mode by electron cyclotron heating of a tokamak edge plasma

Hoshino, Katsumichi; Yamamoto, Takumi; Suzuki, Norio; Kawashima, Hisato; Kasai, Satoshi; Kawakami, Tomohide; Maeda, Hikosuke; Matoba, Toru; Matsuda, Toshiaki; Matsumoto, Hiroshi; et al.

Nuclear Fusion, 28(2), p.301 - 306, 1988/00

 Times Cited Count:22 Percentile:73.49(Physics, Fluids & Plasmas)

no abstracts in English

JAEA Reports

Design of divertor plate and measurements of double-null open divertor plasma in the JFT-2M tokamak

*; Shoji, Teruaki; Mori, Masahiro; Odajima, Kazuo; Otsuka, Hideo; Suzuki, Norio; Hasegawa, Mitsuru*; *; Sugihara, Masayoshi; Uesugi, Yoshihiko; et al.

JAERI-M 87-192, 21 Pages, 1987/10

JAERI-M-87-192.pdf:0.73MB

no abstracts in English

34 (Records 1-20 displayed on this page)