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Journal Articles

Development of flow-induced vibration evaluation methodology based on unsteady fluid flow analysis for large diameter pipe with elbow in JSFR

Hayakawa, Satoshi*; Ishikura, Shuichi*; Watanabe, Osamu*; Kaneko, Tetsuya*; Yamano, Hidemasa; Tanaka, Masaaki

Proceedings of 8th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-8) (USB Flash Drive), 10 Pages, 2012/12

The present methodology was applied to the analysis for the 1/3-scale experiment of the hot-leg pipe of JSFR, and the predicted stress values were compared with the measured stress values. The predicted stress values were underestimated in the case of using the intact pressure fluctuations obtained by the unsteady fluid flow analysis. Therefore, the improvement of the prediction accuracy of the pressure fluctuations on the pipe wall was attempted.

Journal Articles

Development of hydraulic analysis code for optimizing ceramics reactors

Terada, Atsuhiko; Takegami, Hiroaki; Noguchi, Hiroki; Kamiji, Yu; Ishikura, Shuichi*

Proceedings of 19th International Conference on Nuclear Engineering (ICONE-19) (CD-ROM), 6 Pages, 2011/10

The Japan Atomic Energy Agency has been conducting study on thermo-chemical Iodine-Sulfur (IS) process for water splitting hydrogen production. In design of the IS test equipment, it is important to design ceramics chemical reactors with high performance from the viewpoint of thermal hydraulics and structural integrity. A new simple hydraulic analytical code has been developed for considering sulfuric acid solution as a mixture of two components especially in the H$$_{2}$$SO$$_{4}$$ decomposer. Complex flow with liquid-vaporized interaction involving chemical reaction will be characterized in the H$$_{2}$$SO$$_{4}$$ decomposer. Based on the preliminary analytical results obtained with above mentioned code, conceptual investigation of structural integrity of ceramics decomposer was carried out by a general commercial FEM code.

JAEA Reports

Study on structural design technique of silicon carbide applied for thermochemical hydrogen production IS process

Takegami, Hiroaki; Ishikura, Shuichi*; Terada, Atsuhiko; Inagaki, Yoshiyuki

JAEA-Technology 2011-002, 41 Pages, 2011/03

JAEA-Technology-2011-002.pdf:5.08MB

The IS process is the hydrogen production method which used the thermochemical reaction cycle of sulfuric acid and iodyne. The sulfuric acid decomposer, which is one of the important equipment of the IS process, is the equipment to heat with hot helium and for the sulfuric acid of 90 wt% to evaporate. The heat exchanger is required to be pressure-resistant structure because it uses high-pressure helium of 4 MPa, and the material is required to have heat resistance and corrosion resistance with high temperature sulfuric acid more than 700 $$^{circ}$$C. Therefore, silicon carbide (SiC) was selected from the corrosion experiment as the most excellent material. However, the structure design technique of ceramics structures is not serviced as the standard. In this report, the structural design technique was studied by the material strength characteristic of the ceramics into consideration.

Journal Articles

Thermomechanical simulation of SiC-block-made sulfuric acid decomposer

Ishikura, Shuichi; Terada, Atsuhiko; Noguchi, Hiroki; Kasahara, Seiji; Onuki, Kaoru; Hino, Ryutaro

Nihon Genshiryoku Gakkai Wabun Rombunshi, 7(2), p.134 - 141, 2008/06

The Japan Atomic Energy Agency (JAEA) has been conducting R&D on hydrogen production by the thermo-chemical Iodine-Sulfur (IS) process to meet massive hydrogen demand in future hydrogen economy. In the IS process, sulfuric acid (H$$_{2}$$SO$$_{4}$$) is evaporated and decomposed into H$$_{2}$$O and SO$$_{3}$$ in a H$$_{2}$$SO$$_{4}$$ decomposer operated under high temperature condition up to 500$$^{circ}$$C. We have proposed a new decomposer concept of a block type heat exchanger made of SiC ceramic which has a salient corrosion resistant performance under severe corrosion condition. To verify mechanical feasibility of the concept, temperature distributions of sulfuric acid and helium gas were analyzed with newly coded analytical system applicable to binary mixture such as H$$_{2}$$SO$$_{4}$$ whose boiling point depends on concentration. Thermo-mechanical simulations with a general-purpose FEM code, which used the heat exchange simulation results, showed that maximum stress generated around the dryout region, which was about half of allowable tensile stress of SiC.

JAEA Reports

Development of high-temperature joints for thermochemical hydrogen production by IS process; Applicability examination of the coned-disk springs assembly and seal performance test of candidate gaskets

Kanagawa, Akihiro*; Iwatsuki, Jin; Ishikura, Shuichi; Onuki, Kaoru; Hino, Ryutaro

JAEA-Technology 2007-060, 31 Pages, 2007/11

JAEA-Technology-2007-060.pdf:4.2MB

Thermo-chemical Iodine-Sulfur (IS) process can produce large amount of hydrogen effectively without emission of greenhouse effect gas such as carbon dioxide, where nuclear thermal energy of a high temperature gas-cooled reactor (HTGR) is adopted as a heat source. The IS process uses strong acids such as sulfuric acid and hydriodic acid in high temperature and pressure conditions. Therefore, it is necessary to develop large-size chemical reactors featuring materials that exhibit high temperature and corrosion resistance. A SO$$_{3}$$ decomposer, which is one of key components of the IS process, consists of a pressure vessel for high temperature and high pressure helium gas and an internal structure for SO$$_{3}$$ decomposition by the latent heat of the helium gas. Since joints of the internal structure will be heated up to 700$$^{circ}$$C, we designed a high-temperature joint coupled with coned-disk springs and SiC bolts (coned-disk springs assembly) so as to keep seal performance under high temperature condition. This report presents applicability examination results of designed coned-disk springs assembly as well as seal performance test results of candidate gaskets.

Journal Articles

Development of chemical reactors for thermo-chemical water-splitting IS process

Iwatsuki, Jin; Terada, Atsuhiko; Noguchi, Hiroki; Ishikura, Shuichi; Takahashi, Toshio*; Hino, Ryutaro

Dai-12-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu, p.285 - 286, 2007/06

The Japan Atomic Energy Agency has been proceeding design works on a pilot test plant of 30Nm$$^{3}$$/hr-scale hydrogen production by using thermo-chemical water splitting process by iodine and sulfur (IS process) to contribute future hydrogen economy using high-temperature gas-cooled reactors. In parallel to the design works, key engineering issues on corrosion-resistant pipelines and its sealing using dish-type springs were examined under high temperature conditions. This paper introduces experimental results of heat cycle test results of a glass-lining pipe and seal performance using dish-type springs which works as thermal expansion absorber of bolts.

Journal Articles

Dynamic response of mercury subjected to pressure wave

Kogawa, Hiroyuki; Futakawa, Masatoshi; Ishikura, Shuichi

Journal of Nuclear Science and Technology, 44(4), p.523 - 529, 2007/04

 Times Cited Count:4 Percentile:26.87(Nuclear Science & Technology)

A high power pulsed proton beam will be injected into a mercury target for nuclear spallation reaction. Due to the pulsed proton injection, mercury is heated rapidly and pressure waves are generated. The mercury target vessel, in which mercury is enclosed, is subjected to the pressure waves. Dynamic response of mercury is important to evaluate the integrity of the mercury target vessel. An impact experiments on the mercury by using the split-Hopkinson pressure-bar (SHPB) technique were carried out. Numerical analyses were also carried out to verify the analytical model by using an explicit FEM code. It is found that the analytical results approximately represented the experimental results. And it was recognized that the stiffness of mercury under impact condition was independent of the impact velocity in this experimental range.

Journal Articles

Failure probability estimation of multi-walled vessels for mercury target

Wakui, Takashi; Futakawa, Masatoshi; Kogawa, Hiroyuki; Ishikura, Shuichi

Journal of Nuclear Science and Technology, 44(4), p.530 - 536, 2007/04

 Times Cited Count:7 Percentile:49.85(Nuclear Science & Technology)

A liquid mercury target for MW-class pulse spallation neutron sources is being developed. Failure probability analyses on the mercury target that will be installed at the material and life science facility in the Japan Proton Accelerator Research Complex (J-PARC) were carried out taking account of the stress condition caused by various types of loading and material degradation due to neutron irradiation and pitting damages. The mercury target consists of multi-walled vessels; a mercury vessel and a safety hull, to prevent mercury leakage to the outside, i.e. the mercury vessel that is in contact with mercury is covered by the safety hull. The failure probability of the safety hull was estimated to be lower than 10$$^{-6}$$ for the expected designed lifetime. On the other hand, the failure probability of the mercury vessel directly subjected to thermally shocked pressure waves in mercury increased with the operation time and the proton beam power, and was estimated to be ca. 99.9 % for the designed lifetime of the MW-class target.

Journal Articles

Development of hydrogen production technology by thermochemical water splitting IS process; Pilot test plan

Terada, Atsuhiko; Iwatsuki, Jin; Ishikura, Shuichi; Noguchi, Hiroki; Kubo, Shinji; Okuda, Hiroyuki; Kasahara, Seiji; Tanaka, Nobuyuki; Ota, Hiroyuki*; Onuki, Kaoru; et al.

Journal of Nuclear Science and Technology, 44(3), p.477 - 482, 2007/03

 Times Cited Count:39 Percentile:92.63(Nuclear Science & Technology)

Japan Atomic Energy Agency (JAEA) has been conducting study on thermochemical IS process for hydrogen production. A pilot test of IS process is under planning that covers four R&D subjects: (1) construction of a pilot test plant made of industrial materials and completion of hydrogen production test using electrically-heated helium gas as the process heat supplier, (2) development of analytical code system, (3) component tests to assist the hydrogen production test and also to improve the process performance for the commercial plant, (4) design of HTTR-IS system. Development of innovative chemical reactors is in progress, which are equipped with ceramic heat exchanger. In design of the IS plant, it is important to establish the system for "design by analysis". Therefore, we have developed a multi-phase flow analysis code that can analyze systems in which chemical reactions occur

Journal Articles

Evaluation of the 3-Gev proton beam profile at the spallation target of the JSNS

Meigo, Shinichiro; Noda, Fumiaki*; Ishikura, Shuichi*; Futakawa, Masatoshi; Sakamoto, Shinichi; Ikeda, Yujiro

Nuclear Instruments and Methods in Physics Research A, 562(2), p.569 - 572, 2006/06

 Times Cited Count:15 Percentile:73.49(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Development of chemical reactors for thermochemical water-splitting IS (Iodine-Sulfer) process

Terada, Atsuhiko; Iwatsuki, Jin; Ota, Hiroyuki; Noguchi, Hiroki; Ishikura, Shuichi*; Hino, Ryutaro; Hirayama, Toshio

Koon Gakkai-Shi, 32(1), p.63 - 68, 2006/01

Japan Atomic Energy Research Institute has been conducting study on thermochemical IS process for hydrogen production. A pilot test of IS process is under planning that covers four R&D subjects: (1) construction of a pilot test plant made of industrial materials and completion of hydrogen production test using electrically-heated helium gas as the process heat supplier, (2) development of analytical code system, (3) component tests to assist the hydrogen production test and also to improve the process performance for the commercial plant, (4) design study of HTTR-IS system.

Journal Articles

Pitting damage evaluation by liquid/solid interface impact analysis

Naoe, Takashi; Futakawa, Masatoshi; Oi, Toshiyuki; Ishikura, Shuichi*; Ikeda, Yujiro

Zairyo, 54(11), p.1184 - 1190, 2005/11

High power spallation targets for neutron sources are being developed in the world. Mercury target will be installed at the material science and life facility in J-PARC, which will promote innovative science. The mercury target is subject to the pressure wave caused by the proton bombarding in the mercury. The pressure wave propagation induces the cavitation in mercury that imposes localized impact damage on the target vessel. The impact erosion is a critical issue to decide the lifetime of the target. The electro Magnetic IMpact Testing Machine, MIMTM, was developed to reproduce the localized impact erosion damage and evaluate the damage formation. Additionally, droplet impact analysis was carried out to investigate the correlation between isolate pit profile and micro-jet velocity. We confirmed that value of depth/radius was able to estimate micro jet-velocity. And the velocity at 560W in MIMTM was estimated to be 225$$sim$$325 m/s. Furthermore, surface-hardening treatments were inhibited pit formation in plastic deformation.

Journal Articles

Pitting damage by pressure waves in a mercury target

Futakawa, Masatoshi; Naoe, Takashi; Tsai, C.-C.*; Kogawa, Hiroyuki; Ishikura, Shuichi*; Ikeda, Yujiro; Soyama, Hitoshi*; Date, Hidefumi*

Journal of Nuclear Materials, 343(1-3), p.70 - 80, 2005/08

 Times Cited Count:54 Percentile:95.91(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Effect of proton beam profile on stress in JSNS target vessel

Kogawa, Hiroyuki; Ishikura, Shuichi*; Sato, Hiroshi; Harada, Masahide; Takatama, Shunichi*; Futakawa, Masatoshi; Haga, Katsuhiro; Hino, Ryutaro; Meigo, Shinichiro; Maekawa, Fujio; et al.

Journal of Nuclear Materials, 343(1-3), p.178 - 183, 2005/08

 Times Cited Count:8 Percentile:51.68(Materials Science, Multidisciplinary)

A cross-flow type (CFT) mercury target with flow guide blades, which has been developed for JSNS, can suppress the generation of stagnant flow region especially near the beam window where the peak heat density is generated due to spallation reaction. Then, a flat type beam window has been applied to the CFT target from the viewpoint of suppressing dynamic stress caused by a pressure wave, which has been estimated with a mercury model of the linear equation of state. The recent experimental results obtained by using a proton beam incidents to mercury led that a cutoff pressure model in the equation of state of mercury caused a suitable dynamic stress with experimental results. Dynamic stress analyses were carried out with the cutoff pressure model, in which the negative pressure less than 0.15 MPa was not generated. The generated dynamic stress in the flat beam window became much larger than that in a semi-cylindrical type window. However, the generated stress in the semi-cylindrical type beam window was over the allowable stress of SS316L under the peak heat density of 668 W/cc. In order to decrease the dynamic stress in the semi-cylindrical beam window, the incident proton beam was defocused to decrease the peak heat density down to 218 W/cm$$^{3}$$. As a result, the dynamic stress could be suppressed less than the allowable stress. On the other hand, due to defocus of the proton beam, high heat density was generated on the end of the flow guide blades, which caused high thermal stress exceeding the allowable stress. To decrease the thermal stress, several shapes of the blade ends were studied analytically, which were selected so as not to affect the mercury flow distribution. A simple thin-end blade showed low thermal stress below the allowable stress.

JAEA Reports

Failure probability analysis on mercury target vessel

Ishikura, Shuichi*; Shiga, Akio*; Futakawa, Masatoshi; Kogawa, Hiroyuki; Sato, Hiroshi; Haga, Katsuhiro; Ikeda, Yujiro

JAERI-Tech 2005-026, 65 Pages, 2005/03

JAERI-Tech-2005-026.pdf:2.86MB

Failure probability analysis was carried out to estimate the lifetime of the mercury target which will be installed into the JSNS (Japan spallation neutron source) in J-PARC (Japan Proton Accelerator Research Complex). The lifetime was estimated as taking loading condition and materials degradation into account. Considered loads imposed on the target vessel were the static stresses due to thermal expansion and static pre-pressure on He-gas and mercury and the dynamic stresses due to the thermally shocked pressure waves generated repeatedly at 25 Hz. Materials used in target vessel will be degraded by the fatigue, neutron and proton irradiation, mercury immersion and pitting damages, etc. The imposed stresses were evaluated through static and dynamic structural analyses. The material-degradations were deduced based on published experimental data. As results, it was quantitatively confirmed that the failure probability for the lifetime expected in the design is very much lower, 10$$^{-11}$$ in the safety hull, meaning that it will be hardly failed during the design lifetime. On the other hand, the beam window of mercury vessel suffered with high-pressure waves exhibits the failure probability of 12%. It was concluded, therefore, that the leaked mercury from the failed area at the beam window is adequately kept in the space between the safety hull and the mercury vessel to detect mercury-leakage sensors.

JAEA Reports

Technical report on the structural integrity and the lifetime evaluation for the mercury target vessel

Ishikura, Shuichi*; Futakawa, Masatoshi; Kogawa, Hiroyuki; Meigo, Shinichiro; Maekawa, Fujio; Harada, Masahide; Sato, Hiroshi; Haga, Katsuhiro; Ikeda, Yujiro

JAERI-Tech 2004-028, 123 Pages, 2004/03

JAERI-Tech-2004-028.pdf:9.55MB

This report describes the structural design concept applied to the mercury target vessel used for the spallation neutron source installed in the material and life science experiment facility of J-PARC (Japan Proton Accelerator Complex), and the results evaluated on the basis of the concept. The features of the design concept are as follows: (1) The target vessel design is followed to "Law concerning Prevention from Radiation Hazards due to Radio-Isotopes". That is because (i) there is not the possibility in the target of the RIA (Reactivity Initiated Accident) generally considered in the nuclear power reactors, and (ii) the target vessel is not a permanent structure. (2) Therefore, the Class 1 Vessel of the JIS B-8270 [design code for pressure vessel] that is equivalent to a standard for nuclear power structural design is applicable as a design code for the target to sufficiently keep the safety of target system. The stresses for the design were evaluated using the linear elastic analysis based on the infinitesimal strain theory in order to confirm the safe and rational design.

Journal Articles

Micro pit formation by mercury-sphere collision

Ishikura, Shuichi*; Kogawa, Hiroyuki; Futakawa, Masatoshi; Kaminaga, Masanori; Hino, Ryutaro; Saito, Masakatsu*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(1), p.59 - 66, 2004/03

The development of a MW-class spallation neutron source facility is being carried out under the Japan Proton Accelerator Research Complex (J-PARC) Project promoted by JAERI and KEK. A mercury target working as the spallation neutron source will be subjected to pressure waves generated by rapid thermal expansion of mercury due to a pulsed proton beam injection. The pressure wave will impose dynamic stress on the vessel and deform the vessel, which would cause cavitation in mercury. To evaluate the effect of mercury micro jets, driven by cavitation bubble collapse, on the micro-pit formation, analyses on mercury sphere collision were carried out: single bubble dynamics and collision behavior on interface between liquid and solid, which take the nonlinearity due to shock wave in mercury and the strain rate dependency of yield stress in solid metal into account. Analytical results give a good explanation to understand relationship between the micro-pit formation and material properties: the pit size could decrease with increasing the yield strength of materials.

Journal Articles

Hardening effect on impact erosion in interface between liquid and solid metals

Futakawa, Masatoshi; Naoe, Takashi*; Kogawa, Hiroyuki; Ishikura, Shuichi*; Date, Hidefumi*

Zairyo, 53(3), p.283 - 288, 2004/03

no abstracts in English

JAEA Reports

Structural integrity of heavy liquid-metal target installed in spallation neutron facility, 4; Consideration by fracture mechanics of target container window

Ishikura, Shuichi*; Kogawa, Hiroyuki; Futakawa, Masatoshi; Kikuchi, Kenji; Haga, Katsuhiro; Kaminaga, Masanori; Hino, Ryutaro

JAERI-Tech 2003-093, 55 Pages, 2004/01

JAERI-Tech-2003-093.pdf:5.41MB

To estimate the structural integrity of the heavy liquid-metal (Hg) target used in a MW-class neutron scattering facility, static and dynamic stress behaviors due to the incident of a 1MW-pulsed proton beam were analyzed. In the analyses, two-type target containers with semi-cylindrical type and flat type window were used as analytical models of the structural analysis codes LS-DYNA. As a result, it is confirmed that the stress generated by dynamic thermal shock becomes the largest at the center of window, and the flat type window is more advantageous from the structural viewpoint than the semi-cylindrical type window. It was confirmed to erosion damage the target container by mercury's becoming negative pressure in the window and generating the cavitation by the experiment. Therefore, it has been understood that the point top of the window was in the compression stress field by the steady state thermal stress because of the evaluation from destroying the dynamic viewpoint for the crack in the generated pit and the pit point, and the crack did not progress.

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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