Refine your search:     
Report No.
 - 
Search Results: Records 1-12 displayed on this page of 12
  • 1

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Thermal fatigue test on dissimilar welded joint between Gr.91 and 304SS

Wakai, Takashi; Kobayashi, Sumio; Kato, Shoichi; Ando, Masanori; Takasho, Hideki*

Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 7 Pages, 2017/07

This paper describes a thermal fatigue test on a structural model with a dissimilar welded joint. In the present design of JSFR, there may be dissimilar welded joints between ferritic and austenitic steels especially in IHX and SG. Creep-fatigue is one of the most important failure modes in JSFR components. However, the creep-fatigue damage evaluation method has not been established for dissimilar welded joint. To investigate the evaluation method, structural test will be needed for verification. Therefore, a thermal fatigue test on a thick-wall cylinder with a circumferential dissimilar welded joint between Mod.9Cr-1Mo steel and 304SS was performed. Since the coefficients of thermal expansion of these steels were significantly different, buttering layer of Ni base alloy was installed between them. After the completion of the test, deep cracks were observed at the HAZ in 304SS, as well as at HAZ in Mod.9Cr-1Mo steel. There were many tiny surface cracks in BM of 304SS. According to the fatigue damage evaluation based on the finite element analysis results, the largest fatigue damage was calculated at HAZ in 304SS. Large fatigue damage was also estimated at BM of 304SS. Fatigue cracks were observed at HAZ and BM of 304SS in the test, so that analytical results are in a good agreement with the observations. However, though relatively small fatigue damage was estimated at HAZ in Mod.9Cr-1Mo steel, deep fatigue cracks were observed in the test. To identify the cause of such a discrepancy between the test and calculations, we performed a series of finite element analyses. Some metallurgical investigations were also performed.

Journal Articles

Thermal transient test and strength evaluation of a tubesheet structure made of Mod.9Cr-1Mo steel, 1; Test model design and experimental results

Ando, Masanori; Hasebe, Shinichi; Kobayashi, Sumio; Kasahara, Naoto*; Toyoshi, Akira*; Omae, Takahiro*; Enuma, Yasuhiro*

Nuclear Engineering and Design, 275, p.408 - 421, 2014/08

AA2013-0395.pdf:2.65MB

 Times Cited Count:4 Percentile:31.13(Nuclear Science & Technology)

To clarify the failure mode of a semispherical tubesheet structure originally designed for SG in the JSFR, a cyclic thermal loading test was performed using a tubesheet model test structure. The tubesheet model made of Mod.9Cr-1Mo steel was subjected to 1,873 cycles of severe thermal transient loads using a large-scale sodium loop, in which sodium heated to 600$$^{circ}$$C and 250$$^{circ}$$C was flowed repeatedly with periods for each transient of 2 and 1 h, respectively. After the test, the test model was inspected by PT. Then, observation using a SEM and hardness testing were performed. A thermal-hydraulic analysis was also performed to validate the measured temperature history during the thermal transient. Through these examinations and evaluation with thermal-hydraulic analysis, the manner of failure in the tubesheet under cyclic thermal loading is discussed.

Journal Articles

Thermal transient test and strength evaluation of a tubesheet structure made of Mod.9Cr-1Mo steel, 2; Creep-fatigue strength evaluation

Ando, Masanori; Hasebe, Shinichi; Kobayashi, Sumio; Kasahara, Naoto*; Toyoshi, Akira*; Omae, Takahiro*; Enuma, Yasuhiro*

Nuclear Engineering and Design, 275, p.422 - 432, 2014/08

AA2013-0396.pdf:1.44MB

 Times Cited Count:12 Percentile:67.72(Nuclear Science & Technology)

In this study, the strength of a tubesheet test model simulating a semispherical tubesheet structure subjected to cyclic thermal transients was evaluated using the finite element analysis (FEA). A test model made of Mod.9Cr-1Mo steel was subjected to 1,873 cycles of severe thermal transient loading using a large-scale sodium loop, in which elevated-temperature sodium at 600$$^{circ}$$C and 250$$^{circ}$$C was flowed repeatedly and kept at the final temperature for 2 and 1 h, respectively. Heat transfer analysis and stress analysis were performed using the sodium temperature data measured during the test. Then, the elastic and inelastic stress analysis results were used to investigate the failure mechanism by creep-fatigue damage and evaluate the failure strength. The evaluation based on the results of inelastic analysis estimated the number of cycles to failure within a factor of 3.

Journal Articles

Creep-fatigue evaluation of a structural model made of Mod.9Cr-1Mo steel subjected to the cyclic thermal loading

Ando, Masanori; Hasebe, Shinichi; Kobayashi, Sumio; Kasahara, Naoto*; Toyoshi, Akira*; Omae, Takahiro*; Enuma, Yasuhiro*

Nihon Kikai Gakkai M&M 2013 Zairyo Rikigaku Kanfarensu Koen Rombunshu (CD-ROM), p.OS1510_1 - OS1510_3, 2013/10

To validate the failure mode and assess creep-fatigue damage evaluation, a thick cylinder test model made of Mod.9Cr-1Mo steel was subjected to 1,873 cycles of accelerated thermal transient loading using a large-scale sodium loop through which liquid sodium at 600$$^{circ}$$C and 250$$^{circ}$$C flowed repeatedly, with the period of each transient being 2 h and 1 h, respectively. After completion of the test, liquid penetrant testing, a surface observation and hardness testing were performed to characterize failure mode. Based on the finite element analysis, creep-fatigue life was evaluated by applying the JSME FRs code. The failure cycles evaluated by rules described in the JSME FRs code was shown to have a safety margin of greater than 300 times for this system.

Journal Articles

Thermal fatigue crack growth tests and analyses of thick wall cylinder made of Mod.9Cr-1Mo steel

Wakai, Takashi; Inoue, Osamu*; Ando, Masanori; Kobayashi, Sumio

Transactions of 22nd International Conference on Structural Mechanics in Reactor Technology (SMiRT-22) (CD-ROM), 9 Pages, 2013/08

Journal Articles

Thermal transient test and strength evaluation of a thick cylinder model made of Mod.9Cr-1Mo steel

Ando, Masanori; Hasebe, Shinichi; Kobayashi, Sumio; Kasahara, Naoto*; Toyoshi, Akira*; Omae, Takahiro*; Enuma, Yasuhiro*

Nuclear Engineering and Design, 255, p.296 - 309, 2013/02

 Times Cited Count:19 Percentile:81.46(Nuclear Science & Technology)

To verify the failure mode and assess creep-fatigue damage, a thick cylinder test model made of Mod.9Cr-1Mo steel was subjected to 1,873 cycles of accelerated thermal transient loading using a large-scale sodium loop through which liquid sodium at 600 $$^{circ}$$C and 250 $$^{circ}$$C flowed repeatedly, with the period of each transient being 2 h and 1 h, respectively. After completion of the test, the test model was inspected using liquid penetrant testing. Observations using a scanning electron microscope and hardness testing were then performed to characterize creep-fatigue damage in the structural model subjected to cyclic thermal transient loading in a sodium environment. Finite element analysis were performed to evaluate the relationship between creep-fatigue damage and the observed crack conditions.

Journal Articles

Spectra thermal fatigue tests under frequency controlled fluid temperature variation; Superposed sinusoidal temperature fluctuations tests

Kawasaki, Nobuchika; Takasho, Hideki*; Kobayashi, Sumio; Hasebe, Shinichi; Kasahara, Naoto

Proceedings of 2008 ASME Pressure Vessels and Piping Division Conference (PVP 2008) (CD-ROM), 9 Pages, 2008/07

To clarify frequency-dependent attenuation effects of fluid temperature fluctuation on fatigue strength, thermal fatigue strength tests subjected to superposed sinusoidal temperature fluctuations were performed by the SPECTRA test facility. After these fatigue tests, cylindrical test pieces were cut away from the test loop, and cracks were observed on the inner surface of the test pieces. Fatigue lives at crack initiation positions were evaluated based on the test conditions. Adopting power spectrum density functions and frequency transfer functions, fatigue lives were predicted within a factor 3.

Journal Articles

Spectra thermal fatigue tests under frequency controlled fluid temperature variation; Strength tests

Kawasaki, Nobuchika; Hasebe, Shinichi; Kobayashi, Sumio; Kasahara, Naoto

Proceedings of 2007 ASME Pressure Vessels and Piping Division Conference/8th International Conference on Creep and Fatigue at Elevated Temperatures (PVP 2007/CREEP-8) (CD-ROM), 8 Pages, 2007/07

Thermal fatigue strength tests subjected to sinusoidal fluid temperature waves were performed by the SPECTRA test facility, where frequencies were 0.05, 0.2, and 0.5Hz. Cracks were observed on the inner surface of cylindrical test pieces after testing. 0.05Hz's wave caused a greater number of and deeper cracks than 0.5Hz's wave under the same fluid temperature range and the same fatigue cycles. The crack initiation region of the 0.05Hz's wave was larger than for the 0.5Hz's wave. Estimated fatigue failure cycles based on the frequency transfer functions were compared with test results. Frequency-dependency in failure cycles was observed through these test results, and frequency transfer functions could estimate this dependency. The test results supported the fatigue damage evaluation method with frequency transfer functions.

JAEA Reports

Experimental Study on Properties of High Cycle Thermal Fatigue, 3; Results of sinusoidal temperature fluctuation test at 20 second cycle

Hasebe, Shinichi; Kobayashi, Sumio; Tanaka, Hiroshi*; lbaraki, Koichi*; Fukasaku, Hiroshi*

JNC TN9400 2004-034, 73 Pages, 2004/03

JNC-TN9400-2004-034.pdf:6.02MB

In a nuclear power plant, it is necessary to be attentive to fatigue fracture of the structural material caused by cyclic thermal stress due to the mixing of temperature different fluids. The purpose of this study is to obtain data to demonstrate high cycle thermal fatigue evaluation methods by applying the effects of the frequency of temperature fluctuation. A sinusoidal temperature fluctuation test of with a 20 second period was conducted using high cycle fatigue test equipment (SPECTRA). A SUS304 steel pipe was used as the test sample, at an average sodium temperature of 425 deg-C, fluctuation amplitude of 200deg-C and a sodium flow rate of 300 l/min in the test pipe. The results obtained are as follows: (1)valid strength data to verify evaluation methods could be obtained by applying a 20 second cycle temperature fluctuation to the test sample with SPECTRA. A Crack penetrated at about 157,150 cycles. (2)Numerous cracks in an axial direction were observed on the jnner surface of the test sample in the upper flow area. An air fatigue test demonstrated the difference in the strength of the test sample between axial direction and circumferential direction, revealing that cracks were distributed in an axial direction since anisotropic influences easily appear on the hjgh cycle side. (3)An approximated curve obtained by the common relation of crack and axial direction distance indicates that the boundary of a crack would be located about 430 mm downstream from the tapered end of the test sample with the upper now. (4)Crack occurring on the inner surface progressed to a depth of 1 to 2 mm in thecrystal grain, then progressed along the crystal grain boundary. Striations were formed on areas of the fracture surface in the grain, but were not found on the fracture surface of the grain boundary. Sinusoidal temperature fluctuation tests at the periods of 2,5,10,and 40 seconds are planned to confirm the influence of fluctuation frequency responsiveness on structural material

Journal Articles

Spectra thermal fatigue tests under frequency controlled fluid temperature change; Development of test equipment and preliminary tests

kasahara, Naoto; Hasebe, Shinichi; Kobayashi, Sumio; Ando, Masanori; Kawasaki, Nobuchika; Morita, Hiroshi*

ASME PVP-Vol.472, P. 2986, 2004/00

Focusing on the cover layer materials (as the Radon Barrier Materials), which could have the effect to restrain the radon from scattering into the air and the effect of the radiation shielding, we produced the radon barrier materials with crude bentonite on an experimental basis, using the rotary type comprehensive unit for grinding and mixing, through which we carried out the evaluation of the characteristics thereof.

JAEA Reports

Experimental study on properties of high cycle thermal fatigue; Outline and test plan of high cycle fatigue test equipment on sodium

Hasebe, Shinichi; Kobayashi, Sumio; Ando, Masanori; Kasahara, Naoto

JNC TN9400 2003-004, 110 Pages, 2003/01

JNC-TN9400-2003-004.pdf:4.23MB

At a nuclear power plant, where fluids of high and low temperatures flow into each other, it is necessary to prevent structural failure damage caused by high cycle thermal fatigue (thermal striping phenomenon). High cycle fatigue test equipment on thermal can be develop by modifying the thermal transient test facility for structure (TTS) in order to clarify the effect of temperature fluctuation induced by the thermal striping phenomenon on crack initiation and their propagation behavior. The test equipment has the following characteristic. (1)Fluid is controlled by a circulation pump, and by continuously changing the flow quantity ratio of high and low temperature Sodium, sinusoidal temperature fluctuations at various period of the test samples can be taken. (2)Mixing is done by the jet flow mix, thus it can generate axisymmetric temperature fluctuations by accelerating the mixing process of high and low temperature Sodium. (3)It can also control the temperature fluctuation, in which short and long term changes are superimposed. (4)Because the test sample cylinder is hollow, analysis of thermal stress and data from crack initiation to crack propagation can easily be obtained. Sinusoidal temperature fluctuations, random temperature fluctuations, and strength testing of the weld zone by test samples made of stainless steel are planned in the next stage.

Oral presentation

In-site test of a bentonite pellet backfilling method for prefabricated engineered barrier system module

Mori, Takuo*; Niunoya, Sumio*; Kobayashi, Masato*; Nishimura, Masanobu*; Nakayama, Masashi

no journal, , 

Prefabricated Engineered barrier system Module (PEM) is one of option for Radioactive waste emplacement. Narrow gap between Tunnel and PEM must be backfilled with Bentonite, to prevent water permeability. Authors developed Bentonite Pellet Backfilling Method for the narrow gap. In-site test was executed at Horonobe URL -350m. Bentonite Pellet was backfilled two gaps (Minimum width: 110 mm) between an actual size PEM and the Tunnel. A 1.37 Mg/m$$^3$$ backfill dry density is achieved. It was proofed that the Bentonite Pellet Backfilling Method is averrable for the Radioactive waste emplacement.

12 (Records 1-12 displayed on this page)
  • 1