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C in Mod.9Cr-1Mo steel to 1
10
cyclesToyota, Kodai; Imagawa, Yuya; Onizawa, Takashi; Kato, Shoichi; Furuya, Yoshiyuki*
Nihon Kikai Gakkai Rombunshu (Internet), 89(928), p.23-00206_1 - 23-00206_15, 2023/12
In order to design fast reactors, it is necessary to consider high cycle fatigue of structural materials up to 110
cycles; to evaluate high cycle fatigue at 110 cycles, it is necessary to develop a best-fit fatigue curve applicable up to 110 cycles. In this study, high cycle fatigue tests were conducted under strain-controlled conditions and ultrasonic fatigue tests were also conducted to develop a high cycle fatigue evaluation method for Mod.9Cr-1Mo steel, which is a candidate material for fast reactor structural materials. Based on the test results, the best-fit fatigue curves were extended and the applicability of the JSME best-fit fatigue curves up to 110 cycles was verified.
Ishida, Shinya; Fukano, Yoshitaka
Nihon Kikai Gakkai Rombunshu (Internet), 88(911), p.21-00304_1 - 21-00304_11, 2022/07
In previous studies, the reliability and validity of the SAS4A code was enhanced by applying Phenomena Identification and Ranking Table (PIRT) approach to the Unprotected Loss of Flow (ULOF). SAS4A code has been developed to analyze the early stage of Core Disruptive Accident (CDA), which is named Initiating Phase (IP). In this study, PIRT approach was applied to Unprotected Transient over Power (UTOP), which was one of the most important and typical events in CDA as well as ULOF. The phenomena were identified by the investigation of UTOP event progression and physical phenomena relating to UTOP were ranked. 8 key phenomena were identified and the differences in ranking between UTOP and ULOF were clarified. The code validation matrix was completed and an SAS4A model, which was not validated in ULOF, was identified and validated. SAS4A code became applicable to various scenarios by using PIRT approach to UTOP and the reliability and validity of SAS4A code were significantly enhanced.
Kosaka, Wataru; Uchibori, Akihiro; Yanagisawa, Hideki*; Takata, Takashi; Jang, S.*
Nihon Kikai Gakkai Rombunshu (Internet), 88(905), p.21-00310_1 - 21-00310_9, 2022/01
If a pressurized water/water-vapor leaks from a heat transfer tube in a steam generator (SG) in a sodium-cooled fast reactor (SFR), sodium-water reaction forms high-velocity, high-temperature, and corrosive jet. It would damage the other tubes and might propagate the tube failure in the SG. Thus, it is important to evaluate the effect of the tube failure propagation for safety assessment of SFR. The computational code LEAP-III can evaluate water leak rate during the tube failure propagation with short calculation time, since it consists of empirical formulae and one-dimensional equations of conservation. One of the empirical models, temperature distribution evaluation model, evaluates the temperature distribution in SG as circular arc isolines determined by experiments and preliminary analyses instead of complicated real distribution. In order to improve this model to get more realistic temperature distribution, we have developed the Lagrangian particle method based on engineering approaches. In this study, we have focused on evaluating gas flow in a tube bundle system, and constructed new models for the gas-particles behavior around a tube to evaluate void fraction distribution near the tube. Through the test analysis simulating one target tube system, we confirmed the capability of the models and next topic to improve the models.
Fukasawa, Tsuyoshi*; Miyagawa, Takayuki*; Uchita, Masato*; Yamamoto, Tomohiko; Miyazaki, Masashi; Okamura, Shigeki*; Fujita, Satoshi*
Nihon Kikai Gakkai Rombunshu (Internet), 87(898), p.21-00007_1 - 21-00007_17, 2021/06
This paper describes a fundamental study on the seismic safety margin for the isolated structure using laminated rubber bearings. The variation of the seismic response assumed in the isolated structure will occur under the superposition of "Variations in seismic response due to input ground motions" and "Error with design value accompanying manufacture of the isolation devices ". The seismic response analysis which allows to their conditions is important to assess the seismic safety margin for the isolated structure. This paper clarifies that the seismic safety margin of the isolated structure, which consists of rubber bearings, for Sodium-cooled Fast Reactor (SFR) is ensured against the basis ground motions of Japan Electric Association Guide 4601 (JEAG4601) and SFR through the seismic response analysis considering the variation factors of seismic response. In addition, a relationship between the seismic safety margin and the excess probability of linearity limits is discussed using the results of seismic response analysis.
Furuyama, Taisei*; Thwe Thwe, A.; Katsumi, Toshiyuki; Kobayashi, Hideaki*; Kadowaki, Satoshi
Nihon Kikai Gakkai Rombunshu (Internet), 87(898), p.21-00107_1 - 21-00107_12, 2021/06
The effects of steam addition on the unstable behavior of hydrogen-air lean premixed flames under adiabatic and non-adiabatic conditions were investigated by numerical calculations. Adopting a detailed chemical reaction mechanism of hydrogen-oxyfuel combustion modeled by 17 reversible reactions of 8 active species and diluents, a two-dimensional unsteady reaction flow was treated based on the compressible Navier-Stokes equation. As the steam addition and heat loss increased, the burning velocity of a planar flame decreased and the normalized burning velocity increased. The addition of water vapor promotes the unstable behavior of the hydrogen-air lean premixed flame. This is because the thermal diffusivity of the gas decreases and the diffusion-thermal instability increases. The effect of adding water vapor on the instability of hydrogen premixed flames is a new finding, and it is expected to connect with hydrogen explosion-prevention measures as in NPP.
Suzuki, Tamaki*; Okawa, Teppei*; Harjo, S.; Sasaki, Toshihiko*
Nihon Kikai Gakkai Rombunshu (Internet), 87(894), p.20-00377_1 - 20-00377_15, 2021/02
Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro
Nihon Kikai Gakkai Rombunshu (Internet), 86(883), p.19-00360_1 - 19-00360_13, 2020/03
It is necessary to simulate a eutectic melting reaction and relocation behavior of boron carbide (B
C) as a control rod material and stainless steel (SS) during a core disruptive accident in an advanced sodium-cooled fast reactor designed in Japan because the BC-SS eutectic relocation behavior has a large uncertainty in the reactivity history based on a simple calculation. A physical model simulating the eutectic melting reaction and relocation was developed and implemented into a severe accident simulation code. The developed model must be validated by using test data. To validate the physical model, therefore, the visualization tests of SS-BC eutectic melting reaction was carried out by contacting SS melts of several kg with a BC pellet heated up to about 1500 C. The tests have shown the eutectic reaction visualization as well as freezing and relocation of the BC-SS eutectic in upper part of the solidified test piece due to the density separation. Post-test material analyses by using X-ray diffraction and transmission electron microscope techniques have indicated that FeB appeared at the BC-SS contact interface and (Fe,Cr)
B at the top surface of the test piece. Glow discharge optical emission spectrometry has been applied to quantitative analysis of boron concentration distributions. The boron concentration was high at the upper surface and near the original position of the BC pellet.
Uchibori, Akihiro; Yanagisawa, Hideki*; Takata, Takashi; Ohshima, Hiroyuki
Nihon Kikai Gakkai Rombunshu (Internet), 86(883), p.19-00353_1 - 19-00353_6, 2020/03
Evaluation of occurrence possibility of tube failure propagation under sodium-water reaction accident is an important issue. In this study, a numerical analysis method to predict occurrence of failure propagation by overheating rupture was constructed to expand application range of an existing computer code. Applicability of the method was constructed through the numerical analysis of the experiment on water vapor discharging in liquid sodium.
Aoyagi, Mitsuhiro; Uchibori, Akihiro; Kikuchi, Shin; Takata, Takashi; Ohno, Shuji; Ohshima, Hiroyuki
Nihon Kikai Gakkai Rombunshu (Internet), 86(883), p.19-00366_1 - 19-00366_8, 2020/03
Sodium fire is one of key issues in sodium-cooled fast reactor plant. JAEA has developed sodium fire analysis codes, such as AQUA-SF and SPHINCS, to evaluate the consequence of sodium fire events. This paper describes the PIRT (Phenomena Identification and Ranking Table) process for sodium fire events. Ranking table for important phenomena and an assessment matrix are completed. As a part of comprehensive validation based on the assessment matrix, experimental analyses using the AQUA-SF and SPHINCS codes for a sodium spray fire experiment Run-E1 show good agreement with the experimental result.
Kadowaki, Satoshi; Nogami, Masato*; Thwe Thwe, A.; Katsumi, Toshiyuki*; Yamazaki, Wataru*; Kobayashi, Hideaki*
Nihon Kikai Gakkai Rombunshu (Internet), 85(879), p.19-00274_1 - 19-00274_13, 2019/11
We dealt with three-dimensional cellular premixed flames generated by hydrodynamic and diffusive-thermal instabilities to elucidate the effects of unburned-gas temperature and heat loss by adopting the three-dimensional compressible Navier-Stokes equation. As the unburned-gas temperature became lower and the heat loss became larger, the growth rate decreased and the unstable range narrowed. With a decrease of unburned-gas temperature, the normalized growth rate increased and the normalized unstable range widened, which was because the temperature ratio of burned and unburned gases became larger. The obtained hexagonal cellular fronts were qualitatively consistent with the experimental results. As the heat loss became larger, the burning velocity of a cellular flame normalized by that of a planar flame increased. This was because diffusive-thermal effects became stronger owing to the increase of apparent Zeldovich number caused by the decrease of flame temperature.
Shintaku, Yuichi*; Shinozaki, Yuto*; Fujiwara, Takaki*; Takahashi, Akiyuki*; Kikuchi, Masanori
Nihon Kikai Gakkai Rombunshu (Internet), 85(876), p.19-00141_1 - 19-00141_15, 2019/08
The contribution of this paper is to develop two kinds of numerical simulation method for fatigue crack propagation with plastic-induced crack closure under different cyclic loading conditions. One of the developed methods is Direct Numerical Simulation (DNS) using S-version FEM that allow us to simulate by combining with global mesh only representing whole structure and local mesh including crack. After stress intensity factor is calculated by S-version FEM, crack opening level due to plastic-induced crack closure is determined by elastic-plastic analysis using local mesh which is enough subdivided to realize small plastic zone around crack tip. The crack growth rate considering effect of plastic-induced crack closure is predicted by modified Paris' law in which the stress intensity factor range under cyclic loading is converted into the effective value by the crack opening level. Then, the local mesh is updated by new crack shape determined from crack growth rate. By repeating these processes, our developed method can provide us to simulate fatigue crack propagation with plastic-induced crack closure directly. Another method is simplified one that the effective stress intensity factor range is approximately determined by the relationship between the maximum stress intensity factor and crack opening level as a result of preanalysis using two-dimensional DNS. By comparison of experimental results, it can be confirmed that our developed methods predict propagation of surface crack in specimen under bending and tensile loading conditions.
Okajima, Satoshi
Nihon Kikai Gakkai Rombunshu (Internet), 85(874), p.18-00348_1 - 18-00348_9, 2019/06
Yada, Hiroki; Takaya, Shigeru; Wakai, Takashi; Nakai, Satoru; Machida, Hideo*
Nihon Kikai Gakkai Rombunshu (Internet), 84(859), p.17-00389_1 - 17-00389_15, 2018/03
no abstracts in English
Uesawa, Shinichiro; Horiguchi, Naoki; Shibata, Mitsuhiko; Yoshida, Hiroyuki
Nihon Kikai Gakkai Rombunshu (Internet), 84(859), p.17-00392_1 - 17-00392_10, 2018/03
no abstracts in English
Kurihara, Akikazu; Umeda, Ryota; Shimoyama, Kazuhito; Kikuchi, Shin
Nihon Kikai Gakkai Rombunshu (Internet), 84(859), p.17-00382_1 - 17-00382_11, 2018/03
Wastage on adjacent tubes (target-wastage) arise from water/steam leak in steam generators of sodium-cooled fast reactors (sodium-water reaction). Target-wastage is likely to be caused by liquid droplet impingement erosion (LDI) and Na-Fe composite oxidation type corrosion with flow (COCF) in an environment marked by high temperature and high-alkali (reaction jet) due to sodium-water reaction. In the previous study, the authors quantitatively evaluated the effect of material temperature and fluid velocity on COCF rate, and revealed that COCF was sodium-iron composite oxidation type corrosion from metallographic observation and element assay. In this study, the applicability of new wastage correlations was confirmed for each tube in sodium-water reaction test with straight vertical tube bundle under practical steam generator operation condition. The authors established that the new wastage correlations were applicable to each tube of tube bundle in the above test, and the time progress of wastage was qualitatively investigated for the two penetrated tubes in the period including the water and/or steam blowdown.
Uchibori, Akihiro; Watanabe, Akira*; Takata, Takashi; Ohshima, Hiroyuki
Nihon Kikai Gakkai Rombunshu (Internet), 84(859), p.17-00394_1 - 17-00394_6, 2018/03
For assessment of the wastage environment under tube failure accident in a steam generator of sodium-cooled fast reactors, a mechanistic computer code called SERAPHIM calculating compressible multicomponent multiphase flow with sodium-water chemical reaction has been developed. The original SERAPHIM code is based on the finite difference method. In this study, unstructured mesh-based numerical method was developed and introduced into the SERAPHIM code to advance a numerical accuracy for the complex-shaped domain including multiple heat transfer tubes. Validity of the unstructured mesh-based SERAPHIM code was investigated through the analysis of an underexpanded jet experiment. The calculated pressure profile showed good agreement with the experimental data. Numerical analysis of water vapor discharging into liquid sodium was also performed. It was demonstrated that the proposed numerical method could be applicable to evaluation of the sodium-water reaction phenomenon.
Aoyagi, Mitsuhiro; Takata, Takashi; Ohno, Shuji; Uno, Masayoshi*
Nihon Kikai Gakkai Rombunshu (Internet), 84(859), p.17-00374_1 - 17-00374_13, 2018/03
no abstracts in English
Yoshizawa, Atsufumi*; Oba, Kyoko; Kitamura, Masaharu*
Nihon Kikai Gakkai Rombunshu (Internet), 83(856), p.17-00263_1 - 17-00263_17, 2017/12
Kuroda, Masatoshi*; Kamaya, Masayuki*; Yamada, Teruaki*; Akita, Koichi
Nihon Kikai Gakkai Rombunshu (Internet), 83(852), p.17-00072_1 - 17-00072_7, 2017/07
In order to assess the fatigue damage of austenitic stainless steels by electron backscatter diffraction (EBSD) method more simply and easily, it should be more preferable to use a commercially available general-purpose EBSD analysis software rather than to employ an in-house developed EBSD analysis programme. In the present study, EBSD measurement was performed for Type 316 austenitic stainless steels subjected to cyclic loading, and the applicability of the EBSD parameter relevant to the pattern quality, which could be obtained by the commercial software, to the fatigue damage assessment was discussed by comparing the other EBSD parameter of the averaged local misorientation (Mave), which could be calculated by the in-house developed programme. As a result, the EBSD parameter relevant to the pattern quality, which signified the full width at half maximum (FWHM) of the histogram distribution of the image quality (IQ), was saturated at the beginning stage of the fatigue cycles, while Mave was increased monotonically with the cycles. This suggested that the FWHM of IQ could be useful to detect the initial stage of the fatigue damage, while Mave was suitable for the quantitative evaluation of the fatigue damage. XRD measurement was also carried out for the same samples employed in the EBSD measurement, and the XRD data was compared with the EBSD data to discuss the crystallographic mechanism of the change in the FWHM of IQ. As a result, it was found that the FWHM of the (111) XRD peak correlated well with the FWHM of IQ. Because the (111) plane in fcc metal such as austenitic stainless steel was most preferable for slip system, this implied that the change in the distribution of the pattern quality generated by the fatigue loading could be due to the slip deformation.
Watakabe, Tomoyoshi; Yamamoto, Tomohiko; Fukasawa, Tsuyoshi*; Okamura, Shigeki*; Somaki, Takahiro*; Morobishi, Ryota*; Sakurai, Yu*; Kato, Koji*
Nihon Kikai Gakkai Rombunshu (Internet), 83(850), p.16-00444_1 - 16-00444_14, 2017/06
A seismic isolation system composed of a thick rubber bearing and an oil damper has been developed for Sodium-Cooled Fast Reactor. This paper focused on the aging properties of thick rubber bearings, such as basic mechanical properties and ultimate strength. Aging of the rubber bearings was reproduced using thermal degradation based on Arrhenius law.
