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Futagami, Satoshi; Ando, Masanori; Yamano, Hidemasa
Transactions of the 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 10 Pages, 2024/03
Yoshimura, Kazuo; Doda, Norihiro; Igawa, Kenichi*; Uwaba, Tomoyuki; Tanaka, Masaaki; Nemoto, Toshiyuki*
Transactions of the 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 8 Pages, 2024/03
To investigate possibility of the insertion of the reactivity by the deflection of the upper core support plate, structural mechanics analyses of the domain consisting of the fuel assemblies and core support plates and evaluation of the reactivity due to the inclination of the fuel assemblies in EBR-II were carried out. As a result, it was indicated that the upper core support plate deflected downward larger at the low flowrate condition than that at the high flowrate condition and positive reactivity was inserted due to the inclination of the fuel assemblies at the low flowrate condition.
Wang, Y. W.*; Wang, H. H.*; Su, Y. H.; Xu, P. G.; Shinohara, Takenao
Materials Science & Engineering A, 887, p.145768_1 - 145768_13, 2023/11
Times Cited Count：1 Percentile：54.26(Nanoscience & Nanotechnology)
Mg and long-period stacking ordered phases in a Mg-Zn-Y alloy by hot-extrusion with low extrusion ratioHarjo, S.; Gong, W.; Aizawa, Kazuya; Kawasaki, Takuro; Yamasaki, Michiaki*
Acta Materialia, 255, p.119029_1 - 119029_12, 2023/08
Times Cited Count：6 Percentile：95.52(Materials Science, Multidisciplinary)Yamano, Hidemasa; Futagami, Satoshi; Ando, Masanori
Mechanical Engineering Journal (Internet), 10(4), p.23-00043_1 - 23-00043_12, 2023/08
This study has conducted a detailed structural analysis of a reactor vessel (RV) in a loop-type sodium-cooled fast reactor using a general-purpose finite element analysis code, FINAS/STAR, to understand its deformation behavior under extremely high temperature conditions and to identify the areas which should be focused to mitigate impacts of failure. The RV was heated from the normal operation condition to the sodium boiling temperature in the upper sodium plenum during 20 hours assuming depressurization. The analysis has revealed less significant stress and strain which were sufficiently lower than failure criteria. The upper body of RV was identified as the important area in terms of mitigation of structural failure. The RV was eventually deformed downward about 16 cm, resulting in no failure. This effect contributes to maintaining RV sodium level in a long term, thereby enhancing the RV resilience.
Okuda, Takahiro; Takahashi, Hideki*; Watakabe, Tomoyoshi
Mechanical Engineering Journal (Internet), 10(4), p.23-00075_1 - 23-00075_9, 2023/08
In recent years, to make the seismic design more rational for the piping systems in nuclear power plants, it has been expected to develop a design method considering plastic deformation and the accompanying energy dissipation of the piping itself. In this study, an extensive series of seismic response analyses was conducted to investigate the degree of influence of the plastic deformation of the pipe support structures on the seismic response of the entire piping system. The analyses include; plasticity is considered for (1) none, (2) the piping only, (3) the support structure only, and (4) both the piping and the support structure.
Yoshimura, Kazuo; Doda, Norihiro; Fujisaki, Tatsuya*; Igawa, Kenichi*; Tanaka, Masaaki; Yamano, Hidemasa
Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 10 Pages, 2023/05
The benchmark analyses for the unprotected loss of heat sink (ULOHS) tests in the pool-type experimental SFR in the United States, EBR-II (BOP-301 and BOP-302R) have been conducted in order to validate the evaluation method of the reactivity feedback equipped in the plant dynamics analysis code named Super-COPD. In this study, 1D-CFD coupled analyses adding the core bowing reactivity model were conducted. Through the analysis, the applicability of the modified reactivity model was confirmed for the BOP-301 test. For the BOP-302R test, consideration of the core restraint system in the core and modeling the control rod driveline expansion reactivity was indicated.
Doda, Norihiro; Kato, Shinya; Iida, Masaki*; Yokoyama, Kenji; Tanaka, Masaaki
Proceedings of 12th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS12) (Internet), 8 Pages, 2022/10
In the conventional core design in sodium-cooled fast reactors (SFRs), negative reactivity feedback due to core deformation was neglected because of large uncertainty in analytical evaluation. To optimize core design, it is necessary to develop an analytical evaluation method and eliminate excessive conservativeness. An evaluation method for core deformation reactivity has been developed by coupling analysis of neutronics, thermal-hydraulics, and structural mechanics. For the verification study of the neutronics calculation method, the reactivity was calculated for the deformed core geometry in which the fuel assembly (FA) moved horizontally in the radial direction for each row from the core center. Compared to reference values derived from Monte Carlo calculations, the calculated reactivity due to FA displacement agreed well in the core region and was overestimated in the reflector region. The modification challenges in development of the core deformation model were identified.
Yamano, Hidemasa; Futagami, Satoshi; Ando, Masanori
Proceedings of 29th International Conference on Nuclear Engineering (ICONE 29) (Internet), 7 Pages, 2022/08
This study has conducted a detailed structural analysis of a reactor vessel (RV) in a loop-type sodium-cooled fast reactor using a general-purpose finite element analysis code, FINAS/STAR, to understand its deformation behavior under extremely high temperature conditions and to identify the areas which should be focused to mitigate impacts of failure. The RV was heated from the normal operation condition to the sodium boiling temperature in the upper sodium plenum during 20 hours assuming depressurization. The analysis has revealed less significant stress and strain which were sufficiently lower than failure criteria. The upper body of RV was identified as the important area in terms of mitigation of structural failure. The RV was eventually deformed downward about 16 cm, resulting in no failure. This effect contributes to maintaining RV sodium level in a long term, thereby enhancing the RV resilience.
Katsuyama, Jinya; Yamaguchi, Yoshihito; Nemoto, Yoshiyuki; Furuta, Takuya; Kaji, Yoshiyuki
Proceedings of ASME 2022 Pressure Vessels and Piping Conference (PVP 2022) (Internet), 9 Pages, 2022/07
Futagami, Satoshi; Ando, Masanori; Yamano, Hidemasa
Transactions of the 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 9 Pages, 2022/07
CaIdeguchi, Eiji*; Kib
di, T.*; Dowie, J. T. H.*; Hoang, T. H.*; Kumar Raju, M.*; Aoi, Nori*; Mitchell, A. J.*; Stuchbery, A. E.*; Shimizu, Noritaka*; Utsuno, Yutaka; et al.
Physical Review Letters, 128(25), p.252501_1 - 252501_6, 2022/06
Times Cited Count：2 Percentile：46.35(Physics, Multidisciplinary)no abstracts in English
during high temperature deformationJaladurgam, N. R.*; Lozinko, A.*; Guo, S.*; Harjo, S.; Colliander, M. H.*
Materialia, 22, p.101392_1 - 101392_4, 2022/05
Ominato, Yuya*; Oue, Daigo*; Matsuo, Mamoru
Physical Review B, 105(19), p.195409_1 - 195409_9, 2022/05
Times Cited Count：1 Percentile：17.38(Materials Science, Multidisciplinary)
observation of recrystallization of aluminum single crystals using synchrotron radiation monochromatic X-raysShiro, Ayumi*; Shobu, Takahisa; Okada, Tatsuya*
Zairyo, 71(4), p.354 - 360, 2022/04
Recrystallization process of an aluminum (Al) single crystal was observed in situ using synchrotron X-rays. Al single-crystalline samples were deformed in tension along a 
111
direction to a strain of 8%, and were subsequently annealed at 753 K. The changes in the shape and intensity of diffraction spots were analyzed using a two-dimensional detector. A diffraction spot from the deformation matrix had three peaks which reflected a sub-grained microstructure of the sample. The 
observation during annealing unveiled the appearance of diffraction spots from a recrystallized grain at 330.8 s. As the diffraction spots from the recrystallized grain became larger, the diffraction spots from the deformation matrix gradually disappeared. The application of the X-ray topography method revealed the crystal orientation variation in a recrystallized grain in order of 0.001 degree.
Doda, Norihiro; Uwaba, Tomoyuki; Yokoyama, Kenji; Nemoto, Toshiyuki*; Tanaka, Masaaki
Proceedings of 19th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-19) (Internet), 14 Pages, 2022/03
In sodium-cooled fast reactors, reactivity feedback is generated by thermal deformation of the core fuel assembly during core temperature rise. To utilize the core deformation reactivity as an inherent safety characteristic and to eliminate excessive conservativeness of core design in the safety evaluation, an evaluation method by coupling analyses of neutronics, thermal-hydraulics, and structural deformation has been developed. An experiment of unprotected loss-of-flow event in the experimental fast breeder reactor EBR-II was analyzed. The analysis results show that the core deformation reactivity has a negative feedback effect, and that the deformation reactivity is affected not only by the fuel movement but also by the movement of reflectors around the fuel. As a result, the availability of the evaluation method for core deformation reactivity feedback by coupled analysis approach is confirmed.
Naeem, M.*; He, H.*; Harjo, S.; Kawasaki, Takuro; Lin, W.*; Kai, J.-J.*; Wu, Z.*; Lan, S.*; Wang, X.-L.*
Acta Materialia, 221, p.117371_1 - 117371_18, 2021/12
Times Cited Count：31 Percentile：94.34(Materials Science, Multidisciplinary)Tsuchida, Noriyuki*; Harjo, S.
Metals, 11(12), p.2053_1 - 2053_16, 2021/12
Times Cited Count：2 Percentile：16.86(Materials Science, Multidisciplinary)Kim, Y. S.*; Chae, H.*; Woo, W.*; Kim, D.-K.*; Lee, D.-H.*; Harjo, S.; Kawasaki, Takuro; Lee, S. Y.*
Materials Science & Engineering A, 828, p.142059_1 - 142059_10, 2021/11
Times Cited Count：15 Percentile：80.35(Nanoscience & Nanotechnology)Naeem, M.*; Zhou, H.*; He, H.*; Harjo, S.; Kawasaki, Takuro; Lan, S.*; Wu, Z.*; Zhu, Y.*; Wang, X.-L.*
Applied Physics Letters, 119(13), p.131901_1 - 131901_7, 2021/09
Times Cited Count：9 Percentile：62.1(Physics, Applied)