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Journal Articles

Effects of heterogeneity of geomechanical properties on tunnel support stress during tunnel excavation

Okazaki, Yasuyuki*; Hayashi, Hisashi*; Aoyagi, Kazuhei; Morimoto, Shingo*; Shinji, Masato*

Proceedings of 5th ISRM Young Scholars' Symposium on Rock Mechanics and International Symposium on Rock Engineering for Innovative Future (YSRM 2019 and REIF 2019) (USB Flash Drive), 6 Pages, 2019/12

In the design of tunnel support, the behavior of the rock mass around a tunnel and the stress acting on the tunnel support may be predicted using a numerical analysis. However, in such a numerical analysis, it is common to assume that each stratum comprises a homogeneous material, ignoring the heterogeneity of the geomechanical properties inherent to the rock mass. For this reason, it is not unusual for the results of the numerical analysis to differ from the actual behavior. We performed a tunnel excavation analysis considering the heterogeneity of the geomechanical properties in the rock mass to investigate the local increase in the tunnel support stress obtained in the 350 m gallery at the Horonobe Underground Research Laboratory. The results revealed that, in order to predict the locally increased support stress in advance, it is necessary to carry out a tunneling excavation analysis considering the heterogeneity of the geomechanical properties. It was also revealed that the scale at which the geomechanical properties fluctuate is an important factor.

JAEA Reports

Mechanical properties database of reactor pressure vessel steels related to fracture toughness evaluation

Tobita, Toru; Nishiyama, Yutaka; Onizawa, Kunio

JAEA-Data/Code 2018-013, 60 Pages, 2018/11

JAEA-Data-Code-2018-013.pdf:1.67MB

Mechanical properties of materials including fracture toughness are extremely important for evaluating the structural integrity of reactor pressure vessels (RPVs). In this report, the published data of mechanical properties of nuclear RPVs steels, including neutron irradiated materials, acquired by the Japan Atomic Energy Agency (JAEA), specifically tensile test data, Charpy impact test data, drop-weight test data, and fracture toughness test data, are summarized. There are five types of RPVs steels with different toughness levels equivalent to JIS SQV2A (ASTM A533B Class 1) containing impurities in the range corresponding to the early plant to the latest plant. In addition to the base material of RPVs, the mechanical property data of the two types of stainless overlay cladding materials used as the lining of the RPV are summarized as well. These mechanical property data are organized graphically for each material and listed in tabular form to facilitate easy utilization of data.

Journal Articles

Characterization of the VULCANO test products for fuel debris removal from the Fukushima Daiichi Nuclear Power Plant

Kitagaki, Toru; Ikeuchi, Hirotomo; Yano, Kimihiko; Ogino, Hideki; Haquet, J.-F.*; Brissonneau, L.*; Tormos, B.*; Piluso, P.*; Washiya, Tadahiro

Progress in Nuclear Science and Technology (Internet), 5, p.217 - 220, 2018/11

Journal Articles

Sound speeds in and mechanical properties of (U,Pu)O$$_{2-x}$$

Hiroka, Shun; Kato, Masato

Journal of Nuclear Science and Technology, 55(3), p.356 - 362, 2018/03

 Times Cited Count:2 Percentile:33.17(Nuclear Science & Technology)

The sound speeds of longitudinal and transverse waves in the uranium-plutonium mixed oxide (MOX) pellets were measured as functions of porosity, oxygen-to-metal ratio (O/M) and plutonium content. The effect of each parameter was well fitted by a linear function and the equations were obtained to calculate the sound speeds. Mechanical properties were evaluated with the sound speeds and the result of Young's modulus showed that porosity was the most important factor to decrease Young's modulus. Temperature dependence on Young's modulus was also evaluated with previously reported thermal expansion. Decrease of Young's modules with increasing temperature was in good agreement with available literature.

Journal Articles

Poly(ether ether ketone) (PEEK)-based graft-type polymer electrolyte membranes having high crystallinity for high conducting and mechanical properties under various humidified conditions

Hamada, Takashi; Hasegawa, Shin; Fukasawa, Hideyuki*; Sawada, Shinichi; Koshikawa, Hiroshi; Miyashita, Atsumi; Maekawa, Yasunari

Journal of Materials Chemistry A, 3(42), p.20983 - 20991, 2015/11

 Times Cited Count:27 Percentile:70.78(Chemistry, Physical)

no abstracts in English

Journal Articles

Mechanical properties of small size specimens of F82H steel

Wakai, Eiichi; Otsuka, Hideo*; Matsukawa, Shingo; Furuya, Kazuyuki*; Tanigawa, Hiroyasu; Oka, Keiichiro*; Onuki, Somei*; Yamamoto, Toshio*; Takada, Fumiki; Jitsukawa, Shiro

Fusion Engineering and Design, 81(8-14), p.1077 - 1084, 2006/02

 Times Cited Count:11 Percentile:63.08(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Mechanical characteristics evaluation of fuel cladding tube for reduced-moderation water reactor, 1 (Contract research)

Kaneko, Tetsuji; Tsukatani, Ichiro; Kiuchi, Kiyoshi

JAERI-Research 2005-005, 23 Pages, 2005/03

JAERI-Research-2005-005.pdf:1.65MB

Fuel elements used in The Reduced-Moderation Water Reactor (RMWR) have the lamellar structure consisting of MOX pellets and UO$$_{2}$$ blankets in order to attain the high breeding ratio and high burn-up simultaneously. It is a characteristic of the fuel elements that there is high thermal stress caused by inhomogeneous linear power density along the longitudinal direction of the fuel rod. Therefore, it is important to evaluate the local deformation behavior due to the transient temperature distribution. To estimate the thermal deformation behavior, the temperature and stress distribution of the fuel cladding tube assumed in the designed reactor were analyzed. Moreover, basic physical properties and mechanical properties for analyzing the deformation behavior were obtained by experiment using fuel cladding tubes made of candidate alloys. In addition, the appropriate experimental conditions for realizing the practical thermal deformation behavior of the fuel cladding tube was selected by adjusting the testing temperature distribution based on data obtained with thermal analysis.

Journal Articles

Fabrication of advanced SiC fiber/F-CVI SiC matrix composites with SiC/C multi-layer interphase

Taguchi, Tomitsugu; Nozawa, Takashi*; Igawa, Naoki; Kato, Yutai*; Jitsukawa, Shiro; Koyama, Akira*; Hinoki, Tatsuya*; Snead, L. L.*

Journal of Nuclear Materials, 329-333(Part1), p.572 - 576, 2004/08

 Times Cited Count:42 Percentile:92.95(Materials Science, Multidisciplinary)

The SiC/SiC composite with SiC/C multi-layer interphase coated on advanced SiC fibers was fabricated by the forced thermal-gradient chemical vapor infiltration (F-CVI) process for improvement in mechanical properties. The SEM and TEM observation verified that SiC/C multi-layer interphase was formed on SiC fibers. The both flexural and tensile strengths of SiC/SiC composite with SiC/C multi-layer interphase were approximately 10 % higher than that with single carbon interphase. The SEM observation on the fracture surface of the composite with SiC/C multi-layer reveals that cylindrical steps around the fiber were formed. The several crack deflections occurred within SiC/C multi-layer interphase. The SiC/C multi-layer applied in this study operated efficiently to improve the mechanical properties.

Journal Articles

Mechanical properties and microstructure of F82H steel doped with boron or boron and nitrogen as a function of heat treatment

Wakai, Eiichi; Sato, Michitaka*; Sawai, Tomotsugu; Shiba, Kiyoyuki; Jitsukawa, Shiro

Materials Transactions, 45(2), p.407 - 410, 2004/01

 Times Cited Count:4 Percentile:34.26(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Tensile and impact properties of F82H steel applied to HIP-bond fusion blanket structures

Furuya, Kazuyuki; Wakai, Eiichi; Ando, Masami; Sawai, Tomotsugu; Iwabuchi, Akira*; Nakamura, Kazuyuki; Takeuchi, Hiroshi

Fusion Engineering and Design, 69(1-4), p.385 - 389, 2003/09

 Times Cited Count:18 Percentile:76.42(Nuclear Science & Technology)

In a fusion reactor, a blanket made of a low activation material like F82H is fabricated by solid Hot Isostatic pressing (HIP) joining method. In a previous study, blanket, grain coarsenings were found in a mock-up around HIP-joined region. To verify an effect of the coarsenings on a strength of the HIP-joined region, tensile test and hardness measurement were done. As the results, the tensile strength increased by about 50 MPa, and the elongation decreased by about 4 % in comparison with that of a standard alloy. Though the hardness was almost constant both in the coarsening and a non-coarsening regions, both of these hardness increased by about 5 %. Therefore, it could be judged that change of the tensile property is due to increase of the hardness. On the other hand, tensile and impact tests of a base metal without coarsening resulted in DBTT increase by about 40 K, although the tensile property was nearly equal to that of the joined-region with coarsening. It can be understood that this is the effect of the heat treatments in the fabrication process of the mock-up.

JAEA Reports

Mechanical properties changes of high burnup PWR fuel cladding by temperature transient

Nagase, Fumihisa; Uetsuka, Hiroshi

JAERI-Research 2002-023, 23 Pages, 2002/11

JAERI-Research-2002-023.pdf:1.94MB

To obtain basic data to evaluate fuel rod integrity during abnormal transient and accident of LWRs, high burnup PWR fuel claddings were heated for 0 to 600s at temperatures of 673 through 1173K, and the mechanical property changes were examined by using ring tensile test at room temperature. As a result of the test, it was shown that strength and ductility of the cladding are changed depending on heating temperature and time. The mechanical property changes by temperature transients are considered to be correspondent mainly to recovery of irradiation defect, recovery and recrystallization of the Zircaloy, phase transformations, and associated change of the hydride distribution and morphology. Comparison with unirradiated claddings suggested that irradiation effects are not completely annealed out by the short-term annealing at high temepratures. Radial change of hydrogen concentration was measured for the high burnup PWR fuel cladding and very high hydrogen concentration of about 2400wtppm was detected at the cladding periphery.

Journal Articles

Identification of material constants in constitutive equation by indentation test with different indenters

Wakui, Takashi*; Futakawa, Masatoshi; Tanabe, Yuji*; Ioka, Ikuo

Zairyo, 51(6), p.681 - 687, 2002/06

This paper describes the novel technique for determining constants in constitutive equaution of elastic-palstic materials by the indentation test with indenters having different tip angles. FEM analyses were carried out to evaluate the effect of material constants and the indenter tip angle on the load-depth curve. The constitutive equation was determeined from the characterized curves associated with the effects on the slope. Simiulation analyses were performed for some material models to exammine accuracy of the presented technique. It is confirmed that this technique is useful to determine the constitutive equation of sub-surface of materials or coatings.

Journal Articles

Optimizing the fabrication process for excellent mechanical properties in stoichiometric SiC fiber/FCVI SiC matrix composites

Taguchi, Tomitsugu; Igawa, Naoki; Jitsukawa, Shiro; Nozawa, Takashi*; Kato, Yudai*; Koyama, Akira*; Snead, L. L.*; McLaughlin, J. C.*

Advanced SiC/SiC Ceramic Composites: Developments and Applications in Energy Systems; Ceramic Transactions Vol. 144, p.69 - 76, 2002/00

Process optimization for Forced-thermal gradient Chemical Vapor Infiltration (FCVI) fabrication of 75 mm diameter size SiC composites with advanced SiC fibers; Hi-Nicalon Type S and Tyranno SA, was carried out. The SiC/SiC composites fabricated by FCVI exhibited significant reduction in porosity (15.1%) and more uniform pore distribution by decreasing the MTS and H$$_{2}$$ gases flow rates in the latter part of the FCVI process. The tensile strength of the both composites using Hi-Nicalon Type S or Tyranno SA fibers was slightly increased with increased thickness of carbon interphase in the range of 75-300 nm. In order to perform the comparative testing required to directly compare the thermomechanical property changes following neutron irradiation, larger composites with uniform microstructural property are required. From the results of process optimization for fabrication of 75 mm diameter size FCVI SiC/SiC composites, the definitive purpose in this study is the fabrication of the 300 mm diameter size SiC/SiC composite with the uniform microstructural properties.

Journal Articles

Grain/pore microstructure-based evaluation method for variation of mechanical property of graphite components in the HTGR

Shibata, Taiju; Ishihara, Masahiro

Transactions of 16th International Conference on Structural Mechanics in Reactor Technology (SMiRT-16) (CD-ROM), 8 Pages, 2001/08

no abstracts in English

Journal Articles

Understanding of mechanical properties of graphite on the basis of mesoscopic microstructure (Review)

Ishihara, Masahiro; Shibata, Taiju; Takahashi, Tsuneo*; Baba, Shinichi; Hoshiya, Taiji

Proceedings of OECD/NEA 2nd Information Exchange Meeting on Basic Studies in the Field of High-temperature Engineering, p.225 - 241, 2001/00

no abstracts in English

Journal Articles

Effect of argon ion irradiation on the mechanical properties of carbon materials

Oku, Tatsuo*; Kurumada, A.*; Nakata, M.*; Takeda, K.*; Kawamata, K.*; Arai, Taketoshi; Ishihara, Masahiro

Proceedings of 24th Biennial Conference on Carbon (CARBON '99), p.574 - 575, 1999/07

no abstracts in English

Journal Articles

Correlation among the Changes in Mechanical properties due to neutron irradiation for pressure vessel steels

Onizawa, Kunio; Suzuki, Masahide

ISIJ International, 37(8), p.821 - 828, 1997/08

 Times Cited Count:2 Percentile:30.35(Metallurgy & Metallurgical Engineering)

no abstracts in English

Journal Articles

Application of ultrasonic testing as acceptance test for the graphite component of HTTR

Ishihara, Masahiro; Iyoku, Tatsuo; Shiozawa, Shusaku; *

Transactions of the 13th Int. Conf. on Structural Mechanics in Reactor Technology (SMiRT),Vol. I, 0, p.575 - 580, 1995/00

no abstracts in English

JAEA Reports

Development of irradiation capsule for nuclear research reactor using aromatic polyether (BEK)

Arigane, Kenji; ; Sasajima, Fumio; Takahashi, Hidetake; Seguchi, Tadao; *

JAERI-Tech 94-004, 33 Pages, 1994/07

JAERI-Tech-94-004.pdf:1.37MB

no abstracts in English

24 (Records 1-20 displayed on this page)