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Suzuki, Tamaki*; Okawa, Teppei*; Harjo, S.; Sasaki, Toshihiko*
Nihon Kikai Gakkai Rombunshu (Internet), 87(894), p.20-00377_1 - 20-00377_15, 2021/02
Takahashi, Hiroyuki*; Kudo, Yusuke; Tsuchiya, Katsuhiko; Kizu, Kaname; Ando, Toshinari*; Matsukawa, Makoto; Tamai, Hiroshi; Miura, Yukitoshi
Fusion Engineering and Design, 81(8-14), p.1005 - 1011, 2006/02
Times Cited Count:2 Percentile:17.14(Nuclear Science & Technology)This paper presents dependence of the stress intensity factor, around the defect in the butt joint welding of a superconducting conductor conduit, on a geometrical factor estimated by fracture mechanics analysis. The stress intensity factor can be estimated by the Newman-Raju equation about CICC section, but the effect of the difference between the geometry assumed in the equation and CICC has not been clarified yet. Therefore, the three-dimensional finite element method (3D-FEM) is performed to estimate the geometrical factor. As a result, the Newman-Raju equation is considered to be available for the assessment of the fracture toughness of the conduit of rectangular shape because the maximum stress intensity factor by 3-D FEM is only 3% larger than that by the Newman-Raju equation in the maximum postulated defect.
Nakahira, Masataka
JAERI-Research 2005-030, 182 Pages, 2005/09
It is difficult for Vacuum Vessel (VV) of ITER to apply a non-destructive in-service inspection (ISI) and then new safety concept is needed. Present fabrication standards are not applicable to the VV, because the access is limited to the backside of closure weld of double wall. Fabrication tolerance of VV is 5mm even the structure is huge as high as 10m. This accuracy requires a rational method on the estimation of welding deformation. In this report, an inherent safety feature of the tokamak is proved closing up a special characteristic of termination of fusion reaction due to tiny water leak. A rational concept not to require ISI without sacrificing safety is shown based on this result. A partial penetration T-welded joint is proposed to establish a rational fabrication method of double wall. Strength and susceptibility to crevice corrosion is evaluated for this joint and feasibility is confirmed. A rational method of estimation of welding deformation for large and complex structure is proposed and the efficiency is shown by comparing analysis experimental results of full-scale test.
Nakahira, Masataka
Journal of Nuclear Science and Technology, 40(9), p.687 - 694, 2003/09
Times Cited Count:3 Percentile:25.75(Nuclear Science & Technology)The ITER vacuum vessel is a double-walled torus with large-sized quadrilateral ports and is required to provide a quite high degree of vacuum for deutrium - tritium fusion reaction. The vacuum vessel is required to install after assembled with toroidal field coils. From a radiological safety aspect, the vacuum vessel is functioned as a physical barrier to enclose radioactive materials. Therefore, construction of the vacuum vessel needs application of newly developed technologies on design, fabrication and examination. The technologies include design approach by finite element analysis, and partial penetration T welded joints to join ribs to outer shell. Several issues have to be resolved for applying those technologies to the vacuum vessel. This paper describes several newly developed technologies and key issues for applying to the vacuum vessel and then their resolutions.
Suzuki, Takayuki*; Usami, Saburo*; Kimura, Takae*; Koizumi, Koichi; Nakahira, Masataka; Takahashi, Hiroyuki*
Proceedings of 55th Annual Assembly of International Institute of Welding (IIW2002), 16 Pages, 2002/06
A new type of welded joint for the outer wall and rib of a double-walled vacuum vessel of a fusion reactor has been developed. The joint is manufactured by through-wall electron-beam welding (TW-EBW), in which the beam is injected from the outside of the outer wall. Static and fatigue tests are carried out on one-bead-specimens under an axial load and two-bead-specimens under a bending load. The experimental results are analytically investigated by FEM. Although this joint is partially penetrated, the net yield strength of the bead is increased by the plastic constraint due to triaxial tensile stress in the weldment. This phenomenon reduces the mean equivalent stress on the bead cross section, and the gross strength of the joint is close to that of a full thickness welded joint. The fatigue-strength reduction factor for low-cycle fatigue life is a little larger than four. The calculated fatigue-crack growth rate in the joint is conservatively calculated by using the maximum stress intensity factor of the crack and the fatigue-crack growth rate given in ASME Code Section XI.
Kurata, Yuji; *; *; Tsuji, Hirokazu; *; Shindo, Masami; Suzuki, Tomio
Journal of Nuclear Science and Technology, 36(12), p.1160 - 1166, 1999/00
Times Cited Count:6 Percentile:45.62(Nuclear Science & Technology)no abstracts in English
*; Nakajima, Hideo; Nunoya, Yoshihiko; Miura, Yushi; Kawasaki, T.*; Tsuji, Hiroshi
Advances in Cryogenic Engineering Materials, 44, p.73 - 80, 1998/00
no abstracts in English
; Saito, T.*; Tsuji, Hirokazu; Takatsu, T.*; Shindo, Masami; Nakajima, Hajime
JAERI-Research 97-032, 20 Pages, 1997/05
no abstracts in English
Nakahira, Masataka; Oka, Kiyoshi; *; *; *; Oda, Yasushi*; Kajiura, Soji*; Yamazaki, Seiichiro*; *
Purazuma, Kaku Yugo Gakkai-Shi, 73(1), p.54 - 68, 1997/01
no abstracts in English
*; ; *; Tsuji, Hirokazu; *; Shindo, Masami
Mater. Sci. Eng., A, 234-236, p.1087 - 1090, 1997/00
no abstracts in English
Inagaki, Yoshiyuki; ; *; *; *
Nuclear Technology, 104, p.106 - 117, 1993/10
Times Cited Count:2 Percentile:29.78(Nuclear Science & Technology)no abstracts in English
Inagaki, Yoshiyuki; ; *; *
Nihon Genshiryoku Gakkai-Shi, 35(3), p.227 - 236, 1993/03
Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)no abstracts in English
Inagaki, Yoshiyuki; ; *; *; *; *
JAERI-M 92-151, 49 Pages, 1992/10
no abstracts in English
;
JAERI-M 7152, 31 Pages, 1977/07
no abstracts in English
; ; *; *
JAERI-M 6799, 37 Pages, 1976/11
no abstracts in English