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Yamaguchi, Yoshihito; Katsuyama, Jinya; Onizawa, Kunio; Sugino, Hideharu*; Li, Y.*; Yagawa, Genki*
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 9 Pages, 2009/07
Niigata-ken Chuetsu-oki earthquake was actually happened, whose magnitude was beyond the assumed one provided in seismic design, in July 2007. Through these events, it is becoming the focus of attention to evaluate an effect of large scale earthquake while the SCC and/or fatigue-crack are assumed to piping. Many previous papers have been already published about the retardation effect on fatigue crack growth by excessive loading. The retardation effect is treated qualitatively relating to plastic strain generated by excessive loading. In this work, the crack growth after the excessive loading is evaluated for carbon steel and austenitic stainless steel. Some cyclic excessive loading patterns such as stepwise increase or decrease were applied to fatigue-crack-growth experiments. The FEM analyses were conducted to evaluate the plastic region size during such loading conditions. The PFM analyses were conducted to evaluate the retardation of crack growth influence the probability of failure.
Onizawa, Kunio; Matsuzawa, Hiroshi*
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 8 Pages, 2009/07
The structural integrity of RPV during PTS is assessed by considering important factors related to fracture mechanics analysis such as fracture toughness, PTS transient, and irradiation embrittlement prediction and so on. The effects of such factors have been evaluated with regard to the fracture probability of RPV using probabilistic fracture mechanics (PFM) analysis code PASCAL2. Results from sensitivity analyses on the factors showed that the effect of fracture toughness curve is significant when the curve shape is different at high temperature range. Revised embrittlement correlation method gave slightly lower probability of fracture. The heat transfer coefficient for PTS transient and welding residual stress due to overlay cladding showed some effects to increase the probability of fracture. Uncertainties related to the RTNDT shift with regard to the probabilistic variables such as chemical composition and neutron fluence are compared with the deterministic result with a margin.
Li, Y.*; Hasegawa, Kunio*; Onizawa, Kunio; Shimomoto, Masayoshi*
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 9 Pages, 2009/07
When a flaw is detected in a stainless steel piping system of a nuclear power plant during in-service inspection, the fracture estimation method provided in the codes such as the ASME Code Section XI or the JSME S NA-1-2004 can be applied to evaluate the integrity of the pipe. However, in these current codes, the fracture estimation method is only provided for the pipe containing a single flaw, although multiple flaws such as stress corrosion cracks have actually been detected in the same circumference of stainless steel piping systems. In this paper, a fracture estimation method is proposed by formula for multiple independent circumferential flaws with any number and arbitrary distribution in the same circumference of the pipe. Using the proposed method, the numerical solutions are compared with the experimental results to verify its validity, and several numerical examples are provided to show its effectiveness.
Planman, T.*; Onizawa, Kunio; Server, W.*
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 8 Pages, 2009/07
The fracture toughness transition curve shape in the Master Curve (MC) has been discussed since the original empirical definition of the curve in 1991. In most cases the standard MC approach, assuming a constant transition curve shape, has proven to give a realistic description for also highly irradiated ferritic steels. The fracture toughness data collected and analysed in the IAEA CRP-8 Topic Area 3 supports the validity of the curve shape assumption of ASTM E1921 also in case of irradiated steels and gives no rise to change the present definition. The Master Curve C-parameter (the shape parameter) estimation is proposed as an appropriate analysis method when there is need to estimate also the temperature dependence, whereas the SINTAP procedure is recommended for ensuring conservative lower bound estimates when material in homogeneity is suspected. The results show that irradiation may slightly lower the fracture toughness in the upper transition region in relation to that predicted by E1921, but the effect after moderate T0 shift values seems to be negligible.
Katsuyama, Jinya; Onizawa, Kunio
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 8 Pages, 2009/07
Welding residual stress is one of the most important factors of stress corrosion cracking (SCC) for austenitic stainless steel in pressure boundary piping. The effect of excessive loading, such as an earthquake, on the residual stress is evaluated by three-dimensional analyses based on finite element method (FEM). After conducting welding residual stress simulation, several loading patterns of prescribed displacements for piping butt-welds have been applied in the axial direction by varying loading level and pattern. Bending moments have been also applied considering the start-finish point of girth welding by varying the loading direction and bending angle. The analyses indicated that higher loading to axial and bending stresses caused higher relaxation of welding residual stress even if the applied stress level is below general yield point. We concluded that the SCC growth rate could decrease as the amount of prescribed displacement increased.
Mochizuki, Masahito*; Katsuyama, Jinya; Ihara, Ryohei*; Mori, Hiroaki*; Mikami, Yoshiki*; Onizawa, Kunio
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 8 Pages, 2009/07
Stress corrosion cracking near the welded zone of core internals and recirculation piping has been observed at the surface where tensile residual stress exists due to welding and/or surface machining. The tensile residual stress in the inner surface of the pipe is caused by welding and surface machining. In this study, Vickers hardness and residual stress distributions at the inner surface of butt-weld joint with surface-machining before and after welding were experimentally evaluated. Welding simulation has been performed to study the distribution and the occurrence mechanism of tensile residual stress. It was shown that residual stress and hardness distributions by welding after surface machining depended on the welding condition and that the effect of surface machining disappeared. Residual stress distributions due to surface-finishing after welding were also found to depend on surface-machining condition but the region was limited to a thin area of surface hardened layer.
Nakahira, Masataka*; Niimi, Kenichiro; Irie, Hirosada*
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 7 Pages, 2009/07
A standard of fabrication, installation, NDE and testing for superconducting magnets for fusion facility was developed. For construction of TF coil, a "Fabrication and Installation" standard FM-4000, accompanying a mandatory Appendix 41 "Welded Joint" and a "Nondestructive Examination" standard FM-5000 accompanying a mandatory Appendix 51 for "Ultrasonic Examination Method" and a "Pressure and Leak Testing" standard FM-6000 have been developed, based on other JSME standards for nuclear power plant (JSME S NB1) and also ASME Sec.III ND, NF or Sec.VIII-div.2 Since TF coil structure does not include radioactive materials but is operated under high stress produced by high magnetic field, it is not safety-relevant-barrier. The requirements to construction should be relaxed comparer with a fission reactor.
Nakajima, Hideo; Takano, Katsutoshi; Tsutsumi, Fumiaki; Kawano, Katsumi; Hamada, Kazuya; Okuno, Kiyoshi
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 9 Pages, 2009/07
The Japan Atomic Energy Agency (JAEA) has been evaluating mechanical properties of structural materials for the ITER toroidal field (TF) coils. Newly developed JJ1 forging having thickness of 400 mm, 316LN forging having thickness of 410 mm, and 316LN hot rolled plate having thickness of 200 mm were produced in mass production process to qualify the materials. The distributions of tensile properties at liquid helium temperature (4K) in products have been evaluated to qualify the materials and it has been demonstrated that these materials have good quality and uniform properties, which satisfy the ITER requirements. It is also demonstrated from the results that temperature dependence of strengths are expressed by quadratic curves developed by JAEA, which are expressed as a function of carbon and nitrogen contents and strengths at room temperature. This equation enables to perform quality control of materials at only room temperature. The results obtained from these activities also serve the basis to develop the material material section of "Codes for Fusion Facilities - Rules on Superconducting Magnet Structure (2008)" issued by the Japan Society of Mechanical Engineers (JSME) in October 2008.
Nishimura, Arata*; Nakajima, Hideo
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 8 Pages, 2009/07
Japan Atomic Energy Agency (JAEA) has contributed to development of the structural standard for superconducting magnets entitled "Codes for Fusion Facilities - Rules on Superconducting Magnet Structure (2008)" issued by the Japan Society of Mechanical Engineers (JSME) in October 2009. This code consists of 7 sections, such as general requirements including quality assurance, material, design, fabrication (welding), non-destructive examination, pressure and leak test, and terminology. This paper describes technical contents on material section of the code. The feature of the code is to specify cryogenic materials such as JJ1, which was newly developed by JAEA, and 316LN, which is calcified by the carbon and nitrogen (C+N) contents. The design strengths from room temperature to cryogenic temperature of these materials are given in a quadratic function when the materials are as-solution heat-treated.
Suzuki, Tetsuya*; Nishimura, Arata*; Nakajima, Hideo
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 4 Pages, 2009/07
Japan Atomic Energy Agency (JAEA) has contributed to development of the structural standard for superconducting magnets entitled "Codes for Fusion Facilities - Rules on Superconducting Magnet Structure (2008)" issued by the Japan Society of Mechanical Engineers (JSME) in October 2009. This code consists of 7 sections, such as general requirements including quality assurance, material, design, fabrication (welding), non-destructive examination, pressure and leak test, and terminology. This paper describes technical contents on quality assurance section of the code. Quality assurance requirement consists of 18 articles such as organization, quality assurance program, design control, document control etc. Each article is designed to constitute simplified performance based requirement. In conformity assessment, realistic Qualified Inspection and Design Certification are pursued, considering the legislation, infrastructure and prospective user of standard in Japan. Role and responsibility of Qualified Inspector and Standard-Expert Engineer are newly defined in the code.
Ebihara, Kenichi; Yamaguchi, Masatake; Nishiyama, Yutaka; Onizawa, Kunio; Matsuzawa, Hiroshi*
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 8 Pages, 2009/07
We incorporate the parameters obtained from first-principles calculations into the rate theory model which was developed for bcc lattice, and apply it to the simulation of irradiation-induced phosphorous segregation in bcc iron. We evaluate the grain boundary phosphorous coverage and discuss its dependence on dose-rate and irradiation temperature by comparing our results with previously reported results and experimental data. As results, we find that dose-rate does not affect the grain boundary phosphorous coverage within the range of our simulation condition and that the dependence on irradiation temperature differs remarkably from the previous results.
Okuno, Kiyoshi; Nakajima, Hideo; Takahashi, Yoshikazu; Koizumi, Norikiyo
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 6 Pages, 2009/07
ITER is a joint international project and its participants are the European Union, Japan, the People's Republic of China, India, the Republic of Korea, the Russian Federation and the USA. The ITER, will be constructed in Europe, at Cadarache in France. ITER will demonstrate high power amplification and extended burn of deuterium-tritium plasmas, in a steady state as an ultimate goal, with the technologies essential to a reactor in an integrated system. Superconducting magnets are one of these technologies, which induce an electrical current and confine and control the reacting plasma. The ITER superconducting magnet systems consist of 18 Toroidal Field (TF) coils, 6 Poloidal Field (PF) coils, a Central Solenoid (CS) coil, Correction Coils, and related structures. Maximum fields are 11.8 T in the TF coil, 13 T in the CS, and below 6 T in the PF coils. The CS and TF coils use Nb
Sn superconductor and PF coils use NbTi conductor. Japanese contribution to the construction of the ITER superconducting magnet system is to procure 25% of TF conductors, about half of TF coil winding packs, all of TF coil structures and all of CS conductors. Total amount of raw stainless steel materials required for the TF coil structures is more than 10,000 tons. The Japanese Domestic Agency, represented by Japan Atomic Energy Agency (JAEA), has performed extensive technology development for the preparation of these procurements. These include (1) trial fabrication of the superconductors at industry level and their performance demonstration, (2) manufacturing studies and full-scale trial fabrication of TF coil including its structures, and (3) establishment of database on the structural materials.
Nanstad, R.*; Brumovsky, M.*; Callejas, R.*; Gillemot, F.*; Korshunov, M.*; Lee, B.*; Lucon, E.*; Scibetta, M.*; Minnebo, P.*; Nilsson, K.-F.*; et al.
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 13 Pages, 2009/07
IAEA has developed a coordinated research project (CRP) to evaluate various issues associated with the fracture toughness Master Curve for application to light-water RPVs. Topic Area 1 of the CRP is focused on the issue of test specimen geometry effects, with emphasis on determination of reference temperature T
with the pre-cracked Charpy (PCC) specimen and the bias effect on T. Participating organizations for the experimental part of the CRP performed fracture toughness testing of various steels with various types of specimens under various conditions. Results from fracture toughness tests are compared with regard to effects of specimen size and type on the T. It is apparent from the results that the bias observed between the PCC specimen and larger specimens for Plate JRQ is not nearly as large as that obtained for other steels (-11
C to -45C). This observation is consistent with observations in the literature that show significant variations in the bias that are dependent on the specific materials being tested.
Ando, Masanori; Isobe, Nobuhiro*; Kawasaki, Nobuchika; Sukekawa, Masayuki*; Kasahara, Naoto*
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 10 Pages, 2009/07
Tanaka, Masaaki; Ohshima, Hiroyuki; Monji, Hideaki*
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 10 Pages, 2009/07
We have been developing a numerical simulation code "MUGTHES". MUGTHES employs large eddy simulation approach to calculate unsteady thermal-hydraulic phenomena and the boundary fitted coordinate system to model complex geometry in systems precisely. In this study, numerical simulations were conducted for pipe elbow flows in various curvature radius ratio conditions at several Reynolds number conditions. Through these simulations, applicability of MUGTHES to the elbow pipe flow was confirmed and the characteristics of three-dimensional flow structure that might influence on the structural integrity of the elbow pipe was discussed.
Kitamura, Seiji; Morishita, Masaki; Yabana, Shuichi*; Hirata, Kazuta*; Umeki, Katsuhiko*
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 8 Pages, 2009/07
Inaba, Satoru*; Anabuki, Takuya*; Shirai, Kazutaka*; Yabana, Shuichi*; Kitamura, Seiji
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 8 Pages, 2009/07
Yabana, Shuichi*; Kanazawa, Kenji*; Nagata, Seiji*; Kitamura, Seiji; Sano, Takeshi*
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 9 Pages, 2009/07
Minagawa, Keisuke*; Fujita, Satoshi*; Kitamura, Seiji; Okamura, Shigeki
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 7 Pages, 2009/07
Scibetta, M.*; Altstadt, E.*; Callejas, R.*; Lee, B.*; Miura, Naoki*; Onizawa, Kunio; Paffumi, E.*; Serrano, M.*; Tatar, L.*; Yin, S.*
Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 11 Pages, 2009/07
IAEA has developed a coordinated research project (CRP) to evaluate various issues associated with the fracture toughness Master Curve for application to light-water RPVs. Topic Area 1 of the CRP is focused on the issue of test specimen geometry effects, with emphasis on determination of reference temperature T0 with the pre-cracked Charpy specimen and the bias effect. Within the analytical part, elastic plastic finite element methods are used in order to access local stress and strain information. This analytical round robin exercise has been performed by ten laboratories from nine different countries focusing on the modeling of realistic three dimensional geometries containing shallow and deep crack. Independently of the used code and of relatively small user effect differences, it is found that shallow crack specimens are more sensitive to loss of constraint than deep crack specimens for a given specimen size. The difference in terms of reference temperature between the two geometries is evaluated to be about 40C.