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Chida, Yutaka; Iguchi, Masahide; Nakajima, Hideo; Osemochi, Koichi*; Niimi, Kenichiro*; Tokai, Daisuke*
Proceedings of 2011 ASME Pressure Vessels and Piping Conference (PVP 2011) (CD-ROM), 5 Pages, 2011/07
The Japan Atomic Energy Agency (JAEA), acting as the Japan Domestic Energy Agency (JADA) in the ITER project, is responsible for the procurement of structures for 19 TF coils (including one spare). TF coil structures, which support large electromagnetic force generated in TF coils under the cryogenic temperature (about 4K), are the mega welding structures composed of coil case and support structures made of high strength and high toughness stainless steel. JAEA started the study on welding trials for heavy thickness materials since 2008 and is demonstrating of full scale mock-up model fabrication for main sub-components in 2010 in order to investigate the technical issues for manufacturing of TF coil structures. This paper introduces the results on welding trials and status of full scale mock-up model fabrication to confirm the validity of welding technology and manufacturing design before fabricating actual products. Enough weld joint performance was obtained with the base metal of JJ1 (high strength and high toughness stainless steel developed in Japan) and SS316LN, and also their combination using JJ1 filler wire (developed in Japan) by narrow gap GTAW process. Welding deformation such as angular distortion between outer plate and side plate of U-shape segment could be controlled and minimized by using effective restraint jig and no defects was observed in the welds by radiographic testing (RT) in trial manufacturing of 1m length. Validity of welding technology and manufacturing design such as fabrication sequence, welding procedure specification (WPS), quality control plan is confirmed during full scale mock-up model fabrication.
Tung, Y.-H.*; Johnson, R. W.*; Sato, Hiroyuki
Proceedings of 2011 ASME Pressure Vessels and Piping Conference (PVP 2011) (CD-ROM), 12 Pages, 2011/07
The present study examines the effects of graphite surface roughness on the bypass flow for different relative roughness factors on three gap widths. Wall shear stress and heat transfer results for several turbulence models and their associated wall treatments are first compared for flow in a single tube in the prismatic HTGR core. The results are compared to published correlations for wall shear stress and Nusselt number in turbulent pipe flow. Calculations are also compared to ones made previously using a different CFD code. Results indicate that increasing surface roughness increases the maximum fuel and helium temperatures as do increases in gap width. However, maximum coolant temperature variation due to increased gap width is not changed by surface roughness.
Arakawa, Manabu*; Narumi, Kentaro; Machida, Hideo*; Onizawa, Kunio
Proceedings of 2011 ASME Pressure Vessels and Piping Conference (PVP 2011) (CD-ROM), 8 Pages, 2011/07
This paper describes the benchmark analysis results performed between two PFM analysis codes for structural reliability evaluation of primary loop recirculation system (PLR) piping of a boiling water reactor. The two codes PASCAL-SP and PEPPER-M used for this benchmark analysis have been independently developed by Japan Atomic Energy Agency and TEPCO Systems Corporation, respectively. After the validity of the deterministic analytical procedures in these codes was checked, the failure probability assessment of PLR piping containing cracks due to stress corrosion cracking was carried out according to some regulatory requirements and the rules on fitness-for-service in Japan. The analytical results from both codes were well in agreement. From comparison of the results, influences of some items and parameters on failure probabilities were identified.
Wakai, Takashi; Machida, Hideo*; Yoshida, Shinji*; Kawashima, Fumiko*; Kikuchi, Koichi*; Xu, Y.*; Tsukimori, Kazuyuki
Proceedings of 2011 ASME Pressure Vessels and Piping Conference (PVP 2011) (CD-ROM), 10 Pages, 2011/07
This paper describes the improved COD assessment method and verifies the validity of the method based on the results of a series of four-point bending tests at elevated temperature using thin wall modified 9Cr-1Mo steel pipe containing a circumferential through wall crack. As a result, COD values calculated by the proposed method were in a good agreement with the experimental results for the uniform pipe without weld. In the case that the crack was machined at weld metal or heat affected zone (HAZ), proposed method predicted relatively larger COD than the experimental results. The causes of such discrepancies were discussed comparing with the results of finite element analyses. Based on these examinations, the rational leak rate evaluation method in LBB assessment was proposed.
Wakai, Takashi; Machida, Hideo*; Yoshida, Shinji*; Tokiyoshi, Takumi*; Kikuchi, Koichi*; Xu, Y.*; Tsukimori, Kazuyuki
Proceedings of 2011 ASME Pressure Vessels and Piping Conference (PVP 2011) (CD-ROM), 8 Pages, 2011/07
This paper studies the master curve to estimate the crack length when a postulated initial crack unexpectedly grows and penetrates the pipe thickness. In order to obtain the fatigue crack and creep crack growth characteristics of modified 9Cr-1Mo steel pipes, fatigue crack and creep crack growth tests were conducted using compact tension (CT) specimens and crack growth rates for both fatigue and creep at elevated temperature were obtained. Based on the obtained material characteristics and the results of a series of crack growth calculations, a relationship between the penetrated crack length and the ratio of membrane to total stress, so called as master curve, was proposed. In this study, master curves were proposed for pipes made of modified 9Cr-1Mo steel as a function of pipe geometry, i.e. the ratio of radius to thickness.
Ando, Masanori; Hirose, Yuichi*; Karato, Takanori*; Watanabe, Sota*; Inoue, Osamu*; Kawasaki, Nobuchika; Enuma, Yasuhiro*
Proceedings of 2011 ASME Pressure Vessels and Piping Conference (PVP 2011) (CD-ROM), 11 Pages, 2011/07
Ando, Masanori; Tezuka, Taiji*; Nakamura, Toshio*; Okawa, Tomohiro*; Enuma, Yasuhiro*; Kawasaki, Nobuchika; Tsukimori, Kazuyuki
Proceedings of 2011 ASME Pressure Vessels and Piping Conference (PVP 2011) (CD-ROM), 9 Pages, 2011/07
Ando, Masanori; Tezuka, Taiji*; Nakamura, Toshio*; Okawa, Tomohiro*; Enuma, Yasuhiro*; Kawasaki, Nobuchika; Tsukimori, Kazuyuki
Proceedings of 2011 ASME Pressure Vessels and Piping Conference (PVP 2011) (CD-ROM), 8 Pages, 2011/07
Okajima, Satoshi; Kawasaki, Nobuchika*; Kato, Shoichi; Kasahara, Naoto
Proceedings of 2011 ASME Pressure Vessels and Piping Conference (PVP 2011) (CD-ROM), 8 Pages, 2011/07
Shibama, Yusuke; Masaki, Kei; Sakurai, Shinji; Shibanuma, Kiyoshi; Sakasai, Akira
Proceedings of 2011 ASME Pressure Vessels and Piping Conference (PVP 2011) (CD-ROM), 10 Pages, 2011/07
This paper focuses on the JT-60SA vacuum vessel (VV, 150 tons) and presents manufacturing status of the VV with the design concept and the related technology of welding. The VV is a torus type vessel to ensure the sufficient ultrahigh vacuum space for core plasma and consists of 18 sectors with 73 port penetrations. The dimensions are the maximum major radius of 5.0 m and height of 6.6 m with a double wall structure to secure the stiffness against operational loads. The type 316L stainless steel is selected as a structural material and various welding technologies are developed. The weldment is mostly manipulated to achieve uniform welding quality and the welding conditions are evaluated to explore the distortion reduction, and to increase deposition rate. These resultants are applied to the 20 degree upper half mock-up and the manufacturing procedures, the correction of the welding distortion, and the optimization of constraint jigs are obtained.
Nishida, Akemi; Iigaki, Kazuhiko
Proceedings of 2011 ASME Pressure Vessels and Piping Conference (PVP 2011) (CD-ROM), 9 Pages, 2011/07
A coaxial double-pipe structure is to be used in the primary and auxiliary coolant system of a high-temperature gas-cooled reactor. In order to study the vibration characteristics of the coaxial double-pipe structure, hammering experiments were performed using specimens of the structure. Because the structural responses obtained in the experiments contained high-frequency components, impact response analysis was performed by using the spectral element method, which has high accuracy in the high-frequency region. A comparison between analysis results and experiment results showed good agreement between them. We also performed parametric studies on the damping properties of the specimens. The damping properties determined from the experiment results indicated that the inner and outer pipes had different damping properties.
