Probabilistic Fracture Mechanics Evaluation of Embrittlement Recovery by Annealing of Reactor Pressure Vessel

2000 ◽  
Vol 2000 (0) ◽  
pp. 435-436
Author(s):  
Katsuyuki SHIBATA ◽  
Kunio ONIZAWA ◽  
Yinsheng LI ◽  
Daisuke KATO
2020 ◽  
Vol 7 (3) ◽  
pp. 19-00573-19-00573
Author(s):  
Kai LU ◽  
Jinya KATSUYAMA ◽  
Yinsheng LI ◽  
Yuhei MIYAMOTO ◽  
Takatoshi HIROTA ◽  
...  

Author(s):  
Silvia Turato ◽  
Vincent Venturini ◽  
Eric Meister ◽  
B. Richard Bass ◽  
Terry L. Dickson ◽  
...  

The structural integrity assessment of a nuclear Reactor Pressure Vessel (RPV) during accidental conditions, such as loss-of-coolant accident (LOCA), is a major safety concern. Besides Conventional deterministic calculations to justify the RPV integrity, Electricite´ de France (EDF) carries out probabilistic analyses. Since in the USA the probabilistic fracture mechanics analyses are accepted by the Nuclear Regulatory Commission (NRC), a benchmark has been realized between EDF and Oak Ridge Structural Assessments, Inc. (ORSA) to compare the models and the computational methodologies used in respective deterministic and probabilistic fracture mechanics analyses. Six cases involving two distinct transients imposed on RPVs containing specific flaw configurations (two axial subclad, two circumferential surface-breaking, and two axial surface-braking flaw configurations) were defined for a French vessel. In two separate phases, deterministic and probabilistic, fracture mechanics analyses were performed for these six cases.


Author(s):  
Jongmin Kim ◽  
Bongsang Lee ◽  
Taehyun Kim ◽  
Yoonsuk Chang

It is widely recognized that the state of knowledge and data for the probabilistic calculations which had been proposed in the early 1980s made a conservative treatment of several key factors and models. Recently, applications of some new radiation embrittlement model, material database, calculation method of stress intensity factors and others which can improve fracture mechanics assessment of reactor pressure vessel (RPV) are introduced. This improvement on the accuracy and reliability of the probabilistic fracture mechanics (PFM) analysis necessitated changes in PFM analysis procedures and calculations. Modification and application of newly developed models and calculation methods are the main target of developing a probabilistic fracture mechanics analysis code based on the structure of existing R-PIE and VISA computer code to reflect the latest technical basis. Failure probabilities of reactor pressure vessel under pressurized thermal shock (PTS) conditions were calculated through finite difference method (FDM) and Monte Carlo simulation techniques with user friendly graphic interface. Moreover, various radiation embrittlement models and calculation methods of stress intensity factor at crack tip based on AFCEN code are applied and verified in the present work.


Author(s):  
Hsoung-Wei Chou ◽  
Chin-Cheng Huang ◽  
Kuan-Rong Huang ◽  
Ru-Feng Liu

After the Code Case N-640 was issued in 1999, the fracture toughness curve of reactor pressure vessel materials in ASME Section XI-Appendix G was amended to the KIC curve. In Taiwan, the present pressure-temperature limit curves of normal reactor startup (heat-up) and shut-down (cool-down) for the reactor pressure vessel is still calculated per KIA curve in 1998 or earlier editions. In this paper, the failure risks of a Taiwan domestic reactor pressure vessel under various pressure-temperature limit operations are analyzed. First, the pressure-temperature limit curves of the Taiwan domestic reactor pressure vessel based on KIA and KIC curves, and various levels of embrittlement, are calculated. Then, the ORNL’s probabilistic fracture mechanics code, FAVOR, and the PNNL’s flaw model are utilized to assess the failure probabilities of the reactor pressure vessel under such pressure-temperature limit transients. Further, the deterministic analyses of FAVOR code are also conducted. It is found that under the pressure-temperature limit transients based on KIC curves, the reactor pressure vessel presents higher failure probabilities, but are all below the allowable risk. The present results indicate that using the KIC curve the pressure-temperature limits can either increase the operational margin or still maintains the sufficient stability of the analyzed reactor pressure vessel.


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