Probabilistic Pressurized Thermal Shocks Analyses for a Reactor Pressure Vessel

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Guian Qian ◽  
Markus Niffenegger
Keyword(s):  
Aspect Ratio ◽  
Pressure Vessel ◽  
Crack Depth ◽  
Crack Density ◽  
Reactor Pressure Vessel ◽  
Probabilistic Methods ◽  
Critical Crack ◽  
Research User ◽  
Reactor Pressure ◽  
Thermal Shocks

Both deterministic and probabilistic methods are used to assess the integrity of a reactor pressure vessel (RPV) subjected to pressurized thermal shocks (PTSs). The FAVOR code is applied to calculate the probabilities for crack initiation and failure of the RPV subjected to two transients, by considering crack distributions based on cracks observed in the Shoreham and pressure vessel research user facility (PVRUF) RPVs. The crack parameters, i.e., crack density, depth, aspect ratio, orientation, and location are assumed as random variables following different distributions. KI of the cracks with the same depth increases with its aspect ratio. Both KI and KIc at the crack tip increase with crack depth, which is the reason why a deeper crack does not necessarily lead to a higher failure probability. The underclad crack is the most critical crack and the deeper crack is the least critical one in this study. Considering uncertainties of the transients results in higher failure probabilities.

Probabilistic Pressurized Thermal Shocks Analysis for a Reactor Pressure Vessel

2014 ◽  
Author(s):  
Guian Qian ◽  
Markus Niffenegger
Keyword(s):  
Aspect Ratio ◽  
Pressure Vessel ◽  
Crack Depth ◽  
Crack Density ◽  
Reactor Pressure Vessel ◽  
Probabilistic Methods ◽  
Critical Crack ◽  
Research User ◽  
Reactor Pressure ◽  
Thermal Shocks

Both deterministic and probabilistic methods are used to analyze the integrity of a reactor pressure vessel (RPV) subjected to pressurized thermal shocks (PTSs). The FAVOR code is applied to calculate the probabilities for crack initiation and failure of the RPV subjected to two transients, by considering crack distributions based on cracks observed in the Shoreham and pressure vessel research user facility (PVRUF) RPVs. The crack parameters, i.e. crack density, depth, aspect ratio, orientation and location are assumed as random variables following different distributions. KI of the cracks with the same depth increases with its aspect ratio. Both KI and KIC at the crack tip increase with crack depth, which is the reason why a deeper crack does not necessarily lead to a higher failure probability. The underclad crack is the most critical crack and the deeper crack is the least critical one in this study. Considering uncertainties of the transients results in higher failure probabilities.

Application of Flaw Updating Process on Probabilistic Structural Evaluation for a Reactor Pressure Vessel Under Pressurized Thermal Shocks

2018 ◽  
Author(s):  
Pin-Chiun Huang ◽  
Hsoung-Wei Chou ◽  
Yuh-Ming Ferng
Keyword(s):  
Pressure Vessel ◽  
Nuclear Power ◽  
Structural Integrity ◽  
Fracture Probability ◽  
Reactor Pressure Vessel ◽  
Structural Evaluation ◽  
User Facility ◽  
Research User ◽  
Reactor Pressure ◽  
Thermal Shocks

The structural integrity of a reactor pressure vessel (RPV) is one of the most important issues for the operation of nuclear power plant. Nowadays, the probabilistic fracture mechanics (PFM) technique is widely used in evaluating the structural integrity of RPVs. However, the flaw characteristics used for PFM analysis are mainly derived from the Pressure Vessel Research User Facility (PVRUF) and Shoreham vessel inspection database, which may not be able to truly represent the vessel-specific condition of the analyzed RPV. In this work, the NUREG-2163 procedure which modifies the flaw characteristic parameters is employed. The Bayesian updating process which combines the prior flaw data with non-destructive examination (NDE) results as well as uncertainties is used to develop the posterior vessel-specific flaw distributions. Subsequently, the updated flaw files are used for PFM analysis to investigate the effects of NDE updated flaw characteristics on the fracture probability of RPV subjected to pressurized thermal shocks. Considering the updated flaws based on the NDE data, the analyzed results could be more plant-specific to predict the fracture risks of RPVs during operation.

Probabilistic Pressurized Thermal Shocks Analysis for a Reactor Pressure Vessel by Considering Plume Effect

2015 ◽  
Author(s):  
Guian Qian ◽  
V. F. González-Albuixech ◽  
Markus Niffenegger ◽  
Medhat Sharabi
Keyword(s):  
Crack Initiation ◽  
Conditional Probability ◽  
Pressure Vessel ◽  
Cooling Water ◽  
Reactor Pressure Vessel ◽  
Probabilistic Methods ◽  
Integrity Assessment ◽  
Inner Surface ◽  
Reactor Pressure ◽  
Thermal Shocks

The inner surface of a reactor pressure vessel (RPV) is assumed to be subjected to pressurized thermal shocks (PTSs) caused by the downstream of emergency cooling water. The downstream is not homogeneous but typically in a plume shape coming from the inlet nozzles. In this paper, both deterministic and probabilistic methods are used to assess the integrity of a model RPV subjected to PTS. The FAVOR code is used to calculate the probabilities for crack initiation and failure of the RPV considering crack distributions based on cracks observed in the Shoreham and PVRUF RPVs. The study shows that peak KI of the cracks inside the plume increases about 33% compared with that outside. The conditional probability inside the plume is more than eight orders of magnitude higher than outside the plume. In order to be conservative, it is necessary to consider the plume effect in the integrity assessment.

Probabilistic Pressurized Thermal Shock Analysis for a Reactor Pressure Vessel Considering Plume Cooling Effect

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Guian Qian ◽  
V. F. González-Albuixech ◽  
Markus Niffenegger ◽  
Medhat Sharabi
Keyword(s):  
Crack Initiation ◽  
Pressure Vessel ◽  
Cooling Water ◽  
Reactor Pressure Vessel ◽  
Probabilistic Methods ◽  
Integrity Assessment ◽  
Pressurized Thermal Shock ◽  
Inner Surface ◽  
Reactor Pressure ◽  
Thermal Shocks

The inner surface of a reactor pressure vessel (RPV) is assumed to be subjected to pressurized thermal shocks (PTSs) caused by the injection of emergency cooling water. The downstream is not homogeneous but typically in a plume shape coming from the inlet nozzles. In this paper, both deterministic and probabilistic methods are used to assess the integrity of a model RPV subjected to PTS. The favor code is used to calculate the probabilities for crack initiation and failure of the RPV considering crack distributions based on cracks observed in the Shoreham and PVRUF RPVs. The study shows that peak KI of the cracks inside the plume increases about 33% compared with that outside. The conditional probability inside the plume is more than eight orders of magnitude higher than outside the plume. In order to be conservative, it is necessary to consider the plume effect in the integrity assessment.

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