Cumulative Detection Probability as a Basis for Pressure Vessel Inspection Intervals

1995 ◽  
Vol 117 (4) ◽  
pp. 399-403 ◽  
Author(s):  
G. Garic
Keyword(s):  
Fracture Mechanics ◽  
Pressure Vessel ◽  
Detection Probability ◽  
Flaw Detection ◽  
Probability Of Detection ◽  
Acceptable Level ◽  
Cumulative Probability ◽  
Failure Risk ◽  
Flaw Detection Probability

This work discusses use of the cumulative flaw detection probability as the basis for establishing pressure vessel inspection intervals. The method is based on the accumulated probability of detecting a flaw over several inspections. It explicitly incorporates a user decision as to the acceptable level of failure risk. A four-step approach is outlined including fracture mechanics flaw growth calculations with probabilistic treatment of detection probability. It is concluded that (a) inspection intervals based on the cumulative probability of detection provide significant advantages over traditional cycle-based methods, (b) pressure vessel recertification inspections should rely on high percentage inspections conducted on a relatively infrequent basis.

Effects of Flaw Sizing Errors on the Reliability of Vessels and Piping

1998 ◽  
Vol 120 (4) ◽  
pp. 365-373 ◽  
Author(s):  
F. A. Simonen ◽  
M. A. Khaleel
Keyword(s):  
Detection Probability ◽  
Flaw Detection ◽  
Probability Of Detection ◽  
Limiting Factor ◽  
Numerical Implementation ◽  
Detection Capability ◽  
Acceptance Criteria ◽  
Flaw Sizing ◽  
Detection Capabilities ◽  
Flaw Detection Probability

This paper describes probabilistic fracture mechanics calculations that simulate fatigue crack growth, flaw detection, flaw sizing accuracy, and the impacts of flaw acceptance criteria. The numerical implementation of the model is based on a Latin hypercube approach. Calculations have been performed for a range of parameters. For representative values of flaw detection probability, flaw sizing errors, and flaw acceptance criteria, detection capability is the most limiting factor with regard to the ability of the inservice inspections to reduce leak probabilities. However, gross sizing errors or significant relaxations of current flaw acceptance standards could negate the benefits of outstanding probability of detection capabilities.

Reliability Assessment of Piping in a Nuclear Power Plant Considering Flaw Detection Probability

2004 ◽  
Author(s):  
Hideo Machida ◽  
Norimichi Yamashita ◽  
Shinobu Yoshimura ◽  
Genki Yagawa
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Detection Probability ◽  
Nuclear Power ◽  
Power Plants ◽  
Plant Stress ◽  
Flaw Detection ◽  
Reliability Assessment ◽  
Flaw Detection Probability

This study was performed to clarify the effects of flaw detection probability on piping reliability of a nuclear power plant. Stress-corrosion cracking (SCC) is still sporadically detected in austenitic stainless steel piping in Japanese BWR plants. The suitability for continued service of cracked pipes is basically evaluated by using the “Rules on fitness -for service for nuclear power plants.” Here future inspection rules are employed. However, the possibility of undetection of existing cracks and that of inaccurate measurements cannot be eliminated in UT-based inspection. Thus a probabilistic fracture mechanics (PFM) analysis was carried out referring measured flaw size, and the reliability of piping was evaluated considering the possibility of undetection of existing cracks and that of inaccurate measurements. The results of the analysis indicate that, if the interval and quality of the inspection are maintained at a certain specified level, the possibility of undetection of existing cracks and that of inaccurate measurements less affect failure probability.

scholarly journals Analysis of Low Probability of Detection Capability for Chaotic Standard Map-Based FH-OFDMA System

2021 ◽  
Vol 11 (5) ◽  
pp. 2198
Author(s):  
Junwoo Jung ◽  
Jaesung Lim ◽  
Sungyeol Park ◽  
Haengik Kang ◽  
Seungbok Kwon
Keyword(s):  
Detection Probability ◽  
Probability Of Detection ◽  
Lower Probability ◽  
Symbol Sequence ◽  
Ofdma System ◽  
Standard Map ◽  
Detection Probabilities ◽  
Low Probability ◽  
Transmitted Symbol ◽  
Basic Symbol

A frequency hopping orthogonal frequency division multiple access (FH-OFDMA) can provide low probability of detection (LPD) and anti-jamming capabilities to users against adversary detectors. To obtain an extreme LPD capability that cannot be provided by the basic symbol-by-symbol (SBS)-based FH pattern, we proposed two FH patterns, namely chaotic standard map (CSM) and cat map for FH-OFDMA systems. In our previous work, through analysis of complexity to regenerate the transmitted symbol sequence, at the point of adversary detectors, we found that the CSM had a lower probability of intercept than the cat map and SBS. It is possible when a detector already knows symbol and frame structures, and the detector has been synchronized to the FH-OFDMA system. Unlike the previous work, here, we analyze whether the CSM provides greater LPD capability than the cat map and SBS by detection probability using spectrum sensing technique. We analyze the detection probability of the CSM and provide detection probabilities of the cat map and SBS compared to the CSM. Based on our analysis of the detection probability and numerical results, it is evident that the CSM provides greater LPD capability than both the cat map and SBS-based FH-OFDMA systems.

Reactor Pressure Vessel Integrity Assessment: French Simplified Analysis Method Applied to Underclad Postulated Defect in Nozzle

2016 ◽  
Author(s):  
Adolfo Arrieta-Ruiz ◽  
Eric Meister ◽  
Stéphane Vidard
Keyword(s):  
Fracture Mechanics ◽  
Fracture Risk ◽  
Pressure Vessel ◽  
Reactor Pressure Vessel ◽  
Core Area ◽  
Integrity Assessment ◽  
Elastic Plastic ◽  
The Core ◽  
Simplified Method ◽  
Reactor Pressure

Structural integrity of the Reactor Pressure Vessel (RPV) is one of the main concerns regarding safety and lifetime of Nuclear Power Plants (NPP) since this component is considered as not reasonably replaceable. Fast fracture risk is the main potential damage considered in the integrity assessment of RPV. In France, deterministic integrity assessment for RPV vis-à-vis the brittle fracture risk is based on the crack initiation stage. As regards the core area in particular, the stability of an under-clad postulated flaw is currently evaluated under a Pressurized Thermal Shock (PTS) through a dedicated fracture mechanics simplified method called “beta method”. However, flaw stability analyses are also carried-out in several other areas of the RPV. Thence-forward performing uniform simplified inservice analyses of flaw stability is a major concern for EDF. In this context, 3D finite element elastic-plastic calculations with flaw modelling in the nozzle have been carried out recently and the corresponding results have been compared to those provided by the beta method, codified in the French RSE-M code for under-clad defects in the core area, in the most severe events. The purpose of this work is to validate the employment of the core area fracture mechanics simplified method as a conservative approach for the under-clad postulated flaw stability assessment in the complex geometry of the nozzle. This paper presents both simplified and 3D modelling flaw stability evaluation methods and the corresponding results obtained by running a PTS event. It shows that the employment of the “beta method” provides conservative results in comparison to those produced by elastic-plastic calculations for the cases here studied.

scholarly journals Recent verification activities on probabilistic fracture mechanics analysis code PASCAL4 for reactor pressure vessel

2020 ◽  
Vol 7 (3) ◽  
pp. 19-00573-19-00573
Author(s):  
Kai LU ◽  
Jinya KATSUYAMA ◽  
Yinsheng LI ◽  
Yuhei MIYAMOTO ◽  
Takatoshi HIROTA ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Pressure Vessel ◽  
Reactor Pressure Vessel ◽  
Probabilistic Fracture Mechanics ◽  
Mechanics Analysis ◽  
Reactor Pressure
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