Implementation of a Performance Evaluation System for Nondestructive Testing Methods Daniel Algernon, Sascha Feistkorn and Michael Scherrer SVTI Swiss Association for Technical Inspections Nuclear Inspectorate NDE Laboratory
Outline Nondestructive Testing (NDT) Meaning for Safety (Making it Measurable) Ensuring Reliability (e.g. in the Nuclear Industry) Transferring Concepts between Industries Conclusion
Motivation Highly safety relevant components & industries Assessment of structural integrity: Nondestructive Testing (NDT)
Nondestructive Testing (NDT) NDT Methods Ultrasonic Testing Eddy Current Testing Liquid Penetrant Testing Magnetic Particle Testing Radiographic Testing Thermography Visual Testing
Meaning of NDT for Safety Concepts Safety Structural Integrity Fracture Mechanics Condition Assessment Measures Nondestructive Testing NDT provides safety-relevant information «making safety measurable» requires quantitative information Reliable information! www.svti.ch ICSC 2016 - "Making Safety Measurable" Dr.-Ing. Daniel Algernon
NDT in the Nuclear Industry Operation Safe Operation of Nuclear Power Plants over design life time Long Term Operation based on actual condition Struct. Integrity Structural Iitegrity of safety relevant components Significant aspect of technical condition Testing & Evaluation Nondestructive Testing and Evaluation (NDE) Provide information for condition assessment Reliability Information provided must be reliable, since it is the basis for determining safety Performance Evaluation Performance Evaluation of NDE inspection systems to determine their reliability Demo & TJ Performance assessed in practical demonstrations as well as theoretical investigation (technical justification)
Elements of NDT NDT Method Equipment Procedure Personnel Test Object Target NDT = Information Provider Value of NDT = Value of Information Information must be relevant and reliable Increase in reliability = increase in value Information www.svti.ch ICSC 2016 - "Making Safety Measurable" Dr.-Ing. Daniel Algernon
How to determine reliability? Theoretical Assessment Model & Simulation Field Experience Practical Demonstration «See how NDT System performs» Compare NDT results to true results How to determine truth? Investigate in controlled conditions Test blocks, simulating testing problem
Requirement for Practical Demonstr.! Contradiction: Realistic and Controled (Simulation)
ENIQ-Methodology European Network for Inspection and Qualification Qualification of Inspection Systems Procedure Equipment Personnel Case Specific Practical Demonstration Component and Flaw Specific Postulated flaw mechanism Realistic flaw simulation in test blocks Technical Justification Theoretical Assessment of Inspection System Suitability of Test Blocks and Test Flaws
Practical Demonstrations Physically simulating field conditions Physically simulating relevant flaw types (qualification target) Mockups and test blocks Example: Field Testing Example: Qualification on test block
Component, Test Block, Mockup Component Full-Scale Mockup Weld Test flaws Test Block
Test Flaws Mandatory: realistic test flaws Example: representing intergranular stress corrosion cracking (IGSCC)
Evaluating Practical Demonstrations Test Set = Test block or section containing test flaws Test Sets are given to candidates Several candidates per qualification project
Test set/candidate Relation in IndEva IndEva: Evaluation System of Swiss Qualification Body
Graphic Representation of Testsets Per Test set: As-Built Information Indications reported by candidates
Evaluation Types in IndEva Evaluation 1: Singular relation Test Set / Candidate Evaluation 2: By candidate and related test sets Evaluation 3: Procedure (all candidates and test sets)
Analysis Criteria Detection: What percentage of flaws has been detected False Calls: In absolute numbers In % of actual number of test flaws Per area Determining Length and Thruwall extent: Statistics RMS (Root Mean Square) Mean + Standard deviation Positioning: Tolerance window
IndEva-Output per Candidate Evaluation of each individual candidate regarding qualification criteria for detection, characterization, length and thruwall sizing
IndEva-Results by Procedure Total evaluation taking into account the best, worst and averaged results or median Identification of critical test flaws
IndEva-Results per Test Flaw (Table) List of all individual test flaws and the respective results obtained
Qualification Qualification = Proof (Demonstration) + of Understanding) Performance of Performance Technical Justification (TJ)
Technical Justification: Modeling Use of semi-analytical simulation software CIVA Powerful tool for parametric studies and technical justification Perspective: Reduction of testing effort Validation of model is essential, test blocks still needed!
Technical Justification Practical Trials (Statistics) Engineering Understanding (Technical Justification) Confidence
Technical Justification Practical Trials (Statistics) Engineering Understanding (Technical Justification) Confidence Since number of test flaws and practical trials is limited, technical justification is an important element (e.g. in ENIQ Qualification system)
Quantification of Technical Justification Goal: Combined statistical expression of practical trials and technical justification of results and confidence level Approach: Bayesian Statistics General Idea: Prior set of parameters adjusted according to information gained from technical justification and practical trials, resulting in posterior set of parameters Based on Binomial distribution
Bayesian Approach Gandossi & Simola, 2007
Transfering Concepts between Industries Example: «Nuclear2Civil» Identification of Industry Specific Practices and Needs NDT in the Nuclear Industry Transfer of Quality Concepts Industry (Civil Engineering) Specific Adaption NDT in new Industry (Civil Engineering) Adaption of quality-assurance (qualification) concepts to new industries (e.g. NDT in civil engineering).
Challenging Material vs. Qualification Inhomogeneous material Individual structural design Limited Budget Qualification of Concrete-NDT? Needs Adaption of Concepts! Current Topic for DGZfP Quality Assurance Committee
Concrete-NDE Validation Center Florida Department of Transportation Laboratory Test Frame for automated application of nondestructive testing in civil engineering (NDT-CE)
Conclusion Making Safety Measurable Process/ Value Chain Structural Integrity Quantify Qualification NDT Quantitative Reliability Industry Specific Adaption
Thank you
Conclusion In many industries: NDT provides information used to rate component safety reliability has direct effect on the operational safety of a component. nuclear industry: qualification processes ensure NDT reliability (e.g. ENIQ) Quantitative measures obtained from qualification target and statistical distribution of trials Qualification is combination of theoretical assessment (TJ) and practical demonstration (PD) Need: express theoretical assessment quantitatively and combine with PD Approach: Bayesian statistics (Gandossi & Simola) - capable, though challenging, since it requires adequate evaluation criteria. Tool IndEva: statistical evaluation of the practical demonstration, identifying strengths and weaknesses - Covers TJ quantification approach, currently evaluated Methodology Transfer: qualification process transferred to other industries, but needs adaption - First example established: civil engineering (concrete structures).
Qualification of Inspection Systems Qualification = Proof (Demonstration) of Performance Qualification process is an important element to ensure reliable inspections systems Qualification is essential especially in case of safetyrelevant compent evaluation (e.g. in nuclear power plants) Swiss Association for Technical Inspections (SVTI) serves as the NDE Qualification Body (QSt) in Switzerland
IndEva-Form for Testblocks and Flaws As-Built Information
IndEva-Candidate Indication Lists Taking into account coordinate offsets or scaling: (X + Offset a x ) * Faktor b x + Offset c x (Y + Offset a y ) * Faktor b y + Offset c y
IndEva-Results per Candidate
IndEva-Results per Candidate
IndEva-Results per Candidate WCNDT 2016 Implementation of Performance Evaluation Methodology in INDEVA
IndEva-Results per Candidate WCNDT 2016 Implementation of Performance Evaluation Methodology in INDEVA
IndEva-Results per Candidate WCNDT 2016 Implementation of Performance Evaluation Methodology in INDEVA
IndEva-Results per Candidate
IndEva-Results per Test Flaw (Plot)
IndEva-Results per Test Flaw
IndEva-Results per Test Flaw