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{{#Wiki_filter:NRR Perspectives on Probabilistic Fracture Mechanics | {{#Wiki_filter:NRR Perspectives on Probabilistic Fracture Mechanics Calculations StephenCumblidge MaterialsEngineerNRR/DE/EPNB UnitedStatesNuclearRegulatoryCommission(U.S.NRC) | ||
Tel:+13014152823 Email:stephen.cumblidge@nrc.gov Rockville,MD May212018 | |||
NovelPFMCodes | |||
- | NRCUseofPFMCalculations TheNRChasbeenusingprobabilisticriskassessmentsto guideregulatorydecisionmakinginseveralareasfordecades TheNRChasusedtheprobabilisticfracturemechanics(PFM) codeFAVORtodevelopthealternatePressurizedThermal ShockRule(10CFR50.61a) | ||
PathForward | TheNRCiscooperativelydevelopingtheExtremelyLow ProbabilityofRupture(xLPR)Probabilisticfracturemechanics codetoevaluatetheleakbeforebreakmethodologyin systemswithactivePrimaryWaterStressCorrosionCracking TheNRCisopentoevaluatingandusingnewPFMcodesin thefuturetoassistinregulatorydecisionmaking,and recognizesthepowerfulinsightsprovidedbyPFM 2 | ||
BenefitsofPFMCalculations PFMCalculationscanprovide anoverviewoftheprobabilities ofcrackdepths,leaks,orfailure Onecandecideonaprobability ofaneventasopposedtothe binarycriteriaofa deterministiccalculation PFMandDeterministic Calculationscanbeeffective independentlyormaybe complementary | |||
X or vs. | |||
Deterministic PFM 3 | |||
ConfirmatoryCalculations WhentheNRCstaffperformsatechnicalreview,we checktheimportantcalculationsperformedinthe submittal TheNRChasexpertsinavarietyoffields,including PFM,toallowforthistypeofconfirmatorywork PFMcalculationspresentuniquedifficultiesfor performingconfirmatorycalculations 4 | |||
NovelPFMCodes Withoutaccesstothecodeorindependentreviewof thecodeitcanbeverychallengingtodetermineifthe PFMcalculationsareadequate 5 | |||
NRCReviewofaPFM Possiblemethodsforverifyingthecode | |||
- HavingthecodedirectlyevaluatedbyNRCstaff (TopicalReport) | |||
- Benchmarkingthecodeagainstacodewehavein house(xLPR,FAVOR) | |||
- Benchmarkingthecodeagainstdeterministic calculations | |||
- Independentpeerreviewbyabodywithno conflictofinterest 6 | |||
IssuesWithPreviousPFMCodes Unusualassumptions(e.g.extremelylow possibilityofacircumferentialflawinapiping weld) | |||
PFMdidnotaccountfordegradation mechanismsseeninoperationalexperience Correctionfactorswithlittletonotechnical justification 7 | |||
PathForward TheNRCisdevelopingguidanceontheuseof PFMcalculationsinregulatorysubmittals Thisguidancewillhelptomakesubmittalsusing PFMcalculationsmorerobust,willallowfor moretimelyandpredictablereviews,andmake acceptanceofPFMsubmittalseasier 8}} | |||
Latest revision as of 20:56, 5 January 2025
| ML18141A393 | |
| Person / Time | |
|---|---|
| Issue date: | 05/21/2018 |
| From: | Stephen Cumblidge Piping and NDE Branch |
| To: | |
| Rezai A, NRR-DMLR 415-1328 | |
| References | |
| Download: ML18141A393 (8) | |
Text
NRR Perspectives on Probabilistic Fracture Mechanics Calculations StephenCumblidge MaterialsEngineerNRR/DE/EPNB UnitedStatesNuclearRegulatoryCommission(U.S.NRC)
Tel:+13014152823 Email:stephen.cumblidge@nrc.gov Rockville,MD May212018
NRCUseofPFMCalculations TheNRChasbeenusingprobabilisticriskassessmentsto guideregulatorydecisionmakinginseveralareasfordecades TheNRChasusedtheprobabilisticfracturemechanics(PFM) codeFAVORtodevelopthealternatePressurizedThermal ShockRule(10CFR50.61a)
TheNRCiscooperativelydevelopingtheExtremelyLow ProbabilityofRupture(xLPR)Probabilisticfracturemechanics codetoevaluatetheleakbeforebreakmethodologyin systemswithactivePrimaryWaterStressCorrosionCracking TheNRCisopentoevaluatingandusingnewPFMcodesin thefuturetoassistinregulatorydecisionmaking,and recognizesthepowerfulinsightsprovidedbyPFM 2
BenefitsofPFMCalculations PFMCalculationscanprovide anoverviewoftheprobabilities ofcrackdepths,leaks,orfailure Onecandecideonaprobability ofaneventasopposedtothe binarycriteriaofa deterministiccalculation PFMandDeterministic Calculationscanbeeffective independentlyormaybe complementary
X or vs.
Deterministic PFM 3
ConfirmatoryCalculations WhentheNRCstaffperformsatechnicalreview,we checktheimportantcalculationsperformedinthe submittal TheNRChasexpertsinavarietyoffields,including PFM,toallowforthistypeofconfirmatorywork PFMcalculationspresentuniquedifficultiesfor performingconfirmatorycalculations 4
NovelPFMCodes Withoutaccesstothecodeorindependentreviewof thecodeitcanbeverychallengingtodetermineifthe PFMcalculationsareadequate 5
NRCReviewofaPFM Possiblemethodsforverifyingthecode
- HavingthecodedirectlyevaluatedbyNRCstaff (TopicalReport)
- Benchmarkingthecodeagainstacodewehavein house(xLPR,FAVOR)
- Benchmarkingthecodeagainstdeterministic calculations
- Independentpeerreviewbyabodywithno conflictofinterest 6
IssuesWithPreviousPFMCodes Unusualassumptions(e.g.extremelylow possibilityofacircumferentialflawinapiping weld)
PFMdidnotaccountfordegradation mechanismsseeninoperationalexperience Correctionfactorswithlittletonotechnical justification 7
PathForward TheNRCisdevelopingguidanceontheuseof PFMcalculationsinregulatorysubmittals Thisguidancewillhelptomakesubmittalsusing PFMcalculationsmorerobust,willallowfor moretimelyandpredictablereviews,andmake acceptanceofPFMsubmittalseasier 8