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| {{#Wiki_filter:Notable Failures in Nondestructive Testing Stephen Cumblidge June 4 2013 GoalsofNDE Goals of NDE*Assurestructuralintegrityofcomponents Assure structural integrity of components*Assure leak tightness of reactor pressure boundary*Detect flaws before the y exceed acce p tance criteria yp*Detect and size flaws that meet acceptance criteria 2 | | {{#Wiki_filter:Notable Failures in Nondestructive Testing Stephen Cumblidge June 4 2013 |
| WhenDoesNDEFail?
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| When Does NDE Fail?*Rationalizingawaydetecteddefects Rationalizing away detected defects*Use of NDE techniques that have not been properly qualified through Appendix VIII blind testing*Poor implementation of Appendix VIII-qualified NDE procedures*When Appendix VIII-qualified procedures miss flaws*When NDE is not Used 3
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| Rtiliidttddft R a ti ona li z i ng away d e t ec t e d d e f ec t s 4 2000 Davis Besse HdLk H ea d L ea k age*NDE failures can happen even when the detection is clearAthi*A ny t ec h n ique can fail if assumptions
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| are incorrect 5
| | Goals of NDE |
| DavisBesse2010 Davis Besse 2010*The replacement pressure vessel head leaked in 2010
| | * Assure structural integrity of components |
| *Withincreasedsurveillanceandabetterunderstanding With increased surveillance and a better understanding the degradation was caught quickly *NDE was used in identifying where the cracking was located 6 UfNDEthithth U se o f NDE t ec h n i ques th a t h ave not been properly qualified 7 | | * Assure leak tightness of reactor pressure boundary |
| North Anna Steam Generator 2012 2012*In March of 2012 at least five ilflidb ax i a l fl aws were m i sse d b y an ultrasonic inspection*The licensee used a site specificmockuptoqualifythe specific mockup to qualify the inspection procedure as PDI has no matching test blocks*The licensee used an encoded phased array technique to search for circumferential flaws*The licensee used an lifidllti unqua lifi e d manua l u lt rason i c search unit to search for axial
| | * Detect flaws before theyy exceed acceptance p criteria |
| | * Detect and size flaws that meet acceptance criteria 2 |
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| flaws 8 FactorsinNorthAnna2 Factors in North Anna 2 *The North Anna 2 root cause analysis dibdidttiid The average POD requiredTo miss five flaws is 13%d escr ib e d i na d equa t e t ra i n i ng an d oversight*Team scanning was used
| | When Does NDE Fail? |
| *Thesearchunitshadnotbeenqualified | | * Rationalizing away detected defects |
| *The search units had not been qualified via the blind Appendix VIII process-The ultrasonic search units were more than ten degrees off of the specified angle-The ultrasonic search units were unable to get a strong signal off the end of the site specific mockup block | | * Use of NDE techniques that have not been properly qualified through Appendix VIII blind testing |
| -Modelingshowsthatthesearchunitswere Modeling shows that the search units were not optimized for the component*The probes looked nearly identical but were "Sided", meaning that if the wrong probewasusedtheinspectionquality probe was used the inspection quality would be severely degraded 9
| | * Poor implementation of Appendix VIII-qualified NDE procedures |
| Pilttiflifidthi P oor i mp l emen t a ti on o f qua lifi e d t ec h n i ques 10 DuaneArnold2007 Duane Arnold 2007*Two recirculation riser nozzle-to-safe end dissimilar metal welds at Duane Arnold, RRC-F002 and RRF-F002, contained surface-breaking cracksEidhthtthkt
| | * When Appendix VIII-qualified procedures miss flaws |
| *E v id ence s h ows th a t th e crac ks were presen t as early as 1999 | | * When NDE is not Used 3 |
| *Inspectionsconductedin1999and2005failedto Inspections conducted in 1999 and 2005 failed to detect the cracks*The cracks were found during an inspection in 2007 didt6ihld74%thhll an d s i ze d a t 6 i nc h es l ong an d 74% th roug h wa ll in RRC-F002 and 6 inches long and 55% through wall in RRF-F002 11 MissedFlawsatDuaneArnold Missed Flaws at Duane Arnold*The 1999 ins p ection procedure was not A ppendix VIII ppppqualified and the weld crown reduced inspection coverageEvidencefortheflawswaspresentbutnocallwasmade
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| -Evidence for the flaws was present but no call was made*In the 2005 inspection the weld crowns were removed and an Appendix VIII qualified procedure was used*The 2005 inspection unfortunately used an inappropriate couplant and yielded a low-quality scan Theprocedurewascapableofdetectingtheflaw | |
| -The procedure was capable of detecting the flaw-The inspectors should have rescanned to obtained better coverage-Low quality evidence for the flaw was present but no call was
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| made 12 Poor Coverage -Weld Crown In Place 1999Weld RRF-F002 6"CircumferentialCrack 6 Circumferential Crack55% Through WallNoWeldCrownbutPoorNDE2005No Weld Crown Good UT Procedure 2007 No Weld Crown but Poor NDE 2005 13 WhenAppendixVIIIQualified When Appendix VIII Qualified Procedures Miss Flaws 14 DiabloCanyon2013 Diablo Canyon 2013*Diablo Can y on had allo y 52 weld overla y s installed in a yyy several pressurizer welds in 2008*An acceptance examination was performed using an AdiVIIIlifidtillltd A ppen di x VIII qua lifi e d conven ti ona l manua l u lt rasoun d procedure, including a zero degree inspection to find
| | R ti Rationalizing li i away d detected t t dd defects f t 4 |
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| fabrication flaws*An examination in 2013 using manual phased array UT found several laminar flaws missed by the acceptance examination examination*One of the flaws was 16 inches long and a second was essentiall y 360 de grees around the overla yygy 15 DiabloCanyon2013 Diablo Canyon 2013*Both the 2008 and 2013 techniques wereAppendixVIIIqualified were Appendix VIII qualified*The zero degree beam inspection procedure used for the acceptance examination did provide small responsesfromtheflawsbuttheflaws responses from the flaws but the flaws were not all found were not sized
| | 2000 Davis Besse H d Leakage Head L k |
| | * NDE failures can happen even when the detection is clear |
| | * Any A technique t h i can fail if assumptions are incorrect 5 |
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| correctly in 2008*The procedure used in 2013 used a manualphasedarrayprobethatZero DegreePhased Array manual phased array probe that included many more angles than were used in the acceptance examination*The laminar flaws were at a slight angleanddidnotpeakatzero angle and did not peak at zero degrees*The NRC met with PDI to discuss the Mockups used at PDI and the path forward forward 16 WhNDEiNtUd Wh en NDE i s N o t U se d 17 Leaks in Uninspected Ct C omponen t s*Man y com p onents prone to leakin g are not yppgvolumetrically inspected-Partial Penetration WeldsPressurizerHeaterSleeves
| | Davis Besse 2010 |
| -Pressurizer Heater Sleeves-Socket Welds-Small Diameter Welds*If the goal of NDE is to prevent leakage these areas would need to be addressed with more aggressive NDE 18 Conclusions Conclusions*No ins p ection procedure can succeed if the ins p ectors pppand/or the licensees rationalize away detected indications
| | * The replacement pressure vessel head leaked in 2010 |
| *WhenAppendixVIIIqualifiedproceduresareused When Appendix VIII qualified procedures are used appropriately, ultrasonic inspections have shown to have a high reliability
| | * With increased surveillance and a better understanding the degradation was caught quickly |
| *Thereliabilityofinspectionproceduresdeclinessharply
| | * NDE was used in identifying where the cracking was located 6 |
| *The reliability of inspection procedures declines sharply when the procedures deviate from the Appendix VIII-
| |
|
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| qualified proceduresEAdiVIIIlifiddifl | | Use off NDE ttechniques U h i th thatt h have not been properly qualified 7 |
| *E ven A ppen di x VIII qua lifi e d proce dures can m i ss fl aws*If the NRC and industry goal is to prevent leakage NDE will need to be im plemented in new areas p 19}} | | |
| | North Anna Steam Generator 2012 |
| | * In March of 2012 at least five axial i l fl flaws were missed i db by an ultrasonic inspection |
| | * The licensee used a site specific mockup to qualify the inspection procedure as PDI has no matching test blocks |
| | * The licensee used an encoded phased array technique to search for circumferential flaws |
| | * The licensee used an unqualified lifi d manuall ultrasonic lt i search unit to search for axial flaws 8 |
| | |
| | Factors in North Anna 2 The average POD required To miss five flaws is 13% |
| | * The North Anna 2 root cause analysis d |
| | described ib d iinadequate d t ttraining i i and d oversight |
| | * Team scanning was used |
| | * The search units had not been qualified via the blind Appendix VIII process |
| | - The ultrasonic search units were more than ten degrees off of the specified angle |
| | - The ultrasonic search units were unable to get a strong signal off the end of the site specific mockup block |
| | - Modeling shows that the search units were not optimized for the component |
| | * The probes looked nearly identical but were Sided, meaning that if the wrong probe was used the inspection quality would be severely degraded 9 |
| | |
| | P Poor implementation i l t ti off qualified lifi d ttechniques h i 10 |
| | |
| | Duane Arnold 2007 |
| | * Two recirculation riser nozzle-to-safe end dissimilar metal welds at Duane Arnold, RRC-F002 and RRF-F002, contained surface-breaking cracks |
| | * Evidence E id shows h th thatt th the cracks k were presentt as early as 1999 |
| | * Inspections conducted in 1999 and 2005 failed to detect the cracks |
| | * The cracks were found during an inspection in 2007 andd sized i d att 6 iinches h llong and d 74% th through h wallll in RRC-F002 and 6 inches long and 55% through wall in RRF-F002 11 |
| | |
| | Missed Flaws at Duane Arnold |
| | * The 1999 inspection p p procedure was not Appendix pp VIII qualified and the weld crown reduced inspection coverage |
| | - Evidence for the flaws was present but no call was made |
| | * In the 2005 inspection the weld crowns were removed and an Appendix VIII qualified procedure was used |
| | * The 2005 inspection unfortunately used an inappropriate couplant and yielded a low-quality scan |
| | - The procedure was capable of detecting the flaw |
| | - The inspectors should have rescanned to obtained better coverage |
| | - Low quality evidence for the flaw was present but no call was made 12 |
| | |
| | Poor Coverage - Weld Crown In Place 1999 Weld RRF-F002 6 Circumferential Crack 6 |
| | 55% Through Wall No Weld Crown Good UT Procedure 2007 No Weld Crown but Poor NDE 2005 13 |
| | |
| | When Appendix VIII Qualified Procedures Miss Flaws 14 |
| | |
| | Diablo Canyon 2013 |
| | * Diablo Canyony had alloyy 52 weld overlays y installed in a several pressurizer welds in 2008 |
| | * An acceptance examination was performed using an A |
| | Appendix di VIII qualified lifi d conventional ti l manuall ultrasound lt d procedure, including a zero degree inspection to find fabrication flaws |
| | * An examination in 2013 using manual phased array UT found several laminar flaws missed by the acceptance examination |
| | * One of the flaws was 16 inches long and a second was essentiallyy 360 degrees g around the overlay y |
| | 15 |
| | |
| | Diablo Canyon 2013 |
| | * Both the 2008 and 2013 techniques were Appendix VIII qualified |
| | * The zero degree beam inspection procedure used for the acceptance examination did provide small responses from the flaws but the flaws were not all found were not sized correctly in 2008 Zero Degree Phased Array |
| | * The procedure used in 2013 used a manual phased array probe that included many more angles than were used in the acceptance examination |
| | * The laminar flaws were at a slight angle and did not peak at zero degrees |
| | * The NRC met with PDI to discuss the Mockups used at PDI and the path forward 16 |
| | |
| | Wh NDE iis N When Nott U Used d |
| | 17 |
| | |
| | Leaks in Uninspected C |
| | Components t |
| | * Manyy components p p prone to leaking g are not volumetrically inspected |
| | - Partial Penetration Welds |
| | - Pressurizer Heater Sleeves |
| | - Socket Welds |
| | - Small Diameter Welds |
| | * If the goal of NDE is to prevent leakage these areas would need to be addressed with more aggressive NDE 18 |
| | |
| | Conclusions |
| | * No inspection p p procedure can succeed if the inspectors p |
| | and/or the licensees rationalize away detected indications |
| | * When Appendix VIII qualified procedures are used appropriately, ultrasonic inspections have shown to have a high reliability |
| | * The reliability of inspection procedures declines sharply when the procedures deviate from the Appendix VIII-qualified procedures |
| | * Even E A Appendix di VIII qualified lifi d procedures d can miss i flflaws |
| | * If the NRC and industry goal is to prevent leakage NDE will need to be implemented p in new areas 19}} |
|
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Category:Meeting Briefing Package/Handouts
MONTHYEARML24036A3382024-02-0505 February 2024 Environmental Scoping Meeting for the Diablo Canyon License Renewal Application - February 8 Meeting Slides ML24030A4672024-01-30030 January 2024 Environmental Scoping Meeting for the Diablo Canyon License Renewal Application - February 1 Meeting Slides ML24029A2362024-01-30030 January 2024 Preliminary Results of the Environmental Review, Subsequent License Renewal ML23338A1522023-12-0707 December 2023 Public Meeting Slides for North Anna and Surry Emergency Plan Augmentation Times License Amendment Request ML23255A0992023-09-15015 September 2023 Slides for September 15, 2023 Public Meeting on Poanhi Seismic Evaluations ML23249A1592023-09-13013 September 2023 License Renewal Application Pre-Application Meeting: September 13, 2023 ML23255A0012023-09-13013 September 2023 PG&E Slides for 9/13 Public Meeting Related to Diablo Canyon License Renewal ML23174A0562023-06-26026 June 2023 Slides for TSTF-505 Pre-Submittal Public Teleconference 6-26-2023 ML23143A0882023-05-24024 May 2023 May 24, 2023, Public Meeting Slides Related to Diablo Canyon License Renewal ML23143A0952023-05-0303 May 2023 May 3, 2023, Diablo Public Meeting Slides for PG&E Presentation ML23118A0902023-05-0303 May 2023 May 3, 2023, Diablo Public Meeting Slides ML23103A3482023-04-14014 April 2023 Annual Assessment Meeting Presentation for North Anna and Surry ML23079A0452023-03-16016 March 2023 RIC 2023 Slides - Maureen Zawalick TH19 ML22339A1022022-12-0505 December 2022 Pg_E Presentation for NRC Public Meeting ML22200A0712022-07-21021 July 2022 Post-Shutdown Decommissioning Activities Report Public Meeting Slides - July 21, 2022 ML22200A0722022-07-21021 July 2022 PG&E Slides for Post-Shutdown Decommissioning Activities Report Public Meeting, Site-Specific Decommissioning Cost Estimate, and Irradiated Fuel Management Plan - July 21, 2022 ML22222A1102022-07-21021 July 2022 KM Session Final ML22178A1952022-06-27027 June 2022 2021 Davis Besse Nuclear Power Station End-of-Cycle Meeting Presentation ML21221A0332022-06-17017 June 2022 Meeting Summary: Discussion of Dominion'S Response to Select Staff Requests for Additional Information on Subsequent License Renewal Application (EPID No. L-2020-SLR-0000) - NRC Slides ML22028A3972022-02-0101 February 2022 NRC Regulatory Conference Presentation ML22028A3922022-02-0101 February 2022 Licensee Regulatory Conference Presentation NRC-2020-0148, Comment (1) of Bari Richter on NextEra Energy Duane Arnold, LLC; Duane Arnold Energy Center; Post-Shutdown Decommissioning Activities Report; Reopening of Comment Period2021-12-20020 December 2021 Comment (1) of Bari Richter on NextEra Energy Duane Arnold, LLC; Duane Arnold Energy Center; Post-Shutdown Decommissioning Activities Report; Reopening of Comment Period ML21278A0602021-10-0606 October 2021 Slides for Duane Arnold Virtual PSDAR Meeting - October 6, 2021 ML21223A0842021-08-11011 August 2021 Slides for Post Shutdown EP pre-submittal Public Teleconference 8-30-2021 ML21176A1992021-06-25025 June 2021 Slideshow Presentation for 2020 End -of-Cycle Public Meeting for Davis-Besse and Perry ML21174A3042021-06-23023 June 2021 SLRA RAI Response Public Meeting - 21-06-24 ML21145A1662021-05-27027 May 2021 DAEC Webinar May 27, 2021 ML21146A0562021-05-27027 May 2021 Updated Nextera - Duane Arnold Derecho Event Aug 2020 ML21221A1542021-05-27027 May 2021 Meeting Summary: Discussion of Dominion'S Response to Select Staff Requests for Additional Information on Subsequent License Renewal Application (EPID No. L-2020-SLR-0000) - Dominion Slides ML21145A2172021-05-13013 May 2021 Discussion on May 13, 2021 with Dominion on Select Staff RAIs on North Anna Subsequent License Renewal Application - Dominion Slides ML21132A2892021-05-13013 May 2021 SLRA RAI Response Public Meeting ML21034A5972021-02-10010 February 2021 External Presentation Am Atkinson_Nrc ISG-06 Meeting Dominion Digital IC Project 02102021 ML20288A3472020-10-14014 October 2020 (COVID-19) Emergency Preparedness Exemption Pre-Application Meeting ML20240A2702020-08-27027 August 2020 2019 EOC Slide Presentation ML20223A0562020-08-12012 August 2020 Slides for Decommissioning Webinar Regarding Duane Arnold Energy Center on August 12, 2020 ML20210M0712020-07-27027 July 2020 Combined End-of-Cycle 2019 Public Meeting Slide Presentation ML20099F2992020-04-0909 April 2020 NRC Slides for North Anna pre-app April 9 ML20099F2412020-04-0909 April 2020 Co., NRC Safety Pre& 8208;Application Meeting North Anna Power Station (NAPS) ML20098B6022020-04-0707 April 2020 Annual Assessment Meeting Presentation ML21060B1872020-01-26026 January 2020 Enclosure 3 - 1-26-21 Diablo Canyon Renewal pre-app Meeting Slides ML19297D1872019-11-18018 November 2019 Pre-Application Meeting - Dominion Slides ML19249D0212019-09-0606 September 2019 End-of-Cycle Summary Handout (2018) ML19165A0092019-06-14014 June 2019 Pre-Submittal Meeting - Presentation Slides ML18333A1092018-11-28028 November 2018 Presentation Slides for Diablo Public Meeting to Discuss Proposed Exemption Request for Decommissioning Funds ML18320A2502018-11-20020 November 2018 50.90 License Amendment Request - Dominion Fleet EAL Scheme Changes, November 20, 2018 Public Meeting ML18310A3802018-11-0808 November 2018 Pre-Submittal Meeting Davis-Besse Nuclear Power Station (DB) Post-Shutdown Emergency Plan (PSEP) License Amendment Request ML18180A1962018-06-29029 June 2018 Slides for Davis Besse 2017 EOC Open House ML18141A3072018-05-21021 May 2018 18 - SLR Status ML17296A2222017-08-29029 August 2017 Presentation on Reactor Decommissioning for the August 29, 2017 at Congressman Salud Carbajal'S Public Meeting at San Luis Obispo Near Diablo Canyon ML17229B3382017-08-17017 August 2017 Presentation for 2016 Davis-Besse EOC Open House 2024-02-05
[Table view] Category:Slides and Viewgraphs
MONTHYEARML24036A3382024-02-0505 February 2024 Environmental Scoping Meeting for the Diablo Canyon License Renewal Application - February 8 Meeting Slides ML24029A2362024-01-30030 January 2024 Preliminary Results of the Environmental Review, Subsequent License Renewal ML24030A4672024-01-30030 January 2024 Environmental Scoping Meeting for the Diablo Canyon License Renewal Application - February 1 Meeting Slides ML23338A1522023-12-0707 December 2023 Public Meeting Slides for North Anna and Surry Emergency Plan Augmentation Times License Amendment Request ML23255A0992023-09-15015 September 2023 Slides for September 15, 2023 Public Meeting on Poanhi Seismic Evaluations ML23255A0012023-09-13013 September 2023 PG&E Slides for 9/13 Public Meeting Related to Diablo Canyon License Renewal ML23249A1592023-09-13013 September 2023 License Renewal Application Pre-Application Meeting: September 13, 2023 ML23174A0562023-06-26026 June 2023 Slides for TSTF-505 Pre-Submittal Public Teleconference 6-26-2023 ML23152A2022023-06-0101 June 2023 2022 Davis-Besse End-of-Cycle Meeting Presentation ML23143A0882023-05-24024 May 2023 May 24, 2023, Public Meeting Slides Related to Diablo Canyon License Renewal ML23118A0902023-05-0303 May 2023 May 3, 2023, Diablo Public Meeting Slides ML23143A0952023-05-0303 May 2023 May 3, 2023, Diablo Public Meeting Slides for PG&E Presentation ML23103A3482023-04-14014 April 2023 Annual Assessment Meeting Presentation for North Anna and Surry ML23079A0452023-03-16016 March 2023 RIC 2023 Slides - Maureen Zawalick TH19 ML22339A1022022-12-0505 December 2022 Pg_E Presentation for NRC Public Meeting ML22236A5472022-08-24024 August 2022 NRC Slides for Decommissioning Engagement Panel 8-24-2022 Meeting ML22222A1102022-07-21021 July 2022 KM Session Final ML22200A0722022-07-21021 July 2022 PG&E Slides for Post-Shutdown Decommissioning Activities Report Public Meeting, Site-Specific Decommissioning Cost Estimate, and Irradiated Fuel Management Plan - July 21, 2022 ML22200A0712022-07-21021 July 2022 Post-Shutdown Decommissioning Activities Report Public Meeting Slides - July 21, 2022 ML22178A1952022-06-27027 June 2022 2021 Davis Besse Nuclear Power Station End-of-Cycle Meeting Presentation ML21221A0332022-06-17017 June 2022 Meeting Summary: Discussion of Dominion'S Response to Select Staff Requests for Additional Information on Subsequent License Renewal Application (EPID No. L-2020-SLR-0000) - NRC Slides ML22091A0902022-04-0101 April 2022 Combined 2021 Assessment Meeting Slides ML22061A1052022-02-18018 February 2022 4A-3_of_4-Hunter-Duane_Arnold_ASP_Analysis-SLIDES ML22061A1062022-02-18018 February 2022 4A-2_of_4-Hanna-Duane_Arnold-rev0-SLIDES ML22061A1042022-02-15015 February 2022 4A-4_of_4-Leech-DAEC_LIC504_for_PFHA_Workshop-SLIDES ML22061A1072022-02-15015 February 2022 4A-1_of_4-Brandt-DAEC_Derecho_Sequence_of_Events-SLIDES ML22028A3972022-02-0101 February 2022 NRC Regulatory Conference Presentation ML22028A3922022-02-0101 February 2022 Licensee Regulatory Conference Presentation NRC-2020-0148, Comment (1) of Bari Richter on NextEra Energy Duane Arnold, LLC; Duane Arnold Energy Center; Post-Shutdown Decommissioning Activities Report; Reopening of Comment Period2021-12-20020 December 2021 Comment (1) of Bari Richter on NextEra Energy Duane Arnold, LLC; Duane Arnold Energy Center; Post-Shutdown Decommissioning Activities Report; Reopening of Comment Period ML21278A0602021-10-0606 October 2021 Slides for Duane Arnold Virtual PSDAR Meeting - October 6, 2021 ML21223A0842021-08-11011 August 2021 Slides for Post Shutdown EP pre-submittal Public Teleconference 8-30-2021 ML21176A1992021-06-25025 June 2021 Slideshow Presentation for 2020 End -of-Cycle Public Meeting for Davis-Besse and Perry ML21221A1542021-05-27027 May 2021 Meeting Summary: Discussion of Dominion'S Response to Select Staff Requests for Additional Information on Subsequent License Renewal Application (EPID No. L-2020-SLR-0000) - Dominion Slides ML21221A1482021-05-27027 May 2021 Meeting Summary: Discussion of Dominion'S Response to Select Staff Requests for Additional Information on Subsequent License Renewal Application (EPID No. L-2020-SLR-0000) - NRC Slides ML21145A0302021-05-27027 May 2021 NextEra Energy - Duane Arnold Energy Center - Loss of Offsite Power Due to Derecho (August 2020) ML21145A1662021-05-27027 May 2021 DAEC Webinar May 27, 2021 ML21146A0562021-05-27027 May 2021 Updated Nextera - Duane Arnold Derecho Event Aug 2020 ML21146A1832021-05-27027 May 2021 Updated 2 Nextera - Duane Arnold Energy Center Loss of Offsite Power Due to Derecho Event Aug 2020 ML21132A2892021-05-13013 May 2021 SLRA RAI Response Public Meeting ML21145A2172021-05-13013 May 2021 Discussion on May 13, 2021 with Dominion on Select Staff RAIs on North Anna Subsequent License Renewal Application - Dominion Slides ML21034A5972021-02-10010 February 2021 External Presentation Am Atkinson_Nrc ISG-06 Meeting Dominion Digital IC Project 02102021 ML20310A2792020-11-0505 November 2020 Slides for Defueled TS Pre-Submittal Public Teleconference November 24, 2020 (L-2020-LRM-0101) ML20288A3472020-10-14014 October 2020 (COVID-19) Emergency Preparedness Exemption Pre-Application Meeting ML20253A1912020-09-24024 September 2020 Slides for Decommissioning Webinar Regarding Duane Arnold Energy Center on September 24, 2020 ML20261H3892020-09-17017 September 2020 Slides for Decommissioning-Overview Webinar Regarding Duane Arnold Energy Center Presented on September 24, 2020 ML20240A2702020-08-27027 August 2020 2019 EOC Slide Presentation ML20223A0562020-08-12012 August 2020 Slides for Decommissioning Webinar Regarding Duane Arnold Energy Center on August 12, 2020 ML20210M0712020-07-27027 July 2020 Combined End-of-Cycle 2019 Public Meeting Slide Presentation ML20099F2992020-04-0909 April 2020 NRC Slides for North Anna pre-app April 9 ML20099F2412020-04-0909 April 2020 Co., NRC Safety Pre& 8208;Application Meeting North Anna Power Station (NAPS) 2024-02-05
[Table view] |
Text
Notable Failures in Nondestructive Testing Stephen Cumblidge June 4 2013
Goals of NDE
- Assure structural integrity of components
- Assure leak tightness of reactor pressure boundary
- Detect flaws before theyy exceed acceptance p criteria
- Detect and size flaws that meet acceptance criteria 2
When Does NDE Fail?
- Rationalizing away detected defects
- Use of NDE techniques that have not been properly qualified through Appendix VIII blind testing
- Poor implementation of Appendix VIII-qualified NDE procedures
- When Appendix VIII-qualified procedures miss flaws
R ti Rationalizing li i away d detected t t dd defects f t 4
2000 Davis Besse H d Leakage Head L k
- NDE failures can happen even when the detection is clear
- Any A technique t h i can fail if assumptions are incorrect 5
Davis Besse 2010
- The replacement pressure vessel head leaked in 2010
- With increased surveillance and a better understanding the degradation was caught quickly
- NDE was used in identifying where the cracking was located 6
Use off NDE ttechniques U h i th thatt h have not been properly qualified 7
North Anna Steam Generator 2012
- In March of 2012 at least five axial i l fl flaws were missed i db by an ultrasonic inspection
- The licensee used a site specific mockup to qualify the inspection procedure as PDI has no matching test blocks
- The licensee used an encoded phased array technique to search for circumferential flaws
- The licensee used an unqualified lifi d manuall ultrasonic lt i search unit to search for axial flaws 8
Factors in North Anna 2 The average POD required To miss five flaws is 13%
- The North Anna 2 root cause analysis d
described ib d iinadequate d t ttraining i i and d oversight
- The search units had not been qualified via the blind Appendix VIII process
- The ultrasonic search units were more than ten degrees off of the specified angle
- The ultrasonic search units were unable to get a strong signal off the end of the site specific mockup block
- Modeling shows that the search units were not optimized for the component
- The probes looked nearly identical but were Sided, meaning that if the wrong probe was used the inspection quality would be severely degraded 9
P Poor implementation i l t ti off qualified lifi d ttechniques h i 10
Duane Arnold 2007
- Two recirculation riser nozzle-to-safe end dissimilar metal welds at Duane Arnold, RRC-F002 and RRF-F002, contained surface-breaking cracks
- Evidence E id shows h th thatt th the cracks k were presentt as early as 1999
- Inspections conducted in 1999 and 2005 failed to detect the cracks
- The cracks were found during an inspection in 2007 andd sized i d att 6 iinches h llong and d 74% th through h wallll in RRC-F002 and 6 inches long and 55% through wall in RRF-F002 11
Missed Flaws at Duane Arnold
- The 1999 inspection p p procedure was not Appendix pp VIII qualified and the weld crown reduced inspection coverage
- Evidence for the flaws was present but no call was made
- In the 2005 inspection the weld crowns were removed and an Appendix VIII qualified procedure was used
- The 2005 inspection unfortunately used an inappropriate couplant and yielded a low-quality scan
- The procedure was capable of detecting the flaw
- The inspectors should have rescanned to obtained better coverage
- Low quality evidence for the flaw was present but no call was made 12
Poor Coverage - Weld Crown In Place 1999 Weld RRF-F002 6 Circumferential Crack 6
55% Through Wall No Weld Crown Good UT Procedure 2007 No Weld Crown but Poor NDE 2005 13
When Appendix VIII Qualified Procedures Miss Flaws 14
Diablo Canyon 2013
- Diablo Canyony had alloyy 52 weld overlays y installed in a several pressurizer welds in 2008
- An acceptance examination was performed using an A
Appendix di VIII qualified lifi d conventional ti l manuall ultrasound lt d procedure, including a zero degree inspection to find fabrication flaws
- An examination in 2013 using manual phased array UT found several laminar flaws missed by the acceptance examination
- One of the flaws was 16 inches long and a second was essentiallyy 360 degrees g around the overlay y
15
Diablo Canyon 2013
- Both the 2008 and 2013 techniques were Appendix VIII qualified
- The zero degree beam inspection procedure used for the acceptance examination did provide small responses from the flaws but the flaws were not all found were not sized correctly in 2008 Zero Degree Phased Array
- The procedure used in 2013 used a manual phased array probe that included many more angles than were used in the acceptance examination
- The laminar flaws were at a slight angle and did not peak at zero degrees
- The NRC met with PDI to discuss the Mockups used at PDI and the path forward 16
Wh NDE iis N When Nott U Used d
17
Leaks in Uninspected C
Components t
- Manyy components p p prone to leaking g are not volumetrically inspected
- Partial Penetration Welds
- Pressurizer Heater Sleeves
- Socket Welds
- Small Diameter Welds
- If the goal of NDE is to prevent leakage these areas would need to be addressed with more aggressive NDE 18
Conclusions
- No inspection p p procedure can succeed if the inspectors p
and/or the licensees rationalize away detected indications
- When Appendix VIII qualified procedures are used appropriately, ultrasonic inspections have shown to have a high reliability
- The reliability of inspection procedures declines sharply when the procedures deviate from the Appendix VIII-qualified procedures
- Even E A Appendix di VIII qualified lifi d procedures d can miss i flflaws
- If the NRC and industry goal is to prevent leakage NDE will need to be implemented p in new areas 19