Oconee Five Years of Utilizing Single Pass Analysis

Tim Thulien – Duke Energy Dan Mayes – Duke Energy

Jim Baumann – BWXT Tom Bipes - Zetec

35th Annual EPRI Steam Generator NDE and Tube Integrity Workshop

Clear Water Beach, Florida July 18th-20th

Operating Characteristics – Oconee Nuclear Station Units 1, 2 & 3

• 860 MW Pressurized Water Reactor (PWR) Babcock & Wilcox 2 loop Nuclear Steam Supply System (NSSS).

• Steam Generators are Babcock & Wilcox Canada Replacement Once-Through Steam Generator (ROTSG) type containing 15,631 tubes each.

• Tubing material is thermally treated CrFeNi alloy (Inconel 690) with 0.625-inch outside diameter (OD) and 0.038 inch nominal wall thickness. The tubing has low noise levels.

• The tube sheets are 22.562 inch thick carbon steel, open crevice type, with a 13 inch minimum length hydraulic expansion near both the upper and lower tube ends.

• The tube supports are 410 stainless steel, 1.50 inch thick. • 15 trefoil broached TSP, 14 TSP is drilled around the periphery • The Steam Generators were replaced in 2003 and 2004.

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Oconee History

• Oconee has thousands of tube support plate wear indications that are readily detectable by automated analysis

• All of the in-service tubes are inspected by bobbin at each inspection outage.

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Single Pass Auto Analysis History • 2010 Spring Unit 2 EOC 25 & Fall Unit 3 EOC 25

RevospECT™ was used as tertiary analysis. • Duke Energy deviation to Section 6.3.3.2 of EPRI Steam

Generator Management Program: Pressurized Water Reactor Steam Generator Examination Guidelines, Revision 7, dated March 31, 2011.

• Industry FOAK implementation of single pass auto analysis during Oconee Unit 1 EOC26.

• CDS was utilized for the first outage of implementation on each of the 3 units to validate the results of RevospECT™.

• RevospECT™ has now been used at 9 inspections in the stand alone mode

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Why did Duke elect to use Single Pass

• Reduced number of Analysts available in the industry.

• A more consistent approach to analysis reduction of human error factor.

• High speed of analysis – one analyst per 4 GT’s • No ramp-up lag at the beginning of the

outage.

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Outage Duration

• Number of analysts in 2006 (53) vs 2016 (9) total

• 2006 outage duration 9 days around 220 hrs (we did do more array testing at this time)

• 2016 outage duration 4 days around 90 hrs

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Single Pass Auto Analysis Approach-Pre-outage

• Configurations are created – Bobbin and array – References Degradation Assessment – In accordance with site ETSS’s, Duke Guidelines, and

BWXT ET examination procedure • Tested and validated against previous outage data

– 100% sample for bobbin • Separate validation review by Duke/BWXT • Software is “locked down” • Site SSPD is performed just before outage start

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Single Pass Auto Analysis Outage Approach

• 8 Guide Tubes of data acquired (2 robots in each ROTSG) • 1 RevospECT lead, + 2 dashboard operators (DO’s) per shift

– DO’s not allowed to edit/delete any degradation call – DO’s are allowed to address duplicate tubes, tube messages,

locating errors, other “editorial” changes – DO’s perform auto and manual data quality verification

• Lead Analyst (Pass 1 Resolution)on each shift reviews every cal group – Reviews all I-Codes, significant and/or new degradation – Reviews PLP’s, historic calls, R-codes – Reviews calls that have “changed”, and noise outliers

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Single Pass Auto Analysis Outage Approach-Cont.

• IQDA (Pass 2 on Resolution) on each shift reviews every cal group – Reviews all I-Codes, TSP wear >=20%TW, PLP’s,

INF’s, etc – Reviews calibration set ups – Reviews a sample of the raw data for process

adherence, detection and sizing accuracy

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Single Pass Auto Analysis Outage Approach-Cont.

• Lead Level III and IQDA must agree on all calls • Problem Description Sheet (PDS) completed

for: – Any degradation call that is discarded – New calls (including from noise outliers) – Any violation or perceived limitation to adherence

to a procedure, ETSS or Guidelines • Duke Lead Level III, IQDA and Lead Analyst

agree on Resolution of each PDS

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Single Pass Auto Analysis Implementation Results

• Bobbin inspection data has never been completely reanalyzed during an inspection

• Problem description sheets are reviewed to determine areas for improvement usually resulting in tweaks to the analyzers or software

• Validation was performed on prior outage data for the unit prior to each inspection

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Single Pass Auto Analysis Implementation Results – Cont.

• Lessons Learned collected during outage • PDS’s also reviewed for Lessons Learned • Summary of Lessons Learned:

– Configuration improved with experience each outage – Overcall trends (TS mix residual, high frequency noise, etc)

identified to be rectified in following configuration – Very small TSP wear (5 – 10% TW) “come and go” from

outage to outage (Wear configuration “tweaked” to discern actual low level wear from noise)

– Tube-to-Tube wear discerned at low level and sizing curves added (ETSS 13902.1)

– Data spikes being called as wear – created spike filters.

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Single Pass Auto Analysis Implementation Results – Cont.

• CDS was again run as a check of the single pass auto analysis system at the Unit 3 EOC28 outage (May 2016)-no indications ≥ 20% TW were missed.

• Noise measurements and monitoring since the first implementation outage.

• There have been few changes in the configuration during between inspections noting a mature process.

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HDC - Historical Data Compare

• In 2012 Zetec developed a new product called HDC (Historical Data Compare)

• Fall of 2013 Unit 2 EOC 26, HDC was used as an aid to the resolution process allowing the comparison of multiple outage in the same screen for quick comparison of delta.

• Spring 2014 Unit 3 EOC 27, HDC ran in the automated mode in parallel with RevospECT™ Lead/Resolution review.

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HDC – Historical Data Compare

• Currently HDC is not qualified through the EPRI AAPDD. EPRI would need data sets of NDD tubes and inject signals to create an AAPDD for HDC.

• Duke Energy desired to take credit for the results of HDC as a separate qualified analysis program.

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HDC Qualification

• Fall of 2015 we approached Zetec after qualification was complete and asked can you turn RevospECT™ off and all outage years other than BL to run HDC stand-alone.

• We developed a small data set specific to HDC to see what kind of results we would get.

• Initial results were good, we requested a couple minor adjustments.

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HDC Qualification

• Spring 2016- a data set was developed of 39 tubes for TSP wear.

• These 39 tubes contain TSP wear indications, 39 indications were ≥40% TW and 73 indications < 40% thru wall totaling 108 indications.

• Tube to Tube (TTW) wear we had 39 tubes.

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HDC Qualification Results

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Where do we go from here. • Continue to improve on beneficial tools as

HDC. • Could you say we have a head start on

Delivering the Nuclear Promise

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• Questions

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