NOC-AE-14003139, RE16 Inspection Summary Report for Steam Generator Tubing
| ML14161A146 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 05/22/2014 |
| From: | Berg M South Texas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NOC-AE-14003139 | |
| Download: ML14161A146 (13) | |
Text
Nuclear Operating Company South Texas Pro/ed E/kdrc GnerngSttlon P. Box 289 Mdsworth, Tewas77483 VV* -
May 22, 2014 NOC-AE-14003139 File No.: G25 10 CFR 50.55a Attention: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 South Texas Project Unit 2 Docket No. STN 50-499 2RE16 Inspection Summary Report for Steam Generator Tubing Enclosed are four copies of the summary report describing the results of the South Texas Project Unit 2 steam generator tube inspection performed during refueling outage 2RE16. The summary report satisfies the reporting requirements of ASME Section Xl, Article IWA-6230, and Section 6.9.1.7 of the South Texas Project Technical Specifications. This report provides the information required by Technical Specification 6.8.3.o for maintaining steam generator tube integrity.
There are no commitments in this letter.
If there are any questions regarding this report, please contact either Mr. Drew Richards at (361) 972-7666 or me at (361) 972-7030.
Michael Berg Manager, Design Engineering Testing & Programs Engineering
Enclosure:
2RE1 6 Inspection Summary Report for Steam Generator Tubing of the South Texas Project Electric Generating Station Unit 2 STI: 33878334 3e 73
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NOC-AE-14003139 Page 2 of 2 cc:
(paper copy) (electronic copy)
Regional Administrator, Region IV A. H. Gutterman, Esquire U. S. Nuclear Regulatory Commission Morgan, Lewis & Bockius LLP 1600 East Lamar Boulevard Arlington, TX 76011-4511 Balwant K. Singal U. S. Nuclear Regulatory Commission Balwant K. Singal John Ragan Senior Project Manager Chris O'Hara U.S. Nuclear Regulatory Commission Jim von Suskil One White Flint North (MS 8 B1) NRG South Texas LP 11555 Rockville Pike Rockville, MD 20852 Kevin Polio NRC Resident Inspector Cris Eugster U. S. Nuclear Regulatory Commission L. D. Blaylock P. 0. Box 289, Mail Code: MN16 CPS Energy Wadsworth, TX 77483 Jim Collins City of Austin Peter Nemeth Electric Utility Department Crain Caton & James, P.C.
721 Barton Springs Road Austin, TX 78704 C. Mele City of Austin Richard A. Ratliff Texas Department of State Health Services Robert Free Texas Department of State Health Services
Attachment NOC-AE-14003139 Page 1 of 11 2RE16 INSPECTION
SUMMARY
REPORT FOR STEAM GENERATOR TUBING (Rev 0) of the SOUTH TEXAS PROJECT ELECTRIC GENERATING STATION UNIT 2 P.O. BOX 289 WADSWORTH, TEXAS 77483 Commercial Operation: June 19,1989 Issue Date: May 22, 2014
Attachment NOC-AE-14003139 Page 2 of 11 2RE16 INSPECTION
SUMMARY
REPORT FOR STEAM GENERATOR TUBING (Rev. 0) of the SOUTH TEXAS PROJECT ELECTRIC GENERATING STATION UNIT 2 USNRC DOCKET NO.: 50-499 OPERATING LICENSE NO.: NPF-80 COMMERCIAL OPERATION DATE: June 19,1989 Prepared By:
D. C. Sicking Date Steam Generator Engineer Approved By:
)/Date M. J. Benrg -
Manager, Desiangineering
Attachment NOC-AE-1 4003139 Page 3 of 11 SOUTH TEXAS PROJECT UNIT 2 2RE16 INSPECTION
SUMMARY
REPORT FOR STEAM GENERATOR TUBING Introduction This summary report describes the inspection of steam generator tubing at South Texas Project (STP)
Unit 2 performed during refueling outage 2RE16 in December 2013. Eddy current inspection, sludge lancing, and Foreign Object Search and Retrieval (FORSAR) were conducted in steam generators (SG) 2A, 2B, 2C and 2D. Additional inspections of the secondary side of SG 2A and 2B were also performed.
The eddy current inspection performed during 2RE16 completed the first interval inspection requirements for all Unit 2 steam generators. The outage was performed following 112.19 effective full power months cumulative service with the Delta 94 replacement steam generators. This report provides the information required by Technical Specification 6.8.3.0 for maintaining steam generator tube integrity and the reporting requirements of Technical Specification 6.9.1.7.
Scope of Examination The-inspection Plan, "2013 Outage Plan In-Service Steam Generator Inspection for South Texas Unit 2 (2RE16) November 2013," identified the steam generator tube areas to be examined by eddy current testing and the related procedures to be used during the inservice inspection. A Degradation Assessment written prior to the outage established the following scope of primary and secondary side inspections:
Primary Side Inspection Scope As required by the EPRI Steam Generator Examination Guidelines, the inspection program addressed the known degradation mechanism(s) observed in STP Unit 2 in the prior inspection, as well as those regarded as potential degradation mechanisms. The following outlines the 2RE16 initial inspection plan, as justified in the Degradation Assessment, applicable to STP Unit 2 steam generators SG-2A, SG-2B, SG-2C, and SG-2D:
Bobbin Coil Inspection
" Full length bobbin inspection of 100% of the outer three (3) peripheral tubes from tube end to tube end, including ten (10) tubes inwards into the no-tube lane from the periphery.
- Full length bobbin inspection of 50% of all tubes. Scope shall include all tubes not inspected full length during 2RE13. The Technical Specification requires full length bobbin inspection of all tubes in either 2RE13 or 2RE16.
Rotating Coil Inspection U-Bend
Rotating Coil Inspection - Straight Section
- +Point inspection of outer three tubes of periphery and divider lane TTS +6 inches/-3 inches to aid in loose parts detection including HL and CL.
- 20% Sample +Point inspection of TSH +6 inches/-3 inches.
- >20% Sample +Point inspection of TSH +6 inches/-16 inches in tubes with bulges and over-expansions.
Attachment NOC-AE-1 4003139 Page 4 of 11 Rotatinq Coil Inspection - Special Interest
- +Point inspection of all previously identified dents and dings >5 volts.
- +Point inspection of all prior and 2RE16 "I-code" and/or non-quantifiable indications as determined by bobbin inspection or any previously reported signal that has changed.
- +Point inspection of PLP in the eddy current database as identified by previous eddy current inspections.
- +Point inspection of all foreign objects not retrieved in 2RE13.
- +Point inspection of a minimum two tube locations surrounding any newly identified PLP.
- +Point inspection of a minimum two tube locations surrounding newly identified foreign objects that are classified as having the potential to cause tube damage or wear.
- +Point inspection of the cold leg 8th support of tube A-R7C57 (Previously reported CL TSP Wear).
- +Point inspection of all tube-to-tube wear indications detected by bobbin coil.
- +Point inspection of all reportable proximity (PRO) indications.
- +Point inspection of all MBM bobbin indications that have increased by 40.5 volt. This includes both new and changed bobbin MBM indications.
Other Primary-Side Inspections
- Video Inspection of all installed plugs.
- Video Inspection of hot and cold leg bowl drain area looking for thinning or missing cladding and associated wastage, if any (STP CR 12-1018).
- Conduct stud hole gauging and stud gauging on SG-2C.
Secondary Side Inspection Scope
- Ultra sludge lancing on all four steam generators.
- Sludge collector inspection and cleaning on SG-2A.
- Upper steam drum inspection on SG-2A.
- Video probe inspection of 9th support plate on SG-2A.
- Feedring, spray nozzles, and separator risers and barrel, as well as the primary separator vanes examination on SG-2A and SG-2B.
- TTS FOSAR in all four steam generators including annulus and no-tube lane.
- TTS In-bundle FOSAR as follows.
- 1. SG-2A inspect every fourth column both hot leg and cold leg beginning with column 2.
- 2. SG-2B inspect every fourth column both hot leg and cold leg beginning with column 1.
- 3. SG-2C inspect every fourth column both hot leg and cold leg beginning with column 1.
- 4. SG-2D inspect every 2nd column both hot leg and cold leg beginning with column 1.
- FOSAR of all loose parts left in service during 2RE13, if reachable by tooling.
- FOSAR of all possible loose parts (PLP) indications identified by eddy current inspection, if reachable by tooling.
Attachment NOC-AE-1 4003139 Page 5 of 11 Examination Results Table 1 provides a summary of the 2RE16 eddy current indications reported. Table 2 and Table 3 provide details of the potential loose part (PLP) calls and resolution thereof, respectively.
No cracking or corrosion was identified in any tube. The only degradation identified were wear indications at tube support plates, as described further below. A few benign signals were observed, including dings (DNG), manufacturing burnish marks (MBM), and signals cleared as free from degradation (NQS) by motorized rotating pancake coil (MRPC) (+Point) examination. Signals representative of tube diameter increases (bulges-BLG) were also reported from the bobbin inspection analyses. Based on historical data, all identified bulges were introduced as part of the manufacturing process. Benign signals in the 2RE16 inspection data were assessed by reviewing the prior available inspection data. If the historical lookup did not support the classification as a pre-existing benign signal or the signal exhibited a significant change, they were resolved by MRPC inspection. All identified benign signals are to be inspected in future outages as required by EPRI guidelines.
As noted in Table 2, a total of 9 PLP calls were reported in 2RE16. As required by EPRI guidelines, coordination between the eddy current and secondary visual inspection results was maintained. For those PLP locations where secondary access was available, tube locations showing PLP signals by eddy current were visually inspected to identify the source of the signal. In addition, all TTS tube locations where foreign objects were identified during visual inspections were included in the TTS +Point inspection program. As seen in Table 3, 6 PLP calls were reported in SG 2A, no calls were reported in SG 2B, no calls were reported in SG 2C, and three calls were reported in SG 2D. All new PLP calls were "boxed-in" by additional eddy current inspections. The disposition of all PLP calls is also shown in Table 3. Disposition of legacy PLP calls was based on reviewing historical data and 2RE16 eddy current data for PLP signals and wear. No tube wear was reported associated with any of the PLP calls.
Table 4 lists the three reported VOL calls with their through-wall depths. The Degradation Assessment categorized tube support plate (TSP) wear as an existing degradation mechanism. During the STP Unit 2 steam generator inspections conducted during 2RE13, one tube was found to have a pin-point indication of wear that resulted from incomplete machining on one land of the broached hole support plate. This same mechanism was reported on two additional tubes during the inspections conducted in 2RE16.
Location A-R7C57-08C had a reported indication of 4% TW (percent throughwall) at 2RE13, as sized by bobbin. At 2RE16, this same location was sized by bobbin to be 8% TW. The indication is associated with only one of the three trefoil lands, lending credence to incomplete machining being the cause of the minor wear.
Location A-R8C154-06C had a reported indication of 9% TW at 2RE16. A review of the 2RE13 data ascertained that a depth of 5% TW could be assigned to this indication. The indication is observed on only one of the three trefoil lands.
Location D-R23C153-09C had a reported indication of 5% TW at 2RE16. A review of the 2RE13 data ascertained that a depth of 3% TW could be assigned to this indication. The indication is observed on only one of the three trefoil lands.
Attachment NOC-AE-14003139 Page 6 of 11 These later two small indications were not recorded in 2RE13 since the small signal(s) were hidden within the noise of the bobbin data. The signals are very much like the residual on each edge of the TSP. For the 2RE16 inspection, the overall noise was less and the signal(s) were larger and thus more defined from its surroundings.
The level of TSP wear observed during 2RE16 will not have an impact on future SG inspection scope, nor limit the planned three cycles of operation prior to the 2RE19 steam generator inspection outage. No degradation due to anti-vibration bar wear or loose parts wear was observed. No tube-to-tube wear was observed. A review of MBM and PRO indications did not indicate the presence of tube-to-tube wear. No corrosion induced wear was observed.
Site-specific eddy current detection and sizing techniques qualified in accordance with EPRI non-destructive examination guidelines were used to perform the analyses.
All VOL indications were evaluated against the in-situ screening criteria. No burst or leak testing was required, and no tubes were removed from service.
Table 1 - Summary of Eddy Current Indications Reported During 2RE16 2RE16 Indication Condition SG2A SG2B SG2C SG2D Codes BLG Apparent diameter increase 1 1 DNG Freespan or TSP ding 132 36 80 15 DNS Distorted ding or new ding - cleared 77 74 78 28 DSS DSI - cleared 2 INF Indication Not Found 1 4 1 7 INR Indication Not Reportable 53 46 70 29 MBM Manufacturing Buff Marks 57 64 56 84 NDD No Detectable Degradation 8575 8777 8737 8804 NDF No Detectable Flaw 34 20 10 13 NQS NQI cleared by +Point or historical 14 42 16 data evaluation PBC Previous Bobbin Call 6 2 PLP Possible Loose Part 6 3 PRO Tube to tube proximity 12 12 14 RBD Retest Bad Data 67 206 122 155 RIC Incomplete test 1 RMB PVN cleared w/Rotating Mag Bias 4 probe VOL Volumetric indication 2 Note 1 Note 1 One of Two Indications are Legacy Wear from 2RE 13
Attachment NOC-AE-1 4003139 Page 7 of 11 TABLE 2 -
SUMMARY
OF 2RE16 POTENITAL LOOSE PART CALLS TTS SG HL CL A 5 1 B 0 0 C 0 0 D 3 0 TABLE 3 - 2RE16 TOP OF TUBESHEET POTENTIAL LOOSE PART RESOLUTION SG ID ROW COLUMN LEG ELEVATION COMMENT PLP-A-001 5 35 HL TTS +0.12" Re-examined by video, nothing seen PLP-A-002 4 36 HL TTS +0.32" Re-examined by video, nothing seen A PLP-A-003 6 36 HL TTS +0.12" Re-examined by video, nothing seen PLP-A-004 50 118 HL TTS +0.08" Re-examined by video, nothing seen PLP-A-005 49 119 HL TTS +0.06" Re-examined by video, nothing seen PLP-A-006 127 75 CL TTS +1.30" Removed PLP-D-005 122 80 HL TTS +0.14" Foreign Object D027 - Retrieved PLP-D-006* 18 134 HL TTS + 0.16" Foreign Object D015 - object not retrieved -Evaluated PLP-D-007* 20 134 HL TTS +00.10" Foreign Object D015 - object not retrieved -Evaluated
- Object D015 detected in rows 18 and 20 @ column 134
Attachment NOC-AE-14003139 Page 8 of 11 TABLE 4 -
SUMMARY
OF 2RE16 VOLUMETRIC CALLS SG LOCATION THROUGHWALL COMMENT DEPTH (%)
A R7C57 CL 8 th TSP 8 4% Thru Wall in 2RE13 R8C154 CL 6 th TSP 9 Low level signal noted in 2RE13 D R23C153 CL 9 thTSP 5 Low level signal noted in 2RE13 Plug Inspection Results All installed plugs were visually examined. No anomalies were noted.
Bowl Inspection Results A visual inspection of the bottom of the SG channel head bowl was performed in all SGs during 2RE16, based on industry operating experience discussed in the Degradation Assessment.
Visual inspections of the SG hot leg and cold leg divider plate base, and with particular attention to the bottom 36-inch radius of the bowl, were performed in accordance with Westinghouse NSAL-12-01 using the SG manway channel head bowl cameras. Satisfactory inspection results were observed in all SGs.
Stud Hole Gauging Stud hole go/no-go gauging and stud gauging were performed on SG-2C. All results were satisfactory.
Tube Plugging The total number of tubes plugged per steam generator to date is as follows:
Generator Tubes Plugged Percent Steam Generator 2A 1 0.013%
Steam Generator 2B 2 0.026%
Steam Generator 2C 3 0.04%
Steam Generator 2D 4 0.053%
No tubes were plugged during 2RE16.
Attachment NOC-AE-14003139 Page 9 of 11 Foreign Object Search and Retrieval Foreign object search and retrieval was performed at the top of the tubesheet, the tube bundle-shell annulus, and the tube lane in all four SGs. A total of seventy-four (74) foreign objects were identified during the top of tubesheet video probe inspections. There were thirty-six (36) objects that could not be removed from the steam generators. These are summarized in Table 5. Each identified foreign object, not removed from the respective steam generator, was subjected to a foreign object wear analysis to support the planned operating period through Cycle 19.
Table 5 - Irretrievable 2RE16 Foreign Objects SG ID Description Elev Col Row Leg Length Width Height Metallic Legacy A 2A002 Scale TTS 82 36 HL 0.16 0.04 0.08 no no A 2A003 Graphoil TTS 102 64 HL 0.22 0.16 0.05 no no A 2A005 Sludge rock TTS 86 12 CL 0.14 0.13 0.06 no no A 2A006 Graphoil TTS 86 12 CL 0.3 0.07 0.05 no no A 2A009 Scale TTS 102 6 CL 0.1 0.1 0.05 no no B 2B001 Bristle TTS 77 113 HL 0.5 0.01 0.01 yes no B 2B004 Graphfoil TTS 85 79 HL 0.1 0.05 0.05 no no B 2B009 Scale TTS 73 11 HL 0.15 0.07 0.04 no no B 2B011 Wire TTS 77 25 HL 0.2 0.04 0.04 yes no B 2B012 Wire TTS 77 27 HL 0.3 0.04 0.04 yes no B 2B016 Sludge TTS 78 96 CL 0.05 0.04 0.05 no no C 2C002 Wire TTS 71 21 HL 0.08 0.02 0.02 yes no C 2C003 Sludge rock TTS 72 8 HL 0.22 0.14 0.08 no no C 2C004 Wire TTS 72 28 HL 0.08 0.02 0.02 yes no C 2C005 Sludge rock TTS 73 13 HL 0.14 0.08 0.03 no no C 2C006 Wire TTS 73 13 HL 0.08 0.02 0.02 yes no C 2C007 Sludge rock TTS 73 15 HL 0.17 0.08 0.06 no no C 2C008 Gasket TTS 73 21 HL 0.18 0.08 0.06 yes no C 2C010 Gasket TTS 77 49 HL 0.1 0.1 0.06 yes no C 2C011 Wire TTS 77 33 HL 0.75 0.02 0.02 yes no C 2C012 Wire TTS 77 31 HL 0.4 0.02 0.02 yes no C 2C013 Wire TTS 77 29 HL 0.08 0.02 0.02 yes no C 2C014 Wire TTS 77 27 HL 0.1 0.02 0.02 yes no C 2C015 Wire TTS 66 26 HL 0.5 0.02 0.02 yes no C 2C018 Scale TTS 73 17 CL 0.125 0.02 0.06 no no D 2D001 Sludge rock TTS 59 81 HL 0.375 0.12 0.12 no no D 12D002 Wire TTS 74 28 HL 0.375 0.04 0.04 yes no D 2D005 Graphfoil TTS 57 35 CL 0.12 0.12 0.12 no no D 2D008 Scale UTS 90 118 HL 0.161 0.04 0.161 no no D 2D010 Graphfoil TTS 99 3 HL 0.1 0.032 0.125 no no D 2D011 Graphfoil TTS 101 93 HL 0.161 0.032 0.125 no no D 2D014 Graphfoil TTS 121 3 HL 0.08 0.05 0.08 no no D 2D015 Weld U'S 134 18 HL 0.3 0.15 0.2 yes yes D 2D017 Graphfoil TTS 98 96 CL 0.25 0.04 0.04 no no D 2D022 Graphfoil TTS 132 28 CL 0.125 0.01 0.125 no no D 2D026 Gasket -ITS 74 28 HL 0.18 0.04 0.05 yes no
Attachment NOC-AE-14003139 Page 10 of 11 Sludge Lancing and Sludge Collector Flushing All four STP Unit 2 SGs were sludge lanced. In addition, the sludge collector of SG-2A was flushed. Table 6 provides a summary of the sludge collected from both operations.
Table 6 - Sludge Collected During 2RE16 Steam Generator 2RE16 Sludge Weight A - Tubesheet 20.96 lbs B - Tubesheet 17.98 lbs C - Tubesheet 12.66 lbs D - Tubesheet 17.37 lbs A - Sludge Collector 13.46 lbs Steam Drum Inspection - SG 2A and 2B Visual observations were made of the steam drum for steam generators 2A and 2B to assess the condition of the steam drum and to ensure reliable operations until the next inspection period. The steam drum was inspected for erosion, mechanical damage, cracked welds, corrosion, foreign material and any unusual conditions.
The sludge collector level, primary separator level, and the manway level were inspected in SG 2A and 2B. In addition the venturi level was inspected in SG-2A.
The inspection revealed no abnormal conditions. All components were in good condition with no cracking, erosion, or deformation. The inspection of the steam drums showed that all surfaces were gray in color, similar to last inspection during 2RE1 3.
Ninth Support Plate Inspection In order to obtain visual information on the deposit loading in the upper region of the tube bundle, an in-bundle inspection of the 9th tube support plate of SG-2A was performed. Video probes were deployed from the tube lane using extensions that permitted visual observation of flow slots, tube surfaces, and trefoil ligaments.
The inspection showed a thin layer of magnetite covering the TSP top surface. A thin layer of scale provided a continuous cover of all the tube surfaces. The trefoils surfaces are also minimally fouled. No deposit bridging across the trefoil to tube OD surface was seen.
No departures from the expected appearance of the TSP ligaments were observed
Attachment NOC-AE-1 4003139 Page 11 of 11 Condition Monitoring Conclusion Based on the Condition Monitoring evaluation, inservice inspection of tubes in service during Cycle 16 confirms that they all meet the structural integrity requirements of Steam Generator Integrity assessment guidelines, Revision 3. The minor tube support plate wear does not challenge structural integrity limits. Since no degradation mechanisms challenging structural integrity limits were detected during the 2RE16 inspection and no primary-to-secondary leakage was observed prior to the end of Cycle 16, the condition monitoring assessment requirements for SG operation are satisfied. With no significant indications of tube degradation, tube pulls and in-situ tests were not required. No challenges to the SG Performance Criteria were identified; therefore, the condition monitoring requirements for the Unit 2 RSG tube bundles at the end of Cycle 16 are satisfied. The next Unit 2 steam generator inspection is scheduled for refueling outage 2RE19.