ML093210539
| ML093210539 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 11/17/2009 |
| From: | Robert Williams Entergy Services |
| To: | Plant Licensing Branch IV |
| Kalyanam N, NRR/DLPM, 415-1480 | |
| Shared Package | |
| ML093210496 | List: |
| References | |
| Download: ML093210539 (7) | |
Text
Steam Generator Batwing InspectionsFall 2009 Refuel 16 OutagePreliminary ResultsPage 1 of 7An augmented inspection of Steam Generator #1 (SG-1) and Steam Generator #2 (SG-2) wasperformed during the November 2009 Refuel-16 (RF16) outage per work orders 153097-01 and153098-01 respectively to determine if there were any changes in extent of condition or the criticalvariables that were the basis for the Refuel-14 repair plan and the Cycle 15 operational assessment.The RF16 augmented inspections included:Visual exam of upper batwing weld and wrap around bar
-verify no upper batwing weld/clip failures in stay cavity area
-verify no gross deformation twisting of wrap around barThrough-tube bundle diagonal (45 Degree) visual inspection of upper stay cavity area
-provide assurance that stabilized tubes are attenuating forces developed by brokenbatwingsBottom-up visual inspection of stay cavity area
-monitor batwing degradation
-verify no indications of gross tube deformationForeign object search and retrieval (FOSAR)
-verify no large batwing segments are present
-remove accessible foreign objectsThe augmented inspection performed met the established acceptance criteria. There were no changes tothe extent of condition and the critical variables that were the basis for the RF 14 repair plan.Steam Generator #1Condition ReportsCR-WF3-2009-06620 documents a discrepancy discovered between the actual batwing locationsand the titled locations recorded on video.This is a labeling issue only, which will be resolved with a translation table in the final report.This does not impact the technical evaluation of the weld inspections.Upper Weld and Wrap Around Bar InspectionThe wrap around bar and upper batwing to wrap-around bar welds were inspected from column50 through 120, which bounds the stay cavity region area of interest, columns 64 through 113.The upper batwing to wrap-around bar welds were intact with no gross deformation or twistingof the wrap around bar or other significant degradation observed. The upper welds and wraparound bar condition had not noticeably changed from the previous inspections. All inspectionacceptance criteria were met with no concerns identified.
Steam Generator Batwing InspectionsFall 2009 Refuel 16 OutagePreliminary ResultsPage 2 of 745º Through-Tube Bundle InspectionThe batwing to tube interface around the stay cavity region area of interest was visuallyinspected. The stabilized tubes were intact with no gross deformation or severe damageindicated. Although the batwing damage had progressed with new batwings observed brokenat center notch and displaced sideways, this was expected and the batwing to tube interfacecondition had not noticeably changed from the previous inspections. The progression of thebatwing condition is following the progression observed in SG-2, excepting that the extent ofdamage is much less, no intrados tube wear has been observed, and no loose batwingsegments have formed. All tubes met the acceptance criteria of less than 33% through tubewear, with no concerns identified.Bottom-Up Video InspectionThe bottom-up visual inspection of stay cavity region area of interest was performed. No grosstube deformation was indicated and no unexpected batwing degradation was found. Theprogression of the batwing condition is following the progression observed in SG-2, exceptingthat the extent of damage is much less. 18 batwings were identified broken at center notchversus 8 in RF15. One batwing had bent over and was above the other displaced batwings,which is also similar to but bounded by the conditions observed in SG-2. No missing batwingpieces had formed. All batwings met the acceptance criteria of less than 36" segments formed,with no concerns identified.The composite bottom-up video inspection was parsed and compiled to form a composite view.The composite view from RF16 and RF15 are provided as figures 1a and 1b, respectively.Foreign Object Search and Retrieval InspectionThe annulus between the tube bundle and shroud, blowdown lane, and blowdown dome area atthe top of tubesheet were visually inspected for foreign objects. The foreign object search andretrieval inspection met the acceptance criteria with no batwing segments or accessible foreignobjects found.
Steam Generator Batwing InspectionsFall 2009 Refuel 16 OutagePreliminary ResultsPage 3 of 7Figure 1a: RF16 SG-1 CompositeFigure 1b: RF15 SG-1 Composite Steam Generator Batwing InspectionsFall 2009 Refuel 16 OutagePreliminary ResultsPage 4 of 7Steam Generator #2All inspections results are bounded by the acceptance criteriaCondition ReportsCR-WF3-2009-06206 documents a loose part (M2x3mm) noted as missing from Telexcommunication video equipment that was used inside the generator during inspections. Smallscrew missing was a size M2 x 3mm.CR-WF3-2009-06486 documents intrados tube wear appearing to be through wall and throughportions of the stabilizer.CR-WF3-2009-06620 documents a discrepancy discovered between the actual batwing locationsand the titled locations recorded on video.This is a labeling issue only, which will be resolved with a translation table in the final report.This does not impact the technical evaluation of the weld inspections.Upper Weld and Wrap Around Bar InspectionThe wrap around bar and upper batwing to wrap-around bar welds were inspected from column50 through 120, which bounds the stay cavity region area of interest, columns 64 through 113.The upper batwing to wrap-around bar welds were intact with no gross deformation or twistingof the wrap around bar or other significant degradation observed. The upper welds and wraparound bar condition had not noticeably changed from the previous inspections. All inspectionacceptance criteria were met with no concerns identified.45º Through-Tube Bundle InspectionResultsThe batwing to tube interface around the stay cavity region area of interest was visuallyinspected. The stabilized tubes were intact with no gross deformation or severe damageindicated. Although the batwing damage had progressed, this was expected and thebatwing to tube interface condition had not noticeably changed from the previousinspections. The intrados tube wear that had been previously observed was examined indetail. The wear models predicted the stabilized tubes adjacent to the stay cavity regioncould have through-tube wear, and established gross tube damage criteria that wouldcharacterize unexpected or unacceptable wear. The gross tube damage was defined asirregular tube spacing, tube dislocation, through-wall wear greater than 180 degrees of thetube circumference or, if stabilized, the stabilizer is visibly scalloped, gouged or torn suchthat the structural integrity of the stabilizer fence around the stay cavity boundary may notbe able to restrain the forces generated. During the mid-cycle outage and RF15 outage, onecold leg tube had what appeared to be a teardrop-shaped wear scar (approximately 1 1/2inches long by 3/8 inch wide) on the intrados tube wall at or near the C103 tube. This wearscar had progressed, and is now about 25% through tube wear, with two strands of thestabilizer having visible wear. Figures 2a and 2b are of this wear. All tubes met the Steam Generator Batwing InspectionsFall 2009 Refuel 16 OutagePreliminary ResultsPage 5 of 7acceptance criteria of less than 33% through tube wear, and observed stabilizer wear wasanalyzed and confirmed to be acceptable with at least 30% of the stabilizer remaining at theend of the cycle 17.Figure 2a: RF16 Intrados Tube WearFigure 2b: RF15 Intrados Tube Wear Steam Generator Batwing InspectionsFall 2009 Refuel 16 OutagePreliminary ResultsPage 6 of 7Bottom-Up Video InspectionThe bottom-up visual inspection of stay cavity region area of interest was performed. No grosstube deformation was indicated and no unexpected batwing degradation was found. 25batwings were identified broken at center notch, 18 of which had separated half horizontal barsegments of about 6.5 inches in length versus 4 in RF15. Otherwise, the general batwingcondition remained similar to the conditions previously observed in SG-2. 5 loose batwingsegments were located. Previous analyses accept worst case wear from the loose batwingsegments and all loose batwing segments met the acceptance criteria of less than 36". No otherconcerns were identified.The composite bottom-up video inspection was parsed and compiled to form a composite view.The composite view from RF16 and RF15 are provided as figures 3a and 3b, respectively.Figure 3a: RF16 SG-2 Composite Steam Generator Batwing InspectionsFall 2009 Refuel 16 OutagePreliminary ResultsPage 7 of 7Figure 3b: RF15 SG-2 CompositeForeign Object Search and Retrieval InspectionThe annulus between the tube bundle and shroud, blowdown lane, and blowdown dome area atthe top of tubesheet were visually inspected for foreign objects. The foreign object search andretrieval inspection met the acceptance criteria with no batwing segments or accessible foreignobjects found.