WGLF CREEK 'NUCLEAR OPERATING CORPORATION Terry J. Garrett Vice President, Engineering April 8, 2010 ET 10-0012 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Subject: Docket No. 50-482: Results of the Sixteenth Steam Generator Tube Inservice Inspection Gentlemen: Attachment I, the Steam Generator Tube Inspection Report, is being submitted in accordance with Wolf Creek Generating Station (WCGS) Technical Specification (TS) 5.6.10, "Steam Generator Tube Inspection Report." This report provides the results of WCGS's sixteenth steam generator (SG) tube inservice inspection. The Steam Generator Tube Inspection Report includes the following: a. The scope of inspections performed on each SG; b. Active degradation mechanisms found; c. Nondestructive examination techniques utilized for each degradation mechanism; d. Location, orientation (if linear), and measured sizes (if available) of service induced indications; e. Number of tubes plugged during the inspection outage for each active degradation mechanism; f. Total number and percentage of tubes plugged to date; and g. The results of condition monitoring, including the results of tube pulls and in-situ testing; The following items are also included in accordance with the One-time Alternate Repair Criteria, H*, which was approved to support WCGS's Refueling Outage 17 and the subsequent operating cycle: h. Following completion of an inspection performed in Refueling Outage 17 (and any inspections performed in the subsequent operating cycle) the primary to secondary LEAKAGE rate observed in each SG (if it is not practical to assign the LEAKAGE to an individual SG, the entire primary to secondary LEAKAGE should be conservatively assumed to be from one SG) during the cycle preceding the inspection which is the subject of the report; P.O. Box 411/ Burlington, KS 66839 / Phone: (620) 364-8831 An Equal Opportunity Employer M/F/HC/VET
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WGLF CREEK'NUCLEAR OPERATING CORPORATION
Terry J. GarrettVice President, Engineering
April 8, 2010ET 10-0012
U. S. Nuclear Regulatory CommissionATTN: Document Control DeskWashington, DC 20555
Subject: Docket No. 50-482: Results of the Sixteenth Steam GeneratorTube Inservice Inspection
Gentlemen:
Attachment I, the Steam Generator Tube Inspection Report, is being submitted in accordancewith Wolf Creek Generating Station (WCGS) Technical Specification (TS) 5.6.10, "SteamGenerator Tube Inspection Report." This report provides the results of WCGS's sixteenthsteam generator (SG) tube inservice inspection. The Steam Generator Tube Inspection Reportincludes the following:
a. The scope of inspections performed on each SG;b. Active degradation mechanisms found;c. Nondestructive examination techniques utilized for each degradation mechanism;d. Location, orientation (if linear), and measured sizes (if available) of service induced
indications;e. Number of tubes plugged during the inspection outage for each active degradation
mechanism;f. Total number and percentage of tubes plugged to date; andg. The results of condition monitoring, including the results of tube pulls and in-situ testing;
The following items are also included in accordance with the One-time Alternate Repair Criteria,H*, which was approved to support WCGS's Refueling Outage 17 and the subsequentoperating cycle:
h. Following completion of an inspection performed in Refueling Outage 17 (and anyinspections performed in the subsequent operating cycle) the primary to secondaryLEAKAGE rate observed in each SG (if it is not practical to assign the LEAKAGE to anindividual SG, the entire primary to secondary LEAKAGE should be conservativelyassumed to be from one SG) during the cycle preceding the inspection which is thesubject of the report;
i. Following completion of an inspection performed in Refueling Outage 17 (and anyinspections performed in the subsequent operating cycle) the calculated accidentinduced leakage rate from the portion of the tubes below 13.1 inches from the top of thetubesheet for the most limiting accident in the most limiting SG. In addition, if thecalculated accident induced leakage rate from the most limiting accident is less than2.50 times the maximum operational primary to secondary leak rate, the report shoulddescribe how it was determined; and
j. Following completion of an inspection performed in Refueling Outage 17 (and anyinspections performed in the subsequent operating cycle) the results of monitoring forthe tube axial displacement (slippage). If slippage is discovered, the implications ofdiscovery and corrective action shall be provided.
Enclosures 1 and 2 contain all service-induced indications identified in SGs A and D duringWCGS's Refueling Outage 17.
No commitments are contained in this correspondence.
If you have any questions concerning this matter, please contact me at (620) 364-4084, or Mr.Richard Flannigan at (620) 364-4117.
Sincerely,
Terry J. Garrett
TJG/rlt
Attachment
Enclosure 1: Steam Generator A Service-Induced IndicationsEnclosure 2: Steam Generator D Service-Induced Indications
cc: E. E. Collins (NRC), w/a, w/eG. B. Miller (NRC), w/a, w/eB. K. Singal (NRC), w/a, w/eSenior Resident Inspector (NRC), w/a, w/e
Attachment to ET 10-0012Page 1 of 7
STEAM GENERATOR TUBE INSPECTION REPORT
This report is being submitted pursuant to Technical Specification (TS) 5.6.10, "SteamGenerator Tube Inspection Report," to report the results of the sixteenth steam generator (SG)tube inservice inspection.
Summary
The sixteenth SG tube inservice inspection was completed by Westinghouse ElectricCorporation on October 27, 2009, during Refueling Outage 17 (RF17). Initial entry into MODE4 was achieved on November 16, 2009.
Refueling Outage 17 was the second inspection of the third sequential inspection interval (60Effective Full Power Months (EFPMs)), and is the approximate midpoint of the third inspectioninterval. At the Start of Refueling Outage 17 the SGs had operated for a total of 247.16 EFPMs(20.6 Effective Full Power Years (EFPYs)).
Permanent approval of an alternate repair criteria, H*, for indications within the tubesheet couldnot be achieved prior to Refueling Outage 17. As a result, a One-time Alternate Repair Criteria,H*, was approved which revised TS 5.5.9, "Steam Generator (SG) Program" and TS 5.6.10,"Steam Generator Tube Inspection Report" for Wolf Creek Generating Station's (WCGS's)Refueling Outage 17 and the subsequent operating cycle. The following alternate tube repaircriteria, H*, shall be applied as an alternative to the 40% depth-based criteria:
H* is the distance from the top of the tubesheet (TTS) into the tubesheet expansion region thattubes must be free of stress corrosion flaws to assure that the tubes do not pull out of thetubesheet under the limiting loads with appropriate factors of safety. For WCGS, the H*distance is 13.1 inches. All defects below the H* distance are not relevant to the integrity of thetube. Therefore, inspection and repair below the H* distance is not required by technicalspecification. For Refueling Outage 17 and the subsequent operating cycle, tubes with service-induced flaws located greater than 13.1 inches below the top of the tubesheet do not requireplugging. Tubes with service-induced flaws located in the portion of the tubesheet from the topof the tubesheet to 13.1 inches below the top of the tubesheet shall be plugged upon detection.
No corrosion related tube degradation mechanisms were detected in any region of the SGs.
Wear at Anti-Vibration Bar (AVB) intersections is an existing damage mechanism.
Secondary side maintenance and inspections were also performed.
The condition of the SGs has met all industry and regulatory structural and leakage integrityrequirements.
Section 1 of this report describes the scope of inspections performed, including thenondestructive examination techniques utilized for each degradation mechanism.
Section 2 contains the location, orientation (if linear), and measured sizes (if available) ofservice induced indications.
Section 3 contains the inspection results, which include:a. Active degradation mechanisms found;
Attachment to ET 10-0012Page 2 of 7
STEAM GENERATOR TUBE INSPECTION 'REPORT
b. Number of tubes plugged during the inspection outage for each active degradationmechanism;
c. Total number and percentage of tubes plugged to date;d. The results of condition monitoring, including the results of tube pulls and in-situ testing;e. The primary to secondary leakage rate observed in each SG;f. The calculated accident leakage rate from the portion of the tube below 13.1 inches
from the top of the tubesheet for the most limiting accident in the most limiting SG; andg. The results of monitoring for the tube axial displacement (slippage).
Attachment to ET 10-0012Page 3 of 7
STEAM GENERATOR TUBE INSPECTION REPORT
Section 1: Scope and Examination Techniques of Inspections Performed
The actual inspections performed during Refueling Outage 17 exceeded both the TS minimumrequirements and the requirements of the Electric Power Research Institute (EPRI) PressurizedWater Reactor (PWR) Steam Generator Examination Guidelines. The following primary sideinspections were performed:
* 100% Bobbin examination of tubes in SGs A and D, full length except for Rows 1 and 2,which are inspected with the bobbin from tube end to tube support plate (TSP) #7 onboth the hot leg (HL) and cold leg (CL).
* 50% Row 1 and Row 2 U-bends, mid-range Plus Point examination in SG A and SG D.
* Hot leg tubesheet +3"/-13.1", mid-range Plus Point examination of SGs A and D: 55%of tubes, including 100% of the peripheral tubes, 2 pitches into the bundle.
* Cold leg tubesheet peripheral tubes, ± 3", mid-range Plus Point examination of SGs Aand D: 100% of peripheral tubes; 2 pitches into the bundle.
* Dings (freespan) > 5 volts: 50% of all previously identified and new dings >5 volts in thehot leg (including the U-bends) with the mid-range Plus Point probe in SGs A and D.
* Dents (structures) > 2 volts: 50% of all previously identified and new dents >2 volts inthe hot leg (including the U-bends) with the mid-range Plus Point probe in SGs A and D.
* Plus Point examination of all "I-code" indications that are not resolved after historyreview.
* Visual inspection of all plugs in SGs A and D.
* Plus Point examination of a 5% sample of bobbin indications that have not changedsince the prior inspection ("H" and "S" codes).
• Plus Point inspection to bound (all surrounding tubes, at least one pitch removed) thetubes exhibiting possible loose parts (PLP) signals during the inspection.
* Plus Point inspection of a sample of tubes to support the scale profiling effort.
In addition, the following secondary side maintenance and inspections were performed:
" Sludge Lancing of SGs A and D.
" Foreign Object Search and Retrieval (FOSAR) of SGs A and D to locate, identify, andretrieve foreign objects that were present on the steam generator tubesheet. FOSARwas also performed to inspect for any Possible Loose Parts (PLP) identified during theEddy Current Program.
" In-Bundle Inspection (IBI) of SGs A and D to inspect the condition of the top of thetubesheet and to augment the FOSAR effort.
* Upper Steam Drum Inspection in SG A to evaluate the condition of the upper steamdrum components with regard to damage of any kind.
Attachment to ET 10-0012Page 4 of 7
STEAM GENERATOR TUBE INSPECTION REPORT
Section 2: Indication Listing
The following Enclosures contain all service-induced indications for SGs A and D. Thisencompasses the location, orientation (if linear), and measured sizes (if available) of serviceinduced indications
Enclosure 1: Steam Generator A Service-Induced IndicationsEnclosure 2: Steam Generator D Service-Induced Indications
The key below provides a description of the abbreviations used in the tables.
COL Column
PER Percent
LOCN Location
INCH1 Distance from location
#H, #C (# = Support Plate Number) Hot Leg or Cold Leg Side
AV# Anti-Vibration Bar (# = number)
TSH Tube Sheet Hot Leg
FBC Flow Baffle Cold Leg
FBH Flow Baffle Hot Leg
Attachment to ET 10-0012Page 5 of 7
STEAM GENERATOR TUBE INSPECTION REPORT
Section 3: Inspection Results
Active Degradation Mechanisms Found
The inspection results indicate that wear at AVB locations is an active degradation mechanismin SGs A and D. Other existing degradation mechanisms include wear at the flow distributionbaffle and wear due to foreign objects.
Total Number of Tubes Plugged in Each Steam Generator
Steam Generator Total Number ofTubes Plugged
ABCD
*425328128
Total PercentagePlugged0.75%0.94%0.50%2.28%
*An additional 3 plugs are installed in SG A cold leg only, due to tubesheet drilling errors duringmanufacturing. No tubes are installed in those locations.
Attachment to ET 10-0012Page 6 of 7
STEAM GENERATOR TUBE INSPECTION REPORT
Results of Condition Monitorinq
The examination results confirm that the Wolf Creek Generating Station (WCGS) SGs currentlymeet all industry and regulatory structural and leakage integrity guidance. No indications werefound to exceed structural limits. No tube pulls or in-situ testing were required.
* AVB wear is an existing degradation mechanism.* The maximum observed indication (51% through wall depth (TWD) at an AVB location)
meets the structural and leakage requirements.* Two geometric anomalies were reported from the top of tubesheet plus point program.
The plus point data indicated possible degradation in the signals but this was notconfirmed by use of the Ghent probe. Both indications were co-located at the site of anaxially oriented, linear geometric response running to, and through, the expansionregion. The linear responses are seen in the historical data and are likely related tooriginal SG manufacturing. The indication in SG D was present in historic data. Theindication in SG A could not be found in the historic data; however, the previous dataquality did not support detection of a low level signal such as this. The analystconsensus is that these indications are related to geometric variations and are notindications of degradation. Nevertheless, Wolf Creek conservatively chose toadministratively plug these tubes.
" Wear at the flow distribution baffle (FDB) is an existing degradation mechanism that isnot progressing. FDB wear is attributed to a prior application of pressure pulse cleaningof the SGs. No new indications were reported as expected; all indications werepreviously reported at RF13 and RF15. The magnitude of the wear does not challengethe performance requirements for condition monitoring.
* Wear detected at three TSP intersections in SG D is an existing degradationmechanism that is not progressing. This degradation mechanism is not an operationaldegradation mechanism but is the result of previous transient foreign objects interactingwith the tubes. The current indications of wear at the tube support plates meet theperformance criteria for condition monitoring.
" Volumetric indications detected at the TTS have not changed since the prior inspectionat RF13 and RF15. One previously reported TTS volumetric indication was not found atRF17. The reported changes in depth are small and within the normal variability of thesizing technique. The likely source of these indications is wear due a transient foreignobject at a prior time. No new wear indications from foreign objects were detected. Noforeign objects were found among the tubes with volumetric indications and theirneighboring tubes. The largest indication is 17% TWD, which poses no challenge to thecondition monitoring performance criteria.
* No corrosion related degradation mechanisms were observed.* No degradation indications were observed related to potential precursor signals such as
dents and dings, or to interferences such as permeability variations, etc." Leakage is not an issue for any indication detected. There is currently no leakage in the
SGs." All plugs were found to be in acceptable condition based on visual inspection." No precursor signals (e.g., Distorted Support Indication (DSI)) were found in tubes
identified as potentially having an elevated residual stress condition.* No tube-to-tube contact wear was found on any tubes adjacent to tubes that were
previously identified as potentially requiring stabilization due to continuing wear after
Attachment to ET 10-0012Page 7 of 7
STEAM GENERATOR TUBE INSPECTION REPORT
plugging for AVB wear. Therefore, in accordance with evaluations documented in theDegradation Assessment, stabilization of any previously plugged tubes was notrequired.
" The commitment for H* to calculate accident induced leakage by a prescribed methodwas met. Because there is no existing normal operating leakage at WCGS and thereare no damage mechanisms for which leakage is predicted, the predicted accidentinduced leakage for WCGS is zero. No adjustment to the administrative shutdownleakage limit is required.
* The commitment for H* to monitor for tube slippage was met. The absence of tubeslippage was determined by confirming that there were no tube severances below theH* distance.
* Sludge lancing activities removed 21.5 pounds from SG A and 22 pounds from SG D.* Foreign object search and retrieval (FOSAR) activities in SGs A and D identified and
removed some minor foreign objects. Possible loose part (PLP) indications reported byeddy current testing were further evaluated by visual inspection and bounded using thePlus Point probe. No degradation was associated with any PLP indication. Minorforeign objects remaining in the SG are bounded by a prior analysis and are acceptablefor continued operation. The analysis concluded that the.known foreign objects will notlimit operation of the SGs.
" Secondary side visual inspection activities performed at the top of the tubesheet in SGsA and D were successful in gathering additional information which is used to determinefuture maintenance and cleaning strategies. No immediate concerns were identified.
* Upper steam drum inspections in SG A collected additional data used for monitoring andtrending of upper steam drum components. No immediate concerns were identified.
* Analysis of the data collected for scale profiling is currently on-going. This information isused in conjunction with visual inspection data to continue trending the condition of thesecondary side of the steam generators in order to plan future maintenance andcleaning strategies. No immediate concerns are expected from this analysis.
Enclosure 1 to ET 10-0012
Steam Generator A Service-Induced Indications
SG - A Service Induced Indications
Wolf Creek 1 RFO XVIISAP 20091001 11/03/2009 13:32:20
ROW COL PER LOCN INCHI1------------------------------- +