ML102010007

Summary of Telephone Conference Call Regarding the Fall 2007 Steam Generator (SG) Tube Inspections

ML102010007
Person / Time
Site:	Catawba
Issue date:	07/21/2010
From:	Thompson J H Plant Licensing Branch II
To:	Morris J R Duke Energy Carolinas
Thompson, Jon 415-1119
References
Download: ML102010007 (9)

Text

UNITED NUCLEAR REGULATORY WASHINGTON, D.C. 20555-0001 July ;7,1,2010 Mr. J. R. Morris Site Vice President Catawba Nuclear Station Duke Energy Carolinas, LLC 4800 Concord Road York, SC 29745 CATAWBA NUCLEAR STATION, UNIT 2 (CATAWBA 2) -

SUMMARY

OF TELEPHONE CONFERENCE CALL REGARDING THE FALL 2007 STEAM GENERATOR (SG) TUBE INSPECTIONS

Dear Mr. Morris:

On October 4, 2007, U.S. Nuclear Regulatory Commission (NRC) staff participated in a conference call with representatives of Duke Energy Carolinas, LLC (the licensee), regarding its ongoing SG tube inspection activities at Catawba 2. Enclosed is a summary of the conference call. The NRC staff did not identify any issues that would warrant immediate follow-up action. If you have any questions, please contact me at (301) 415-1119 or send an e-mail to Jon.Thompson@nrc.gov.

Sincerely, Jon Thompson, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-414 Conference Call cc w/encl: Distribution via

SUMMARY

OF OCTOBER 4, 2007, CONFERENCE CALL WITH DUKE ENERGY CAROLINAS, LLC REGARDING THE 2007 STEAM GENERATOR TUBE INSPECTION RESULTS CATAWBA NUCLEAR STATION, UNIT 2 DOCKET NO. 50-414 On October 4,2007, the U.S. Nuclear Regulatory Commission (NRC) staff participated in a conference call with representatives of Duke Energy Carolinas, LLC (the licensee), regarding its fall 2007 ongoing steam generator (SG) tube inspection activities at Catawba Nuclear Station, Unit 2 (Catawba 2). The inspection activities were conducted during the end-of-cycle 15 refueling outage. To facilitate this conference call, the licensee provided supplemental material which is included as an attachment to this enclosure.

At the time of the call, SG tube inspections were still in progress.

Catawba 2 has four Westinghouse Electric Company Model D5 SGs, 2A through 2D, which were placed in service in 1986. Each SG has 4,570 thermally treated Alloy 600 tubes with an outside diameter of 0.75 inches and a nominal wall thickness of 0.043 inches. The tubes are hydraulically expanded for the full depth of the tubesheet at each end. The tubes are supported by Type 405 stainless steel support plates with quatrefoil-shaped holes. The U-bend region of the tubes installed in Rows 1 through 9 was thermally treated after bending in order to reduce stress. During the October 4, 2007, conference call, the licensee provided additional clarifying information, or information not included in the attached material, which is summarized below:

• An axial crack-like indication was detected in the tube located in row 15, column 79 in SG B. The indication was located slightly above the top of the tubesheet on the hot-leg side. The indication was not associated with the expansion transition, but was located within the sludge pile region. The length of the indication was 0.27 inches. All three probes used to inspect the indication (array, +PointŽ, and Ghent) yielded comparable length estimates.

This location was last inspected during the end-of-cycle 14 outage in 2006. During the 2006 outage, there was no evidence of a crack-like indication at this location, but there were indications of deposits at this location.

• A second axial crack-like indication in the tube located in row 26, column 64 in SG B is similar in size to the indication in row 15, column 79. The licensee thought the tube in row 26, column 64 had been inspected during the last SG inspection outage (however, they had not verified this at the time of this call).

• Both of the axial crack-like indications were located slightly above the secondary face of the hot-leg tubesheet and were detected with the array probe. Both of the indications were above the expansion transition.

Enclosure

-2 The sludge pile height is 2 inches above the top of the tubesheet.

Although the inspection scope at the top of the tubesheet only requires inspecting to 3 inches above the top of the tubesheet, usually data is acquired up to 4 inches above the top of the tubesheet. With respect to indications of wear at the anti-vibration bars, the maximum depth observed was 35-percent through-wall.

The growth rate for the indications of wear at the anti-vibration bars was consistent with past inspections.

The NRC staff did not identify any issues that warranted immediate follow-up action during the conference call.

Catawba Unit Stream NRC Conference October 4, Purpose Notify NRC of observation of OOSCC [outside diameter stress corrosion cracking]

like indications in B steam generator

[SG]. Background Information Original Westinghouse

[Westinghouse Electric Company] Model 0-5 Steam Generators with Alloy 600 IT [thermally treated] tubing Base scope inspection being performed with the x probe Previous history of 10 [inside diameter]

crack like indications at high stress locations (tack expansions, etc) Indication Information SG Tube Location (in) Depth % Length (in) Surface Orientation In situ B 15-79 1 TSH;j +0.18 23 0.27 00 4 Axial N B 26-64£ TSH+0.57 1=plus POint 2=array [3 -TSH = tubesheet [4 -00 = Outer The indication in tube 15 -79 was confirmed by the array, plus point and The inspection sample in B SG has been expanded from 20 % to 100 expansion transitions of the hot leg There was already a 20 % inspection sample in all other steam Other active AVB [anti-vibration bar] wear -looks normal Tube end PWSCC [primary water stress corrosion cracking]

-new indications, growth of previous indications Current Status Steam Generator A B C D % complete 74 55 72 52 Expected Finish Oay Sunday 10/7 Tuesday 10/9 Sunday 10/7 Sunday 10/7 Attachment

-2 Scope Baseline inspection scope shall include full length data acquisition and bobbin coil data analysis on all four (4) steam generators as follows. ECT [eddy current testing], data from all active coils shall be recorded full length. All tubes with previous indications, e.g., wear, DNT [dent], PLP [possible loose part], etc. (above ARC [alternate repair criteria]

elevation) All tubes surrounding plugged tubes one tube deep. Periphery tubes two rows deep (outer perimeter, open lane, and T-slot) 20% sample of Row 1 through Row 10 Tubes susceptible to "Seabrook type" ODSCC due to cold work (approx. 27 tubes) 25% random sample of remaining tubes not inspected during EOC [end-of-cycle]

14 Special interest inspection scope shall include data acquisition and array data analysis as follows: 1) Special interest based on new bobbin calls (new wear indications, all bobbin "I" codes, and some miscellaneous codes) 2) 20% sample of tubesheet region in all four (4) steam generators from TEH [tube-end hot] to TSH [tubesheet cold] +3 inches 20% sample of Row 1 and 2 u-bend regions in all four (4) steam generators 20% sample of Row 10 u-bend regions in all four (4) steam generators

5) 20% sample of Rows 1 through 10 at tube supports 08H and 09C in all four (4) steam generators (for evidence of complete blockage)

6) 20% sample of pre-heater expansions in all four (4) steam generators

7) Periphery tubes two rows deep (TSH to TSH + 3", TSC to TSC + 3") in all four (4) steam generators (Outer perimeter, open lane, and T-slot) 8) Periphery tubes at 18th tube support plate on cold leg (two rows deep) in all four (4) steam generators g) 100% of Tubesheet OXP's [overexpansions]

and bulges in Steam generator "B" hot leg (above ARC elevation) 1 0) 20% of tubesheet OXP's and bulges in all remaining channel heads (above ARC elevation) New dent indications and existing dent indications not analyzed during EOC14 Bounding inspections two tubes around all PLP indications confirmed with array Bounding inspections two tubes around all PLP indications dating back to EOC 11 if indications are still present/confirmed with array. Plug inspection scope shall be as follows: 1) Visual inspection of all plugs

-3 Plant Information The end of cycle 15 was 1.36 EFPY [effective full power years]. The total EFPY is 17.43. Plant Information Commercial Operation Current Operating Cycle Steam Generator Manufacturer Steam Generator Model Number of Steam Generators S/G Tube Material S/G Support Plate Material S/G Support Plate Design Number of S/G Support Plates SG tubesheet Nominal S/G Tubesheet Expansion S/G Peening (Hot or Cold Leg) U-bend stress relief Thot Tcold # Tubes in RSG Nominal Wall Thickness Plugging Limit Turbine Manufacturer Secondary System Construction Feedwater Heater Tube Material Condenser Tube Material MSR Tube Material Condensate Polishers Condenser Cooling Water Makeup Water System Secondary Chemistry Program NRC Generic Questions Unit 2 8/86 15 Westinghouse D5 4 1-600 n 405 SS [stainless steel] Quadrefoil Broached 19 21" thick with 0.20" Alloy 600 cladding Hydraulic Expansion No Row 1-9 by manufacturer 615lF 556lF 4570 + 8 tubesheet hole plug assemblies.

0.043 10% General Electric All Ferrous 304 SS 316 SS 439 SS Filter/Demins Cooling Towers Filtration/RO

[reverse osmosis]/Demins 3-MPA/DMA/Hydrazine Discuss any trends in the amount of primary-to-secondary leakage observed during the recently completed operating cycle. There has been no primary-to-secondary leakage during the recently completed operating cycle. Discuss whether any secondary side pressure tests were performed during the outage and the associated results. No secondary side pressure tests have been performed.

None are planned. Discuss any exceptions taken to the industry guidelines.

-4 No exceptions have been taken to the EPRI [Electric Power Research Institute]

and PWR [pressurized-water reactor] Steam Generator Examination Guidelines. For each steam generator, provide a description of the inspections performed including the areas examined, the probes used, and the expansion criteria.

Also, discuss the extent of rotating probe inspections performed in the portion of the tube below the expansion transition region. See above For each area examined, provide a summary of the number of indications found to date for each degradation mode. For the most significant indications in each area, provide an estimate of the severity of the indication.

In particular, address whether tube integrity was maintained during the previous operating cycle. In addition, discuss whether any location exhibited a degradation mode that had not previously been observed at this location in this unit. See above Describe repair/plugging plans. Two tubes to date Describe in-situ pressure test and tube pull plans and results. No in-situ pressure testing or tube pulls are planned. Provide the schedule for steam generator related activities during the remainder of the current outage. See above Discuss the following regarding loose parts: What inspections are performed to detect loose parts, a description of loose parts identified and their location within the steam generator, if loose parts were removed, tube damage associated with loose parts, and the source or nature of the loose parts. Secondary side visual inspections have been completed for all 4 steam generators.

These inspections included a post sludge lance top of tubesheet tube free lane, annulus, and selected in-bundle columns to verify effectiveness of the sludge lance. Additionally, confirmation that the 14 support blocks (Item 13) welded to the wrapper and underneath Plate A (0'1 Hand 19C) were intact. No anomalies were identified.

Top of pre-heater baffle plate (18C) visual inspections were performed on all Steam Generators.

This was a follow up inspection to those performed during EOC13 and EOC14 outages. The foreign material identified is consistent with that discovered in the

-5 previous outages with those objects removed that have high likelihood to damage the tubing. All objects that could not be retrieved are evaluated as acceptable for one cycle of operation.

An inspection was performed in one steam generator for the top tube support to characterize the tube deposit loading and broach blockage.

No observations were made to indicate sever broach blockage or tube deposit loading to require immediate action. Steam drum inspections were completed in two steam generators to assess the condition of following components.

No anomalies were identified.

(8) Secondary Moisture Separator Banks: Perforated Plate, Chevron Vanes and Drain Lines (16) Primary Moisture Separators:

Swirl Vane Assemblies, Downcomer Barrel, Tangential Nozzles, Riser Barrel and Riser Barrel Slip Fit Joint (4) Decks: Upper, Mid, Intermediary and Lower Deck Decking support (2) Ladders (1) Auxiliary Feedwater Piping July21,2010 Mr. J. R. Morris Site Vice President Catawba Nuclear Station Duke Energy Carolinas, LLC 4800 Concord Road York, SC 29745 CATAWBA NUCLEAR STATION, UNIT 2 (CATAWBA 2) -

SUMMARY

OF TELEPHONE CONFERENCE CALL REGARDING THE FALL 2007 STEAM GENERATOR (SG) TUBE INSPECTIONS

Dear Mr. Morris:

On October 4,2007, U.S. Nuclear Regulatory Commission (NRC) staff participated in a conference call with representatives of Duke Energy Carolinas, LLC (the licensee), regarding its ongoing SG tube inspection activities at Catawba 2. Enclosed is a summary of the conference call. The NRC staff did not identify any issues that would warrant immediate follow-up action. If you have any questions, please contact me at (301) 415-1119 or send an e-mail to Jon.Thompson@nrc.gov.

Sincerely, IRA! Jon Thompson, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No.

Conference Call cc w/encl: Distribution via DISTRIBUTION:

PUBLIC RidsNrrDorlDpr Resource RidsRgn2MailCenter Resource LPL2-1 RlF RidsNrrDorlLpl2-1 Resource KKarwoski, NRRlDCI/CSGB RidsAcrsAcnw_MailCTR Resource RidsOgcRp Resource AJohnson, NRRlDCI/CSGB RidsNrrDciCsgb Resource RidsNrrPMCatawba Resource RidsNrrLAMOBrien Resource(hard copy) ADAMS Accession No. ML 102010007

• no significant changes f rom input sent 10/2 5/07 ML o 7 2990379 OFFICE DORULPL2-1/PM DORULPL2-1/LA DCI/CSGB/BC*

DORULPL2-1/BC DORULPL2-1/PM NAME JThompson MO'Brien AHiser* GKulesa JThompson DATE 07/21/10 07/21/10 10/25/07 07/21/10 07/21/10 OFFICIAL RECORD COPY