ML13084A030

9/13/2012 - Summary of Conference Call with Florida Power & Light Co. Re. the Findings of the Fall 2012 Steam Generator Tube Inspections at Saint Lucie Plant, Unit No. 2

ML13084A030
Person / Time
Site:	Saint Lucie
Issue date:	04/04/2013
From:	Orf T Plant Licensing Branch II
To:	Florida Power & Light Co
Rodriguez R NRC/DORL/LPL2-2 415-1558
References
TAC ME9534
Download: ML13084A030 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 April 4, 2013 LICENSEE: Florida Power & Light Co.

FACILITY: Saint Lucie Power Plant, Unit No.2

SUMMARY

OF SEPTEMBER 13, 2012, CONFERENCE CALL WITH FLORIDA POWER & LIGHT COMPANY REGARDING THE FINDINGS OF THE FALL 2012 STEAM GENERATOR TUBE INSPECTIONS AT SAINT LUCIE PLANT, UNIT NO.2 (TAC NO. ME9534)

On September 13, 2012, a Category 1 conference call was held between the U.S. Nuclear Regulatory Commission (NRC) and representatives of Florida Power & Light Company at NRC Headquarters, One White Flint North, 11555 Rockville Pike, Rockville, Maryland. The purpose of the call was to discuss the findings of the steam generator tube inspection activities performed at Saint Lucie Plant, Unit No.2 during fall 2012. A list of attendees is provided as and a summary of the discussion is provided in Enclosure 2.

Members of the public were not in attendance. Public meeting feedback forms were not received during the conference call.

Please direct any inquiries to me at 301-415-2788, or e-mail me at Tracy.Orf@nrc.gov.

Tracy J. Orf, Proj ct Manager Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-389

Enclosures:

1 . List of attendees

2. Summary of Conference Call cc w/encls: Distribution via Listserv

LIST OF ATTENDEES SEPTEMBER 13. 2012. CONFERENCE CALL WITH FLORIDA POWER AND LIGHT CO.

FALL 2012 STEAM GENERATOR TUBE INSPECTIONS AT ST. LUCIE. UNIT NO.2 Name Organization Kenneth Karwoski NRC Tracy J. Ort NRC Louis Lake NRC Jack Hoffman FPL Russ Cipolla Intertec Ed Korkowski FPL Allen Brown AREVA Enclosure 1

SUMMARY

OF CONFERENCE CALL WITH ST. LUCIE PLANT UNIT NO.2 REGARDING THE FALL 2012 STEAM GENERATOR TUBE INSPECTION RESULTS DOCKET NO. 50-389 On September 13, 2012, the U.S. Nuclear Regulatory Commission (NRC) staff participated in a conference call with representatives of Florida Power & Light Company (the licensee), regarding their ongoing steam generator tube inspection activities at Saint Lucie Plant (St. Lucie), Unit NO.2. Information provided by the licensee in support of the conference call is located in the Agencywide Documents Access Management System under Accession No. ML12258A080.

St. Lucie Unit 2 has two Areva-NP Model 86/19TI replacement steam generators (SGs) that were installed in January 2008. Each SG has 8,999 thermally-treated Alloy 690 tubes with a nominal outside diameter of 0.75 inches and a nominal wall thickness of 0.043 inches. During manufacturing, all tubes were hydraulically expanded at both ends over the full depth of the tubesheet. The tubesheet was drilled on a triangular pitch with 1-inch spacing, center-to-center.

The radius of the row 1 U-bends is 4.134 inches. The U-bends in rows 1 through 15 were stress relieved after bending. Seven tube support plates (TSPs), each 1.181 inches thick and made from Type 410 stainless steel, support the vertical section of the tubes. The TSPs have broached trefoil holes. Four sets of anti-vibration bars (AVBs), each 0.112 inches thick and made from Type 405 stainless steel, support the U-bend section of the tubes.

Additional clarifying information regarding the licensee-provided document and information not included in the licensee-provided document is summarized below.

• The licensee indicated that at the time of the call, the bobbin coil inspections were greater than 99 percent complete in both SG A and SG B.

• There was no correlation found between AVB and TSP wear indications.

• The total number of indications in the "History of wear indications/affected number of tubes (Cumulative)" table on page 1 of the licensee's informational document is different from the "Wear distribution" histogram on page 2 because they were generated at different times during the outage. However, the general distribution and trend shown in the histogram remains the same when all the data from the table on page 1 is included.

Regarding the two new indications with depths between 30 and 34 percent reported in the histogram on page 2, one of the two indications is a 34-percent through wall (TW) indication that is located in a tube that had prior wear indications. The second indication is a 32-percent TW indication in a tube on the periphery of SG A, in a location where tube wear has already been seen.

• The licensee indicated that they evaluate whether the growth rate is a function of the beginning-of-cycle (BOC) depth. They indicated in the prior inspections, the growth rates for flaws less than or equal to 13-percent TW were dependent on the BOC depth, but no such correlation existed for flaws greater than 13-percent TW.

Enclosure 2

-2

• The licensee indicated that they had implemented modifications to access covers in a prior outage to deal with nuts that loosened during operation, that the modification was working as designed, and that no new loose nuts were noted during this inspection.

There was no degradation or anomalous conditions identified during the inspection.

• Profiling of the wear indications had commenced and was being performed to determine if there was any change in the specific type of wear that was occurring in the SG tubes.

The licensee indicated that the indications tend to be flat, centered, and no longer than the AVBs causing the wear.

• The licensee stated that there was no observed primary-to-secondary leakage during the recently completed operating cycle. Also, there were no exceptions taken to the industry guidelines (including the chemistry, inspection, and integrity assessment guidelines).

• The licensee indicated that the prior operational assessment had predicted that 30-34 tubes would require plugging in SG A during the current inspection, and the actual amount of required plugging was just 7 tubes in SG A. Overall, the licensee indicated that the general trend of the inspection findings was in line with the predicted findings of the prior operational assessment.

• Seven indications that measured 40-percent TW were detected in 2012. Only one similar indication (40-percent TW) was detected in the last outage.

• The licensee indicated it was reviewing the increase in the number of new indications in SG B since the number of new indications per cycle increased in the latest inspection.

• The licensee is scheduled to implement a power uprate during this cycle.

At the end of the call, the NRC staff inquired about potentially being briefed on the results of the inspections and the final Condition Monitoring Operational Assessment since they are complicated. The representatives from St. Lucie indicated they would work with the NRC project manager in setting up such a meeting.

Additional abbreviations used in the licensee-provided document include:

• Avg. - Average

• CMOA - Condition Monitoring and Operational Assessment

• EFPY - Effective Full Power Years

• FOSAR - Foreign Object Search and Retrieval

• OA - Operational Assessment

• POB - Probability of Burst

• SONGS - San Onofre Nuclear Generating Station

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