ML15209A646

Review of the Spring 2014 Steam Generator Tube Inservice Inspection Report for Refueling Outage

ML15209A646
Person / Time
Site:	Saint Lucie
Issue date:	08/19/2015
From:	Farideh Saba Plant Licensing Branch II
To:	Nazar M Nextera Energy
Buckberg P
References
TAC MF4847
Download: ML15209A646 (4)

Text

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• • • 1<. August 19, 2015 Mr. Mano Nazar President and Chief Nuclear Officer Nuclear Division NextEra Energy P.O. Box 14000 Juno Beach, Florida 33408-0420

SUBJECT:

ST. LUCIE PLANT, UNIT NO 2 - REVIEW OF THE SPRING 2014 STEAM GENERA TOR TUBE INSERVICE INSPECTION REPORT FOR REFUELING OUTAGE 21 (TAC NO. MF4847)

Dear Mr. Nazar:

By letter dated September 18, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14279A237), Florida Power and Light Company (the licensee) submitted information summarizing the results of the spring 2014 steam generator tube inspection report, for the twenty-first St. Lucie Unit No. 2 Refueling Outage in accordance with Technical Specification (TS) Section 6.9.1 12. In addition to the above report, the U.S. Nuclear Regulatory Commission (NRC) staff summarized a conference call held with the licensee in a letter dated August 8, 2014 (ADAMS Accession No. ML14189A090). Also, the licensee submitted additional information regarding the 2014 inspections in letters dated March 23 (ADAMS Accession No. ML15091A306) and June 18, 2015 (ADAMS Accession No. ML15190A336).

The NRC staff has completed its review of these submittals and concludes that the licensee provided the information required by its TSs and that no additional followup is required at this time.

The NRC staff's review of the report is enclosed.

Sincerely,

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Fandeh E. Saba, Project Manager Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-389

Enclosure:

Inspection Summary Report cc w/encl: Distribution via ListServ

REVIEW OF THE 2014 STEAM GENERATOR TUBE INSERVICE INSPECTION REPORT ST. LUCIE PLANT, UNIT NO. 2 DOCKET NO. 50-389 TAC NO. MF4847 By letter dated September 18, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14279A237), Florida Power & Light Company (the licensee) submitted information summarizing the results of the spring 2014 steam generator (SG) tube inspections performed at St. Lucie Unit No. 2. These inspections were performed during Refueling Outage 21 (RFO 21). The U.S. Nuclear Regulatory Commission (NRC) staff summarized a conference call held with the licensee in a letter dated August 8, 2014 (ADAMS Accession No. ML14189A090). The licensee submitted additional information regarding the 2014 inspections in letters dated March 23 (ADAMS Accession No. ML15091A306) and June 18, 2015 (ADAMS Accession No. ML15190A336).

St. Lucie Unit No. 2 has two Model 86/19TI replacement SGs that were manufactured by AREVA and installed in 2007. Each SG has 8,999 thermally treated Alloy 690 tubes with a nominal outside diameter of 0.75 inch and a nominal wall thickness of 0.043 inch. 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 1.0-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 Type 410 stainless steel support plates (each 1.181 inches thick with broached trefoil holes) support the vertical section of the tubes. Four sets of anti-vibration bars (each 0.112 inch thick and made from Type 405 stainless steel) support the U-bend section of the tubes.

The licensee provided the scope, extent, methods, and results of their SG tube inspections in the documents referenced above. In addition, the licensee described corrective actions, such as tube plugging, taken in response to the inspection findings. The tubes in both SGs were inspected during this refueling outage.

Based on its review of the reports submitted, the NRC staff has the following observations and comments:

• The four feedring inspection port covers (two per SG) were found to be loose during secondary side inspections. The loose covers allowed the feedrings to drain, which created a steam void in the feedring system resulting in a water hammer event in the feedrings that damaged the feedring supports for both SGs. The supports were repaired during RFO 21 and all four inspection port covers were replaced with welded end caps to prevent loosening in the future.

Enclosure

• One tube located in row 91, column 24 (R91 C24) of SG A was plugged due to wear associated with a neighboring (R90C23) V-shaped support pad. The V-shaped support pads support the anti-vibration bar system. This is the first reported occurrence of this type of wear at St. Lucie Unit No. 2. Contact between the V-shaped support pad and adjacent tubes is not expected by design and the discovered indication is likely the result of misalignment of the V-shaped support pad during manufacturing.

Based on its review, the NRC staff concludes that the licensee submitted the information required by its TSs. In addition, the staff concludes there are no technical issues that warrant followup action at this time, since the inspections appear to be consistent with the objective of detecting potential tube degradation, and inspection results appear to be consistent with industry operating experience at similarly designed and operated units. Although the number of wear indications is greater than the number of wear indications found at other AREVA SGs of similar age, the depths of these indications (i.e., the severity) are comparable to those observed at other plants.

Mr. Mano Nazar President and Chief Nuclear Officer Nuclear Division NextEra Energy P.O. Box 14000 Juno Beach, Florida 33408-0420

SUBJECT:

ST. LUCIE PLANT, UNIT NO. 2 - REVIEW OF THE SPRING 2014 STEAM GENERATOR TUBE INSERVICE INSPECTION REPORT FOR REFUELING OUTAGE 21 (TAC NO. MF4847)

Dear Mr. Nazar:

By letter dated September 18, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14279A237}, Florida Power and Light Company (the licensee) submitted information summarizing the results of the spring 2014 steam generator tube inspection report, for the twenty-first St. Lucie Unit No. 2 Refueling Outage in accordance with Technical Specification (TS) Section 6.9.1.12. In addition to the above report, the U.S. Nuclear Regulatory Commission (NRC) staff summarized a conference call held with the licensee in a letter dated August 8, 2014 (ADAMS Accession No. ML14189A090). Also, the licensee submitted additional information regarding the 2014 inspections in letters dated March 23 (ADAMS Accession No. ML15091A306) and June 18, 2015 (ADAMS Accession No. ML15190A336).

The NRC staff has completed its review of these submittals and concludes that the licensee provided the information required by its TSs and that no additional followup is required at this time.

The NRC staff's review of the report is enclosed.

Sincerely, Farideh E. Saba, Project Manager Plant Licensing Branch 11-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-389

Enclosure:

Inspection Summary Report cc w/encl: Distribution via ListServ DISTRIBUTION:

PUBLIC LPL2-2 R/F RidsAcrsAcnw_MailCTR Resource RidsNrrDeEsgb Resource RidsNrrPMStLucie Resource RidsNrrDorlLpl2-2 Resource AJohnson, NRR RidsNrrLABClayton Resource RidsRgn2MailCenter Resource KKarwoski, NRR ADAMS A No.: ML15209A646 *b OFFICE LPL2-2/PM LPL2-2/LA ESGB/BC* LPL2-2/BC LPL2-2/PM NAME PBuckberg BClayton GKulesa SHelton FSaba ~

DATE 07/28/15 07/28/15 07/13/15 08/17/15 08/19/15 OFFICIAL AGENCY COPY