ML100670440

Review of Results of the Steam Generator Tube Inspections Performed During Refueling Outage 13

ML100670440
Person / Time
Site:	South Texas
Issue date:	03/10/2010
From:	Thadani M Plant Licensing Branch IV
To:	Halpin E South Texas
Thadani, M C, NRR/DORL/LP4, 415-1476
References
TAC ME1618
Download: ML100670440 (4)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 l\1arch 10, 2010 Mr. Edward D. Halpin President and Chief Nuclear Officer STP Nuclear Operating Company South Texas Project P. O. Box 289 Wadsworth, TX 77483

SUBJECT:

SOUTH TEXAS PROJECT, UNIT 2 - REVIEW OF RESULTS OF THE STEAM GENERATOR TUBE INSPECTIONS PERFORMED DURING REFUELING OUTAGE 13 (TAC NO. ME1618)

Dear Mr. Halpin:

By letter dated March 24, 2009 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML090970281), as supplemented by letter dated February 11, 2010 (ADAMS Accession No. ML100501157), STP Nuclear Operating Company (the licensee),

submitted information summarizing the results of the fall 2008 steam generator tube inspections performed at the South Texas Project (STP), Unit 2. These inspections were performed during the 13th refueling outage.

The Nuclear Regulatory Commission (NRC) staff has completed its review of the inspection summary report and concludes that the licensee provided the information required by the STP, Unit 2 Technical Specifications and no additional follow-up is required at this time. The results of the NRC staff's review of the report submitted by the licensee are summarized in the enclosed staff evaluation. If you have any questions, please contact me at 301-415-1476 or via e-mail at Mohan.Thadani@nrc.gov.

Sincerely, Mohan C. Thadani, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-499

Enclosure:

As stated cc w/encl: Distribution via Listserv

OFFICE OF NUCLEAR REACTOR REGULATION THE STAFF'S EVALUATION OF INSPECTION REPORT FOR 2008 STEAM GENERATOR TUBE INSPECTIONS PERFORMED DURING REFUELING OUTAGE 13 STP NUCLEAR OPERATING COMPANY SOUTH TEXAS PROJECT, UNIT 2 DOCKET NO. 50-499 By letter dated March 24, 2009 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML090970281), as supplemented by letter dated February 11, 2010 (ADAMS Accession No. ML100501157), STP Nuclear Operating Company (the licensee),

submitted information summarizing the results of the fall 2008 steam generator tube inspections performed at South Texas Project (STP), Unit 2. These inspections were performed during the 13th refueling outage.

STP, Unit 2 has four Westinghouse model Delta 94 steam generators (SGs). Each SG contains 7,585 thermally treated Alloy 690 tubes. The tubes have a nominal outer diameter of 0.688 inches, a nominal wall thickness of 0.040 inches, and are supported by stainless steel tube support plates (TSPs) with trefoil-shaped holes. The U-bends of the tubes in rows 1 through 17 were thermally stress relieved after bending.

As of the end of Cycle 13 (October 2008), the SGs had approximately 63.42 effective full power months of operation.

The licensee provided the scope, extent, methods, and results of the SG tube inspections in the above-referenced submittals. In addition, the licensee described corrective actions (i.e., tube plugging) taken in response to the inspection findings.

After review of the information provided by the licensee, the Nuclear Regulatory Commission (NRC) staff has the following comments/observations:

• Four tubes were plugged in SG D as a result of a foreign object that could not be removed. The object appeared to be weld slag. No indications of wear were noted in the four tubes that were plugged adjacent to the foreign object, and none of the tubes were stabilized since the projected amount of wear is not expected by the licensee to cause tube shear.

• One tube in SG A contained a 4 percent throughwall flaw. This indication was characterized as a service-induced volumetric flaw caused by wear at the 8th TSP.

• Several components on the secondary side were visually inspected during the 2008 refueling outage. No anomalies were noted during these inspections.

Enclosure

-2 Some minor deposits were observed on the tubes and there was essentially no fouling in the trefoil-shaped tube support openings.

Based on the review of the information provided, the NRC staff concludes that the licensee provided the information required by the STP, Unit 2, Technical Specifications. In addition, the staff concludes that there are no technical issues that warrant follow-up action at this time since the inspections appear to be consistent with the objective of detecting potential tube degradation and the inspection results appear to be consistent with industry operating experience at similarly designed and operated units.

ML100501157), STP Nuclear Operating Company (the licensee),

submitted information summarizing the results of the fall 2008 steam generator tube inspections performed at the South Texas Project (STP), Unit 2. These inspections were performed during the 13th refueling outage.

The Nuclear Regulatory Commission (NRC) staff has completed its review of the inspection summary report and concludes that the licensee provided the information required by the STP, Unit 2 Technical Specifications and no additional follow-up is required at this time. The results of the NRC staff's review of the report submitted by the licensee are summarized in the enclosed staff evaluation. If you have any questions, please contact me at 301-415-1476 or via e-mail at Mohan.Thadani@nrc.gov.

Sincerely, IRN Mohan C. Thadani, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-499

Enclosure:

As stated cc w/encl: Distribution via Listserv DISTRIBUTION:

PUBLIC RidsNrrDorlLpl4 Resource RidsRgn4MailCenter Resource LPLIV Reading RidsNrrPMSouthTexas Resource TMorgan, NRRlDCI/CSGB RidsAcrsAcnw_MailCTR Resource RidsNrrLAJBurkhardt Resource RidsNrrDciCsgb Resource RidsOgcRp Resource ADAMS Accession No ML100670440 *memo dated OFFICE NRRlLPL4/PM NRRlLPL4/LA DCI/CSGB/BC NRR/LPL4/BC NRRlLPL4/PM NAME MThadani JBurkhardt RTaylor* MMarkley MThadani DATE 3/10/10 3/10/10 3/5/10 3/10/10 3/10/10