ML101820099
| ML101820099 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 07/07/2010 |
| From: | Jacqueline Thompson Plant Licensing Branch II |
| To: | Morris J Duke Energy Carolinas |
| Thompson, Jon 415-1119 | |
| References | |
| TAC MD3419 | |
| Download: ML101820099 (5) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 July 7, 2010 Mr. J. R. Morris Site Vice President Catawba Nuclear Station Duke Energy Carolinas, LLC 4800 Concord Road York, SC 29745
SUBJECT:
CATAWBA NUCLEAR STATION, UNIT 2 (CATAWBA 2) - REVIEW OF THE STEAM GENERATOR (SG) TUBE INSPECTIONS DURING REFUELING OUTAGES 13 AND 14 END OF CYCLE (EOC 13 and EOC 14) (TAC NO.
MD3419)
Dear Mr. Morris:
By letters dated October 21,2004 (Agencywide Documents Access and Management System (ADAMS), Accession No. ML043070616), and January 17,2005 (ADAMS Accession No. ML050240371), Duke Energy Carolinas, LLC (the licensee), submitted information summarizing the results of the 2004 SG tube inspections at Catawba 2. These inspections were performed during EOC 13. In addition to these licensee reports, the U.S. Nuclear Regulatory Commission (NRC) staff summarized a conference call concerning the 2004 steam generator tUbe inspections at Catawba 2 in a letter dated November 11, 2004 (ADAMS Accession No. ML043130438).
By letters dated July 18, 2006 (ADAMS Accession No. ML062060296), and August 31, 2006 (ADAMS Accession No. ML062550112), the licensee submitted information summarizing the results of the 2006 SG tube inspections at Catawba 2. These inspections were performed during the EOC 14.
Additional information regarding the SG tube inspections at Catawba 2 during EOC 13 and 14 was submitted by the licensee in letters dated May 7,2007 (ADAMS Accession No. ML071350378) and May 31,2007 (ADAMS Accession No. ML071630231).
The NRC staff has completed its review of the information submitted and concludes that the licensee provided the information required by the Catawba 2 technical specifications. No additional follow-up is required at this time. The NRC staff's review is enclosed.
J. Morris
- 2 If you have any questions, please call me at 301-415-1119.
Sincerely, Jon Thompson, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-414
Enclosure:
As stated cc w/encl: Distribution via Listserv
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 STAFF EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO RESULTS OF STEAM GENERATOR TUBE INSPECTIONS PERFORMED DURING REFUELING OUTAGES 13 AND 14 CATAWBA NUCLEAR STATION, UNIT 2 DOCKET NO. 50-414 By letters dated October 21, 2004 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML043070616), and January 17, 2005 (ADAMS Accession No. ML050240371), Duke Energy Carolinas, LLC (the licensee), submitted information summarizing the results of the 2004 steam generator (SG) tube inspections at Catawba 2. These inspections were performed during EOC 13. In addition to these licensee reports, the U.S. Nuclear Regulatory Commission (NRC) staff summarized a conference call concerning the 2004 SG tube inspections at Catawba 2 in a letter dated November 11, 2004 (ADAMS Accession No. ML043130438).
By letters dated July 18, 2006 (ADAMS Accession No. ML062060296), and August 31, 2006 (ADAMS Accession No. ML062550112), the licensee submitted information summarizing the results of the 2006 SG tube inspections at Catawba 2. These inspections were performed during the EOC 14.
Additional information regarding the SG tube inspections at Catawba 2 during EOC 13 and 14 was submitted by the licensee in letters dated May 7, 2007 (ADAMS Accession No. ML071350378) and May 31, 2007 (ADAMS Accession No. ML071630231).
Catawba 2 has four Westinghouse Electric Company Model D5 SGs, which are designated 2A through 2D. All four SGs were inspected during both the EOC 13 and EOC 14 refueling outage.
Each SG has 4,570 thermally treated Alloy 600 tubes with an outside diameter of 0.750 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.
The licensee provided the scope, extent, methods, and results of the Catawba 2 SG tube inspections in the documents referenced above. In addition, the licensee described corrective actions (i.e., tube plugging) taken in response to the inspection findings.
The NRC staff has the following notes/observations as a result of reviewing the information provided by the licensee.
Enclosure
- 2 During the EOC 13 refueling outage inspections the licensee identified 16 tubes in SG 2B with crack-like indications in the portion of the tube contained within the tubesheet.
The NRC staff contracted with Argonne National Laboratory (ANL) to perform an evaluation of the eddy current data for these 16 tubes. ANL's report is available at ADAMS Accession No. ML072350497. All 16 of these tubes in SG 2B were plugged.
During the EOC 14 outage, additional crack-like indications were found near the tube end in all four SGs. All of these indications were left in service since they were located in a region of the tubesheet where flaws are not required to be removed from service in accordance with the Technical Specifications (TSs). The TSs were modified following the EOC 13 outage to permit flaws located near the tube-end to remain in service regardless of their depth.
The licensee performed secondary side inspections of the pre-heater baffle plate and pre-heater water-boxes for erosion and wear as a follow-up to industry events at other plants with the same model of SG. As a result of the inspection of the baffle plate in EOC 14, a total of 202 objects were identified in the four SGs. Of these 202 objects, 133 were removed. All of the remaining objects were evaluated by the licensee for acceptability to leave in place for one cycle of operation. The waterbox cap plate region of all four SGs were inspected during both the EOC 13 outage and the EOC 14 outage.
Since SG 2A did not have a cap plate cutout (as confirmed during the EOC 13 outage), it was not reinspected during the EOC 14 outage. The EOC 13 inspection showed the welds associated with the cap plate cutout region were structurally sound. The inspections of the waterbox cap plate region during the EOC 14 outage in SGs 28, 2C, and 2D did not show any change in condition in these welds. No unusual wear was found.
An inspection of the primary moisture separator region is planned for EOC 15 in 2007.
The licensee indicated that certain wear indications were not sized during the outage, but that they were determined to meet structural and TS tube repair limits and left in service (Le., < 40% through-wall).
Based on a review of the information provided, the NRC staff concludes that the licensee provided the information required by their TSs. In addition, the NRC 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.
- transmitted by memo dated (ML072350489)
OFFICE NRRlLPL2-1/PM NRRlLPL2-1/LA NRRlCSGB/BC NRRlLPL2-1/BC NRRlLPL2-'I/PM NAME JThompson MO'Brien AHiser*
GKulesa JThompson DATE 7/1/10 7/7/10 8/30/07 7/7/10 7/7/10