ML071140006
| ML071140006 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 04/26/2007 |
| From: | Thadani M NRC/NRR/ADRO/DORL/LPLIV |
| To: | Blevins M TXU Power |
| Thadani, M C, NRR/DORL/LP4, 415-1476 | |
| References | |
| TAC MD6952 | |
| Download: ML071140006 (5) | |
Text
April 26, 2007 Mr. M. R. Blevins Senior Vice President &
Chief Nuclear Officer TXU Power Attn: Regulatory Affairs Department P. O. Box 1002 Glen Rose, TX 76043
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION, UNIT 2 -
SUMMARY
OF STAFF REVIEW OF THE STEAM GENERATOR TUBE INSERVICE INSPECTION REPORT FOR THE EIGHTH REFUELING OUTAGE (2RF08)
Dear Mr. Blevins:
By letters dated April 28, 2005, and February 14, 2006, TXU Generation Company LP, the licensee for Comanche Peak Steam Electric Station (CPSES), summarized information of the 2RF08 refueling outage steam generator tube inservice inspection for CPSES, Unit 2. By letter dated November 1, 2006, the licensee provided a response to the Nuclear Regulatory Commission (NRC) request for additional information.
The NRC staff has completed its review of the licensees submittals. Based on that review, the NRC staff concludes that the licensee provided the information required by its technical specifications. 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 and the inspection results appear to be consistent with industry operating experience at similarly designed and operated units.
Sincerely,
/RA/
Mohan C. Thadani, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-446
Enclosure:
Summary of Staff Review cc w/encl: See next page
April 26, 2007 Mr. M. R. Blevins Senior Vice President &
Chief Nuclear Officer TXU Power Attn: Regulatory Affairs Department P. O. Box 1002 Glen Rose, TX 76043
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION, UNIT 2 -
SUMMARY
OF STAFF REVIEW OF THE STEAM GENERATOR TUBE INSERVICE INSPECTION REPORT FOR THE EIGHTH REFUELING OUTAGE (2RF08)
Dear Mr. Blevins:
By letters dated April 28, 2005, and February 14, 2006, TXU Generation Company LP, the licensee for Comanche Peak Steam Electric Station (CPSES), summarized information of the 2RF08 refueling outage steam generator tube inservice inspection for CPSES, Unit 2. By letter dated November 1, 2006, the licensee provided a response to the Nuclear Regulatory Commission (NRC) request for additional information.
The NRC staff has completed its review of the licensees submittals. Based on that review, the NRC staff concludes that the licensee provided the information required by its technical specifications. 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 and the inspection results appear to be consistent with industry operating experience at similarly designed and operated units.
Sincerely,
/RA/
Mohan C. Thadani, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-446
Enclosure:
Summary of Staff Review cc w/encl: See next page DISTRIBUTION PUBLIC RidsNrrPMMThadani LPLIV Reading RidsNrrLALFeizollahi RidsNrrDorlLpl4 RidsOgcRp RidsRgn4MailCenter RidsNrrDciCsgb RidsAcrsAcnwMailCenter EMurphy, NRR ACCESSION NO: ML071140006 *No significant change to SE input.
OFFICE NRR/LPL4/PM NRR/LPL4/LA NRR/CSG/BC NRR/LPL4/BC NAME MThadani LFeizollahi AHiser* MMarkley for THiltz DATE 4/26/07 4/26/07 2/22/07 4/26/07 OFFICIAL RECORD COPY
Comanche Peak Steam Electric Station cc:
Senior Resident Inspector Mr. Richard A. Ratliff, Chief U.S. Nuclear Regulatory Commission Bureau of Radiation Control P.O. Box 2159 Texas Department of Health Glen Rose, TX 76403-2159 1100 West 49th Street Austin, TX 78756-3189 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Mr. Brian Almon 611 Ryan Plaza Drive, Suite 400 Public Utility Commission Arlington, TX 76011 William B. Travis Building P.O. Box 13326 Mr. Fred W. Madden, Director 1701 North Congress Avenue Regulatory Affairs Austin, TX 78701-3326 TXU Generation Company LP P.O. Box 1002 Ms. Susan M. Jablonski Glen Rose, TX 76043 Office of Permitting, Remediation and Registration George L. Edgar, Esq. Texas Commission on Environmental Morgan Lewis Quality 1111 Pennsylvania Avenue, NW MC-122 Washington, DC 20004 P.O. Box 13087 Austin, TX 78711-3087 County Judge P.O. Box 851 Terry Parks, Chief Inspector Glen Rose, TX 76043 Texas Department of Licensing and Regulation Environmental and Natural Boiler Program Resources Policy Director P.O. Box 12157 Office of the Governor Austin, TX 78711 P.O. Box 12428 Austin, TX 78711-3189 December 2004
SUMMARY
OF COMANCHE PEAK UNIT 2 SPRING 2005 STEAM GENERATOR INSERVICE INSPECTIONS TAC NO. MC6952 DOCKET NO. 50-446 By letters dated April 28, 2005 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML051250408) and February 14, 2006 (ADAMS Accession No. ML060540491), TXU Generation Company LP, the licensee for Comanche Peak Steam Electric Station (CPSES), Unit 2, summarized its refueling outage 2RF08 (spring 2005) steam generator (SG) tube inservice inspection for CPSES, Unit 2. By e-mail dated August 15, 2006 (ADAMS Accession No. ML062330074), the Nuclear Regulatory Commission (NRC) staff requested additional information regarding the licensees submittals. In its letter dated November 1, 2006 (ADAMS Accession No. ML063110573), the licensee provided responses to the request for additional information.
CPSES, Unit 2, has four Westinghouse Model D5 SGs. Each SG contains 4,570 thermally treated Alloy 600 tubes. Each tube has a nominal outside diameter of 3/4 inch and a nominal wall thickness of 0.043 inch. The tubes were hydraulically expanded at both ends for the full length of the tubesheet and are supported by a number of Type 405 stainless steel supports with quatrefoil shaped holes.
The licensee provided the scope, extent, methods, and results of its SG tube inspections in the documents referenced above. In addition, the licensee described corrective actions taken in response to the inspection findings.
The licensee determined that the wear at the anti-vibration bar supports is the dominant degradation mechanism for the CPSES, Unit 2, SG tubes, in terms of the number of indications and number of tubes affected. All indications were found to be less than the technical specification repair limit (i.e., 40 percent of the initial tube wall thickness).
Three tubes were observed to contain volumetric indications at tube freespan locations.
The licensee noted that these indications exhibited no change relative to earlier inspections and attributed these indications to lap signals (associated with tube manufacturing), as have been observed at other plants including CPSES, Unit 1. Another tube with a volumetric indication at a tube support plate was found to have remained unchanged since 1994 and has also been attributed as a manufacturing anomaly. All above discussed tubes were plugged. These tubes were not stabilized, since none exhibited evidence of any active loose parts that could cause tube damage.
The licensee plugged a few tubes, which were found to have loose parts wear. Two of these tubes, SG3-R6C33 and SG3-R7C33, were just inboard of two other tubes, SG3-R8C33 and SG3-R9C33, in the same column. Those tubes were plugged during the refueling outage (2RF06) in April 2002, due to indications attributed to loose parts damage. The loose parts indications in these four tubes were located at a baffle plate on the cold-leg side. The location of these indications was not accessible for video inspection or for removal of the loose parts.
Based on the sequence of the damage, the licensee believes that the subject loose parts are gradually migrating toward the middle of the bundle along this column. All surrounding tubes within a zone extending three columns and three rows of the affected tubes were inspected with no further related indications. The affected tubes were stabilized prior to plugging. Tubes SG3-R48C40 and SG3-R48C41 also contained indications, at a baffle plate on the cold-leg side, attributable to loose parts. All immediately adjacent tubes were eddy current inspected with no further related indications. Video inspection did not identify any loose parts at this location or other locations several rows inward in the flow direction. Therefore, the licensee concluded that the loose parts may have migrated away from this region. The licensee did not stabilize these tubes prior to plugging since no further loose parts damage would be expected for these tubes.
Based on the above review summary of the information provided, the NRC staff concludes that the licensee provided the information required by its 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.
Principal Contributor: E. Murphy Date: April 26, 2007