ML051240034

May 11, 2005, Palo Verde Unit 3 - Review of Steam Generator Tube Inspection Summary Report (Tac No. MC1351)

ML051240034
Person / Time
Site:	Palo Verde
Issue date:	05/11/2005
From:	Fields M NRC/NRR/DLPM/LPD4
To:	Overbeck G Arizona Public Service Co
Fields M B ,NRR/DLPM,415-3062
References
TAC MC1351
Download: ML051240034 (5)

Text

Mr. Gregg R. Overbeck May 11, 2005 Senior Vice President, Nuclear Arizona Public Service Company P. O. Box 52034 Phoenix, AZ 85072-2034

SUBJECT:

PALO VERDE NUCLEAR GENERATING STATION, UNIT 3 - REVIEW OF STEAM GENERATOR TUBE INSPECTION

SUMMARY

REPORT (TAC NO. MC1351)

Dear Mr. Overbeck:

The NRC staff has completed its review of the report submitted by Arizona Public Service (APS) summarizing the steam generator tube inspections performed during the 2003 Palo Verde Nuclear Generating Station (Palo Verde) Unit 3 refueling outage. This report was provided in the APS letter dated May 1, 2003 (ML031280157), as supplemented by letters dated October 15, 2003 (ML032960550) and March 25, 2005 (ML051020397).

As discussed in the enclosed safety evaluation, the NRC staff concludes that APS has provided the information required by the Palo Verde Unit 3 technical specifications. In addition, the NRC staff did not identify any technical issues that warranted follow-up action at this time.

Sincerely,

/RA/

Mel B. Fields, Senior Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. STN 50-530

Enclosure:

Safety Evaluation cc w/encl: See next page

Palo Verde Generating Station, Units 1, 2, and 3 cc:

Mr. Steve Olea Mr. John Taylor Arizona Corporation Commission Public Service Company of New Mexico 1200 W. Washington Street 2401 Aztec NE, MS Z110 Phoenix, AZ 85007 Albuquerque, NM 87107-4224 Douglas Kent Porter Ms. Cheryl Adams Senior Counsel Southern California Edison Company Southern California Edison Company 5000 Pacific Coast Hwy Bldg DIN Law Department, Generation Resources San Clemente, CA 92672 P.O. Box 800 Rosemead, CA 91770 Mr. Robert Henry Salt River Project Senior Resident Inspector 6504 East Thomas Road U.S. Nuclear Regulatory Commission Scottsdale, AZ 85251 P. O. Box 40 Buckeye, AZ 85326 Terry Bassham, Esq.

General Counsel Regional Administrator, Region IV El Paso Electric Company U.S. Nuclear Regulatory Commission 123 W. Mills Harris Tower & Pavillion El Paso, TX 79901 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 Mr. John Schumann Los Angeles Department of Water & Power Chairman Southern California Public Power Authority Maricopa County Board of Supervisors P.O. Box 51111, Room 1255-C 301 W. Jefferson, 10th Floor Los Angeles, CA 90051-0100 Phoenix, AZ 85003 Brian Almon Mr. Aubrey V. Godwin, Director Public Utility Commission Arizona Radiation Regulatory Agency William B. Travis Building 4814 South 40 Street P. O. Box 13326 Phoenix, AZ 85040 1701 North Congress Avenue Austin, TX 78701-3326 Mr. Craig K. Seaman, Director Regulatory Affairs/Nuclear Assurance Palo Verde Nuclear Generating Station Mail Station 7636 Phoenix, AZ 85072-2034 Mr. Hector R. Puente Vice President, Power Generation El Paso Electric Company 340 E. Palm Lane, Suite 310 Phoenix, AZ 85004

May 11, 2005 Mr. Gregg R. Overbeck Senior Vice President, Nuclear Arizona Public Service Company P. O. Box 52034 Phoenix, AZ 85072-2034

SUBJECT:

PALO VERDE NUCLEAR GENERATING STATION, UNIT 3 - REVIEW OF STEAM GENERATOR TUBE INSPECTION

SUMMARY

REPORT (TAC NO. MC1351)

Dear Mr. Overbeck:

The NRC staff has completed its review of the report submitted by Arizona Public Service (APS) summarizing the steam generator tube inspections performed during the 2003 Palo Verde Nuclear Generating Station (Palo Verde) Unit 3 refueling outage. This report was provided in the APS letter dated May 1, 2003 (ML031280157), as supplemented by letters dated October 15, 2003 (ML032960550) and March 25, 2005 (ML051020397).

As discussed in the enclosed safety evaluation, the NRC staff concludes that APS has provided the information required by the Palo Verde Unit 3 technical specifications. In addition, the NRC staff did not identify any technical issues that warranted follow-up action at this time.

Sincerely,

/RA/

Mel B. Fields, Senior Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. STN 50-530

Enclosure:

Safety Evaluation cc w/encl: See next page DISTRIBUTION PUBLIC RidsAcrsAcnwMailCenter PDIV-2 r/f RidsOgcRp RidsNrrDlpmLpdiv (HBerkow) RidsNrrDlpmLpdiv2 (RGramm)

RidsRgn4MailCenter (TPruett) RidsNrrPMMFields MMurphy RidsNrrLADBaxley YDiaz RidsNrrDlpmDpr ACCESSION NO: ML051240034 NRR-106 *SE Input OFFICE PDIV-2/PM PDIV-2/LA EMCB/SC* PDIV-2/SC NAME MFields DBaxley LLund RGramm DATE 5-11-05 5/11/05 3/24/05 5/11/05

OFFICIAL RECORD COPY SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION STEAM GENERATOR TUBE INSPECTION REPORTS ARIZONA PUBLIC SERVICE COMPANY, ET AL.

PALO VERDE NUCLEAR GENERATING STATION, UNIT 3 DOCKET NO. STN 50-530

1.0 INTRODUCTION

Arizona Public Service (APS), the licensee for Palo Verde Nuclear Generating Station (Palo Verde), Units 1, 2, and 3 submitted information summarizing the steam generator (SG) tube inspections performed during the 2003 Palo Verde Unit 3 refueling outage. The initial report was provided in the APS letter dated May 1, 2003 (ML031280157), and was supplemented by letters dated October 15, 2003 (ML032960550) and March 25, 2005 (ML051020397).

Palo Verde Unit 3 has two Combustion Engineering System 80 SGs. There are 11,012 mill annealed Alloy 600 tubes in each SG. The tubes have an outside diameter of 0.75-inch, a wall thickness of 0.042-inch, and are supported at various locations by ferritic stainless steel eggcrate tube supports, diagonal bars, and/or vertical straps.

2.0 REGULATORY EVALUATION

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 (i.e.,

tube plugging or repair) taken in response to the inspection findings.

Based on a review of these documents, the NRC staff prepared a request for additional information (RAI) which was forwarded to the licensee shortly before their next Unit 3 SG tube inspections. Given that the next Unit 3 SG tube inspections would be conducted prior to the licensee being able to respond to this RAI, the NRC staff factored these questions into the discussions it had with the licensee regarding the results of their 2004 tube inspections at Unit

3. These discussions were documented in a letter dated February 23, 2005 (ML050490197).

The licensee subsequently responded to the RAI on the 2003 outage by letter dated March 25, 2005 (ML051020397).

During the Palo Verde Unit 3 spring 2003 outage, the licensee performed a supplemental rotating probe inspection of the upper cold leg region. These inspections were in response to findings in their Unit 1 SG. During the Unit 1 inspection, the licensee identified 26 tubes with stress corrosion cracking (SCC) indications at upper bundle support locations on the cold leg side of the SG. All of these indications were detected using a bobbin coil probe. These indications represented a first time discovery of this type of degradation in the cold leg region at

Palo Verde. No indications of SCC were discovered in this region at Unit 3 during the spring 2003 outage.

During the spring 2003 outage, the licensee identified a free-span axial crack approximately 10-inches above the tubesheet on the hot leg side of the SG. This indication was identified with a bobbin coil and was associated with localized sludge deposits. The licensee expanded its inspection by inspecting a five tube buffer zone around the tube with the indication using a

+PointTM probe. No other indications were identified.

Based on review of the information provided, the NRC staff concludes that the licensee provided the information required by the Palo Verde Unit 3 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.

Principal Contributor: Y. Díaz Date: May 11, 2005