ML073460517

Request for Additional Information the 2006 Steam Generator Tube Inspections (Tac MD5981)

ML073460517
Person / Time
Site:	Palo Verde
Issue date:	01/09/2008
From:	Markley M NRC/NRR/ADRO/DORL/LPLIV
To:	Edington R Arizona Public Service Co
Markley, M T, NRR/DORL/LP4, 301-415-5723
References
TAC MD5981
Download: ML073460517 (5)

Text

January 9, 2008 Mr. Randall K. Edington Senior Vice President, Nuclear Mail Station 7602 Arizona Public Service Company P. O. Box 52034 Phoenix, AZ 85072-2034

SUBJECT:

PALO VERDE NUCLEAR GENERATING STATION, UNIT 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING THE 2006 STEAM GENERATOR TUBE INSPECTIONS (TAC NO. MD5982)

Dear Mr. Edington:

By letters dated February 9, and May 3, 2007, Arizona Public Service Company submitted information related to the 2006 inservice inspection examination conducted at Palo Verde Nuclear Generating Station, Unit 2. These inspections were performed during the 13th refueling outage of Unit 2 that was conducted from September 30 to November 14, 2006.

The Nuclear Regulatory Commission (NRC) staff has reviewed the information provided and determined that additional information is required in order to complete the evaluation. The additional information being requested is related to the 2006 steam generator tube inspections.

The staffs request was provided to your staff via electronic mail on December 7, 2007. As discussed with Glenn Michael of your staff, the NRC staff is requesting a response within 60 days of the date of this letter.

If you have any questions, please contact me at 301-415-5723.

Sincerely,

/RA/

Michael T. Markley, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. STN 50-529

Enclosure:

Request for Additional Information cc w/encl: See next page

January 9, 2008 Mr. Randall K. Edington Senior Vice President, Nuclear Mail Station 7602 Arizona Public Service Company P. O. Box 52034 Phoenix, AZ 85072-2034

SUBJECT:

PALO VERDE NUCLEAR GENERATING STATION, UNIT 2 - REQUEST FOR ADDITIONAL INFORMATION REGARDING THE 2006 STEAM GENERATOR TUBE INSPECTIONS (TAC NO. MD5982)

Dear Mr. Edington:

By letters dated February 9, and May 3, 2007, Arizona Public Service Company submitted information related to the 2006 inservice inspection examination conducted at Palo Verde Nuclear Generating Station, Unit 2. These inspections were performed during the 13th refueling outage of Unit 2 that was conducted from September 30 to November 14, 2006.

The Nuclear Regulatory Commission (NRC) staff has reviewed the information provided and determined that additional information is required in order to complete the evaluation. The additional information being requested is related to the 2006 steam generator tube inspections.

The staffs request was provided to your staff via electronic mail on December 7, 2007. As discussed with Glenn Michael of your staff, the NRC staff is requesting a response within 60 days of the date of this letter.

If you have any questions, please contact me at 301-415-5723.

Sincerely,

/RA/

Michael T. Markley, Senior Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. STN 50-529

Enclosure:

Request for Additional Information cc w/encl: See next page DISTRIBUTION:

PUBLIC RidsNrrDorlDpr RidsNrrPMMMarkley RidsRgn4MailCenter LPLIV r/f RidsNrrDciCsgb RidsNrrLAJBurkhardt AJohnson, NRR/DCI/CSGB RidsAcrsAcnwMailCenter RidsNrrDorlLpl4 RidsOgcRp KKarwoski, NRR/DCI/CSGB ADAMS Accession No.: ML073460517 (*) RAI input memo OFFICE NRR/LPL4/PM NRR/LPL4/LA NRR/DCI/CSGB NRR/LPL4/BC NAME MMarkley JBurkhardt AHiser (*) THiltz DATE 1/9/08 12/17/07 11/29/07 1/9/08 OFFICIAL AGENCY RECORD

REQUEST FOR ADDITIONAL INFORMATION ARIZONA PUBLIC SERVICE COMPANY, ET. AL.

PALO VERDE NUCLEAR GENERATING STATION, UNIT 2 DOCKET NO. STN 50-529 By letter dated February 9, 2007 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML070510481), Arizona Public Service Company (APS, the licensee) submitted the Palo Verde Nuclear Generating Station, Unit 2, summary report regarding inservice inspection examinations performed during the 13th refueling outage of Unit 2 that was conducted from September 30 to November 14, 2006. In addition, APS submitted by letter dated May 3, 2007 (ADAMS Accession No. ML071360096), the special report which discussed Unit 2's steam generator (SG) tube plugging during its 13th refueling outage.

The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the information provided and determined that the following additional information is required in order to complete the evaluation:

1. Section 3.0 of the May 3, 2007, SG Tube Inspection Report discusses the pre-outage predictions from the Unit 2 cycle 13 (U2R13) operational assessment, which predicted a maximum through-wall (TW) depth for batwing-related tube degradation of 48 percent, based on a beginning-of-cycle value of 18 percent.

The maximum measured batwing-related degradation in U2R13 was 49 percent.

It appears that APS took the largest beginning-of-cycle measured indication and added a maximum or highly conservative growth rate to predict the maximum TW depth at the end-of-cycle. In consideration of the fact that the maximum measured TW depth was slightly larger than the predicted value, please discuss any corrective actions taken in response to this operating experience.

2. Please discuss the scope and results of any secondary-side inspections, including foreign object search and retrieval. Please discuss the extent to which visual inspections were performed at possible loose-part indications identified through eddy current examinations and the results of these exams. Please discuss the extent to which loose parts were identified visually but not by eddy current examination.

3. Please discuss the extent to which rotating probes were used to inspect dents/dings or other locations such as small-radius U-bends or top-of-tubesheet locations. Please discuss whether any distorted dent indications were detected during the inspections.

4. Please provide the cumulative effective full power months of operation for each refueling outage, or SG inspection outage, since the steam generators were installed.

ENCLOSURE

5. In Table 1, Examination Summary, of the SG Tube Inspection Report, APS provides the number of exams performed. Appendix E, Plug Lists, Plug Maps, Plug History, indicates that APS performed a bobbin exam of 100 percent of the tubes. Please clarify whether all tubes were examined full length (using a combination of bobbin or rotating probe techniques). It is not apparent from the NRC staffs review of Table 1 that all tubes were inspected in the U-bend region.

6. In Table 2, Indication Summary, of the SG Tube Inspection Report, four volumetric indications were reported in SG 22. Since Note 2 of Table 2 states that this is the number of tubes and not indications, please discuss the nature of the volumetric indications in the tube that was not plugged and the basis for not plugging this tube.

7. In SG 22, the tube in row 39 column 86 was preventively plugged and stabilized, since it was next to a non-stabilized tube that was plugged for wear. Please discuss why this one tube was plugged and stabilized but other adjacent tubes do not appear to have been plugged and stabilized.

Palo Verde Nuclear Generating Station 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 Mr. Douglas Kent Porter Mr. Geoffrey M. Cook Senior Counsel Southern California Edison Company Southern California Edison Company 5000 Pacific Coast Hwy Bldg D21 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 Mr. Jeffrey T. Weikert Assistant General Counsel Regional Administrator, Region IV El Paso Electric Company U.S. Nuclear Regulatory Commission Mail Location 167 Harris Tower & Pavillion 123 W. Mills 611 Ryan Plaza Drive, Suite 400 El Paso, TX 79901 Arlington, TX 76011-8064 Mr. John Schumann Chairman Los Angeles Department of Water & Power Maricopa County Board of Supervisors Southern California Public Power Authority 301 W. Jefferson, 10th Floor P.O. Box 51111, Room 1255-C Phoenix, AZ 85003 Los Angeles, CA 90051-0100 Mr. Aubrey V. Godwin, Director Mr. Brian Almon Arizona Radiation Regulatory Agency Public Utility Commission 4814 South 40 Street William B. Travis Building Phoenix, AZ 85040 P.O. Box 13326 1701 North Congress Avenue Mr. Scott Bauer, Acting General Manager Austin, TX 78701-3326 Regulatory Affairs and Performance Improvement Ms. Karen O'Regan Palo Verde Nuclear Generating Station Environmental Program Manager Mail Station 7636 City of Phoenix P.O. Box 52034 Office of Environmental Programs Phoenix, AZ 85072-2034 200 West Washington Street Phoenix AZ 85003 Mr. Matthew Benac Assistant Vice President Nuclear & Generation Services El Paso Electric Company 340 East Palm Lane, Suite 310 Phoenix, AZ 85004