ML110880072
| ML110880072 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 03/17/2011 |
| From: | Hesser J Arizona Public Service Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 102-06331-JHH/GAM | |
| Download: ML110880072 (6) | |
Text
m A subsidiary of Pinnacle West Capital Corporation Palo Verde Nuclear Generating Station John H. Hesser Vice President Nuclear Engineering Tel: 623-393-5553 Fax: 623-393-6077 Mail Station 7605 PO Box 52034 Phoenix, Arizona 85072-2034 102-06331 -JHH/GAM March 17, 2011 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001
Dear Sirs:
Subject:
Palo Verde Nuclear Generating Station (PVNGS)
Units 1, 2, and 3 Docket Nos. STN 50-528, 50-529 and 50-530 Clarification to Response to Request for Additional Information for the Review of the PVNGS License Renewal Application (LRA), and LRA Amendment No. 31 By letter no. 102-06285, dated November 23, 2010 (NRC Agencywide Document Access and Management System [ADAMS] Accession No. ML103420101), Arizona Public Service Company (APS) submitted responses to a request for additional information regarding steam generators (SGs) related to the PVNGS license renewal application (LRA). A correction to the RAI response, and LRA Amendment No. 30 containing a change to Commitment No. 61 was provided in letter no. 102-06324, dated February 25, 2011 (ADAMS Accession No. ML110670168). contains a clarification to Commitment No. 61. Clarification is also provided regarding the materials of the SG divider patch plate cap screws and divider bar set screws. Amendment No. 31 of the LRA in Enclosure 2 contains the updated LRA Commitment No. 61.
Should you need further information regarding this submittal, please contact Glenn Michael, Licensing Engineer for License Renewal, at (623) 393-5750.
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ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Clarification to Response to Request for Additional Information for the Review of the PVNGS License Renewal Application (LRA), and LRA Amendment No. 31 Page 2 I declare under penalty of perjury that the foregoing is true and correct.
Executed on 3/I 7/II (date)
JHH/RAS/GAM/gat
Enclosures:
- 1. Clarification to Response to Request for Additional Information Regarding Steam Generators
- 2. Palo Verde Nuclear Generating Station License Renewal Application Amendment No. 31 cc:
E. E. Collins Jr.
J. R. Hall L. K. Gibson M. A. Brown L. M. Regner G. A. Pick NRC Region IV Regional Administrator NRC NRR Senior Project Manager NRC NRR Project Manager NRC Senior Resident Inspector for PVNGS NRC License Renewal Project Manager NRC Region IV (electronic)
ENCLOSURE 1 Clarification to Response to Request for Additional Information Regarding Steam Generators Clarification to Response to Request for Additional Information Regarding Steam Generators By letter no. 102-06285, dated November 23, 2010 (NRC Agencywide Document Access and Management System [ADAMS] Accession No. ML103420101), Arizona Public Service Company (APS) submitted responses to a request for additional information regarding steam generators (SGs) related to the PVNGS license renewal application (LRA). A correction to the RAI response and LRA Amendment No. 30 containing a change to Commitment No. 61 was provided in letter no. 102-06324, dated February 25, 2011 (ADAMS Accession No. ML110670168).
In order to clarify the inspection of the divider plate bars in the Unit 2 SGs, Commitment No. 61 in LRA Table A4-1 is changed from inspecting the "exposed portions" of the divider plate bars to inspecting "accessible surfaces" of the divider plate bars. This change, which is intended to use standard industry terminology to refer to surfaces that can be accessed for examination, is shown in LRA Amendment No. 31 in Enclosure 2.
Clacddin g Accessible Surfaces Generatorl Divider Setscrew D'ivider Plate Bat, Weld I
The February 25, 2011, letter stated that the divider bar set screws and the divider patch plate cap screws in the SGs are made of materials other than Alloy 690.
Although the SGs' parts lists specified the use of either Alloy 600 or Alloy 690 for the divider patch plate cap screws, further reviews have identified that the installed divider patch plate cap screws in all SGs are made of Alloy 690. The need to submit this clarification is being tracked as Palo Verde Action Request (PVAR) No. 3666912. The divider bar set screws are made of stainless steel and are under a compressive stress, and therefore are not susceptible to primary water stress corrosion cracking (PWSCC).
Further, the set screws are welded in place.
1
ENCLOSURE 2 Palo Verde Nuclear Generating Station License Renewal Application Amendment No. 31 LRA Section Table A4-1, Item 61
Palo Verde Nuclear Generating Station License Renewal Application Amendment No. 31 LRA Table A4-1, License Renewal Commitment No. 61 (new text underlined, deleted text shown with strike-through):
Item Commitment LRA Section
[ Implementation No, Schedule____
61 In response to the NRC staff concern regarding potential failure of the SG reactor coolant system pressure boundary due to possible PWSCC of SG divider plate bar welds in all units and the divider plate bars in Unit 2, APS commits to perform one of the following three resolution options:
- 1. Perform an inspection of each Palo Verde Unit 1, 2, and 3 steam generator to assess the condition of the divider plate bar welds in all units, and the exposed portions accessible surfaces of the divider plate bars in Unit 2. The examination technique(s) will be capable of detecting PWSCC in the divider plate bar welds in all units, and in the exposed potions accessible surfaces of the divider plate bars in Unit 2.
Response to Draft RAI Regarding Steam Generators in APS letter No. 102-06285, dated November 23, 2010.
and Supplemental Response to Draft RAI Regarding Steam Generators in APS letter No. 102-06324, dated February 25, 2011.
and Clarification in APS letter No. 102-06331, dated March 17, 2011.
If Option (1) is selected, it will be completed for each SG in each unit during an SG tube eddy-current inspection outage between 20 and 25 calendar years of SG operation.
If Option (2) or Option (3) is selected, it will be completed prior to September 1, 2023.
OR 2.
Of Perform an analytical evaluation of the steam generator divider plate bar welds in all units, and the divider plate bars in Unit 2, in order to establish a technical basis which concludes that the SG reactor coolant system pressure boundary is adequately maintained with the presence of steam generator divider plate bar weld cracking.
- 3. If results of industry and NRC studies and operating experience document that potential failure of the SG reactor coolant system pressure boundary due to PWSCC cracking of SG divider plate bar welds and the divider plate bars in Unit 2 is not a credible concern, this commitment will be revised to reflect that conclusion.
(RCTSAIs 3561775 [U11, 3561777 [U21, 3561779 [U31)