ML062970080
| ML062970080 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 10/12/2006 |
| From: | Mauldin D Arizona Public Service Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 102-05584-CDM/TNW/GAM, GL-04-002 | |
| Download: ML062970080 (6) | |
Text
Generic Letter 2004-02 David Mauldin Mail Station 7605 Palo Verde Nuclear Vice President Tel: 623-393-5553 PO Box 52034 Generating Station Nuclear Engineering Fax: 623-393-6077 Phoenix, Arizona 85072-2034 102-05584-CDM/TNW/GAM October 12, 2006 Attn: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001
Dear Sirs:
Subject:
Palo Verde Nuclear Generating Station (PVNGS)
Unit 2 Docket No. STN 50-529 Request for Extension to Delay Implementation of Containment Sump Strainer Changes Associated with NRC Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" By letter no. 102-05336, dated September 1, 2005, Arizona Public Service Company (APS) submitted to the NRC a response to Generic Letter (GL) 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors." In that submittal, APS committed to install new containment sump strainers in PVNGS Units 1, 2, and 3 during the refueling outages scheduled for spring 2007, fall 2006, and fall 2007, respectively. This submittal is requesting an extension to delay the installation of the new containment sump strainers in Unit 2 until the refueling outage scheduled for April 2008.
APS has been aggressively pursuing the completion of the design and procurement of the new sump strainers in order to meet the fall 2006 Unit 2 refueling outage installation commitment. A letter of intent was issued to Control Components, Inc., (CCI) in August 2005 to design and provide the new containment sump strainers for PVNGS, and APS has maintained regular contact with CCI to help assure that the material delivery schedule would be met. APS has been actively working with CCI to assure that the materials and documentation would be available in time for the fall 2006 Unit 2 outage installation. However, it was very recently determined that the materials and material documentation for the new sump strainers would not be available in time for the modification to be mockup tested and installed in Unit 2 during the fall 2006 refueling outage. The delay is a result of CCI's workload, which has included designing and supplying new containment sump strainers to other nuclear plants with fall 2006 refueling outages. This delay is not expected to impact the replacement sump strainer installation In Units I and 3 during their scheduled 2007 refueling outages.
A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway e Comanche Peak a Diablo Canyon
- Palo Verde
- South Texas Project e Wolf Creek
ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Request for Extension to Delay Implementation of Containment Sump Strainer Changes Associated with NRC Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" Page 2 In SECY-06-0078, dated March 31, 2006, the NRC staff recognized that licensees may encounter situations that could delay the implementation of the final containment sump strainer hardware modifications as committed in response to GL 2004-02. SECY 0078 states the following with respect to extension requests to delay the implementation of final containment sump hardware modifications for GL 2004-02:
Proposed extensions to permit changes at the next outage of opportunity after December 2007 may be acceptable if, based on the licensee's request, the staff determines that:
" the licensee has a plant-specific technicaYexperimental plan with milestones and schedule to address outstanding technical issues with enough margin to account for uncertainties; and
" the licensee identifies mitigative measures to be put in place prior to December 31,2007, and adequately describes how these mitigative measures will minimize the risk of degraded ECCS and CSS functions during the extension period.
APS is requesting an extension to delay the installation of the new containment sump strainers in Unit 2 until the next outage opportunity after December 31, 2007, which would be the Unit 2 refueling outage scheduled for April 2008. APS has the following plant-specific technical/experimental plan with milestones and schedule to address outstanding technical issues with enough margin to account for uncertainties:
- The new strainer confirmatory head-loss testing, capture ratio verification, and chemical effects margin validation are scheduled to be completed by March 31, 2007, as shown in the attached commitments list.
The following mitigative measures have been or will be put in place in Unit 2 prior to December 31, 2007:
- The compensatory operator actions described in APS letter no. 102-05236, dated March 25, 2005, in response to NRC Bulletin 2003-01, "Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized Water Reactors," have been implemented.
- The Fiberfrax insulation will be removed from Unit 2 during the fall 2006 refueling outage, as shown in the attached commitment list.
ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Request for Extension to Delay Implementation of Containment Sump Strainer Changes Associated with NRC Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" Page 3
- The changes to programs and procedures to ensure and/or enhance the control of transportable debris in containment will be implemented in Unit 2 during the fall 2006 refueling outage, as shown in the attached commitment list.
In addition, the following favorable conditions exist at PVNGS Unit 2:
" The existing PVNGS Unit 2 sump screens (two sumps with screens approximately 210 sq. ft. each) are relatively large compared to typical plant screens prior to the GL 2004-02 replacements.
" Although PVNGS Unit 2 uses trisodium phosphate as a containment pH buffer, no calcium silicate insulation material is used in containment that might react to form calcium phosphate precipitate.
If approved, APS commits to install new sump strainers in PVNGS Unit 2 during the 2R14 refueling outage scheduled to be completed by approximately May 15, 2008. The list of GL 2004-02 commitments and status or due dates is provided in the attachment.
If you have any questions, please contact Thomas N. Weber at (623) 393-5764.
Sincerely, CDM/TNW/GAM/
Attachment:
As stated cc:
B. S. Mallett NRC Region IV Regional Administrator M. B. Fields NRC NRR Project Manager G. G. Warnick NRC Senior Resident Inspector for PVNGS
Attachment List of Generic Letter 2004-02 Commitments and Status or Due Dates GL 2004-02 REGULATORY COMMITMENT PREVIOUS REVISED (from APS letter no. 102-05560 DUE DATE DUE DATE or dated August 30, 2006)
STATUS
- 1. Evaluate the recommendations contained in the December 31, Completed Westinghouse downstream effects evaluation for 2005 PVNGS and establish an implementation schedule for appropriate recommendations.
- 2. Perform confirmatory head-loss testing of new March 31, No Change strainer with plant specific debris to ensure an 2007 adequate design.
- 3. Verify that a capture ratio of 97% or higher can be March 31, No Change achieved in the final design of the new sump screen 2007 to ensure that the fuel evaluation contained in the Westinghouse downstream effects evaluation is bounding.
- 4. Perform sump strainer structural evaluation to October 31, No Change ensure seismic and operational integrity.
2006
- 5. Validate allocated margins for Chemical Effects in March 31, No Change strainer head-loss to ensure an adequate design.
2007
- 6. Perform a confirmatory containment latent debris June 30, 2006 Completed walkdown of PVNGS Units 1 and 3.
- 7. Perform a confirmatory containment unqualified June 30, 2006 Completed coating walkdown of PVNGS Units I and 3.
- 8. Review the existing programmatic controls for November 30, No Change containment coatings identified in the response to 2006 GL 98-04, "Potential for Degradation of the Emergency Core Cooling System and the Containment Spray System after a Loss-of-Coolant Accident Because of Construction and Protective Coating Deficiencies and Foreign Material in Containment," for their adequacy.
- 9. Review the existing programmatic and procedural November 30, No Change controls in place to prevent potentially transportable 2006 debris (insulation, signs and foreign material) in the containment building to ensure that the bounding assumptions in the design of the new strainers will be maintained.
1
Attachment List of Generic Letter 2004-02 Commitments and Status or Due Dates GL 2004-02 REGULATORY COMMITMENT PREVIOUS REVISED (from APS letter no. 102-05560 DUE DATE DUE DATE or dated August 30, 2006)
STATUS
- 10. Implement in Unit I changes to programs and 1R13 refueling No Change procedures to ensure and/or enhance the control of outage transportable debris in containment.
(approx.
May 31, 2007)
- 11. Implement in Unit 2 changes to programs and 2R1 3 refueling No Change procedures to ensure and/or enhance the control of outage transportable debris in containment.
(approx.
Nov. 30, 2006)
- 12. Implement in Unit 3 changes to programs and 3R13 refueling No Change procedures to ensure and/or enhance the control of outage transportable debris in containment.
(approx.
Dec. 31, 2007)
1 R1 3 refueling No Change outage (approx.
May 31, 2007)
2R13 refueling 2R14 refueling outage outage (approx.
(approx.
Nov. 30, 2006) May 15, 2008)
3R1 3 refueling No Change outage (approx.
Dec. 31, 2007)
- 16. Remove installed Fiberfrax insulation in PVNGS 1R13 refueling No Change Unit 1.
outage (approx.
May 31, 2007)
- 17. Remove installed Fiberfrax insulation in PVNGS 2R13 refueling No Change Unit 2.
outage (approx.
Nov. 30, 2006) 2
Attachment List of Generic Letter 2004-02 Commitments and Status or Due Dates GL 2004-02 REGULATORY COMMITMENT PREVIOUS REVISED (from APS letter no. 102-05560 DUE DATE DUE DATE or dated August 30, 2006)
STATUS
- 18. Remove installed Fiberfrax insulation in PVNGS 3R1 3 refueling No Change Unit 3.
outage (approx.
Dec. 31, 2007)
- 19. By June 30, 2006, after plant specific strainer March 31, No Change testing has been completed and the Westinghouse 2007 downstream effects evaluation for PVNGS has been evaluated, APS will submit an update to the NRC to report the validation of the allocated margins for chemical effects and identify any recommendations from the Westinghouse evaluation to be implemented.
3