NOC-AE-06001968, Supplement 2 to the Response to Generic Letter 2004-02

Supplement 2 to the Response to Generic Letter 2004-02

ML060370145
Person / Time
Site:	South Texas
Issue date:	01/30/2006
From:	Jordan T South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GL-04-002, NOC-AE-06001968, TAC MC4719, TAC MC4720
Download: ML060370145 (4)

Text

Nuclear Operating Company South TewsPr/csdEklctrcGnratingStation PO. o289 HMdsavrth, fiwas77483 JAVA January 30, 2006 NOC-AE-06001968 10CFR50.54(f)

U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 South Texas Project Units 1 and 2 Docket Nos. STN 50-498 and STN 50-499 Supplement 2 to the Response to Generic Letter 2004-02 (TAC Nos. MC4719 and MC4720)

Reference:

Letter, T. J. Jordan to Document Control Desk, "Supplement 1 to the Response to Generic Letter 2004-02", dated August 31, 2005 (NOC-AE-05001922, ML052500311)

In the referenced letter regarding STPNOC's response to Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized Water Reactors", STPNOC committed to provide an update of pending analyses and testing by January 31, 2006. Attachment 1 to this letter provides the current status.

The commitments in this letter are listed in Attachment 2.

If there are any questions regarding this response, please contact Scott Head at (361) 972-7136 or me at (361) 972-7902.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on J L AyV: 30,0 zoo Vice President, Engineering awh/

Attachments:

1. Supplement 2 to the Response to Gaeneric Letter 2004-02

2. List of Commitments 06001968 (Supplement 2 Reponse to GNL 2004-02, Sump lssue).doc STI:31978136

NOC-AE-06001 968 Page 2 of 2 cc:

(paper copy) (electronic copy)

Bruce S. Mallett A. H. Gutterman, Esquire Regional Administrator, Region IV Morgan, Lewis & Bockius LLP U. S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Mohan C. Thadani Arlington, Texas 76011-8064 U. S. Nuclear Regulatory Commission Richard A. Ratliff Jack A. Fusco Bureau of Radiation Control Michael A. Reed Texas Department of State Health Services Texas Genco, LP 1100 West 49th Street Austin, TX 78756-3189 Jeffrey Cruz C. Kirksey U. S. Nuclear Regulatory Commission City of Austin P. 0. Box 289, Mail Code: MN1 16 Wadsworth, TX 77483 Jon C. Wood Cox Smith Matthews C. M. Canady J. J. Nesrsta City of Austin R. K. Temple Electric Utility Department E. Alarcon 721 Barton Springs Road City Public Service Austin, TX 78704 NOC-AE-06001968 Page 1 of 1 SUPPLEMENT 2 TO THE RESPONSE TO GENERIC LETTER 2004-02 As previously stated, STP Nuclear Operating Company (STPNOC) will be in full compliance with the regulatory requirements discussed in the applicable regulatory requirements section of GNL 2004-02 by December 31, 2007. This includes the full implementation of all plant modifications and required corrective actions.

STPNOC has a contract in place for Performance Contracting Inc. to provide an advanced design sump strainer for each Unit to replace the current sump screens. The modifications are scheduled to be implemented in Unit 1 during the Fall 2006 refueling outage and in Unit 2 during the Spring 2007 refueling outage. Laboratory testing for the STP specific strainer design is pending. *The testing will demonstrate the adequacy of the Net Pump Suction Head margins for the Emergency Core Cooling System and Containment Spray System Pumps. The strainer testing will also include bypass sampling and an evaluation to determine the quantity and characteristics of debris that bypasses the strainer.

A three-dimensional computational fluid dynamics analysis for debris transport is being finalized. The results are expected to yield transport fractions that are smaller than those determined in the baseline transport analysis. This will result in less debris loading on the strainer.

A latent debris walkdown inside containment was previously scheduled for the Fall 2005 refueling outage in Unit 2. This walkdown has been rescheduled to be performed in Unit 1 during power operation prior to the start of the Fall 2006 refueling outage. The at-power walkdown near the end of the fuel cycle is expected to be more representative of latent debris conditions than during an outage when the Unit is shutdown and many maintenance and inspection activities are taking place.

Resolution of the debris blockage issue concerning fuel assemblies is pending. A generic approach is ongoing by the Westinghouse Owners Group that includes evaluation of flow paths within the reactor vessel and evaluation of proposed testing of fuel assemblies in the laboratory. In addition, the results of the strainer bypass tests mentioned above will be used to reduce the fiber loading on the fuel assemblies.

A coatings test will be conducted by Westinghouse to demonstrate that the zone of influence for coatings may be defined using a radius of 5D (5 times the diameter of the break pipe). This result may be used to reduce the debris loading on the sump and to demonstrate margin for the new sump strainer design. The testing is planned to be completed by the second quarter of 2006.

Chemical effects testing and evaluation is; being conducted by the Westinghouse Owners Group. The results will be applied by STPNOC to the sump strainer design to show that acceptable NPSH margins are maintained.

STPNOC will provide another supplemental response with an update on the sump performance evaluation upon completion of pending analyses and testing.

Attachment 2 NOC-AE-06001 968 Page 1 of 1 List of Commitments The following table identifies those actions to which STP Nuclear Operating Company committed in this document. Any statements in this submittal with the exception of those in the table below are provided for information purposes and are not considered commitments. Please direct questions regarding these commitments to Scott Head at (361) 972-7136.

Commitment Due Date Condition Report

1. STPNOC will provide a Supplemental Response to August 31, 04-12498-11 Generic Letter 2004-02 upon completion of pending 2006 analyses and testing.

Text

Nuclear Operating Company South TewsPr/csdEklctrcGnratingStation PO. o289 HMdsavrth, fiwas77483 JAVA January 30, 2006 NOC-AE-06001968 10CFR50.54(f)

U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 South Texas Project Units 1 and 2 Docket Nos. STN 50-498 and STN 50-499 Supplement 2 to the Response to Generic Letter 2004-02 (TAC Nos. MC4719 and MC4720)

Reference:

Letter, T. J. Jordan to Document Control Desk, "Supplement 1 to the Response to Generic Letter 2004-02", dated August 31, 2005 (NOC-AE-05001922, ML052500311)

In the referenced letter regarding STPNOC's response to Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized Water Reactors", STPNOC committed to provide an update of pending analyses and testing by January 31, 2006. Attachment 1 to this letter provides the current status.

The commitments in this letter are listed in Attachment 2.

If there are any questions regarding this response, please contact Scott Head at (361) 972-7136 or me at (361) 972-7902.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on J L AyV: 30,0 zoo Vice President, Engineering awh/

Attachments:

1. Supplement 2 to the Response to Gaeneric Letter 2004-02

2. List of Commitments 06001968 (Supplement 2 Reponse to GNL 2004-02, Sump lssue).doc STI:31978136

NOC-AE-06001 968 Page 2 of 2 cc:

(paper copy) (electronic copy)

Bruce S. Mallett A. H. Gutterman, Esquire Regional Administrator, Region IV Morgan, Lewis & Bockius LLP U. S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Mohan C. Thadani Arlington, Texas 76011-8064 U. S. Nuclear Regulatory Commission Richard A. Ratliff Jack A. Fusco Bureau of Radiation Control Michael A. Reed Texas Department of State Health Services Texas Genco, LP 1100 West 49th Street Austin, TX 78756-3189 Jeffrey Cruz C. Kirksey U. S. Nuclear Regulatory Commission City of Austin P. 0. Box 289, Mail Code: MN1 16 Wadsworth, TX 77483 Jon C. Wood Cox Smith Matthews C. M. Canady J. J. Nesrsta City of Austin R. K. Temple Electric Utility Department E. Alarcon 721 Barton Springs Road City Public Service Austin, TX 78704 NOC-AE-06001968 Page 1 of 1 SUPPLEMENT 2 TO THE RESPONSE TO GENERIC LETTER 2004-02 As previously stated, STP Nuclear Operating Company (STPNOC) will be in full compliance with the regulatory requirements discussed in the applicable regulatory requirements section of GNL 2004-02 by December 31, 2007. This includes the full implementation of all plant modifications and required corrective actions.

STPNOC has a contract in place for Performance Contracting Inc. to provide an advanced design sump strainer for each Unit to replace the current sump screens. The modifications are scheduled to be implemented in Unit 1 during the Fall 2006 refueling outage and in Unit 2 during the Spring 2007 refueling outage. Laboratory testing for the STP specific strainer design is pending. *The testing will demonstrate the adequacy of the Net Pump Suction Head margins for the Emergency Core Cooling System and Containment Spray System Pumps. The strainer testing will also include bypass sampling and an evaluation to determine the quantity and characteristics of debris that bypasses the strainer.

A three-dimensional computational fluid dynamics analysis for debris transport is being finalized. The results are expected to yield transport fractions that are smaller than those determined in the baseline transport analysis. This will result in less debris loading on the strainer.

A latent debris walkdown inside containment was previously scheduled for the Fall 2005 refueling outage in Unit 2. This walkdown has been rescheduled to be performed in Unit 1 during power operation prior to the start of the Fall 2006 refueling outage. The at-power walkdown near the end of the fuel cycle is expected to be more representative of latent debris conditions than during an outage when the Unit is shutdown and many maintenance and inspection activities are taking place.

Resolution of the debris blockage issue concerning fuel assemblies is pending. A generic approach is ongoing by the Westinghouse Owners Group that includes evaluation of flow paths within the reactor vessel and evaluation of proposed testing of fuel assemblies in the laboratory. In addition, the results of the strainer bypass tests mentioned above will be used to reduce the fiber loading on the fuel assemblies.

A coatings test will be conducted by Westinghouse to demonstrate that the zone of influence for coatings may be defined using a radius of 5D (5 times the diameter of the break pipe). This result may be used to reduce the debris loading on the sump and to demonstrate margin for the new sump strainer design. The testing is planned to be completed by the second quarter of 2006.

Chemical effects testing and evaluation is; being conducted by the Westinghouse Owners Group. The results will be applied by STPNOC to the sump strainer design to show that acceptable NPSH margins are maintained.

STPNOC will provide another supplemental response with an update on the sump performance evaluation upon completion of pending analyses and testing.

Attachment 2 NOC-AE-06001 968 Page 1 of 1 List of Commitments The following table identifies those actions to which STP Nuclear Operating Company committed in this document. Any statements in this submittal with the exception of those in the table below are provided for information purposes and are not considered commitments. Please direct questions regarding these commitments to Scott Head at (361) 972-7136.

Commitment Due Date Condition Report

1. STPNOC will provide a Supplemental Response to August 31, 04-12498-11 Generic Letter 2004-02 upon completion of pending 2006 analyses and testing.