ML16020A332

Intent to Implement Recommendations of Westinghouse Technical Bulletin 15-1 and Unlikely Loss of Both Rwsts

ML16020A332
Person / Time
Site:	North Anna
Issue date:	01/13/2016
From:	Mark D. Sartain Virginia Electric & Power Co (VEPCO)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
15-558
Download: ML16020A332 (3)

Text

VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 January 13, 2016 10 CFR 50.90 U.S. Nuclear Regulatory Commission Serial No.15-558 Attention: Document Control Desk NLOS/DEA R0 Washington, DC 20555 Docket Nos.: 50-338/339 License Nos.: NPF-4/7 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION)

NORTH ANNA POWER STATION UNITS I AND 2 INTENT TO IMPLEMENT RECOMMENDATIONS OF WESTINGHOUSE TECHNICAL BULLETIN 15-1 AND UNLIKELY LOSS OF BOTH RWSTS This correspondence is to formally document an email communication sent to Mr. Tony Brown (NRC) from Mr. Mark Sartain (Dominion) on November 19, 2015. The purpose of the email was to; 1) discuss the status of Dominion's response to Westinghouse Technical Bulletin (TB) 15-1, and 2) provide supplemental information regarding the unlikely failure of both Refueling Water Storage Tanks (RWSTs) due to tornado generated missiles at North Anna Power Station. The technical content of the email to Mr. Brown is provided below:

Westingqhouse Technical Bulletin 15-1. Reactor Coolant System Temperature and Pressure Limits for the No. 2 Reactor Coolant Pump Seal Westinghouse Technical Bulletin (TB) 15-1 was issued on March 17, 2015 and recommended implementation of an extended cooldown of the Reactor Coolant System (RCS) to less than 350 degrees within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to maintain the integrity of the No. 2 reactor coolant pump (RCP) seal following a loss of all RCP seal cooling event.

Dominion reviewed the TB and entered the information into the Corrective Action system for further evaluation.

Dominion has been assessing the recommendations of TB 15-1 with the understanding that Westinghouse is evaluating less stringent cooldown requirements and intends to issue a revision to the TB. Additionally, Dominion has been working closely with Westinghouse and the Pressurized Water Reactor Owner's Group to determine the best solution that could qualify the No. 2 seal for higher temperatures and allow for relaxation of the cooldown time and temperature requirements.

North Anna Power Station intends to implement the vendor recommendations of the revised TB to ensure integrity of the RCP seal package while avoiding concerns of unintended consequences with TDAFW pump operation associated with the original TB recommendations.

_Supplemental Information Reqardingq the Unlikely Failure of Both North Anna Power Station RWSTs due to a Tornado Generated Missile The Refueling Water Storage Tanks (RWSTs) at North Anna Power Station are safety related structures that are seismically designed and protected from high winds, but are

Serial No: 15-558 Docket Nos.: 50-338/339 Page 2 of 3 not protected from tornado generated missiles. In the responses to Interim Staff Evaluation Confirmatory Item 3.2.1.9.A, Safety Evaluation (SE) #8, and SE #11, Dominion has stated that the loss of both site Refueling Water Storage Tanks (RWSTs) is highly unlikely. Regardless, the North Anna Power Station FLEX strategies can conservatively accommodate the loss of both RWSTs.

The loss of both RWSTs due to a tornado generated missile is highly unlikely based on the following: 1) the two RWSTs are approximately 450 feet apart and are located on opposite ends of the power block; separated by the Auxiliary Building and the Containment buildings, 2) a portion of the Auxiliary Building and the Containment buildings are tornado generated missile protected structures and the RWST top elevations are below the top elevations of the Auxiliary Building and Containments, 3) each RWST is further shielded by several other structures (including the Safeguards Buildings, Emergency Condensate Storage Tanks (ECSTs), the AFW Pumphouses, the Main Steam Valve houses, and the Service Building) on three of four sides. All of these structures, except the Service Building, are protected from tornado generated missiles, and 4) the side of each RWST that is not shielded by other structures is exposed to tornado generated missiles coming from opposite directions, thus minimizing the likelihood that missiles generated by a tornado would impact and damage both RWSTs.

Therefore, it is unlikely that tornado generated missiles will damage both RWSTs and it is reasonable to conclude that one of the two RWSTs would remain available as a borated water source following a tornado event.

Should you have any questions in regard to this submittal, please contact Ms. Diane E. Aitken at (804) 273-2694.

Si nce rely, Mar D"SrtinVicki L.Huill " t MakD.Srti NOTARY PUBLIC Vice President - Nuclear Engineering eg of Virgi04 a

SMy*Com~jissiofl Expires May 31, 2018 COMMONWEALTH OF VIRGINIA)

)

COUNTY OF HENRICO)

The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Mark D. Sartain, who is Vice President - Nuclear Engineering of Virginia Electric and Power Company. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that Company, and that the statements in the document are true to the best of his knowledge and belief.

Acknowledged before me this /**" day of 2.*UCy.7 ,2016.

My Commission Expires: ________ oO. */ Nl**bic A_*

Serial No: 15-558 Docket Nos.: 50-338/339 Page 3 of 3 Commitments made in this letter: No new regulatory commitments.

cc: U.S. Nuclear Regulatory Commission - Region II Marquis One Tower 245 Peachtree Center Avenue, NE Suite 1200 Atlanta, GA 30303-1 257 Dr. V. Sreenivas NRC Project Manager - North Anna U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 G-9A 11555 Rockville Pike Rockville, MD 20852-2738 Ms. Karen Cotton-Gross NRC Project Manager U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 G-9A 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector North Anna Power Station

VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 January 13, 2016 10 CFR 50.90 U.S. Nuclear Regulatory Commission Serial No.15-558 Attention: Document Control Desk NLOS/DEA R0 Washington, DC 20555 Docket Nos.: 50-338/339 License Nos.: NPF-4/7 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION)

NORTH ANNA POWER STATION UNITS I AND 2 INTENT TO IMPLEMENT RECOMMENDATIONS OF WESTINGHOUSE TECHNICAL BULLETIN 15-1 AND UNLIKELY LOSS OF BOTH RWSTS This correspondence is to formally document an email communication sent to Mr. Tony Brown (NRC) from Mr. Mark Sartain (Dominion) on November 19, 2015. The purpose of the email was to; 1) discuss the status of Dominion's response to Westinghouse Technical Bulletin (TB) 15-1, and 2) provide supplemental information regarding the unlikely failure of both Refueling Water Storage Tanks (RWSTs) due to tornado generated missiles at North Anna Power Station. The technical content of the email to Mr. Brown is provided below:

Westingqhouse Technical Bulletin 15-1. Reactor Coolant System Temperature and Pressure Limits for the No. 2 Reactor Coolant Pump Seal Westinghouse Technical Bulletin (TB) 15-1 was issued on March 17, 2015 and recommended implementation of an extended cooldown of the Reactor Coolant System (RCS) to less than 350 degrees within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to maintain the integrity of the No. 2 reactor coolant pump (RCP) seal following a loss of all RCP seal cooling event.

Dominion reviewed the TB and entered the information into the Corrective Action system for further evaluation.

Dominion has been assessing the recommendations of TB 15-1 with the understanding that Westinghouse is evaluating less stringent cooldown requirements and intends to issue a revision to the TB. Additionally, Dominion has been working closely with Westinghouse and the Pressurized Water Reactor Owner's Group to determine the best solution that could qualify the No. 2 seal for higher temperatures and allow for relaxation of the cooldown time and temperature requirements.

North Anna Power Station intends to implement the vendor recommendations of the revised TB to ensure integrity of the RCP seal package while avoiding concerns of unintended consequences with TDAFW pump operation associated with the original TB recommendations.

_Supplemental Information Reqardingq the Unlikely Failure of Both North Anna Power Station RWSTs due to a Tornado Generated Missile The Refueling Water Storage Tanks (RWSTs) at North Anna Power Station are safety related structures that are seismically designed and protected from high winds, but are

Serial No: 15-558 Docket Nos.: 50-338/339 Page 2 of 3 not protected from tornado generated missiles. In the responses to Interim Staff Evaluation Confirmatory Item 3.2.1.9.A, Safety Evaluation (SE) #8, and SE #11, Dominion has stated that the loss of both site Refueling Water Storage Tanks (RWSTs) is highly unlikely. Regardless, the North Anna Power Station FLEX strategies can conservatively accommodate the loss of both RWSTs.

The loss of both RWSTs due to a tornado generated missile is highly unlikely based on the following: 1) the two RWSTs are approximately 450 feet apart and are located on opposite ends of the power block; separated by the Auxiliary Building and the Containment buildings, 2) a portion of the Auxiliary Building and the Containment buildings are tornado generated missile protected structures and the RWST top elevations are below the top elevations of the Auxiliary Building and Containments, 3) each RWST is further shielded by several other structures (including the Safeguards Buildings, Emergency Condensate Storage Tanks (ECSTs), the AFW Pumphouses, the Main Steam Valve houses, and the Service Building) on three of four sides. All of these structures, except the Service Building, are protected from tornado generated missiles, and 4) the side of each RWST that is not shielded by other structures is exposed to tornado generated missiles coming from opposite directions, thus minimizing the likelihood that missiles generated by a tornado would impact and damage both RWSTs.

Therefore, it is unlikely that tornado generated missiles will damage both RWSTs and it is reasonable to conclude that one of the two RWSTs would remain available as a borated water source following a tornado event.

Should you have any questions in regard to this submittal, please contact Ms. Diane E. Aitken at (804) 273-2694.

Si nce rely, Mar D"SrtinVicki L.Huill " t MakD.Srti NOTARY PUBLIC Vice President - Nuclear Engineering eg of Virgi04 a

SMy*Com~jissiofl Expires May 31, 2018 COMMONWEALTH OF VIRGINIA)

)

COUNTY OF HENRICO)

The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Mark D. Sartain, who is Vice President - Nuclear Engineering of Virginia Electric and Power Company. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that Company, and that the statements in the document are true to the best of his knowledge and belief.

Acknowledged before me this /**" day of 2.*UCy.7 ,2016.

My Commission Expires: ________ oO. */ Nl**bic A_*

Serial No: 15-558 Docket Nos.: 50-338/339 Page 3 of 3 Commitments made in this letter: No new regulatory commitments.

cc: U.S. Nuclear Regulatory Commission - Region II Marquis One Tower 245 Peachtree Center Avenue, NE Suite 1200 Atlanta, GA 30303-1 257 Dr. V. Sreenivas NRC Project Manager - North Anna U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 G-9A 11555 Rockville Pike Rockville, MD 20852-2738 Ms. Karen Cotton-Gross NRC Project Manager U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 08 G-9A 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector North Anna Power Station