ML11180A008

Response to Request for Additional Information on Severe Accident Management Design Alternatives

ML11180A008
Person / Time
Site:	Watts Bar
Issue date:	06/27/2011
From:	Stinson D Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC MD8203
Download: ML11180A008 (2)

Text

Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000 June 27, 2011 10 CFR 50.4 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 2 NRC Docket No. 50-391

Subject:

WATTS BAR NUCLEAR PLANT (WBN) UNIT 2 - RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ON SEVERE ACCIDENT MANAGEMENT DESIGN ALTERNATIVES (SAMDA) (TAC NO.

MD8203)

References:

1. E-mail from Justin C. Poole, U.S. Nuclear Regulatory Commission, to William D. Crouch, TVA, dated June 21, 2011

2. TVA letter to NRC dated June 17, 2011, "Watts Bar Nuclear Plant (WBN) - Unit 2 - Response to Request for Additional Information Regarding Severe Accident Management Alternative Review (TAC NO. MD8203)"

The purpose of this letter is to respond to a request for additional information (RAI) provided in Reference 1. TVA's June 17, 2011 letter (Reference 2) stated that the mission time for the Reactor Protection System (RPS), Engineered Safety Feature Actuation System (ESFAS), and instrumentation is 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The NRC questioned what instrumentation had the 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> mission time.

Subsequently, TVA verbally clarified and herein confirms that this reference to instrumentation was meant to refer to instruments associated with a reactor trip, but not specifically classified as RPS or ESFAS. The 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> mission time was not meant to encompass all plant instrumentation. Instrumentation necessary and sufficient to monitor safe shutdown is considered to have a mission time of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

IL U.S. Nuclear Regulatory Commission Page 2 June 27, 2011 There are no new commitments provided in this letter. If you have any questions, please contact Bill Crouch at (423) 365-2004.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 2 7 th day of June, 2011.

Respectfully, David Stinson Watts Bar Unit 2 Vice President cc:

U. S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, Georgia 30303-1257 NRC Resident Inspector Unit 2 Watts Bar Nuclear Plant 1260 Nuclear Plant Road Spring City, Tennessee 37381