ML071930363

MCR and ESGR e-mail Surry RAI Response for La

ML071930363
Person / Time
Site:	Surry
Issue date:	07/12/2007
From:	Siva Lingam NRC/NRR/ADRO/DORL/LPLII-1
To:	Geoffrey Miller Dominion
Lingam, Siva NRR/DORL 415-1564
References
TAC MD4622, TAC MD4623
Download: ML071930363 (3)

Text

From: Siva Lingam To: gary.D.Miller@Dom.com Date: 7/12/2007 11:29:43 AM

Subject:

Re: SURRY RAI RESPONSE Please note the Andrew's comments/suggestions when you are providing responses.

Siva P. Lingam Project Manager (NRR/DORL/LPL2-1)

Surry Nuclear Station Location: O8-D5 Mail Stop: O8-G9 Telephone: 301-415-1564 Fax: 301-415-1222 E-mail address: spl@nrc.gov

>>> Andrew Howe 7/12/2007 10:45 AM >>>

Considering what was said in the call, I think a limited response may be more appropriate. If the licensee responded to questions a and f, on why the PRA model is conservative by assuming control room abandonment (i.e., actual expected temperatures and equipment qualification, procedures for use of alternate cooling at lower temperatures, availability of backup chillers not credited in the PRA), then responses to b - e would not be necessary to support the SE. I would propose the formal additional RAI to replace questions a - e:

The licensee's PRA model assumes that for a loss of MCR cooling, the MCR would be abandonned and the plant would be shut down from the ASP. The licensee should describe why this PRA assumption is conservative, addressing the anticipated temperature transient in the control room, equipment qualification of the MCR components, and the availability and procedural controls for alternate cooling capabilities not assumed to be used in the PRA.

Andrew J Howe USNRC - Office of Nuclear Reactor Regulation Division of Risk Assessment 301-415-3078

>>> Siva Lingam 7/3/2007 1:45 PM >>>

Attached please find additional RAIs Andrew wants to discuss with a conference call. Please give me a call.

Siva P. Lingam Project Manager (NRR/DORL/LPL2-1)

Surry Nuclear Station Location: O8-D5 Mail Stop: O8-G9 Telephone: 301-415-1564 Fax: 301-415-1222 E-mail address: spl@nrc.gov

>>> Andrew Howe 7/3/2007 1:37 PM >>>

I have reviewed Surry's 6/28 response to APLA's RAI. Some additional clarifications are still

required, and perhaps a phone call might be appropriate:

6/5/07 RAI a - Is control room abandonment for high temperature conditions proceduralized and trained, and what is the cue(s) for abandonment? Is the control room equipment qualified up to the temperature at which abandonment occurs, or are equipment failures possible due to high temperatures prior to abandonment?

b - Why is RCP seal integrity not a requirement for a remote safe shutdown?

c - Is a long term AFW supply available to maintain hot standby conditions without transition to cold shutdown and RHR cooling?

d - What is changed in the ESGRs such that less cooling is required depending upon the control staff location?

e - What probability is used for successful transfer to the ASP, and what is the basis for that probability?

f - Would the nonsafety chillers in fact be available and used rather than control room abandonment (i.e., is this a conservative assumption, or does it reflect actual plant limitations)?

Andrew J Howe USNRC - Office of Nuclear Reactor Regulation Division of Risk Assessment 301-415-3078 CC: Andrew Howe Mail Envelope Properties (469648E7.529 : 13 : 35786)

Subject:

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