ML062210005

LAR for EDG Extension and Completion Time

ML062210005
Person / Time
Site:	Prairie Island
Issue date:	08/08/2006
From:	Mahesh Chawla NRC/NRR/ADRO/DORL/LPLE
To:	Vincent D Nuclear Management Co
M. Chawla LPL3-1
References
TAC MC9001, TAC MC9002
Download: ML062210005 (2)

Text

From: Mahesh Chawla To: dale.Vincent@nmcco.com Date: 08/08/2006 1:50:06 PM

Subject:

PI - LAR for EDG Extension and Completion Time - MC9001/MC9002

Dale, Following are the questions which the staff would like to discuss with your representatives during the telephone conference scheduled for tomorrow @ 3.00 pm.

The staff would like to discuss the licensee's delta CDF (and LERF) calculations with respect to the assumed amount of unavailability of the EDGs.

Prairie Island explained (in response to NRC question) how they arrived at the EDG unavailability in the current model. In order to determine delta CDF, they estimated what EDG unavailability would be if the extended CT were granted. They said:

one 14-day EDG outage over 17 months operating cycle equals ~9.9 days unavailability per year => 2.7E-2 This is the value (2.7E-2) they used for the PRA calculation.

This number ignores any other contribution to unavailability, from corrective maintenance, from surveillance testing, etc. Instead of adding the additional unavailability to the current value, the licensee assumed that unavailability would increase to ~9.9 days per year.

The staff would like to know what delta CDF/LERF would be assuming 14 days of unavailability is added to the existing numbers.

CC: Ogbonna Hopkins; Steven Laur Mail Envelope Properties (44D8CECE.5C3 : 2 : 35476)

Subject:

PI - LAR for EDG Extension and Completion Time -

MC9001/MC9002 Creation Date 08/08/2006 1:50:06 PM From: Mahesh Chawla Created By: MLC@nrc.gov Recipients Action Date & Time nmcco.com Transferred 08/08/2006

1:50:42 PM dale.Vincent (dale.Vincent@nmcco.com) nrc.gov OWGWPO04.HQGWDO01 Delivered 08/08/2006 1:50:11 PM OLH CC (Ogbonna Hopkins) nrc.gov TWGWPO01.HQGWDO01 Delivered 08/08/2006 1:50:12 PM SAL CC (Steven Laur) Opened 08/08/2006 1:50:15 PM Post Office Delivered Route nmcco.com OWGWPO04.HQGWDO01 08/08/2006 1:50:11 PM nrc.gov TWGWPO01.HQGWDO01 08/08/2006 1:50:12 PM nrc.gov Files Size Date & Time MESSAGE 1759 08/08/2006 1:50:06 PM Options Auto Delete: No Expiration Date: None Notify Recipients: Yes Priority: Standard ReplyRequested: No Return Notification: None Concealed

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