ML080790515

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Draft RAI on Proposed Amendment Re Recirculation Riser Differential Pressure
ML080790515
Person / Time
Site: Monticello Xcel Energy icon.png
Issue date: 03/18/2008
From: Tam P
NRC/NRR/ADRO/DORL/LPLIII-1
To: Arias J, Blake T, Loeffler R
Nuclear Management Co
References
TAC MD6864
Download: ML080790515 (2)


Text

From: Peter Tam Accession No. ML080790515 To: Arias, Jesus; Loeffler, Rick; Blake, Timothy Date: 03/18/2008 4:29:11 PM

Subject:

Monticello - Draft RAI re. proposed amendment on recirculation riser diff.

pressure (TAC MD6864)

Rick:

We are reviewing your application dated 9/25/07 for the subject amendment. Our reviewer, Leonard Ward, has written the following draft RAI questions on the thermal hydraulic aspects of the proposed amendment. Please set up a conference call with me to discuss these draft questions. We plan to issue these questions formally around 4/4/08:

(1) For the LPCI system in the residual heat removal operating mode, please address the potential for a LOCA with certain postulated single failures in electrical distribution that could leave the plant vulnerable regardless of offsite power status. For loop select logic plants operating in this mode, for example, the loop select logic mechanism could allow a single active failure (i.e., an LPCI injection valve in the path to the intact recirculation loop) to disable the entire LPCI system, placing dependence on the core spray system to accomplish the low pressure core cooling function. Please explain.

(2) Please provide the axial power shape used in the SBLOCA re-analysis for the limiting break. What is the PLHGR applied to the peak power position for this shape?

(3) For the limiting SBLOCA, does the PCT terminate due to top down cooling (i.e.,

counter-current flow) into the hot bundle and hot rod from the core spray? Please explain.

The solely purpose of this e-mail is to prepare you and others for the proposed conference call.

This e-mail does not convey an NRC staff position, and does not formally request for additional information.

Peter S. Tam, Senior Project Manager Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation e-mail: pst@nrc.gov Tel.: 301-415-1451 CC: Anthony Mendiola; Leonard Ward Mail Envelope Properties (47E02617.E7C : 12 : 35330)

Subject:

Monticello - Draft RAI re. proposed amendment on recirculation riser diff. pressure (TAC MD6864)

Creation Date 03/18/2008 4:29:11 PM From: Peter Tam

Created By: PST@nrc.gov Recipients Action Date & Time nmcco.com Transferred 03/18/2008 4:29:49 PM Jesus.Arias (Jesus Arias)

Richard.Loeffler (Rick Loeffler) tmblake (Timothy Blake) nrc.gov TWGWPO01.HQGWDO01 Delivered 03/18/2008 4:29:21 PM AJM CC (Anthony Mendiola) Opened 03/19/2008 7:17:27 AM nrc.gov TWGWPO04.HQGWDO01 Delivered 03/18/2008 4:29:20 PM LWW CC (Leonard Ward)

Post Office Delivered Route nmcco.com TWGWPO01.HQGWDO01 03/18/2008 4:29:21 PM nrc.gov TWGWPO04.HQGWDO01 03/18/2008 4:29:20 PM nrc.gov Files Size Date & Time MESSAGE 2676 03/18/2008 4:29:11 PM Options Auto Delete: No Expiration Date: None Notify Recipients: Yes Priority: Standard ReplyRequested: No Return Notification: None Concealed

Subject:

No Security: Standard To Be Delivered: Immediate Status Tracking: Delivered & Opened