ML090820099

Draft RAI from the Balance of Plant Branch Re the Proposed Amendment on Extended Power Uprate

ML090820099
Person / Time
Site:	Monticello
Issue date:	03/23/2009
From:	Tam P Plant Licensing Branch III
To:	Gabor S, Pointer K Northern States Power Co, Xcel Energy
Tam P
References
TAC MD9990
Download: ML090820099 (3)

Text

Accession No. ML090820099 From: Peter Tam Sent: Monday, March 23, 2009 8:59 AM To: 'Pointer, Kenneth'; 'Salamon, Gabor' Cc: Karl Feintuch; Steve Jones

Subject:

Monticello - Draft RAI from Balance of Plant Branch re. Proposed EPU Amendment (TAC MD9990)

Ken:

Our review of your 11/5/09 application for an extended power uprate (EPU) amendment is ongoing. Our Balance of Plant Branch has provided the following draft RAI questions (see below). Please contact me to set up a conference call to discuss these questions. If you desire to have the proposed conference call during 3/24/09 - 4/10/09 when I am on leave, please contact my back up Karl Feintuch (301-415-3079).

SBPB 2.5-1: Table 2.2-1, Liquid Line Breaks, indicates the flooding elevation within the reactor building and turbine building will increase. Section 2.2.1.2 of the PUSAR states that the reactor building and turbine building pressure, temperature, flooding, and relative humidity profiles at EPU conditions were evaluated for the effect on equipment qualification as discussed in Sections 2.2.5 and 2.3.1. Explain the criteria used to evaluate the effect of increased flooding elevations on safe shutdown equipment and the basis for the acceptance criterion for flooding elevation.

SBPB 2.5-2: Section 2.5.3.1 of the PUSAR describes that the limiting condition for the spent fuel pool (SFP) heat load (the emergency heat load) is a heat load value of 24.7 MBtu/hr and that this design basis limiting heat load does not change at EPU conditions. However, Section 10.2.2 of the MNGP USAR states that the emergency heat load condition assumes that a full core discharge that fills the last 484 spaces in the pool is required 30 days following the last refueling discharge and the full core discharge is complete 150 hours0.00174 days <br />0.0417 hours <br />2.480159e-4 weeks <br />5.7075e-5 months <br /> after shutdown. Since the USAR information specifies a fuel quantity and a decay time, it is not clear how the design basis maximum heat load would remain unchanged for operation at the EPU power level. Clarify the PUSAR statement considering the increased decay heat load of each fuel assembly following operation at EPU power levels and describe any operational restrictions related to the maximum SFP heat load.

SBPB 2.5-3: Section 2.5.3.1 of the PUSAR describes that the SFP would reach the boiling temperature in 6.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> in the worst case conditions after the limiting full core offload and the boil-off rate at these design conditions would be 53 gpm.. However, Section 10.2.2 of the MNGP USAR states that the minimum possible time to achieve bulk pool boiling is 10.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> (assuming a maximum initial fuel pool temperature of 120°F) and the maximum evaporation rate after bulk boiling commences is 43 gpm. List the initial conditions and assumptions/methods used for each analysis, and explain any differences. Also, specify which initial conditions of the EPU analysis that would be included among the administrative controls used to establish the fuel offload schedule for refueling.

SBPB 2.12-1: Section 11.8.2.3 of the Monticello USAR states that the feedwater pumps will automatically trip on high water level following transients and that this automatic feature decreases the possibility of main steam line flooding following transients. Main steam line

flooding creates an adverse system interaction in that flooding would affect the operation of the high pressure coolant injection and reactor core isolation cooling systems. The 2002 Monticello plant response to a load rejection suggests that the feedwater system could routinely challenge the high level feedwater pump trip following main turbine trips. Considering the proposed EPU modifications to support increased main feedwater flow, describe how the high reactor water level setpoint has been verified to protect against main steam line flooding. In the discussion, address potential single operator and equipment failures, and discuss the uncertainty in the analysis results relative to the need for testing.

SBPB 2.12-2: Section 7.7.4.2 of the Monticello USAR states that the feedwater pumps will automatically trip on low suction pressure and, after a time delay, low suction flow. Consistent with the guidance of SRP Section 14.2.1, explain any analyses or testing that will be conducted to ensure the modified feedwater and condensate systems perform in a manner that avoids unexpected system interactions that increase the frequency of loss of feedwater events.

This e-mail aims solely to prepare you and others for the requested conference call. This e-mail does not convey a formal 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 Tel. 301-415-1451 E-mail Properties Mail Envelope Properties (C56E360E9D804F4B95BC673F886381E71DBE15C06F)

Subject:

Monticello - Draft RAI from Balance of Plant Branch re. Proposed EPU Amendment (TAC MD9990)

Sent Date: 3/23/2009 8:58:38 AM Received Date: 3/23/2009 8:58:00 AM From: Peter Tam Created By: Peter.Tam@nrc.gov Recipients:

Kenneth.Pointer@xenuclear.com ('Pointer, Kenneth')

Tracking Status: None Gabor.Salamon@xenuclear.com ('Salamon, Gabor')

Tracking Status: None Karl.Feintuch@nrc.gov (Karl Feintuch)

Tracking Status: None Steve.Jones@nrc.gov (Steve Jones)

Tracking Status: None

Post Office:

HQCLSTR02.nrc.gov Files Size Date & Time MESSAGE 15104 3/23/2009 Options Expiration Date:

Priority: olImportanceNormal ReplyRequested: False Return Notification: False Sensitivity: olNormal Recipients received: