ML042670381

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E-mail from M. Webb to J. Loya Retran Rai'S Westinghouse Draft Preliminary Response
ML042670381
Person / Time
Site: South Texas  STP Nuclear Operating Company icon.png
Issue date: 03/26/2004
From: Michael Webb
NRC/NRR/DLPM/LPD4
To: Loya J
South Texas
Webb M, NRR/DLPM, 415-1347
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I Michael Webb - Re: RETRAN RAI's Westinghouse Draft Preliminary Response -- I , - Page 1 I a07um TE Ks /to 4& 7-A From: Michael Webb To: Loya,Joe - 49 ,Va- /9' Date: 3/26/04 10:27AM

Subject:

Re: RETRAN RAI's Westinghouse Draft Preliminary Response P/<,4jc< A'14vi Joe, I received the questions (actually two questions and a clarification) below from the newly assigned Reactor Systems Branch (SRXB) reviewer in response to the RAI response you provided.

The reviewer indicated that when you have provided the formal response to the earlier RAI and his additional questions, we should have the information necessary to write a Safety Evaluation. He will be available to discuss any of the RAls with you after April 6.

Mike Webb We understand that analyzes using a stand alone NOTRUMP model of the South Texas steam generators will be used to determine the steam generator water mass that will be present when a low level reactor trip occurs. This mass will then be used to set the reactor trip logic in the RETRAN model that will be used to analyze plant response to loss of feedwater, loss of offsite power and feedwater line breaks.

The NOTRUMP computer code has many options for calculating bubble rise inthe fluid nodes and drift flux in the flow links. These models will affect the water mass calculated to be in a steam generator.

Please identify which models will be used to determine steam generator water mass for analysis of loss of feedwater, loss of offsite power and feedwater line breaks. Justify that these models have been verified to be accurate for the conditions that would occur within the South Texas steam generators during these events.

For analysis of feedwater line breaks using NOTRUMP, please discuss the models used to predict break flow and liquid entrainment from the broken steam generator. Justify that the models are conservative for determining the low level trip water mass to be input into RETRAN. Provide a comparison of the break flow rate predicted by NOTRUMP to that predicted by RETRAN.

We understand that the RETRAN model of the South Texas steam generators utilizes homogeneous mixing below the steam separators and assumes perfect separation of above the steam separators. The feedwater lines are below the steam separators so that so that the fluid entering a postulated broken feedwater line would be inthe homogeneous flow condition. The assumption of homogenous flow would be conservative for calculating reactor system overheating following a feedwater line beak. We also understand that break flow iscalculated using the Henry-Fauske (subcooled) and Moody (saturated) options which are also conservative. Please verify that the staff's understanding is correct or discuss the conservatism of other models that are used.

>>> Loya, Joe" <jaloya@STPEGS.COM> 02/19/04 09:35AM >>>

Dave, Attached are the draft preliminary RETRAN RAI responses. Please let me know when we can set up a conference call to review and discuss the draft.

As we discussed earlier with Scott Head, Charlie Albury, Ulhas Patil and I will be participating in this phone call.

Please advise.

Joe Loya South Texas Project Nuclear Operating Company Licensing Engineer (361) 972-7922

Zesponse

[Mic'hael Webb - Re: RETRAN RAIs Westinghouse Draft Preliminary PVa6e-f Pager: 0656 CC: Head, Scott

. 1 1a - 1 I

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Re: RETRAN RAI's Westinghouse Draft Preliminary Response Creation Date: 3/26/04 10:27AM From: Michael Webb Created By: MKW@nrc.gov Recipients Action Date & Time nrc.gov owf4_po.OWFNDO Delivered 03/26/04 10:27AM MKW BC (Michael Webb) Opened 03/26/04 10:58AM STPEGS.COM Transferred 03/26/04 10:27AM jaloya (Loya, Joe) smhead CC (Head, Scott)

Post Office Delivered Route owf4_po.OWFNDO 03/26/04 10:27AM nrc.gov STPEGS.COM Files Size Date & Time MESSAGE 4371 03/26/04 10:27AM Options Auto Delete: No Expiration Date: None Notify Recipients: Yes Priority: Standard Reply Requested: No Return Notification: None Concealed

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[ Michael Webb - Re: STP PROPOSED EXIGENT TECH SPEC - CONTROL ROOM page 1I Page 1 Michael Webb Re: STP PROPOSED EXIGENT TECH SPEC CONTROL ROOM From: Michael Webb To: Taplett, Kenneth Date: 3/26/04 2:18PM

Subject:

Re: STP PROPOSED EXIGENT TECH SPEC - CONTROL ROOM Ken, I have attached the (slightly reformatted, but substantively the same) questions related to the exigent TS request that were forwarded to you by Mark Blumberg yesterday afternoon.

After you and your colleagues have had a chance to evaluate them, we can set up a call to discuss them further if you desire to do so.

Thanks, Mike Webb NRC Project Manager for South Texas Project 301-415-1347 CC: Head, Scott

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Re: STP PROPOSED EXIGENT TECH SPEC - CONTROL ROOM Creation Date: 3/26/04 2:18PM From: Michael Webb Created By: MKW@nrc.gov Recipients Action Date & Time nrc.gov owf4_po.OWFN_DO Delivered 03/26/04 02:18PM MKW BC (Michael Webb) Opened 03/26/04 02:26PM STPEGS.COM Transferred 03/26/04 02:18PM kjtaplett (Taplett, Kenneth) smhead CC (Head, Scott)

Post Office Delivered Route owf4.po.0WFNDO 03/26/04 02:18PM nrc.gov STPEGS.COM Files Size Date & Time MC2358RAI-SPSB .wpd 11727 03/26/04 02:07PM MESSAGE 1215 03/26/04 02:18PM Options Auto Delete: No Expiration Date: None Notify Recipients: Yes Priority: Standard Reply Requested: No Return Notification: None Concealed

Subject:

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

REQUEST FOR ADDITIONAL INFORMATION REGARDING PROPOSED AMENDMENT TO TECHNICAL SPECIFICATIONS TECHNICAL SPECIFICATION 3/4.7.7 CONTROL ROOM MAKEUP AND CLEANUP FILTRATION SYSTEM SOUTH TEXAS PROJECT NUCLEAR OPERATING COMPANY UNITS 1 AND 2 DOCKET NO 50-498 AND 50-499 By letter dated March 18, 2004, South Texas Project Nuclear Operating Company submitted a proposed amendment to the Technical Specifications (TSs) for the South Texas Project Units 1 and 2. The Nuclear Regulatory Commission (NRC) staff has reviewed the information the licensee provided that supports the proposed TS changes. In order for the staff to complete its evaluation, the following additional information is requested:

I1. The current licensing bases for the control room as described in the STP Technical Specifications and UFSAR states that the control room envelope is maintained at a minimum 0.1 25-inch positive water gauge with respect to adjacent areas. The proposed technical specification would allow positive pressure less than 0.125-inch water gauge with "appropriate compensatory measures." This proposed change represents a decrease in the pressure margin used to assure that unfiltered inleakage is minimized.

In light that this decreased positive pressure condition may exist for approximately 18 months, there are no provisions to compensate for possible boundary degradation or variances in pressure conditions external to the control room boundary. The staff believes that compensatory measures are necessary to offset this decreased margin.

Please specify and justify the "appropriate compensatory measures" to be taken to offset this decrease in the pressure margin (for example, increased surveillance frequency, potassium iodide and/or self-contained breathing apparatus (SCBA)). If potassium iodide and SCBA are deemed appropriate measures to insure that GDC 19 is maintained, Regulatory Position 2.7.3 of NRC Regulatory Guide, 1.196, "Control Room Habitability at Light-Water Nuclear Power Reactors provides a method for crediting these compensatory measures. If Regulatory Guide 1.196 is used please verify if these provisions are met. The staff believes that inclusion of these compensatory measures in the bases is necessary to provide reasonable assurance that these compensatory measures are "appropriate."

2. With these compensatory measures available for use in case of an accident provide an estimate of the maximum unfiltered inleakage allowable to meet GDC 19.
3. Provide the measurement uncertainty of the measurements made for Surveillance Requirement 4.7.7.e.3 and state whether this uncertainty is included in surveillance. If the uncertainty is not included justify exclusion of the uncertainty.
4. State whether the most limiting points measured for the Component Test will be included in future 4.7.7e.3 surveillance tests. If these limiting points will be excluded justify the exclusion of these points.

Enclosure

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