ML062560258

Preliminary Request for Information - E-Mail to Licensee

ML062560258
Person / Time
Site:	Comanche Peak
Issue date:	07/06/2006
From:	Thadani M NRC/NRR/ADRO/DORL/LPLIV
To:	Buschbaum D TXU Power
Thadani, M C, NRR/DORL/LP4, 415-1476
References
TAC MC9500, TAC MC9501, TAC MD0187, TAC MD0188
Download: ML062560258 (2)

Text

From: Mohan Thadani To: Internet:dbuschb1@txu.com; Internet:fred.madden@txu.com Date: 7/6/2006 10:23:57 AM

Subject:

Preliminary Request for Additional Information- TAC Numbers MC9500 and MC9501 Fred/Denny:

The NRC staff has reviewed the TXU Generation Company LP's request for amendments, dated February 21, 2005, revising the Technical Specifications to reflect the replacement of Steam Generators. The staff has identified the following preliminary request for additional information. I will appreciate your assistance in providing your response to the following questions in a timely manner.

Please let me know, by an email, when the TXU Generation Company LP will be able to respond. Also, let me know If you need a formal letter for this request. I will then promptly process a formal letter for this request.

Thank you for your cooperation.

Mohan 301 415-1476 PRELIMINARY REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST 05-08 REVISION TO TECHNICAL SPECIFICATIONS FOR NOMINAL TRIP SETPOINTS AND AV SETPOINTS FOR SG WATER LEVEL LOW-LOW AND HIGH-HIGH COMANCHE PEAK STEM ELECTRIC STATION UNITS 1 AND 2 TXU GENERATION COMPANY, LP TAC NOS. MD0187 AND MD0188 By letter dated February 21, 2006, the licensee of the Comanche Peak Steam Electric Station proposed to revise the nominal trip setpoints (NTS) and Allowable Values (AV) of setpoints for steam generator (SG) water level low-low and high-high. The changes are applicable to the replacement SGs in Unit 1. The licensee indicated that the changes had included the SG water level measurement uncertainties discussed in Westinghouse Nuclear Safety Advisory Letters (NSALs).

NSAL-02-3 and its revision dealt with the uncertainty in the SG water level measurement caused by the placement of mid-deck plate between the upper and lower pressure taps.

NSAL-02-4 dealt with uncertainties in the measurement created because the void content of the two-phase mixture above the mid-deck plate was not reflected in typical setpoint calculations.

NSAL-02-5 dealt with potential inaccuracies in the initial conditions assumed in safety analysis affected by SG water level. NSAL-03-9 discussed a program for Westinghouse Owners' Group that evaluated the effects on the SG water level control system uncertainties from various items, including the mid-deck plate, feedwater ring and feedwater ring supports, lower-deck plate supports, ono-recoverable losses due to carryunder, decrease in subcooling due to carryunder, and transient conditions due to event such as single loop loss of normal feedwater, etc..

(a) Please discuss how the specific plant accounted for the applicable uncertainties documented in the above Westinghouse NSALs in determining the SG water level (low-low and high-high) NTS and AV setpoints.

(b) Please discuss the results of non-LOCA transients that were analyzed to determine uncertainties for the SG water level low-low and high-high setpoints. Identify and justify the limiting cases used to determine the proposed NTS and AV setpoints. The discussion should include a description of the methods or computers codes used in the analysis, and demonstrate

the appropriateness of the methods and codes used.

(c) Please provide the actual calculations or the results of summary sheets for the proposed NTS and AV setpoints.

CC: Nakoski, John; Reyes-Maldonado, Ruth; Sun, Summer Mail Envelope Properties (45080639.B3F : 23 : 35106)

Subject:

Fwd: Preliminary Request for Additional Information- TAC Numbers MC9500 and MC9501 Creation Date 9/13/2006 9:23:05 AM From: Mohan Thadani Created By: MCT@nrc.gov Recipients nrc.gov OWGWPO01.HQGWDO01 JCB2 (Janet Burkhardt)

Post Office Route OWGWPO01.HQGWDO01 nrc.gov Files Size Date & Time MESSAGE 5052 9/13/2006 9:23:05 AM Options Expiration Date: None Priority: Standard ReplyRequested: No Return Notification: None Concealed

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