TXX-4456, Significant Deficiency Rept SDAR-173 Re Auxiliary Feedwater Pressure Control.Hydraulic & Instrumentation Calculations Which Will Result in Revised Setpoint & Scalling Documents Will Be Completed by 850531

Significant Deficiency Rept SDAR-173 Re Auxiliary Feedwater Pressure Control.Hydraulic & Instrumentation Calculations Which Will Result in Revised Setpoint & Scalling Documents Will Be Completed by 850531

ML20204K090
Person / Time
Site:	Comanche Peak
Issue date:	04/15/1985
From:	Clements B TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	Hunter D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
SDAR-173, TXX-4456, NUDOCS 8504250312
Download: ML20204K090 (2)

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o TEXM UTILITIES GENERATING COMPANY MKYWAY TOW':N . 400 NORTH OLIVE MTHEET. L.B. Al . DALLAM TEXAM 75201 m i';'f!,." d S E!* . April 15, 1985 TXX-4456 Mr. D.R. Hunter, Chief Reactor Project Branch 2 U.S. Nuclear Regulatory Commission Office of Inspection & Enforcement 611 Ryan Plaza Drive, Suite 1000 Docket Nos.: 50-445 Arlington, TX 76012 50-446 COMANCHE PEAK STEAM ELECTRIC STATION AUXILIAPY FEEDWATER PRESSURE CONTROL QA FILE: CP-85-12; SDAR-173 FILE N0.: 10110

Dear Mr. Hunter:

In accordance with 10CFR50.55(e), we are submitting the enclosed report of ctions taken to correct a deficiency regarding a preliminary flow balance calculations that have been identified as unacceptable setpoints for the auxiliary feedwater system.

Supporting documentation is available at the CPSES site for your Inspector's review.

Very truly yours, BRC:tig Attachment cc: 'NRC Region IV - (0 + 1 copy) E ggg j,,g Director, Inspection & Enforcement (15 copies) {

U.S. Nuclear Regulatory Commission APR l 6l985 Washington, DC 20555 b

q 8504250312 850415 ~

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ADOCK 05000445 PDR ] {M 211 A Dis'ENEON OF TEXAN VTILITIEN ELECTNIC COME%NY

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TXX-4456 4/15/85 Page 2 ATTACHMENT AUXILIARY FEEDWATER PRESSURE CONTROL Description As a result of an unrelated evaluation, preliminary flow balance calculations by TUGCo Nuclear Engineering (TNE) have identified unacceptable setpoints involving the auxiliary feedwater control valves. Our review indicates the condition can be attributed to two (2) issues. Initially, the setpoint calculations did not properly reflect the certified " pump" curve submitted by the supplier which reflects actual pump operation. In addition, a site-generated system modification has not been considered in the existing calculations.

The auxiliary feedwater system control valves regulate supply flow to the

. steam generators by sensing the discharge pressure of the auxiliary feedwater pumps. The existing setpoints for these valves would result in flow approx-imately 17% below that required. These conditions would restrict steam generator supply to below prescribed technical specification levels and would unacceptably decrease decay heat removal for postulated accidents and safe shutdown.

As a result of the status of Unit 2 construction, the concern is limited to Unit 1.

Safety Implications In tiie event the concern had remained undetected, the ability of the operator to achieve safe shutdown or mitigate an accident could be impaired.

Corrective Actions Engineering activities which include hydraulic calculations and instrumentation calculations will result in revised setpoint and scalling documents. These

! efforts should be concluded by May 31, 1985.

Recalibration of the control valves will be accomplished by Operations. As governed by the technical specifications, these activities will be accomplished prior to system operations in Modes 1, 2 or 3.

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