TXX-6886, Interim Deficiency Rept CP-87-108 Re Low Suction Pressure Trip Function of Auxiliary Feedwater (AFW) Pumps Which May Render AFW Sys Inoperable.Initially Reported on 870924. Evaluation Underway.Next Rept Will Be Submitted on 880223

Interim Deficiency Rept CP-87-108 Re Low Suction Pressure Trip Function of Auxiliary Feedwater (AFW) Pumps Which May Render AFW Sys Inoperable.Initially Reported on 870924. Evaluation Underway.Next Rept Will Be Submitted on 880223

ML20236G304
Person / Time
Site:	Comanche Peak
Issue date:	10/26/1987
From:	Counsil W, Woodlan D TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
CP-87-108, TXX-6886, NUDOCS 8711020490
Download: ML20236G304 (2)

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=M Log # TXX-6886 l L-

___, $ Fi1e # 10110-910,4 i M# ELECTRIC Ref # 10CFR50.55(e) {

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wuuam c. coomu nuoi,v, va emau October 26, 1987 l n ,

U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES) ,

DOCKET NOS. 50-445 AND 50-446 i AUXILIARY FEEDWATER PUMP LOW SVCTION TRIP SDAR: CP-87-108 (INTERIM REPORT)

Gentlemen: l On September 24, 1987, we verbally notified your Mr. I. Barnes of a deficiency involving the low suction pressure trip function of. the Auxiliary Feedwater (AFW) ) umps which may render the AFW System inoperable. We have determined througl engineering evaluation that.if this condition remained uncorrected, the safe operation of the plant could have been adversely affected.

Therefore, this issue is reportable under the provisions of'10CFR50.55(e) and  ;

.the required information is as follows:  :

Description The low suction pressure bi-stables 1PB-2475B and IPB-24768 associated with the motor driven auxiliary feedwater pumps CP1-AFAPMD-01 and CP1-AFAPMD-02, respectively, and the pressure switches 1PS-2470A and IPS-2470B, associated with the turbine driven auxiliary feedwater pump CPI-AFAPTD-01, can cause

-spurious signals. This could result in tripping the pumps due to pressure j oscillations in the suction lines during pump startup. This is.a significant i deficiency in final design as approved and released for construction. This i deficiency was discovered during the design validation process of the AFW j System.  !

A parallel experience at the Millstone 3 facility was reported during the surveillance tests of the motor driven auxiliary feedwater pumps, as evidenced by NUSCO's Licensee Event Report (LER) 87-004-00 to the NRC.

Safety Implications The auxiliary feedwater pumps are used under accident conditions when normal feedwater flow to the steam generators is not available to achieve and

!- maintain safe plant shutdown. The described spurious trips could p <ent

. achieving the design flows assumed in Chapter 15 (Accident Analysisf of the FSAR.

8711020490 371026 5 PDR ADOCK O 8 800 North Olive Street LB 81 Dallas, Texas 73201 i

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o lr TXX-6886.

T0ctober 26;:1987-~

Page-2.of.2

' Corrective Action, We areLcurrently evaluating the~ possibility 31 disconnecting the CPSES. low

• pressure trip instrumentation.

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Our next re) ort for this issue will be submitted 'no later than February 23, .

1988. At tlat time we will' discuss the' root. cause and. generic implications ofl this: issue,-the corrective action required, and the implementati.on' schedule

for the: corrective action.

/

very truly yours,

.h

, . . W. G. Counsil By

1 D. R. Woodlan~

Supervisor, Docket' Licensing-

-.MCP/gj

c - Mr. R..D.: Martin, Region IV-Resident inspectors, CPSES (3)

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