ML20043H703

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Discusses Mod/Rework to Auxiliary Feedwater Sys Check Valves Mfg by Bw/Ip Intl,Inc.All But One Affected Check Valve modified.Motor-driven Auxiliary Feedwater Pump Discharge Valve Check Valve Body Replaced
ML20043H703
Person / Time
Site: Comanche Peak Luminant icon.png
Issue date: 06/18/1990
From: William Cahill
TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
TXX-90215, NUDOCS 9006260321
Download: ML20043H703 (2)


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- l.og # TXX 90215 L -2 File # 910.4

{' E # 903.9 TUELECTRIC

June 18, 1990 William J. Cahill, Jr.

Dmstve Vke freskJent i

U. S. Nuclear Regulatory Commission Attn: Document Control Desk.

Washington, D.C. 20555

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION .(CPSES)

L, DOCKET NO. 50 445 H0DIFICATION/ REWORK TO AUXILIARY FEEDWATEP. (AFW) SYSTEM CHECK VALVES l

REF: TV Electric letter logged TXX-90188 from W. J. Cahill, Jr.

to~the NRC dated May 18.-1990 Gentlemen:

s In the referenced l'etter, TV Electric indicated that a-modification would be performed on eight (8) AFW check valves manufactured by BW/IP International Inc. to improve disc / seat surface contact. The proposed modification involved moving the clevis slightly on the valves. The-letter further stated that the

' internals of:eight (8) BW/IP check valves from_ Unit 2 would be so modified' for- ,

! installation in Unit 1 during a cold shutdown period of: sufficient duration.

l Subsequently,'the vendor (BW/IP) determined-that this modification would result _in internal clearances to the' valve which would complicate valve disassembly and reassembly. . Consequently. TV Electric elected to pursue-an alternate approach to. improve disc / seat. contact. This_ approach, which was

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1 discussed with members of the NRC on June 7, 1990, involved the_ addition of a threaded cylindrical weight of approximately 8 ounces welded to the stud on the back of the. disc assembly. Addition of this weight will provide greater '

seating-force at conditions of low differential. pressure. This in turn should reduce backleakc9e *.hrough the valves. The effects of this modification on:

valve operability. . unction, disc travel and valve degradation were reviewed by. BW/IP, APTECH,11C TU Electric engineering prior to implementation and were found to be'accepcaole.

All affected check valves, with one exception, were modified as described above. During' leakage testing 1- AF 0101 (#2 motor driven AFW pump discharge valve-to No. 4 Steam Generator) wr.s observed to have backleakage through an-internal seal weld that joins the backing ring to the valve's seat sleeve. As y  ; a conservative measure, the check valve body was replaced and the modified d internals of the original valve reinstalled.

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.TXX-90215' June 18,: 1990 '

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'In accordance with-the referenced letter,- members of the NRC staff were kept advised of the modification as it progressed, ,

If you have any' questions on this matter please contact me.  :

Sincerely, i

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- William J. Cahill, Jr.

TLH/daj '

l c Mr. R. D. Hartin, Region IV Resident Inspectors, CPSES (3)

D. Chamberlain, Region IV e

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