ML20043H703
| ML20043H703 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| 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
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- 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 REF:
TV Electric letter logged TXX-90188 from W. J. Cahill, Jr.
l 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 1
discussed with members of the NRC on June 7, 1990, involved the_ addition of a
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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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June 18,: 1990 Page.2 of 2~-
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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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