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AO 50-237/75-58:on 750615,isolation Condensor Outboard Steam Supply Valve MO-2-1301-2 Found W/Bent Stem.Possibly Caused by Combination of Excessive Cycling of Valve 1301-2 & Maladjustment of Limit Switches for Valve Travel
	ML20084D177
Person / Time
Site:	Dresden
Issue date:	06/25/1975
From:	; COMMONWEALTH EDISON CO.
To:	James Keppler; NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20084D157	List: ML20084D154; ML20084D177;
References
	394-75, 6992, AO-50-237-75-58, NUDOCS 8304080487
	Download: ML20084D177 (3)
	v • d • e

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Com 'wnith Edison One FihrnIational Plaza, Chicago. tilinois O

.o , Address Reply to: Post O!hce Box 767 C,hicago. Illinois 60690 BBS Ltr. #394-75 Dresden Nuclear Power Station R. R. #1 . . uw."

Morris, Illinois 60450 ;)

June 25,1975 N '- /

l'.' ,fli~\\d p y Mr. James G. Keppler, Regional Director j Gi b lb d M N Q g $ t+ rd Directorate of Regulatory Operation-Region III u e eu U. S. Nuclear Regulatory Co:m:ission ,

Qi 799 Roosevelt Road & (slp u

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D-Glen Ellyn, Illinois 60137 f,.h o d

SUBJECT:

REPORT OF AFi!OR /AL OCCURRD!CE PER SECTION 6.6.A 0F THE TECHNICAL SPECIFICATIONS FAILURE OF VALVE MO-2-1'D1-2 TO OPERATE

References:

1) Regulatory Guide 1.16 Rev.1 Appendix A

2) Notification of Region III of U. S. Nuclear Regulatory Co:x:ission Telephone: Phil Johnson, 1355 hours0.0157 days 0.376 hours 0.00224 weeks 5.155775e-4 months on June 15, 1975 Telegram: J. Keppler, 1102 hours0.0128 days 0.306 hours 0.00182 weeks 4.19311e-4 months on June 16, 1975

3) Drawing Number 12E2507A Report Number: 50-237/75-38 Report Date: June 25, 1975 Occurrence Date: June 15, 1975 .

Facility: Dresden Nuclear Power Station, Morris, , Illinois IDEUPIFICATION OF OCCURRE* ICE At 0300 hours0.00347 days 0.0833 hours 4.960317e-4 weeks 1.1415e-4 months on June 15, 1975, isolation condensor outboard steam supply valve MO-2-1301-2 was found to have a bent stem.

CONDITIONS PRIOR TO OCCURRD!CE Unit-2 was in the shutdown mode during a weekend maintenance outap. The instrument mechanics were performing the high flow isolation valve surveille.w.' test which causes valve 1301-2 to cloco.

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. r, & James G. Keppl Jun3 25, 1975 D$SCRIPPICN OF CCCURRD;CE Following a work request for a tripped circuit breaker, the electrical maintenance department made an inspection of valve 1301-2. During testing of the breaker and Limitorque operator, the valve was found to have a bent stem.

DESIGNATION OF APPARENT CAUSE OF OCCURRENCE (Equipment Failure)

No definite cause has been determined at this time; however, two problems apparently contributed to the occurrence:

1) Excessive cycling of valve 1301-2 during maintenance and surveillance testing of the high flow isolation AP switches caused the breaker to trip thermally.

The control room operator inadvertently placed the control switch in the

" auto" position instead of the closed position specified in the surveillance procedure. The " auto" position allowed the valve to cycle cach time the AP switches were tripped. '

2) A possible maladjustment of the limit switches for valve travel may have allowed the valve's torque switch to be bypassed, causing the valve to close with excessive force and bending the stem.

ANALYSIS OF OCCURRMICE Since Unit-2 was in the shutdown mode with pressure under 90 psig, the isolation condensor was not required to be operable. The outboard valve 1301-2 was in the closed position (isolated) and was capable of isolating the inboard valve 1301-1 if isolation had been required. Plant personnel and the public were not jeopardized by this occurrence.

CORRECTIVE ACTION The i: mediate corrective action was to submit a work request for inspection of the valve and breaker. The electrical maintenance department had the valve taken out of service for disassembly and replacement of the stem. The Limitorque drive nut and the valve stem threads were worn significantly; consequently, a valve stem and Limitorque operator from the Unit-3 1301-2 valve were installed.

The limit and torque switches were inspected for damage and found to be in good condition; however, the initial limit switch settings were not checked before disassembly.

After assembly, the valve was successfully cycled three times, both locally and from the control room. All aspects of the control circuitry performed as designed. The valve was also successfully leak-rate tested before being placed back in service.

The control room operators have been cautioned to place valves in the closed position, as specified in the surveillance procedure, to avoid valve cycling during testing.

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ML20084D177

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