05000237/LER-1978-056, Forwards LER 78-056/01T-0

Forwards LER 78-056/01T-0

ML17173A355
Person / Time
Site:	Dresden
Issue date:	11/01/1978
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML17173A356	List: 05000237/LER-1978-056, Forwards LER 78-056/01T-0 05000237/LER-1978-056-01, /01T-0 on 781012:diff Press Switch Isolation Valve for DPIS 2-1622A Was Found Closed Because of Unknown Cause. Subj Valve Will Be Opened Slowly After Dis 1600 Survey
References
NUDOCS 7811140193
Download: ML17173A355 (3)

LER-1978-056, Forwards LER 78-056/01T-0

Event date:
Report date:
2371978056R00 - NRC Website

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i Commonwel Edison Dresden Nuclear Power Station R.R. #1 Morris, Illinois 60450 Telephone 815/942-2920

• November 1, 1978 BBS Ltr. #78-1443 James G. Keppler, Regional Director Directorate of Regulatory Operations - Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137 Reportable Occurrence Report //78-056/0lT-O, Docket 11050-237 is hereby suomitted to your office in accordance with Dresden Nuclear Power Station Technical Specification 6.6.B.l.(b), operation of the unit or affected systems when any parameter or operation suoject to a limiting condition is less conservative than the least conservative aspect of the limiting condition for operation estaolished in the technical specifications.

Dresden BBS/deo Enclosure cc:

Director of Inspection & Enforcement Director of Management Information & Program Control File/NRC

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{7*771 LICENSEE EVENT REPOf1T U.-UCL,:;\\H REGULATOl->Y COMl1111:0:510N CON TR 0 L BLOCK: l.__.____.__~_._-.____,l Q 1

6 (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION!

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I I I LID I RI s I 2101 0 I 0 I -10 I 0 I 0 I 0 I 0 I 0 I 0 I 0 101 4 I 1 I ] I i I ] 101 I I Gt.

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9 LICE.NSEE CODE 14 15 LICENSE NUMBER 25 26 LICENSE TYPC:

.JO 57 CAT 58 CON'T

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~~~~; L1.1©.I o I s I o I o I o I 2 I 3 I 7 101 1 I o I 1 I 2 I z I a IG) I 1 I 1 I a I, I 1 I a I G) 60 61 DOCKET NUMaEA 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION~ND PROBABLE CONSEQUENCES@

I While performing quarterly Surv. DIS 1600-3, Diff. Press. Sw. !sol. Valve for DPIS 2-1622A was found closed.

DPIS 2-1622 A monitors press. betwee.n Torus and Rx. Bld. anq

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is calibrated to trip open at -12.5 +/- 1 in. H20 increasing *. Isolation valvemay hav~

[Q]1J been left closed during previous surv. on 7/13/78.

Safety significance minimal wbile I*

remaining vacuum sw. 2-1622B was operable to actuate redundant vacuum breaker.

10/1/78, redundant vacuum breaker was inoperable for approx. 8 hrs. to replace

• c j 8 I fuse F-16 on panel 902-3.

No previous similar events.

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CAUSE

CAUSE CODE SUBCODE COMPONENT CODE

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11 12 13 18 CO~lP.

SUBCODE L!J@)

19 VALVE SUBCODE

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20 On SEOUE~TIAL OCCURRENCE REPORT TYPE REVISION LE R/RO [Evo'lT YE,>.A REPORT NO.

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23 24 26 27 28 29 L2J 30 NO.

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32 80 ACT:ON FUTURE EFFECT SHUT:JC'V'iN ATTACHMENT TA~E'~

ACTiON ON PLANT

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SUBMITTED NPRD-4 FOAM :.US.

31 PRIME COMP.

SUPPLIER COMPONENT MANUFACTURER [3r18)~@)

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'0 36 37 40 41 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS @

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47 44 I Cause unknown.

Surv. DIS 1600-3 requires isolation valve to be opened slowly upon completion of surv.

DIS 1600-3 has been revised to require Inst. Mech. to sign data sheet upon valving isol. valve back into service.

For 90 days, IM supervisors will visually examine "AS LEFT" position of all critical non-indicating safety OITI IL-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

o:ID I related valves, which are repositioned during surveillances.

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80 FA.CILITY

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10 12 11 44 ACTIVITY CONTENT

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RELE/l.SED OF RELEASE AUOUNT OF ACTIVITY '2_V

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9 10 11 45 46 80 LOCATION OF RELEASE @

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80 PERSONNEL EXPOSURES Q,

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TYPE

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8 s 11 i2 13 80 PERSONNEL INJURIES

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10------------------------------~68 69

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ATTACHJ1ENT TO LICENSEE EVENT REPORT 78-056/0lT-0 COMHONWEALTH EDISON COHPANY (CWE)

DRESDEN UNIT -2 (IJ.DRS-2)

DOCKET II 050-237 While performing quarterly surveillance DIS 1600-3, the differential pressure switch isolation valve for DPIS 2-1622A was found closed.

The Diff~rential Pressure Switch is designed to monitor theAP between the Torus and Reactor Building and is calibrated to trip open at -12.5 +/- 1 inch n2o vacuum increasing.

Technical Specification 3.7.3.a limits the maximum negativeAP referenced to Torus at -13.7 inches H2o. At -12.5 +/- 1" H20 increasing vacuum, either AO 2-1601-20A is opened by switch DPIS 2-1622A or AO 2-1601-20B opens in response to DPIS 2-1622B (both vacuum breaker valves arranged in parallel).

This relieves the torus negative pressure from the.reactor building.

All trip setpoints in the surveillance were found within the Dresden Tech Spec Limits.

However,** prior to the surveillance the isolation valve upstream of Differential Pressure Switch 2-1622-A, was found closed which caused the switch to be inoperable. It is assumed that the isolation valve was left closed after completion of the previous quarterly surveillance on 7/13/78.

The safety consequence was minimal while the remaining Pressure Suppression to Rx Building Vacuum Switch 2-1622B and vacuum breaker A02-1601-20B were operable.

On 10/1/78, the A0-2-1601-20B valve was also rendered inoperable for approximately 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, however, to replace Fuse F-16 on panel 902-.3.

. During that period, vacuum protecti.on was not available for the torus.

DIS 1600-3 had already correctly contained a step requiring the instrument isolation valve to be opened slowly upon completion of the surveillance.

However, to provide better assurance that the step is completed, DIS 1600-3 has been additionally modified to require the Instrument Maintenance Mechanic assigned to the surveillance to sign the data sheet upon valving the switches back into service.

In addition for the next 90 days an Instrument Maintenance Supervisor will visually examine the "As Left" position of all critical non-indicating Safety-Related valves which are repositioned during instrument surveillances and similarly co-sign each associated surveillance upon its completion.

The Pressure Suppression to Rx Building Vacuum Switches will continue to be tested quarterly to ascertain compliance with the Technical Specifications.