ML20010F762

Forwards LER 81-129/03L-0.Detailed Event Analysis Encl

ML20010F762
Person / Time
Site:	McGuire
Issue date:	09/01/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20010F763	List: ML20010F762 ML20010F765
References
NUDOCS 8109110298
Download: ML20010F762 (2)

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Dunn POWER COSIPANY POWER l.lUllDING 422 SOUTH CHURCH STHEET, CHAH1DT'E, N. C. coah n  ;

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Vice PatsiotwT TEL E PwoN E:Anta704 set.w Paoovevio~ 373-4o83 ggg 1, gg Mr. James P. O'Reilly, Director U, 3. Nuclear Regulatory Commission Q.

p'yr i Region II f 101 Marietta Street, Suite 3100 q ' g UL, L

Atlanta, Georgia 3i903

, ! SCf'101981mh 9.g.. COMMAS%sgl log Re: McGuire Nuclear Station Unit 1 Docket No. 50-369 k k'b/ 6'

Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report R0-369/81-129. This report concerns T.S. 3.4.1.4, "Two residual heat removal (RHR) loops shall be operable and at least one RHR loop shall be in operation." This incident was considered to be of no significance with respect to the health and safety of the public.

Very truly yours, [

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n__-/ l0<u William O. Parker, Jr. l PBN/php Attachment cc: Director Mr. Bill Lavallee Office of Management and Program Analysis Nuclear Safety Analysis Center U. S. Nuclear Regulatory Commission P. O. Box 10412 Washington, D. C. 20555 Palo Alto, California 94303 Ms. M. J. Grahad.

Reside.nt Inspector-NRC McGuire Nuclear Station

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l' 0109110298 810901 PDR ADOCK 05000369 S PDR ,

McGUIRE NUCLEAR STATION REPORTABLE OCCURRENCE REPORT NUMBER: 81-129 REPORT DATE: September 1, 1981 OCCURRENCE DATE: August 4, 1981 FACILITY: McGuire Unit 1, Cornelius, NC IDENTIFICATION OF OCCURRENCE: Both trains of the Residual Heat Removal (ND)

System were declared inoperable when an inlet isolation valve was inadvertently closed at 1215.

CONDITION PRIOR TO OCCURRENCE: Mode 5, Cold Shutdown, prior to initial criticality.

DESCRIPTION OF OCCURRENCE: When the circuit breaker for the motor operated inlet isolation valve was closed the valve Lumediately ahut. System low flow alarms occurred in the Control Room and an operator was dispatched to open the valve by hand. Flow was subsequently restored and the system was declared operable at 1230.

APTARENT CAUSE OF OCCURRENCE: A " shut" control signal was being transmitted to the valve operator controller as a result of Channel B vide range pressure instrumentation maintenance action. When motive power was provided to the motor by closing its power supply breaker it functioned to shut the valve.

ANALYSIS OF OCCURRENCE: Redundant trains of the ND System are supplied through a common inlet line from NC loop 3. The inlet line contains two essential motor-operated isolation valves in series. Shutting either valve renders the ND trains inoperable, which is prohibited during Mode 5 operation by Technical Specification 3.4.1.4.

If reactor coolant system pressure is less than ~400 pounds, the wide range pressure process control instrumentation channels send signals to the two inlet isolation valves to keep them open. In order to perform maintenance on Channel B, the power supply breaker was also opened to ensure that the valve would stay open. However, maintenance on Channel B required it be placed in

" Test," which deenergized the "Open" signal. Thus, when the circuit breaker was closed, the lack of an "Open" signal from the pressure instrumentation caused the motor operator of the valve to be energized. Consequently, the valve was shut and ND was inoperable.

SAFETY ANALYSIS: The loss of ND in this incident was momentary and had no effect on the health and safety of the public. Analysis indicates that even after the reactor is critical, the Residual Heat Removal System may be inoperable up to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> before core coolant boiling would occur.

CORRECTIVE ACTION: The Wide Range Pressure Calibration Procedure is being modified to include appropriate prerequisites (e.g., tag-out of specific breakers) to ensure that required maintenance will have no adverse ef fects on plant operation. Additionally, a general review of process control instru-mentation procedures which are susceptible to this type of deficiency is being initiated.

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