ML20009C352

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Forwards LER 81-044/03L-0.Detailed Event Analysis Encl
ML20009C352
Person / Time
Site: McGuire Duke Energy icon.png
Issue date: 05/07/1981
From: Parker W
DUKE POWER CO.
To: James O'Reilly
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20009C355 List:
References
NUDOCS 8107200482
Download: ML20009C352 (2)


Text

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I' h DUKE POWER COMPANY dp POWER DUILDING [

422 Socrn Cituacit SrazzT, C:uutorTz, N. C. as24a WILLIAM O. PAR K ER J R.

May 7, 1981 Tcu. o c.A. 7 s[cE ".'o'o've'r'[o~

//- d5/- 634 Mr. J. P. O'Reilly, Director U. S. Nuclear Regulatory Commission Region II - tu -

101 Marietta Street, Suite 3100 Atlanta, Georgia 30303 [k ~ ]/b,CYd g r pF

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Re: McGuire Nuclear Station Unit 1 2 JUL 171981 > r Docket No. 50-369 u.a. tuu4a nnouuman -4 6',. soeuusm

Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report R0-369/81-44. This report concerns the operability of Train A of the Control Area Ventilation System. This incident was censidered to be of no significance with respect to the health and safety of the public.

Very truly yours, tu&

William O. Parker, Jr.

O PA, .

pg RWO:djs cc: Director Mr. Bill Lavalee Office of Management cnd Program Analysis Nuclear Safety Analysis Center i U. S. Nuclear Regulatory Commission Post Office Box 10412 Washington, D. C. 20555 Palo Alto, California 94303 M. J. Graham i Resident Inspector l

McGuire Nuclear Station l hh L

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8107200482 810307 gDRADOCK 05000369 PDR

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McGUIRE NUCLEAR STATION

. INCIDENT REPORT REPORT NUMBER: 81- 44 REPORT DATE: April 28, 1981 OCCURRENCE DATE: April 10, 1981 FACILITY: McGuire Unit 1, Cornelius, N.C.

IDENTIFICATION OF OCCURRENCE: Train A of the Control Area Vencilation (VC)

System was declared inoperable. Reportable pursuant to Technical Specifi-cation 3.7.6.

CONDITIONS PRIOR TO OCCURRENCE: Mode 3, Hot Standby DISCRIPTION OF OCCURRENCE: Train A of the Control Area Ventilation System was declared inoperable because the A chiller would not start. The A chiller provides cooling water to the A train Control Room and control area air handling units.

APPARENT CAUSE: The chilled water thermostat on the A chiller was set too low causing the chiller to trip.

ANALYSIS OF OCCURRENgE: The Control Area Ventilation System is sized to cool the Control Room and areas below the Control Room under the most strenuous conditions. Heat loads from the two operating units and high outside temperatures would contribute to this design capacity. There are two chillers in the system, each designed to carry 75% of the load. With Unit f/2 still under construction, unit #1 in hot standby (no power output), and mild cut-side temperatures, the heat load on "A" chiller was a small percentage of its design capacity. The chilled water temperature control thermostat was set too low for the low chiller load and the refrigerant low temperature thermo-stat opened in the control circuit. This prevented the chiller from re-starting. By the time the mechanical maintenance technialan dot to the chiller, the refrigerant temperature had increased enough to reset the thermostat. He reset the alarm (LOW REGRIG TEMP) and started the chiller.

Using the chilled water outlet thermometer as a guide, he adjusted the chilled water control to maintain 45 F.

CORRECTIVE ACTION: The corrective action was to restart the chiller and then readjust the chilled water temperature controller.

SAFETY ANALYSIS: VC Train A was backed up by and replaced with 7C Train B so that no equipment was overheated and damaged. If the train A chiller was needed, it could have been restarted after the refrigerant warmed up.

As the heat load increases, the chilled water temperature controller set-point will become less sensitive. Since no overheating occurred in Control Room area equipment, the health and safety of the public were not affected.

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