05000317/LER-1979-031-01, During Followup Testing on Efs Actuation Sys Undervoltage Logic Circuit A,15-volt Dc Power Supplies to Undervoltage Logic a & B Would Not Respond When Signaled

During Followup Testing on Efs Actuation Sys Undervoltage Logic Circuit A,15-volt Dc Power Supplies to Undervoltage Logic a & B Would Not Respond When Signaled

ML20072C532
Person / Time
Site:	Calvert Cliffs
Issue date:	06/09/1983
From:	Basso L, Russell L BALTIMORE GAS & ELECTRIC CO.
To:	Allan J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
LER-79-031-01X, LER-79-31-1X, NUDOCS 8306210101
Download: ML20072C532 (3)

LER-1979-031, During Followup Testing on Efs Actuation Sys Undervoltage Logic Circuit A,15-volt Dc Power Supplies to Undervoltage Logic a & B Would Not Respond When Signaled

Event date:
Report date:
3171979031R01 - NRC Website

text

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NRC FORy a66 U. S. NUCLEA2 REGULATORY COMMISSION (717) '

LICENSEE EVENT REPORT UPDATED REPORT PREVIOUS REPORT DATE: 08-14-79 CONTROL BLOCK: l l

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60 61 DOCKET NUMBER 68 69 EVENT DATE 74 7b REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 l Durine full power operation at about 1330, after troubleshooting, follow l

[o lal i up testing was being performed on the ESFAS UV A logic circuit. When the l

1o I4 l l UV A-4 logic would not initiate, it was observed that the 15 VDC power l

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supplies to A and B UV Actuation cabinets were deenergized (no output l

o 6 l Voltage with switch turned on). In this condition, the A and B UV logic l

l0 l7l l would not respond when signaled. The power supplies were reset and the l

lolal l UV actuation drawers were returned to service by 1500. No similar events.

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3J 34 3b 36 31 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h l 110 l I The suspected cause of the power supplies' output loss is a voltage I

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disturbance in the inverter output, which affected the input voltage of I

ltl2l l the power supplies, causing actuation of the power supplies' overvoltage l

l i 13 l l protection. Instrument bus and inverter modifications have been done to l

mI prevent recurrence. No further action deemed necessary for this event.

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% POWER OTHER STATUS I OV RY DISCOVERY DESCRIPTION W h l1l0lO!@l N/A l

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301-269-4933 E,

NAME OF PREPAREn L. F. Bass PHON E:

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LER No.

79-31/1X, Rev. 1 DOCKET No.

50-317 LICENSE NO.

DPR 53 EVENT DATE 07-31-79 REPORT DATE 05-09-83 ATTACHMENT CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (CONT'D)

The suspected cause of the loss of output of Ch. A UV Actuation 15 VDC power supply is a voltage disturbance in the output of the vital inverter that feeds this power supply. It is possible that the power supply's input voltage increased to a value above the 16 VDC actuation point of the power supplies overvoltage protection circuitry.

Instrument bus and inverter modifications have been performed to improve the reliability of the'120 VAC vital instrument power system (FCR 83-1001).

No further preventive action is deemed necessary for this event.

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B ALTIMORE G AS AND ELECTRIC COMPANY P.O. B O X 14 7 5 B A LTI M O R E. M A R Y L A N D 212o3 HUCLEAR POWER DEPARTMENT CALVERT CLIFFS NUCLE AR POWER PL ANT LUSBY, M ARYLAND 20657 June 9, 1983 Mr. James M. Allan Docket No. 50-317 Acting Regional Administrator License No. DPR 53 U. S. Nuclear Regulatory Commission Region 1 631 Park Avenue King of Prussia, PA 19406

Dear Mr. Allan:

In accordance with Technical Specification 6.9 please find the attached updated report for LER 79-31/1X, Revision 1.

Should you have any questions regarding this report, we would be pleased to discuss them with you.

Very truly yours, M

L. B. Russel:.

Plant Superintendent LBR:LFB:bsb cc: Director, Office of Management Information and Program Control Messrs:

A. E. Lundvall, Jr.

J. A. Tiernan e

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