05000369/LER-1981-107, Forwards LER 81-107/03L-0.Detailed Event Analysis Encl

Forwards LER 81-107/03L-0.Detailed Event Analysis Encl

ML20010A604
Person / Time
Site:	McGuire
Issue date:	08/03/1981
From:	Parker W DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20010A605	List: 05000369/LER-1981-107, Forwards LER 81-107/03L-0.Detailed Event Analysis Encl 05000369/LER-1981-107-03, /03L-0:on 810704,auxiliary Feedwater Flow Gauges for Steam Generator C & D Declared Inoperable.On 810706, Plant Entered Mode 3 from Mode 4.Caused by External Source Tied Into Instrument Loops Causing Power Supply to Fail
References
NUDOCS 8108110600
Download: ML20010A604 (3)

LER-1981-107, Forwards LER 81-107/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3691981107R00 - NRC Website

text

,

, - c, p r -

DUKE POWER = COhiPAITY Powru Ucit.nixo

.ma Sourit Catencit STurer GnAut.or,T%dj C. 2824a

.g

,t3 f*

C ii WI L LI A M O. PA R M E R J R.

Vice PRCtsDFNT August 3, 1981

'"" "'k^,"3.'.o $'

$? CAM Pacouctom Mr. J. P. O'Reilly, Director U. S. Nuclear Regulatory Commission T.agion II 101 Marietta Street, Suite 3100 A lanta, Georgia 30303 Re: McGuire Nuclear Station Unit 1 Docket No. 50-369

Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report R0-369/81-107. This report concerns Technical Specification 3.3.3.6, "The accident monitoring instrumentation channels shown in Table 3.3-J ') shall be operable". This i

incident was considered to be of no significance with rcspect to the health and safety of the public.

V [y truly yours, bwc d, ett c

William O. Parker, Jr.

PBN:krh Attachment cc: Director Mr. Bill Lavalee Office of Management and Program Analysis Nuclear Safety Analysis Center U. S. Nuclear Regulatory Commission Post Office Box 10412 Washington, D. C. 20555 Palo Alto, California 94303 Ms. M. J. Graham

)

f/,.

Resident Inspector-NRC g

g McGuire Nuclear Station v y. 4 9_-

9

%g 11 Y

~

y t

5

/

4/'

d

.)

f w,,

Sif 8108110600 810803 PDR ADOCK 05000369-S PDR;

~

McGUIRE NUCLEAR STATION REPORTABLE OCCURRENCE REPORT NUMBER: 81-107 REPORT DATE: August 3, 1981 OCCURRENCE DATE: July 4, 1981 l

FACILITY: McGuire Unit 1 Cornelius, NC IDENTIFICATION OF OCCURRENCE: The Auxiliary Feedwater Flow Rate Instrumentation for Accident Monitoring was declared inoperable.

CONDITION PRIOR TO OCCURRENCE: Mof 4. Hot Shutdown DESCRIPTION OF OCCURRENCE: On July 4, 1981, Control Room personnel found that the Auxiliary Feedwater flow gauges for Steam Generators (S/G) "C" and "D" were defective. Sheir indicating pointers (needles) were missing, and thus these flow monitoring devices were declared inoperable. A work request was immedi&tely initiated to repair and calibrate the instruments. On July 6, 1981, the plant entered mode 3 from made 4; hence, this became a reportable incident pursuant to Technical Specification 3.3.3.6.

APPARENi' CAUSE OT 'CCURRENCE: The S/G's "C" and "D" Auxiliary Feedwater Flow Monitoring Instruxants became inoperable because an external source (600 volts) tied into the instrument loops. This caused the loops' power supply, transmitteru (Barton, Modci 386A), and indicators to fail.

ANALYSIS OF OCCURRENCE:

S/G's "C" and "D" Auxiliary Feedwater Flow instrumentation loops share a common power supply.

Each of the flow transmitters receives an input of 48V DC from this source and delivers an output of 4-20 milliamperes to its re-spective indicator. On July 4, 1981, Control Room personnel noticed that the needle on each flow indicator was missing. They were de-'s ed inoperable and a work request was initiated for their repair and calle et.

ine needle on the "C" loop l

indicator was found to be bent and the "D" loop's was broken. The flow transmitters had burned resistors on their circuit board, and their common power supply was also burned.

It was discovered that a wire connection tied one phase of the 60V AC source l

of valve 1KC18B through the instrument loop to ground. The loop was recently grounded as a part of the corrective maintenance from a previous flow instrument failure. When valve 1KC18B was operated its 600V source apparently made a continuous path through the instrument loops causing the damage to the equipment.

SAFETY ANALYSIS

The auxiliary feedwater flow transmitters are used to provide indication for accident monitoring. They do not provide controls or interlocks to the pumps and valves of the Auxiliary Feedwater System.

If the plant had been in normal operation, and a normal or abnormal shutdown was required, the inopereb-ility of these instruments would not have affected the Auxiliary Feedwater System in providing its necessary function. Therefore, the plant's safe operation and the health and safety of the public were not affected by this indicent.

_ _ _ _ __I

{

Report Number 81-107 Page 2

CORRECTIVE ACTION

A modification was initiated *o remove the wire connection.

The "C" and "E G oops' transmitters and indicators were replaced and calibrated per procedures "I.T.T.

Barton 386A, 763A and 764A Transmitter Calibration" and "Barton Replacement and Re-Installation".

The instrumentation loops' power supply was replaced.

The Auxiliary Feedwater Flow Rate Instrumentation was declared operable on July 10, 1981.

i