ML19350D786

LER 81-019/03L-0:on 810420,during 100% Power,Pressurizer Level Channel I Indicated High.Caused by Instrument Drift, Leakage of Condensate Pot Packing Root Valve & Pressure Transmitter Isolation Valve.Transmitter Was Recalibr

ML19350D786
Person / Time
Site:	North Anna
Issue date:	05/13/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19350D785	List: ML19350D784 ML19350D786
References
LER-81-019-03L, LER-81-19-3L, NUDOCS 8105190263
Download: ML19350D786 (2)

Text

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U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT

(' 'l' CONTROL BLOCK / / / / / '/ / (1) (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

/0/1/ /V/A/N/A/S/1/ (2) /0/0/-/0/0/0/0/0/-/0/0/ (3) [4]I/1/1/1/ (4) / / / (5)

LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT ,

g/ (6) /0/5/0/0/0/3/3/8/ (7) /0/4/2/0/8/1/ (8) /o /5 /1/3 /8 /1/ (9)

DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

/0/2/ / On April 20, 1931, with Unit I at 100% power, the pressurizer level channel I /

/0/3/- / (LI-1459A) indicated high and deviated from the average of the other level /

/0/4/ / indications by greater than 3.5%. Since the channel was placed in trip in /

/0/5/ / one hour as required by T.S. 3.3.1.1, and two redundant level protection /

/0/6/ / channels remained available for reactor trip actuation if needed, the public /

/0/7/ / health and safety were not affected. /

/0/8/ / /

SYSTEM CAUSE CAUSE COMP. VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

/0/9/ /I/A/ (11) /E/ (12) M/ (13) /I/N/S/T/R/U/ (14) g/ (15) g/ (16)

SEQUENTIAL OCCURRENCE REPORT REVISION LER/RO- EVENT YEAR REPORT NO. CODE TYPE NO.

(17) REPORT NUMBER /8/1/ /-/ /0/1/9/ /\/ /0/3/ g/ [-/ g/

ACTION FUT111E EIFECT Sl!UTDOWN ATTAClfMENT NPRD-4 PRIME COMP. COMPONENT TAKEN ACTION ON PLANT MET 110D }{0URS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER g/ (18) g/ (19) g/ (20) g/ (21) /0/0/0/0/ (22) g/ (23) g/ (24) [NJ (25) /B/0/8/0/ (26)

CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

/__1/0/ / The cause of this event was instrument drif t, a root valve on the condensate /

/1/1/ / pot packing leak, and an isolation valve on pressure transmitter (PT1455) /

/1/2/ leaking. The level transmitter was recalibrated, the root valve backseated and/

/1/3/ / the leaking isolation valve tightened. The affected transmitter was then /

/1/4/ / returned to service. /

FACILITY MET 110D OF STATUS  % POWER OTHER STATUS DISCOERY DESCRMION (32)

/1/5/ /E/ (28) /1/0/0/ (29) / NA / (30) DISC M/ (31) M RY/ OPERATOR OBSERVATION /

ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35) LOCATION OF RELEASE (36)

/1/6/ LZ/ (33) LZ/ (34) / NA / / NA /

PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)

/1/7/ /0/0/0[ (37) /E (38) / NA /

PERSONNEL INJURIES NUMBER DESCRIPTION (41)

/1/8f_ /0/0/0/ (40) / NA /

LOSS OF OR DAMAGE TO FACILITY TYPE DESCRIPTION b3)

/1/9/ /2/[(42) / NA /

PUBLICITY ISSUED . DESCRIPTION (45) NRC USE ONLY

/2/0/ [Nf,(44) / NA /////////////

NAME OF PREPARER W. R. CARTWRIGilf Pif0NE (701) 894-5151 8105190 2 Q

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Virginia Electric and Power Company North Anna Power Station, Unit #1

Attachment:

Page 1 of 1 .

Docket No. 50-338 Report No. LER 81-019/03L-0 Description of Event On April 20, 1981, with Unit I in Mode I at 10 power, the pressurizer level indication provided by level transmitter (LT- 9A) deviated by > 3.5%

from the average of the other level transmittee indi tions. This event is contrary to T.S. 3.3.1.1 and reportable pursuant to T.3. 6.9.1.9.a.

Probable Consequences of Occurrence Since two redundant protection channels remained available and the affected level channel was placed in trip within one hour, the public health and safety were not affected.

Cause of Event The causes for level transmitter 1459A reading high were the following three problems: instrument drift (worse case was 500 my high); a root valve on the condensate pot packing leak, and a leaking isolation valve on pressure transmitter 1455. Both pressure transmitter 1455 and the affected level transmitter 1459A have a common tap which caused the leak on one to affect the other. No problems existed with pressure transmitter 1455 and no further problems were found with the affected level transmitter.

Both channels were subsequently returned to service.

Immediate Corrective Action .

The immediate action was to declare the affected channel inoperable and. place it in a trip mode. Subsequent to placing channel I (L-1459A) in the trip mode, the affected transmitter was recalibrated and the leaking root valve on the condensate pot was backseated. Additional action taken prior to returning the loop to service included tightening a leaking isolation drain valve en pressure transmitter P-455.

Scheduled Corrective Action No further action is scheduled.

Actions Taken to Prevent Recurrence No further action is required.

Generic Implications There are no generic implications to this event.

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