ML19318A637

LER 80-006/03L-0:on 800520,during Startup Testing in Mode 3, B Steam Generator Narrow Range Level Channel III Was Observed Reading Below Redundant Level Channels & Drifting Low.Caused by Air Pocket in Steam Generator Sensing Line

ML19318A637
Person / Time
Site:	North Anna
Issue date:	06/19/1980
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19318A636	List: ML19318A635 ML19318A637
References
LER-80-006-03L-01, LER-80-6-3L-1, NUDOCS 8006230539
Download: ML19318A637 (2)

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U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT CONTROL BLOCK / / / / / / / (1)~ (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

{/0/1/ /V/A/N/A/S/2/ (2) /0/0/-/0/0/0/0/0/-/0/0/ (3) /4/1/1/1/1 (4) / / / (5)

LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT

/0/1/ /L/ (6) /0/5/0/0/0/3/3/9/ (7) /0/5/2/0/8/0/ (8) /0 /6 /1/9 /B /0 (9)

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

j/0/2/ / On May 20, 1980, during startup testing in Mode 3, "B" Steam Generator Narrow /

!/0/3/' / Range Level Channel III was observed reading 10% below redundant level channels /

and drifting low. Since the affected channel was placed in the tripped con-f/0/4/ / /

/0/5/ / dition and redundant level protection was available, the health and safety of / <

j/0/6/ / the general public were not affected. Reportable pursuant to T.S. 6.9.1.9.b. /

!/0/7/ / /

l/0/8/ / /

SYSTEM CAUSE CAUSE ___GUMP. VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

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

SEQUENTIAL OCCURRENCE REPORT REVISION 1 LER/R0 EVENT YEAR REPORT NO. CODE TYF" NO.

(17) REPORT NUMBER /8/0/ /-/ /0/0/6/ /\/ /0/3/ /L/ /-/ /_0/

ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP. COMPONENT TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER

/E/ (18) /Z/ (19) /2/ (20) /Z/ (21) /0/0/0/0/ (22) g/ (23) /N/ (24) fjy_ (25) /R/3/6/9/ (26).

! CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

{/1/0/ / This event is believed to have been caused by an air pocket in the steam gener-/

l/1/1/ / ator low side sensing line. The instrument channel remained in the trip mode /

l/1/2/ / for approximately 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br />. The transmitter was isolated and the line was blown /

f/1/3/ / down after which correct indication was observed. The normal channel func- /

l/1/4/ / tional test was performed to assure satisfactory operation. /

i FACILITY METHOD OF STATUS  % POWER OTHER STATUS DISCO M DESCR N ON (32) j/1/5/

I

/B/ (28) /0/0/0/ (29) / NA / (30) DISCO /A/ (31)N L OPERATOR OBSERVATION /

ACTIVITY CONTENT l RELEASED OF RELEASE AMOUNT OF ACTIVITY (35) LOCATION OF RELEASE (36) l/1/6/, /Z/ (33) /Z/ (34) / NA / / NA /

l PERSONNEL EXPOSURES l NUMBER TYPE DESCRIPTION (39) l/1/7/ /0/0/0/ (37) /Z/ (38) / NA /

PERSONNEL INJURIES NUMBER DESCRIPTION (41) l/1/8/ /0/0/0/ (40) / NA /

LOSS TYPE OF OR DAMAGE TO FACILITY (43)

DESCRIPTION

!/1/9/ /Z/ (42) / NA /

PUBLICITY ISSUED ' DESCRIPTION (45) g NRC USE ONLY

!/2/0/ /N/_(44) / NA 30 $3} /////////////

NAME.0F~ PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151 -

I l

I I

-Virginia Electric and Power Company North Anna Power Station, Unit #2

Attachment:

Page 1 of 1 Docket No. 50-339 Report No. LER 80-06/03L-0 Description of Event On May 20, 1980, with the unit in a hot standby condition (Mode 3),

, the control room operator noticed that "B" Steam Generator Narrow Range Level Channel III was indicating about 10% lower than the redundant level channels. The failed channel was placed in the tripped condition as per T.S. 3.3.2.1 and declared inoperable.

Frobable Consequences of Occurrence The consequences of this event were limited because the affected channel was placed in a tripped condition within the hour and redundant narrow range level protection channels I and II were both available to initiate engineered safety systems if required. As a result, the health and safety of the general public were not affected by this occurrence.

This failure does not present a generic problem for Unit I and 2 instru-mentation.

.Cause of Event The erratic behavior of the level channel is thought to have been caused by entrapped air in the low side sensing line of the steam gen-erator.

Immediate Corrective Action The channel was placed in the trip mode and a maintenance request was submitted. The associated transmitter was isolated and the low side sensing line was blown down which removed the entrapped air and restored proper. indication to the channel. The normal functional surveillance test for the affected channel (2-PT-32.1.8) was satisfactorily performed to prove operability and the channel was returned to service.

Scheduled Corrective Action No scheduled corrective action is required.

Actions Taken to Prevent Recurrence No further actions are required.

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