ML19209C618

LER 79-115/03L-0:on 790913,loop B Steam Indicator Read Lower than Redundant Indicator.Caused by Leaking of Transmitter Root Valves Resulting in Loss of Ref Leg Level.Steam Flow Channel Tripped & Loop Calibr

ML19209C618
Person / Time
Site:	North Anna
Issue date:	10/12/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19209C617	List: ML19209C616 ML19209C618 ML19209C619 ML19209C620 ML19209C621
References
LER-79-115-03L, LER-79-115-3L, NUDOCS 7910160491
Download: ML19209C618 (2)

Text

NRC FORM 366 U. S. NUCLE AR Rf CULATORY COMMISSION (7 77)

• LICENSEE EVENT REPORT

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EVENT DESCRIPHON ANDECPROBAE S ENCES F TTl ion September 13, 1979, during Mode 1 operation, loop B steam flow iud _icator FI-1485 _

l After ensuring that an actual low 10131 1 read lower than the redundant indicator FI-1484.

0 4 [ steam flow did not exist, the channel was placed in the tripped condition and I O s declared inoperable. Since the affected channel was placed in " Test" and the redun- 1 O e [ dant channel remained operable, the health and safety of the general public were not i O 7 l_ jeopardized. Reportable pursuant to T.S. 6.9.1.9.b. I c I a i

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33 34 36 J/ 40 42 44 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i o 1 Steam flow indicator FI-1485 indicated low because the root valves for the trans- I

[Tlf] mitter were leakinq causing a loss of referer.c.c leo level . The steam finw ch?nrol I i 7 was placed in the tripped condition and the loop was calibrated and functionally I l i i a l I tested satisfactorily. The transmitter root valve will be reworked durino the I i 4 I current refueling outage. I i 8 9 80 STA S  % POWER OTHER STAT US DISC El Y DISCOVEllY DLSCHiPTION W [Ej @ [0 419]@lNA l LA_J@l Operator Observation l ACT:ViTY CONTENT RELE ASED OF HE LE ASE AVOUNT OF ACTIVITY LOCATION OF HLL EASE i e [z_j @ lz l@l NA l l NA l 7 N 9 10 11 44 45 80 PLH50NNEL E APOSUHLS NUV3 E H TYPE DESCRIPTION -

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g I 0160 +N I IIIIIIillIIIi 7 8 9 10 08 69 80 5 NAME OF PREPAHER W. R. La,i,tright pnONE: 703-894-5151

Virginia Electric and Power Company North Anna Power Station, Unit #1 Attachmco.: Page 1 of 1 Docket No. 50-338 Report No. LER 79-115/03L-0 Description of Event On September 13, 1979, during Mode 1 operation at 49% power, loop B steam flow indicator FI-1485 gave a low flow indication. The redundant loop B steam flow indicator FI-1484 did not indicate a low flow. The affected channel was placed in the tripped condition and declared inoperable.

Probable Consequences of Occurrence Steam line flow is used to initiate both a reactor trip and a safety injection. A safety injection will occur on a high steam line flow coincident with low steam line pressure or low-lcw TAVG. A reactor trip will be actuated by a steam flow /feedwater flow mismatch and low steam generator '.2 vel. Since the affected steam flow channel was placed in the tripped condi lon and the redundant channel remained operable, the health and safety of the general public were not affected

• by this event. There are no generic implications associated with this occurrence.

Cause of Occurrence Loop B steam flow indicator FI-1485 gave low indication because the root valves for the flow transmitter were both leaking causing a loss of referen:e icg level.

Immediate Corrective Action The channel was placed in the tripped condition and the root valve was teaporarily repaired.

Scheduled Corrective Action The transmitter root valves will be reworked during the refueling outage presently in progress.

Actions Taken to Prevent Recurrence No further actions are required.

\\63 147