05000339/LER-1980-047-03, /03L-0:on 800819,in Mode 2 at 3% Power,Steam Flow Indications on Loops A,B & C Gave Erroneous Readings.Caused by Design Deficiency in Pressure Sensing Sys of Venturi in Main Steam Line.Engineering Study & Design Mod Carried

/03L-0:on 800819,in Mode 2 at 3% Power,Steam Flow Indications on Loops A,B & C Gave Erroneous Readings.Caused by Design Deficiency in Pressure Sensing Sys of Venturi in Main Steam Line.Engineering Study & Design Mod Carried Out

ML19338D619
Person / Time
Site:	North Anna
Issue date:	09/18/1980
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19338D610	List: 05000339/LER-1980-047, Forwards LER 80-047/03L-0 05000339/LER-1980-047-03, /03L-0:on 800819,in Mode 2 at 3% Power,Steam Flow Indications on Loops A,B & C Gave Erroneous Readings.Caused by Design Deficiency in Pressure Sensing Sys of Venturi in Main Steam Line.Engineering Study & Design Mod Carried
References
LER-80-047-03L-01, LER-80-47-3L-1, NUDOCS 8009230577
Download: ML19338D619 (2)

LER-1980-047, /03L-0:on 800819,in Mode 2 at 3% Power,Steam Flow Indications on Loops A,B & C Gave Erroneous Readings.Caused by Design Deficiency in Pressure Sensing Sys of Venturi in Main Steam Line.Engineering Study & Design Mod Carried Out

Event date:
Report date:
3391980047R03 - NRC Website

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Attachment: Page 1 of 1 Docket ' No. '50-339

- Report No. LER 80-047/03L-0

Description of Event

OnAugust[19.1980;whileoperating'inMode2at3%powerthesteam flow indications (chanagl III) on loops'A, B, and C gave erroneous 5

- readings of *~1.25.x'10 pyh when the expected value is

• 1.20 x 10 pph.

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Probable Consequences'of Occurrence Since all.three channels were placed in the tripped mode within.one-hour, as specified by T.S. 3.3.1.1 and 3.3.2.1, the health and safety of the public were not affected. Reportable pursuant to T.S. 6.9.1.9.b.

Cause of Event-The steam flow indications were in error because.of a design deficiency

.in the pressure sensing lines off the venturi'in the main steam line.

The pressure densing lines connecting the venturi to the condensate pots were so long that steam' condensed in the lines prior to reaching the condensate pots. This situation caused the DP cells to sense erroneous differential pressure values resulting in high steam flow indications.

- Immediate' Corrective Action.

The channel III signals on' loops A, B, and C were placed in the tripped mode.

As'a' temporary measure, small vent holes were drilled through the caps above the. vent valve on top of the condensate pots.

This measure was sufficient'for the short term until a permanent modifi-

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cation could be: implemented.

Scheduled Corrective Action No further actions are required since a Design Change was implemented to resolve'the problem.

Action Ta' ken to Prevent Recurrence

- All twelve condensate potsrhave been relocated closer to their respective. venturi,' thereby.el N 4.nating the problem of condensation occurring in_the' pressure sensing lines. Relocation of four of the six DP transmitters was'also'necessary.

Generic Implications There are'no~ generic implications.

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