05000324/LER-1982-139-01, /01T-0:on 821216,while Investigating Downscale Indication on Reactor Water Cleanup Differential Flow Indicator,Determined That Three Flow Transmitters Supplying Erroneous Signals to Summer Circuit

/01T-0:on 821216,while Investigating Downscale Indication on Reactor Water Cleanup Differential Flow Indicator,Determined That Three Flow Transmitters Supplying Erroneous Signals to Summer Circuit

ML20028C279
Person / Time
Site:	Brunswick
Issue date:	12/31/1982
From:	Poulk R CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20028C272	List: 05000324/LER-1982-139, Forwards LER 82-139/01T-0 05000324/LER-1982-139-01, /01T-0:on 821216,while Investigating Downscale Indication on Reactor Water Cleanup Differential Flow Indicator,Determined That Three Flow Transmitters Supplying Erroneous Signals to Summer Circuit
References
LER-82-139-01T, LER-82-139-1T, NUDOCS 8301070291
Download: ML20028C279 (3)

LER-1982-139, /01T-0:on 821216,while Investigating Downscale Indication on Reactor Water Cleanup Differential Flow Indicator,Determined That Three Flow Transmitters Supplying Erroneous Signals to Summer Circuit

Event date:
Report date:
3241982139R01 - NRC Website

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NRC FORM 366 U. S. NUCLEA3 REGULATORY COMMISSION (7-77)

LICENSEE EVENT REPORT

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8 60 61 DOCKET NUMBE R 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES gogy, ; While investigating the cause of a ownscale indication on the RWCU differential flowg indicator 2-G31-R615, it was determined that the three flow transmitters 2-G31-FT-g g 3 g N012, NO36 and N041 were supplying erroneous signals to summer circuit 2-G31-K604.

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, R615 provides an indication for one of two parallel outputs from K604 g

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,,;g; l An investigation of the transmitters determined that air in the sensing lines

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LER ATTACHMEN'T - RO #2-82-139 Facility:

BSEP Unit No. 2 Event Date: December 16, 1982 During the morning of December 13, 1982, Operations personnel noticed that the RWCU differential flow indicator 2-G31-R615 was reading on the downscale meter stop. After discussion with the Control Operator, a Work Request and Authorization form (WR&A), number 2-E-82-5051, was written to investigate the downscale reading. This WR&A was given to the responsible Shift Foreman for processing. The R615 is a local indicator (not technical specification required) which is used to perform the required channel check for the RWCU high differential flow isolation instruments 2-G31-FDS-N603 (A&B).

When the Shift Foreman reviewed WR&A 5051, he viewed the problem as being with the ladicator only and not with the isolation circuitry.

Other Shift Foremen who noticed the unprocessed WR&A on the Shift Foreman's desk till December 15, 1982, were of the same opinion as the first Shift Foreman. Their reasoning for this belief was based on their knowledge of the circuitry design. Three flow transmitters, one on the RWCU suction line and one each on the two discharge lines, feed a summing circuit. The summer circuit takes the suction flow and compares it with the combined discharge flow to produce a differential flow signal to the isolation circuits. iiie R615 is a direct reading indicator off one of the two parallel signals from the summer.

Prior to reaching the isolation setpoint for differential flow, a " Differential Flow High" alarm followed by a " Differential Flow High-High" alarm is received.

During evolutions which were performed during the preceding and proceeding days, either or both of these alarms were received. Although a cisck of the meter indication was not performed for comparison when the alarms annunciated, it was felt, due to the annunciators, that the isolation circuits were operable.

During the day of December 15, 1982, the Shift Foreman who originally reviewed the WR&A processed it for work.

Because he felt that the I&C personnel might only look at the R615, he had added to the WR&A to also check the transmitters. The WREA was placed in routing basket for delivery to I&C as a routine priority item.

l At approximately 0300 on December 16, 1982, Operations personnel who had l

witnessed the problem on December 13, 1982, but had been off-shift since, noticed that the R615 was still downscale and that the WR&A (5051) had not l

been worked.

I&C was immediately requested to begin an investigation of the l

R615. At approximately 0700 on December 16, 1982, the Shift Foreman was notified that the output from the three flow transmitters were incorrect and the indication on R615 did reflect system conditions. An LCO was immediately established on the RWCU differential flow isolation instrumentation and the RWCU System was isolated.

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LER ATTACHMENT - RO #2-82-139 (Continued)

Investigations by I&C personnel determined that the sensing lines to the transmitters contained air, causing their output signals to be in error in the nonconservative direction.

Interpolation of the as found condition indicated that the system would probably have isolated at approximately 65 gpm instead of the techn.. specification value of n 53 gpm.

The air was removed from the sensing lines and the entire circuitry was calibrated and returned to service.

This event was caused by the failure of the Shift Foreman to initiate timely corrective actions when the reliability of the instrument was questionable.

As a result, the Shift Foreman was counseled on the need for timely resolution i

of problems relating to technical specification instrumentation, He was also removed from licensed activities for two weeks.

Additional corrective actions included the writing of a Standing Instruction describing this event and emphasizing the need for timely resolution. Also, due to the various indications that could be noted on the R615 indicator i

(depending on plant conditions, it could read from 0 to 30 gpm), a review is in progress by Operations personnel and the Rk'CU System engineer to develop meaningful sound-based criteria for performing an instrument check on this instrument. This should also assist in identifying unusual indications in a more timely manner.

The technical specifications involved in this report are Table 3.3.2-1, item 3a and Section 6.9.1.8 (b and f).

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