ML17266A104

RO-335-79-30:on 790921,low Level Trip Setpoint of Reactor Protection Sys Steam Generator in Error by Approx 2%.Caused by Vendor Using Design Specs Rather than as-built Dimensions to Establish Instrument Span.Setpoint Raised

ML17266A104
Person / Time
Site:	Saint Lucie
Issue date:	09/24/1979
From:	Wethy C FLORIDA POWER & LIGHT CO.
To:
References
688, NUDOCS 7910150500
Download: ML17266A104 (7)

Text

RE ULATORY INFORMATION DISTRIBUTION SYS~VI R

ACCESSION NBR'910150500 DOC. DATE: 79/09/24 NOTAR D:

NO FACIL: 50-335 St.

Lucie Planti Unit fI Florida Poeer 8c Light Co.

50-1rg n1 AUTH. NANE AUTHOR AFFILIATION NETHYn C. N.

Florida Power 8c Light Co.

REC IP. NANE RECIPIENT AFFILIATION O'REILLY'S J. P.

Region 2I Atlanta'ffice of the Director

SUBJECT:

RO-335-79-30: on 790921 i lou level trip setpoint of reactor protection sos steam genel ator in error bg approx 2/. Caused bg vendol using design specs rather than as-built dimensions to establish instrument span. Setpoint raised.

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ADS, JRB, COW, MAS, REU, KNH FLORIDA POWER & LIGHTCOMPANY S'eptember 24, 1979 To:

Mr. J. P. O'Reilly, Director, Region II Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Atlanta, Georgia 30303 From:

Mr. C. M. Wethy, Plant Manager St. Lucie Plant - DPR 67 Florida Power

& Light Company Miami, Florida

Subject:

MEMO FOR FACSIMILE TRANSMISSION TO CONFIRM PROMPT REPORTABLE OCCURRENCE 335-79-30 This memo confirms our telephone notification of the sub5ect 14-day reportable occurrence made on September 21, 1979 to Mr. Martin of your office, During an evaluation of steam generator level sensing instrumentation conducted as part of compliance with NRC I&E Bulletin 79-21, it was noted that the design specifications of the steam generators had been used by the NSSS vendor to establish the instrument span for measuring steam generator level.

In actuality, the as-built dimensions should have been employed for this determination.

The FSAR analysis assumes a reactor trip during a loss of feedwater accident to occur when steam generator water level drops 50 inches below the normal water level.

As a result of using the design instead of the as-built, steam generator dimensions, the low level trip setpoint of 37% is in error {non-conservative) by approximately'%

(4 inches) in comparison with the FSAR criteria.

The FSAR analysis

does, however, also assume an instrument error of 10 inches in analyzing the loss of feedwater accident.

Confirmation was received from the NSSS vendor that past operation with the setpoint error did not have an effect on the safety analysis and did not pose a threat to the health and safety of the public.

Immediate corrective action was to instruct the control center operators that in the event of a low steam generator level condition, the reactor was to be manually tripped upon reaching 39% level.

After confirmation of the plant staff's evaluation of the proper instrument span was received from the NSSS'endor, the Reactor Protective System steam 'generator low level trip setpoint was raised to 39%.

C. M. Wethy Plant Manager St. Lucie Plant CMW/phg

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~O. BOX 128, FT. PIERCE, FL 33450 gal@</Ji

/fan FLORIOA POWER 5 LIGHT COMPANY September 21, 1979 To:

Mr. J. P. O'Reilly, Director, Region II Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission Atlanta, Georgia 30303

.r From:

Ifr. C. M. Wethy, Plant Manager St. Lucie Plant DPR 67 Florida Power

& Light Company Miami, Florida

Subject:

?EMO FOQ COIPIRMING DELETION OF PROMPT REPORTABLE OCCURRENCE 335-79-30 This memo confirms the deletion of the subject 14-day reportable occur-rence that was initially reported to your office via telephone notification to Mr.'. Dyer on September 18, 1979.

Based on telephone conversation with Mr. J. Dyer and Mr. R. Martin of your office on the following day, September 19, 1979, it was agreed upon that this event should not be a reportable occurrence.

This event will be included in the final inspection report on the results of the NRC I & E Bulletin 79-14 inspection evaluation.

The above Licensee Event Report number will be used, if necessary, for a future reportable occurrence.

C. M. Wethy Plant Manager St. Lucie Plant CMW:BJS:esr HELPING BUILD FLORIDA

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