ML19257D090

Final Deficiency Rept Re Ice Condenser Heat Loads Exceeding Design Heat Loads.Glycol Chiller Units Currently Maintaining Temp of 15 F

ML19257D090
Person / Time
Site:	Sequoyah
Issue date:	01/23/1980
From:	Mills L TENNESSEE VALLEY AUTHORITY
To:
References
NCR-NEB-79-1, NUDOCS 8001310359
Download: ML19257D090 (2)

Text

TENNESSEE VALLEY AUTHORITY CH ATTANOOG A. TENNESSEE 37401 400 Chestnut Street Tower II January 23, 1980 lir. James P. O'Re ly, Director Office of Inspecti and Enforcement U.S. Nuclear Regulat ry Commission Region II - Suite 310 101 !!arietta Street Atlanta, Georgia 30303

Dear Mr. O'Reilly:

buQUOYAu NUCLutR FLAWT UNITS 1 AND 2 - ICE CONDENSLR EEAT LOADb FICEED DESIC3 liEAT LOADS - GCR NES 79 FINAL REPORT The subject deficiency was initially reported to NRC-01E Inspector G. A. delisle on August 14, 1979, in accordance with 10 CFR 50.55(e).

Interia reports were submittea on September 11 and November 19, 1979.

Enclosed is our final report.

If you have any questions concerning this =atter, please get in touch wita D. L. Lambert at FTS 6.i4-2581.

Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, "anager Nuclear Regulation and Safety Enclosure cc: tir. Victor Stello, Jr. , Director (Enclosure)y/

Office of Inspection and Enforcement U.S. Nuclear Regulatory Co= mission

".iashington, DC 20555 1845 254 30/9

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SEQUOYAH NUCLEAR PLANT UNIfS 1 AND 2 L ICE CONDENSER HEAT LOADS EXCEED DESIGN HEAT LOADS NCR NE3 79-1 10 CFR 50.55(e)

FINAL REPORT Description During hot functional testing of Sequoyah Nuclear Plant unit 1, it was discovered that f our glycol chiller units wet e required to maintain the required 15 F ice bed temperature. The Sequoyah Nuclear Plant design called for three glycol chillers to be sufficient to maintain the ice bed temperature at 15 F. Based on the performance of unit 1 ice condenser, the present glycol ref rigeration capacity (i.e. , four glycol chiller units per nuclear unit) may be insuf ficient to sustain acceptable ice bed temperatures in both ice condensers during unit 2 ice loading.

This deficiency is reportable because with the present glycol chiller capacity, ice loading of unit 2 might allow temperatures in the ice condensers to rise above 15 F. If temperatures in the le condenser were to rise above 15 F, it is possible that the ice night be degraded.

Degradation of the ice in the ice condenser could adversely affect the safe operation of the plant because the safety analyses for the plant are based on a specific weight and configuraticn of ice in the ice con-denser. Deviation f rcm this specific weight and configuation could invalidate the safety analyses for Sequoyah Nuclear Plant.

The design of the ice condenser f or 'lat ts Bar Nuc1 car Plant is similar to the ice condenser desi;;n for Sequoyah Nuclear Plant; therefore, the possibility of a similar deficiency exists at Watts Bar Nuclear Plant.

Safety Implications If this deficiency had remained uncorrected, the possibility exists that temperatures in the unit 2 ice condenser may have risen so high as to permit sublimation, melting, or solidification of the ice in the ice condenser. If this had occurred, the plant might not have been able to mitigate the effects of a potential LOCA, and thus the safe operation of the plant would have been compromised.

However, Sequoyah Technical Specification 3.6.7.1 requires the unit to be shut down if the ice bed temperature exceeds 27 F for 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />.

Corrective Action Operation of four glycol chillers units has maintained the unit 1 ice condenser temperature around 15 F. TVA has purchased an additional chiller -

package each (containing two glycol chillers) for Sequoyah Nuclear Plant and Watts Bar Nuclear Plant. This additional chiller capacity will permit a 15 F temperature to be maintained in each ice condenser under the maxi-mum heat load conditions expected during normal plant operation.

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