ML19208B268

First Interim Deficiency Rept Re Temp Changes in RCS Which Exceeded Max Heatup & Cooldown Rates.Corrective Action Will Be Taken After Westinghouse Evaluation Is Reviewed by Util

ML19208B268
Person / Time
Site:	Sequoyah
Issue date:	09/04/1979
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML19208B267	List: ML19208B266 ML19208B268
References
NUDOCS 7909190440
Download: ML19208B268 (1)

Text

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ENCLOSURE

. SEQUOYAH NUCLEAR PLANT UNITS 1 AND 2 REACTOR COOLANT SYS' .3 EXCEEDED HEATUP AND C00LDOWN RATES NCR'S 12P AND 13P 10 CFR 50.55(e)

FIRST INTERIM REPORT Description of Deficiency During hot functional testing of unit 1, temperature sensors in the loop 2 hot leg and in the lower portion of the pressurizer indicated temperature changes exceeding the rates in the proposed technical specifications. The s occurrences coincide with formation and collapse of the bubble in the pres-surizer and fill and vent activities in the pressurizer.

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The proposed technical specification maximum heatup and cooldown rates are . -

100 F/hr and 200 F/hr, respectively, for the pressurizer and 100 F/hr (hestup and cooldown) for the Reactor Coolant System (RCS). Temperature Elemegt (TE) 68-24 in the looo 2 hot leg sensed temperature increases from 118 to 250 F in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and from 140 to 250 F in 8 minutes. TE 68-24 also sensed temperature decreases frgm 255 go 129 F in 50 minutes, from 260 to 140 F in 25 minutes, and from 250 to 142 F in 12 minutes.

TE 68-319 in the pressurizer sensed temperature increases from 135 to 262 F in one hour and from 12g to 230 F in one hour. TE 68-319 sensed a temperature decrease from 432 to 180 F in a one-hour period.

The flow of fluid in and out of the pressurizer through the surge line when forming or collapsing the bubble in the pressurizer during heatup and cooldown is a normal operating occurrence. Similarly, the addition of '

cooler water to the pressurizer during fill and vent is a normal occur-rence. The physical locations of TE 68-24 and TE 68-319 make them subject to the resulting localized transient temperature changes which are not _,

indicative of the RCS and pressurizer as a whole. The technical specifi-cations do not make allowance for the special operating situations.

Corrective Action Corrective action will be taken after the evaluation from Westinghouse -

has been reviewed by TVA. ,

In the interim, a check will be made to ensure that operators are aware of the potential for these localized thermal transients and that the proposed technical specification limits are observed. When a permanent solution is developed, it will be applied to Sequoyah and Watts Bar Nuclear Plants and will also be evaluated for applicability to Bellefonte and Yellow Creek Nuclear Plants.

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79091001/927

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