ML19210D815
| ML19210D815 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 11/16/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| References | |
| NUDOCS 7911280109 | |
| Download: ML19210D815 (1) | |
Text
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WALNUT CREEK, CALIFORNI A 94596 November 16, 1979 Docket No. 50-312 Sacramento Municipal Utility District P. 0. Box 15830 Sacramento, California 95813 Attention: Mr. John J. Mattimoe Assistant General Manager Gentlemen:
The enclosed IE Information Notice provides information with regard to the sequence of events that followed incidents involving steam generator tube ruptures at two PWR units.
Sincerely, Lo R. H. Engelken Director
Enclosures:
1.
IE Information Notice 79-27 2.
Recently Issued IE Information Notices cc w/ enclosures:
R. J. Rodriguez, SMUD L. G. Schwieger, SMUD 1435
$5,
,c,
SSIMS Mo.:
6870 Accession No.:
7910250488 IINITED STATES
?.'UCLEAR REGULATORY cn.?ilSSION OFFICE OF INSPECTIO?l Af!D ENFnRCE"ENT WASHINGTON D.C.
20555 November 16, 1979 IE Information 'ntice No. 79-27 STEAM GENEPATOR TUBE RUPTURES AT TWO D'AR PLAtlTS Descriotion c" Circumstances:
In recent months two incidents involvino stean generator tube ructures have occurred.
In both instances, the units were cooled down and placed in the residual heat removal mode with existing crocedures.
Event of June 25, 1979 at the Doel 2 Nuclear Power Plant in Belgium The first event occurred on June 25, 1979, at th' Doel 2 nuclear oower olant in Belgium. The Doel unit is a 390 Mwe WestinghotLe two-loco reactor. The event consisted of a ruoture of several tubes in the 1c00 B steam generator. The resultant leakage between the primary ar.d secondary systems was estimated to be 125 gom. The event started when the plant was heated uo after a shutdown caused by a malfunction of the main steam isolation valve. At the time of tye incident the primary coolant oressure was: 2233 osi and the tenperature: 491 F.
The reactor remained subcritical throughout the event.
The first indication of abnomal behavior was a raoid decrease of the crimary system pressure (accroximately:
23 osi/nin.). This was followed by the sequence of events listed below:
Time, min.
1.
Increase of charcino flow demand, reouir 'na startup of a second 1.8 chargina cumo, 2.
Automatic isolation of the CVCS letdown lv e.
2.4 3.
Shut off of the pressurizer heaters due to low liquid level in the 2.4 pressurizer.
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