ML19210D808
| ML19210D808 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay, Diablo Canyon |
| Issue date: | 11/16/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Crane P PACIFIC GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7911280102 | |
| Download: ML19210D808 (1) | |
Text
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'o UNITED STATES 8 ,P.r cg( j NUCLEAR REGULATORY COMMISSION
' g REGION V Wy// ' [C d
1990 N. CALIFORNI A BOULEVARD f
SUITE 202. WALNUT CREEK PLAZA o
WALNUT CREEK, CALIFORNIA 94596 November 16, 1979 Docket No. 50-133 50-275 50-323 Pacific Gas and Electric Company 77 Beale Street San Francisco, California 94106 Attention: Mr. Philip A. Crane, Jr.
Assistant General Counsel Gentlemen:
The enclosed IE Information Notice provides information with regard to the sequece of events that followed incidents involving steam generator tube ruptures at two PWR units.
Sincerely, e
R. H. Engelken Director
Enclosures:
1.
IE Information Notice 79-27 2.
Recently Issued IE Information Notices cc w/ enclosures:
W. Barr, PG&E W. Raymond, PG&E R. Ramsay, PG&E, Diablo Canyon E. Weeks, PG&E, Humboldt Bay J. Worthington, PG&E 1435 545 7 M 12 80 ldDtt
SSINS No.:
6870 Accession ?!o. :
7910250488 IWITED STATES f:UCLEAR REGULATORY CG!"11SSION OFFICE OF INSPECTI0rl AND ENFnRCE"ENT WASHINGTON D.C.
20555 November 16, 197C IE Information Notice No. 79-27 STEAM GENEPATOR TUBE RUPTURES AT TWO PNR PLANTS Descriotion of Circumstances:
In recent months two incidents involvina steam generator tube ruptures have occurred.
In both instances, the units were cooled down and placed in the residual heat removal mode with existina crocedures.
Event of June 25, 1979 at the Coel 2 Nuclear Power Plant in Belgium The first event occurred on June 25, 1979, at the Doel 2 nuclear oower clant in Belaium. The Doel unit is a 390 "we Westinghouse two-loco reactor. The event consisted of a ruoture of several tubes in the 1000 B steam generator. The resultant leakage between the crimary and 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 nain steam isolation valve. At the time of tge 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 nf the orinary system pressure (acoroximately:
28 osi/ min.). This was followed by the sequence of events listed below:
Time, min.
1.
Increase of charaing flow demand, recuirino startup of a second 1.8 charainq oumo.
2.
Automatic isolation of the CVCS letdown line.
2.4 3.
Shut of# of the cressurizer heaters due to low liquid level in the 2.4 pressurizer.
DUPLICATE DOCUMENT 143.5 546 Entire document previously entered into system under:
79foZb W Tf ANO No. of pages: _
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