ML19211C071
| ML19211C071 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 11/16/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Millen C PUBLIC SERVICE CO. OF COLORADO |
| References | |
| NUDOCS 8001100043 | |
| Download: ML19211C071 (1) | |
Text
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CENTRAL FILES UNITED STATES PDR:HQ pa a8 coq'o, NUCLEAR REGULATORY COMMISSION LP O
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November 16, 1979 Docket No. 50-267 Public Service Company of Colorado ATTN:
Mr. C. K. Millen Senior Vice President P. O. Box 840 Denver, Colorado 80201 Gentlemen:
The enclosed IE Information Notice provides information with regard to the sequence of events that followed incidents involving steam generator tube ruptures at t.wo PWR units.
Sincerely,
/
n.- Karl V. Se rit Director
Enclosures:
1.
IE Information Notice 79-27 2.
Recently Issued IE Information Notices cc:
D. W. Warembourg, Nuclear Production Manager Fort St. Vrain Nuclear Station P. O. Box 368 Platteville, Colorado 80651 L. Brey, Manager, Quality Assurance j[}g 7
N 8001100 P
SSINS No.:
6870 Accession No.:
7910250488 UNITED STATES NUCLEAR REGULATORY COSB1ISST.ON OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON D.C.
20555 IE Information Notice No. 79-27 Date: November 16, 1979 Page 1 of 7 STEAM GENERATOR TUBE RUPIURES AT TWO PWR PLANT 9 Description of Circumstances:
In recent months two incidents involving steam generator tube ruptures have occurred.
In both instances, the units were cooled down and placed in the residual heat removal mode with existing procedures.
Event of June 25, 1979 at the Doel 2 Nuclear Power Plant in Belgium The first event occurred on June 25, 1979, at the Doel 2 nuclear power plant in Belgium.
The Doel unit is a 390 Mwe Westinghouse two-loop reactor.
The event consisted of a rupture of several tubes in the loop B steam generator.
The resultant leakage between the primary and secondary systems was estimated to be 125 gpm.
The event started when the plant was heated up after a shutdown caused by a malfunction of the main steam isolation valve. At the time of the incident the primary coolant pressure was:
2233 psi and the temperature:
491 F.
The reactor remained suberitical throughout the event.
The first indication of abnormal behavior was a rapid decrease of the primary system pressure (approximately:
28 psi / min.).
This was followed by the sequence
~
of events listed below:
Time, min.
1.
Increase of charging flow demand, requiring startup of a second 1.8 charging pump.
2.
Automatic isolation of the CVCS letdown line.
2.4 3.
Shut off of the pressurizer heaters due to low liquid level in tha 2.4 pressurizer.
Closing of block valves in the pressurizer relief line.7 3 9 0 71 1
4.
4.6 5.
Rapid increase of water level in The steam generator was isolated 6.
Startup of the third charging puce DUPLICATE DOCUMENT all charging pumps from the CV t tank.
E Entire document previously entered into system under:
ANO No. of pages:
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