ML19210D803
| ML19210D803 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 11/16/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Gary R TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| References | |
| NUDOCS 7911280096 | |
| Download: ML19210D803 (1) | |
Text
7Ze tlNITED STATES
[ga arcg%n NUCLEAR REGi?LATORY COMMISSION REGloN IV
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-5 ARLINGTON, TEX AS 7G012 "f.
a gv j' November 16, 1979 In Reply Refer To:
RIV Docket Nos.
50-445/IE Information Notice No. 79-27 50-446/IE Information Notice No. 79-27 Texas Utilities Generating Company ATTN:
Mr. R. J. Gary, Executive Vice President and General Manager 2001 Bryan Tower Dallas, Texas 75201 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, C.Karl V frit Director
Enclosures:
1.
IE Information Notice 79-27 2.
Recently Issued IE Information Notices 1435
$41 7D11280Q g
SSINS No.:
6870 Accession No.:
7910250488 UNITED STATES NUCLEAR REGULATORY CO> MISSION 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 RUPTURES AT TWO PWR PLANTS Description of Circumstances:
In recent months two incidents involving steam generator tube ruptures have occurred.
In both in.itances, 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 3pm.
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 be'tavior 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 the 2.4 pressurizer.
4.
Closing of block valves in the pressurizer relief line.
4.6 5.
Rapid increase of water level __
The steam generator was iso 6.
Startup of the third chargit MENT all charging pumps from the tank.
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