ML19253C388
| ML19253C388 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 11/16/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Groce R VERMONT YANKEE NUCLEAR POWER CORP. |
| References | |
| NUDOCS 7912050309 | |
| Download: ML19253C388 (1) | |
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Docket No. 50-271 Vermont fankee Nuclear Power Corporation ATTN:
Mr. Robert H. Groce Licensing Engineer 20 Turnpike Road Westborough, Massachusetts 01581 Gentlemen:
The enclosed IE Information Notice No. 79-27 provides information with regard to the sequence of events that followed incidents involving steam generator tube ruptures at two PWR units.
If you have any questions regarding this matter, please contact this office.
Sincerely, 2LC/.2 5[, h/
- n w - oyce H. Grier
(( 4irector
Enclosures:
1.
IE Information Notice No. 79-27 2.
List of Recently Issued Information Notices CONTACT:
W. H. Baunack (215-337-5334) cc w/encls:
W. F. Conway, Plant Superintendent Ms. J. Abbey, Technical Secretary 1503 357
,:912 o 5 o 309 (p
ENCLOSURE 1 SSINS No.:
6870 Accession No.:
7910250488 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON D.C.
20555 IE Information Notice No. 79-27 Date:
November 16, 1979 Page 1 of 9 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 instances, the units were cooled down and placed in he residual heat removal mode with existie.g procedures.
Event of June 25, 1979 at the Doel 2 Nuclear Pswer Plant in Belgium The first event occurred on June 25, 1979, at the Doel 2 nuc har 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 ti:e plant was heated up after a shutdown caused by a malfunction of the main steam isalation valve.
At the time of the incident the primary coolant pressure was:
2233 psi and the temperature:
491 F.
The reactor remained subcritical throughout the event.
The first indication of abnormal behavior was a rapid decrease of the primary system pressure (approximately:
28 psi / min.).
This was folle;;ad 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 pressuriner heaters due to low liquid level in the 2.4 pressurizer.
1503 358 DUPLICATE DOCUMENT Entire document previously entered into system under:
d b
[D No. of pages:
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