ML19210E555
| ML19210E555 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 11/16/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Dunn C DUQUESNE LIGHT CO. |
| References | |
| NUDOCS 7912050245 | |
| Download: ML19210E555 (1) | |
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UNITED STATES g,
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Docket No. 50-334 IOV 1 B GI?
Duquesne Light Company ATTN:
Mr. C. N. Dunn Vice President Operations Division 435 Sixth Avenue Pittsburgh, Pennsylvania 15219 Gentlemen:
The enclosed IE Information Notice No. 79-27 provides information with regard to the requence of events that followed incidents involving steam generator tube ruptures at two PWR units.
If you have any questier.s regarding this matter, please contact this office.
Sincefeiy,
'!.'O U W. h N b v 7]Dir,ceH.Grier Boy ector
Enclosures:
1.
IE Information Notice No. 79-27 2.
List of Recently Issued h formation Notices CONTACT:
W. H. Baunack (21F-337-5334) cc w/encls:
F. Bissert, Technical Assistant Nuclear R. Washabaugh, QA Manager J. Werling, Station Superintendent G. Moore, General Superintendent, Power Stations Department J. J. Carey, Nuclear Technical Assistant R. Martin, Nuclear Engineer 1500 134 7912050 06h
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 the residual heat removal mode with existing procedures.
Ever.t 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 Nestinghouse 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 heatea 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 subcritical throughout the event.
The first indication of abnormal behavior was a rapid decrease of the pri.::gy 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.
DUPLICATE DOCUMENT Entire document previously entered into system under:
1500 135 ANo 79/o K M W No. of pages:
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