ML19211C070
| ML19211C070 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 11/16/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | William Jones OMAHA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 8001100041 | |
| Download: ML19211C070 (1) | |
Text
bcc to DAC:ADM:
CENTRAL FILES UNITED STATES PDR:HQ
/pa ascoq'o NUCLEAR REGULATORY COMMISSION LPDR O %)j ,'
REGION IV 7 i i o 611 RY AN PLAZA DRIVE. SUITE 1000 NSIC
% g,jgj ARLINGTON, TEXAS 76012
'o
+o November 16, 1979 Docket No.
50-205 Omsha Public Power District ATTN:
W. C. Jones, Division Manager -
Production Operations 1623 Harney Street Omaha, Nebraska 68102 Centle=en:
The enclosed IE Information Nctice provides information with regard to the sequence of events that followed incidents iuvolving stear:t generator tube ruptures at two PWR units.
Sincerely, I
4 arl V k eyfrit K
Director
Enclosures:
1.
IE Information Notice 79-27 2.
Recently Issued IE Information Notices cc:
S. C. Stevens, Manager Fort Calhoun Station Post Office Box 98 Fort Calhoun, Nebraska 68102 1739 068 9
8001100 04:
.d
SSINS No.:
6870 Accession No.:
7910250488 UNITED STATES NUCLEAR REGULATORY COFD1ISSION 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 TU3E RUPTURES AT TWO PWR PLANTS Description of Circumst.nces:
In recen: 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 sas 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 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 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.
1739 069 4.
Closing of block valves in the pressurizer relief line.
4.6 5.
Rapid increase of water level in The steam generator was isolated.
DUPLICATE DOCUMENT 6.
Startup of the third charging pum all charging pumps from the CV ta Entire document previously tank.
entered into system under:
ANO No. of pages:
A v
,