ML19254D006
| ML19254D006 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 09/27/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Parris H TENNESSEE VALLEY AUTHORITY |
| References | |
| NUDOCS 7910190275 | |
| Download: ML19254D006 (2) | |
Text
~/G
- ga 't 49'o UNITED STATES g
[
T,,
g NUCLEAR REGULATORY COMMISSION M
r REGION 11 3g%
O.,
101 MARIETTA ST,. N.W., SUITE.1100
%,..W...,e*
ATLANTA, GEORotA 30303 In Reply Refer To:
SEP 2 71979 RII:JE0__
7 0 259, 50-260';
v 30-296,' 50-327 50'390, 50-391 Tennessee Valley Authority Attn:
H. G. Parris Manager of Power 500A Chestnut Street Tower II Chattanooga, Tennessee 37401 Gentlemen:
The enclosed Bulletin 79-24 is forwarded to you for action. Written responses are required. If you desire additional information regarding this matter, please contact this office.
Sincerely, James P. O'Reilly Director
Enclosure:
1.
Designated Applicants for Operating Licenses D
1190 046
^17k 7910190 G
SEP 2 71979 Tennessee Valley Authority -
cc w/ enc 1:
H. L. Abercrombie Plant Superintendent Post Office Box 2000 Decatur, Alabama 35602 3
F. Cox 400 Commerce Street W10C131 C Knoxville, Tennessee 37902 D. E. McCloud Project Engineer 400 Chestnut Street Toser II Chattanooga, Tennessee 37401 G. G. Stack, Project Manager Post Office Box 2000 Daisy, Tennessee 37319 J. M. Ballentine Plant Superintendent Post Office Box 2000 Daisy, Tennessee 37319 D. L. Lambert, Project Engineer 400 Chestnut Street Tower II Chattanooga, Tennessee 37401 j}9b e
Accession No. 7908220114 SSINS No:
6820 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 September 27, 1979 IE Bulletin No. 79-24 FR0 ZEN LINES Summary:
On January 3, 1979, an unusual event occurred at Davis-Besse, Unit 1.
The event involved the freezing of the water in a portion of the high pressure coolant injection (HPCI) system recirculation line that is common to both high pressure coolant injection pumps. The line was not thawed until January 5, 1979, and the event was not reported to NRC until March 12, 1979.
In addition, over the past five years, there have been several events involving frozen instrument and sampling lines.
Description of Circumstances:
The condition was discovered on January 3, 1979, while the reactor was operating at approximately 96 percent power. During a monthly surveillance test of the HPCI pumps, there was no flow through the recirculation line from the pump discharge to the Borated Water Storage Tank (BWST).
Investigation revealed that water in a portion of the line exposed to the outside weather was frozen.
This portion of the line to the BWST is common to both HPCI pumps. The line har redundant heat tracing (a heated wire to prevent freezing); it is insulated; and it has a low-temperature alarm system to warn of freezing conditions.
Water in the line froze apparently because of prolonged sub-freezing temperatures and a defect in the insulation. There was no apparent malfunction of the heat tracing or temperature alarm circuits, although the temperature sensing elements are located in an area not exposed to the coldest temperature conditions.
This recirculation line serves two purposes: One is to provide a flow path for surveillance testing, and the other is to provide a minimun. flow path to prevent possible damage to the pump in the event it is operated against a closed discharge valve or a reactor coolant system pressure greater than the maximum discharge pressure of the pump (approximately 1600 psig).
In the initial review of the event on January 3, 1979, the licensee concluded that the: pumps were still operable with no immediate action was taken to thaw th January 5, 1979, the line was thawed and was successfully completed.
DUPLICATE DOCUMENT Entire document previously entered into system under:
n c;o u s
^=o 199L6A29/W Mo. of pages:
-