ML19259D274
| ML19259D274 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 10/01/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Arenal A SOUTHERN CALIFORNIA EDISON CO. |
| References | |
| NUDOCS 7910170541 | |
| Download: ML19259D274 (1) | |
Text
p sREco JNITED STATES 3n g
NUCLE AR RiMULATORY COMMISSION (gg 8\\
i' C REGION V S
U[
1990 N. t:AllFORNIA BOULEVARD k
o SUITE 202, WALNUT CREEK PLAZA
- e*
WALNUT CREEK, CALIFORNIA 9459G October 1,1979 Docket flos. 50-206 50-361 50-362 Southern California Edison Company P. O. Box 800 2244 Walnut Grove Avenue Rosemead, California 91770 Attention: Mr. A. Arenal, Vice President Advanced Engineering Gentlemen:
This Information flotice is provided as an early notification of a possibly significant matter.
It is expected that r';ipients will review the information for possible applicability to their facilities.
tio specific action or response is requested at this time.
If further flRC evaluations so indicate, an IE Circular, Bulletin, or Generic Letter will be issued to recommend or request specific licensee actions.
If you have questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, I S % %,-c d L R. H. Engelken Director
Enclosures:
1.
IE Information flotice 79-25 2.
List of IE Information Notices Issued in Last Six Months cc w/ enclosures:
ly(;
- d. o/ 3
' u,_
J. M. Curran, SCE J. T. Head, SCE J. H. Drake, SCE j010170 l
Accession tio.. 7908220125 SSINS No.: 6870 UNITED STATES NUCLEAR REGULATORY C0f0!!SSI0ft 0FFICE OF INSPECTIO!1 AND ENFORCEMEllT WASHINGTON, D.C.
20555 October 1, 1979 IE Information Notice 79-25 REACTOR TRIPS AT TUP, KEY POINT UNITS 3 AliD 4 Sackground On August 3, Turkey Point Units 3 and 4 tripped while operating at full power.
A voltage spike on a second protection channel caused Unit 4 to trip during surveillance testing on the reactor protection system.
This resulted in a loss of offsite power and subsequent shedding of non-essential loads.
Unit 3 tripped as the result of high coolant pressure caused by a turbine runback.
Discussion While performing a periodic test on channel "C" of the T-Average and Delta T Protection Channels, a spurious signal on channel "A" completed a 2 out of 3 trip logic: tripping Unit 4.
This resulted in a loss of offsite power condi-tion for Unit 4.
At this time, the Unit 4 startup transformer was out of service due to performance of periodic maintenance. This condition caused the initiation of the emergency diesel generator load sequencer which resulted in the shedding of non-vital loads. Among the non-vital loads shed, were those on I!otor Control Center (MCC) "D" which is common to both units.
Since the Rod Position Indicatio,1 System for both units is powered by the non-vital portion of NCC-D, a tur bine runback on Unit 3 was initiated upon loss of rod position indication.
This resulted in a reactor trip on high pressurizer pressure. At the time, neither of the two pressurizer spray valves was avail-able. One was considered inoperable prior to the transient and the other, temporarily powered by the non-vital portion of MCCD, had become unavailable earlier as a consequence of the Unit 4 trip.
A subsequent review disclosed inadequacies in the administrative controls over the correction of operational problems exhibited by spray valve PCV-3-4558.
The original Hagan controller for spray valve PCV-3-455B had been disconnected and was replaced by another manual controller which was plugged into the valve control circuit and which had been taped to tne top of a console in the main control room.
The actual installation of the manual controller was not performed Ender established guidelinx Additiona11v. no temocrary procedure had been issued to ensure consistent operational control of this unusual.
DUPLICATE DOCUMENT Entire document previously j
)
g}
entered into system under:
[
ANO No. of pages:
, s m..