ML19254E570
| ML19254E570 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 10/01/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | William Jones OMAHA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 7911010488 | |
| Download: ML19254E570 (1) | |
Text
CENTRAL FILES POR:HQ M(P R UNITED STATES
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NUCLEAR REGULATORY COMMISSION oe REcion iv NSIC n
611 RY AN PL AZA DRIVE, SulTE 1000 I. ( I i,
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art.INGTON, TEXAS 76012
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O October 1, 1979 Docket No.
50-285 Omaha Public Power District ATTN:
W. C. Jones, Division Manager -
Production Operations 1623 Harney Street Omaha, Nebraska 68102 Gentlemen:
This IE Information Notice is provided as an early notification of a possibly significant matter.
It is expected that recipients will review the information for possible applicability to their facilities.
No specific action or response is requested at this time.
If further NRC evaluations so indicate, an IE Circular, Bulletin, or NRR Generic Letter will be issued to recommend or request specific licensee actions.
If you have questions regarding the matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely,
/
0l J}.
1
.j& gljO-Karl V. Seyfrit j
Director
/
Enclosures:
1.
IE Information Notice No. 79-25 2.
List of IE Information Notices Issued in Last Six Months cc:
S. C. Stevens, Manager Fort Calhoun Station Post Office Box 98 1291 161 Fort Calhoun, Nebraska 68102 7 D1101 0 4-F'B'
Accession No.:
7908220125 SSINS No.:
6870 UNITED STATES l
yj" NUCLEAR REGULATORY COMMISSION sjddw 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C.
20555 IE Information Notice 79-25 Date: October 1, 1979 Page 1 of 2 REACTOR TRIPS AT TURKEY POINT UNITS 3 AND 4
Background
On August 3, Turkey Point Units 3 and 4 tripped 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 on 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, Unit 4 start-up tranformer 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 Motor Control Center (MCC) "D" which is common to both units.
Since the Rod Position Indication System for both units is powered by the non-vital portion of MCC-D, a turbine 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 available. 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-3-455B.
The original Hagan controller for spray valve PCV-3-455B had been_ disco h and was placed by another manual contr control circuit and which had been tap control room.
The actual installation DUPLICATE DOCUMENT performed under established guidelines hrd been issued to ensure consistent u Entire document previously operational control of this unusual con entered into system under:
ANO d
1291 162
'~'g No. of pages: