ML19253B615
| ML19253B615 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 10/01/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Woolever E DUQUESNE LIGHT CO. |
| References | |
| NUDOCS 7910160522 | |
| Download: ML19253B615 (1) | |
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UNITED STATES 4
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Docket No. 50-412 007 1 m3 Ouquesne Light Company ATTN:
Mr. E. J. Woolever Vice President 435 Sixth Avenue Pittsburgh, PA 15219 Gentlemen:
This 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, k
cyce H. Grie(r_J3 d* %
~ Director
Enclosures:
1.
IE Information Notice No. 79-25 2.
List of IE Information Notices Issued in the Last Six Months cc w/encls:
R. J. Washabattgh, Quality Assurance Manager 1150 212 N910 m S2p Q
ENCLOSURE 1 Accession No.: 7908220125 SSINS No.: 6870 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE 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 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 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 reacrer 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 MCC-D, 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 disconnected.
It was replaced by another manual controller which was plugged into the valve control circuit and which had been taped to the top of a console in the main control room.
The actual installation of the manual controller was not per-formed under established guidelines.
A dd W a--'-
been issued to ensure consistent under:
control of this unusual component conf DUPLICATE DOCUMENT Entire document previously entered into system under: }}) ANO 790822 O/25 No. of Pages:}}