ML19250C250
| ML19250C250 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 10/01/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Millen C PUBLIC SERVICE CO. OF COLORADO |
| References | |
| NUDOCS 7911230096 | |
| Download: ML19250C250 (1) | |
Text
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PR UNITED STATES I
/ja ascoq'o NUCLEAR REGULATORY COMMISSICN J i+
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REGloN IV U31C 611 RY AN PLAZ A r RIVE, SUITE 1000 7 i Mj o
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p October 1, 1979 Docket No. 50-267 Public Service Company of Colorado ATTN:
Mr. C. K. Millen Senior Vice President P. O. Box 840 Denver, Colorado 80201 Centlemen:
This IE Information Notice is provided as an early notification of a possiblf :tgnificant matter. It is expected that recipients will review the infor.ution for possible applicability to their facilities. No specific action or response is requested at this time.
If further h7C 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.
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Sincerely, l
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Karl V. Seyfrit ' / l Director
Enclosures:
1.
IE Information Notice No. 79-25 2.
List of IE Information Notices Issued in Last Six Months cc:
D. W. Warembourg, Nuclear Production Manager Fort St. Vrain Nuclear Station P. O. Box 368 l s, O /d 7
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Plattevine, Colorado 80651
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L. Brey, Manager, Quality Assurance i.
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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, Turkef 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 liagan controller for spray valve PCV-3-455B had been disconnected and was placed by another manual contr control circuit and which had been tap control room. The actual installation performed under established guidelines.
DUPLICATE DOCUMENT had been issued to ensure consistent u operational control of this unusual co Entire document previously entered into system under:
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