ML16342C859
| ML16342C859 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 03/09/1995 |
| From: | Wegner M NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Rosenthal J NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| Shared Package | |
| ML16342C860 | List: |
| References | |
| AEOD-T95-01, AEOD-T95-1, NUDOCS 9503160307 | |
| Download: ML16342C859 (4) | |
Text
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~O aI aI.*~4 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 March 9, 1995 MEMORANDUM TO:
FROM:
SUBJECT:
Jack E. Rosenthal, Chief Reactor Analysis Branch Safety Programs Division Office for Analysis and Evaluation of Operational Data Wary S.
Wegner Reactor Systems Engineer Reactor Systems Analysis Section Reactor Analysis Branch Safety Programs Division Office for Analysis and Evaluation of Operational Data MAJOR DISTURBANCES ON THE WESTERN GRID AND RELATED EVENTS The attached Technical Review Report discusses the electrical transient which occurred throughout the western United States on December 14, 1994, during which both Diablo Canyon units scrammed from 100 percent power.
Two major disturbances on the Western grid occurred in 1994.
One was caused by an earthquake, one by a contaminated insulator and two coincidental faults.
Additional events from 1987 to the present have also occurred.
Initiators of these events have been forest fires, earthquakes, lightning strikes, line
- faults, and equipment failures, all of which occurred offsi,te from any nuclear plant.
The most significant of these disturbances involved equipment faults severe enough that they actuated a remedial action scheme.
The actuation" of remedial action schemes:
islanding,. shedding load, tripping transmission
- lines, and tripping of generating units are not problems, but steps taken to correct problems.
These actions are taken to preserve the integrity of the system.
The event initiator, be it earthquake or equipment fault, is the problem.
The scramming of the two Diablo Canyon units during the December 14,
- 1994, event was caused by the plants'ogic, not from loss of the grid.
The grid recovered from the initial fault and the scramming of the two Diablo Canyon units without interrupting power to Diablo Canyon, nor did Diablo Canyon lose offsite power following the January 17,
- 1994, earthquake transient.
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J.
Rosenthal The reactions of the Western grid in response to the transient of December 14,
- 1994, appear to have been appropriate to the transient.
The scramming of the Diablo Canyon units in anticipation of a loss of power to the reactor coolant pumps was premature, but in accordance with plant design.
Attachment:
As stated cc w/att:
Mr. Dennis E.
Eyre Administrative Manager Western Systems Coordinating Council University of Utah Research Park 540 Arapeen Drive Suite 203 Salt Lake City, Utah 84108-1288 Mr. Joseph W. Cornish, Director Dispatcher Training Western Systems Coordinating Council Technical Staff University of Utah Research Park 540 Arapeen Drive Suite 300 Salt Lake City, Utah 84108-1288 Distribution w att:
Public
- AChaffee, NRR Central File
- EWeiss, NRR
-RAB R/F
- RJenkins, NRR DHickman
- MTaylor, EDO PBaranowsky
- NSavage, DOE FCongel
- RSavio, ACRS
- KRaglin, TTC
- PLewis, INPO DRoss
- Dgueener, NOAC EJordan
DOCUMENT NAME:
C: iWP51 tt,WPDOCSilTRGRID. MSW
- See previous concurrence:
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C:SPD NAME DATE MWe ner:mmk 02/23/95*
GLanik 02/28/95*
JRos thai 03/
/95