ML20082B667
| ML20082B667 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 07/09/1991 |
| From: | Cottle W ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 91-005, 91-5, GNRO-91-00119, GNRO-91-119, NUDOCS 9107160267 | |
| Download: ML20082B667 (2) | |
Text
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W. T. Cottle 4
s i;e July 9. 1991
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m U.S. Nuclear Regulatory Commission Mail Station P1-137 Washington, D.C.
20555 Attention: Document Control Desk Gentlemen:
SUBJECT:
Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-29 Special Report 91-005 Invalid failure of-Emergency Diesel Generator 11 GNRO-91/00119 On June 18, 1991, the Division 1 Diesel Generator (SDG 11) was started for the performance of the functional test in accordance with Technical Specification 4.8.1.2.
SDG 11 was synchronized to the grid.through the 152-1501 breaker in order to pick up sufficient -load for the test.
Operations personnel loaded SDG 11 to-approximately 5.5 MW.
Approximately 55 minutes-after_ achieving this_ load, the incoming offsite feeder breaker-(152-1501) to bus 15AA' tripped open...The opening of the 152-1501 resulted in a decrease of load being supplied by SDG 11.
The l
load decreased below the minimum value required to qualify _the test as a valid successful test.
Therefoie, the-test was unintentionally termine.ted prior to satisfying the surveillance requirements. The diesel generator continued to run tied on_to the bus during the entire evolution.
A subsequent investigation revealed a loose terminal connection in the paralleling circuitry at the'SDG ll output breaker-(152-1508).
The loose connection caused the 152-1501 breaku to open inadvertently.
The loose terminal connection caused a normally.1nergized relay _in the diesel generator output breaker to deenergize which resulted in the 152-1501 l
breaker opening. -The.cause of the-loose terminal connection was l
indeterminate.
The connection was tightened.and SDG 11 was retested-satisfactorily.
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SPRP9105/SCMPFLR - 1
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2600' 910716o267 910709 PDR ADOCK 0500 6
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4 July 9, 1991 GNR0-91/00119 Page 2 of 3 The 152-1501 breaker is not a part of the diesel generator unit as described in Regulatory Guide 1.108 (Revision 1, August 1977).
Therefore, this is an invalid fatiure of the diesel generator unit.
The paralleling circuit is used during testing and would not be in the circuit during an emergency condition.
The opening of the 152-1501 did not and would not have inhibited the diesel generator from performing its safety function.
Yo,urs truly, fA.O 1.'TURR/cg cc: Mr. D. C. Hintz Mr. J. L. Mathis Mr. R. B. McGehee Mr N. S. Reynolds Mr. H. L. Thomas Mr. F. W. Titus Mr. Stewart D. Ebneter Regional Administrator U.S. Nuclear Regulatory Commission Region 11 101 Marietta St., N.W., Suite 2900 Atlanta, Georgia 30323 Mr. L. L. Kintner, Project Manager Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 11D21 Washington, D.C.
20555 SPRP9105/SCMPFLR - 2
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