ML20065L861
| ML20065L861 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 04/15/1994 |
| From: | Hutchinson C ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| RTR-REGGD-01.108, RTR-REGGD-1.108 GNRO-94-00063, GNRO-94-63, NUDOCS 9404220012 | |
| Download: ML20065L861 (3) | |
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l C. R. Hutchinson te4 s
April 15, 1994 1% u.,
U.S. Nuclear Regulatory Commission Mail Station P1-137 Washington, D.C. 20555 Attention:
Document Control Desk
Subject:
Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-29 Interpretation of Regulatory Guide 1.108 Revision 1,1977 l
i GNRO-94/00063 l
l Gentlemen:
Regarding your request that was specified in Notice 50-416/94-02, we are submitting our interpretation of Regulatory Guide (RG) 1.108. Your request also asked for our rational for the classification of the May 25,1992 trip of the Division 1 Emergency Diesel Generator (EDG).
The RG describes methods that are acceptable to the NRC staff for complying with regulation concerning periodic testing of EDGs to ensure that the onsite power systems meet their availability requirements.
The definition of " Failure" is also indicated in this RG. The RG specifies a " Failure" as being the failure to start, accelerate, and assume the design-rated load within and for the time prescribed during an emergency or a valid test. Therefore, a failure can only occur in the event of an emergency run or a valid test.
Section C.2.e gives guidance in determining valid tests and failures. We consider any test that is not a valid test, as specified by the RG, to be an invalid test and any failure that occurs during this type of test is considered to be invalid.
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The only exception to this position is a run that is performed as a result of maintenance where a trip occurs or a condition is identified that can not be attributed to maintenance that was performed.
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if this trip / condition would have prevented the EDG from starting, accelerating and assuming the required load during an emergency condition, it would have been considered a valid failure of the EDG unit.
The run that was in progress on May 25,1992, was a post-maintenance / post modification test. This test was not being performed to demonstrate operability of the EDG unit. This test was being performed to ensure that all components that were affected by RF05 maintenance (DROR) and modifications were operating properly.
During this run, the EDG output breaker tripped open. This occurrence was attributed to excessive resistance at the rectifier bridge selector switch. During the outage, extensive maintenance had been performed on the EDG that could have affected the resistance of the switch. Therefore, it is considered to be an invalid failure.
This EDG run was inappropriately classified as a valid successful test by operations surveillance coordinator due to an inadequate procedure.
Plant surveillance procedure 06 OP 1P75 V 0011 requires that all start attempts, including those from bona fide signals, be logged. The procedure also directs personnel to describe the occurrence in sufficient detail to permit independent determination of the validity of the run. In this particular case, the diesel was being run in accordance with special instructions prepared by engineering. These instructions directed operations personnel to start the EDG unit using our approved EDG procedures. Operations personnel elected to use the monthly surveillance procedure to start and load the EDG unit.
-i The start was logged as required. However, the log entry did not specify that this i
run was a post-maintenance / post modification run, it only specified the monthly surveillance as the reason for the-start attempt. The independent review of the start of the EDG unit could not distinguish this run from a normal surveillance run.
Due to the EDG unit operating for one hour at 2. 50 % loaa, it was determined to be a valid successful test, as specified by the procedure. This determinetion was in error. The test should have been classified as an invalid test as speci' led by C.2.e.(7).
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l Apr H 15, 1994
~ GNRO-94/00063 Page 3 of 4 Additionally, the procedure also contained an inappropriate statement concerning the length of time that the EDG unit ran at.>_. 50 % load. It stated that if the diesel met this criterion, the test was a valid success and any subsequent failure would be classified as invalid As mentioned above, this statement was inappropriate and contributed to this occurrence.
The procedure has been changed to delete that statement. The log entry associated with subject test was revised to indicate an invalid test. Further reviews are also in progress to determine further enhancements to our current program.
Additionally, this submittal serves as a revision to Special Report 92-003 which was dated June 26,1992.
Yours truly, i
l Y3'Y (,
CRH/RR/
cc:
Mr. R. H. Bernhard Mr. H. W. Keiser Mr. R. B. McGehee Mr. N. S. Reynolds Mr. H. L. Thomas Mr. Stewart D. Ebneter Regional Administrator U.S. Nuclear Regulatory Comrnission Region 11 101 Marietta St., N.W., Suite 2900 Atlanta, Georgia 30323 Mr. P. W. O'Connor (w/2)
Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 13H3 Washington, D.C. 20555 i
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