ML20059L083
| ML20059L083 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 11/08/1993 |
| From: | Hutchinson C ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GNRO-93-00138, GNRO-93-138, NUDOCS 9311160295 | |
| Download: ML20059L083 (4) | |
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e E'ntsrgy Operations,Inc.
N ENTERGY vo -
Fbrt G tsn MS 39150 Te! 601437 2000 C. R. Hutchinson November 8, 1993
$'.77" araw o.muer c:arn U.S. Nuclear Regulatory Commission i
Mail Station F1-137 Washington, D.C.
20555 Attention:
Document Control Desk
Subject:
Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-29 Response to Violation for Inadequate Procedure Results in RCIC Injection Report No. 50-416/93-14, dated 10/08/93 (GNRI-93/00179)
GNRO-93/00138 Gentlemen:
Entergy Operations, Inc. hereby submits the response to the Notice of Violation 50-416/93-14-01 Yours truly, I'
w CRH/RR/
attachment cc:
Mr. R. H. Bernhard(w/a)
Mr. H. W. Keiser(w/a)
Mr. R. B. McGehee (w/a)
Mr. N. S. Reynolds (w/a)
Mr. H. L. Thomas (w/o)
Mr. Stewart D. Ebneter (w/a)
Regional Administrator U.S. Nuclear Regulatory Commission Region II 101 Marietta St.,
N.W.,
Suite 2900 Atlanta, Georgia 30323 Mr.
P. W. O'Connor Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 13H3 Washington, D.C.
20555 93111602?5 93110s i
a gDR ADOCK 05000416
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I PDR Q
Attachment to GNRO-93KK)l38 Page 1 of 3 Notice of Violation 93-14-01 Technical Specification 6.8.1.c requires that written procedures be established, implemented, and maintained covering the applicable procedures recommended in Appendix 'N ofRegulatory Guide 1.33, Revision 2. Regulatory Guide 1.33 recommends that procedures for performing maintenance which can affected the performance of safety related equipment should be properly preplanned and performed in accordance with written procedures and documented instructions.
General Maintenance Instruction 07-S-13-60, Reactor Vessel Reference Leg Purge, provides instructions for purging reference legs of noncondensible gases.
Contrary to the above, Instruction 07-S-13-60 was inadequate in that it did not adequately address the setpoint of slaved trip units which caused an unplanned Reactor Core Isolation Cooling (RCIC) injection on September 14,1993.
5 I..
Admission or Denial of the Allened Violation Entergy Operations, Inc. admits to this violation.
II.
The Reason for the Violation,if Admitted The plant was in OPERATIONAL COND! TION 3. Preparations were in progress to place shutdown cooling in service.
In response to NRC Bulletin (IEB) 93-03 and Generic Letter (GL) 92-04, a commitment for interim actions was made to purge noncondensibles from reference legs which feed shutdown cooling isolation instrumentation. As a part of the interim actions, plant personnel were preparing to manually backfill the instrument reference leg associated with reactor level condensing pot D004B.
There are two (2) RCIC initiation logic channels ("B" and "F") associated with condensing pot D004B. The two channels share a common reference leg. In the event of penurbations on the reference leg during the backfill, a RCIC initiation would have been prevented due I
to one channel being placed in CALIBRATE (CAL).
I Prior to filling condensing pot D004B, master trip unit B21N691B was placed in CAL in accordance with an approved plant procedure. Placing the trip unit in CAL isolates the trip unit from the output ofits associated level transmitter (B21N091B). While in CAL, the trip unit receives the output of an internal power source. The output of the internal power source is adjusted by turning the CAL dial located on the associated CAL station. The output of the power source is increased until it matches the output that would normally be generated by the associated vessel level transmitter.
4 Attachment to GNRO-93/00133 Page 2 of 3 The master unit, in turn, feeds slave trip unit B21N692B This trip unit provides an initiation signal for half of the RCIC one-out-of-two-taken-twice control logic.
On September 14,1993 during the manual backfill of D004B, the input to the master unit was adjusted by tuming the CAL dial three (3) turns clockwise. However, this adjustment I
did not provide an adequate output signal to B21N692B. The procedure did not require B21N692B to be checked to ensure no tripped condition existed following the CAL adjustment.
The master and slave trip units are on the same panel, but B21N692B is not located where personnel would readily notice its condition (e. g. tripped) when adjusting B21N691B.
Therefore, personnel were not aware of the tripped condition of the slave unit.
Plant personnel began backfilling the reference leg for D004B using a hand operated pump. Pump operation caused pressure perturbations on the reference leg and resulted in B21N691F and B21N692F generating a low water level signal to the RCIC control logic.
The existing trip on the "B" channel along with the trip on the "F" channel caused an initiation and injection of the RCIC system.
The system injected for approximately two minutes at a flow rate of 800 gpm. Reactor level increased approximately 20 inches. The output from B21N691B was increased to reset the RCIC initiation logic.
I An investigation was initiated to determine the cause of this occurrence. The mvestigation revealed that the technical review for the procedure governing the backfill evolution was inadequate. The reviewer failed to identify that the output adjustment for the master trip unit was incorrect.
Following the response to GL 92-04 and IEB 93-03, the procedure was issued for use in the field. It had not been performed prior to use on September 14. The investigation also identified that there was no other check for adequacy performed prior to use in the field.
Additionally, two contributing factors were identified during the investigation.
l The procedure did not require personnel to verify that the slave unit was not tripped following the CAL adjustments made to the master unit.
The design configuration of the RCIC low water level instrumentation is such that perturbation on a signal reference leg can cause system initiations.
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Attachment to GNRO-93/00138 Page 3 of 3 Ill.
Corrective Steps Which Have Been Taken and Results Achieved The procedure governing backfill of reference legs was changed to require the output to i
be determined following adjustment of the master unit. This ensures the output of the CAL unit is adequate to prevent a trip of the associated trip units.
The engineer responsible for the procedure's technical review was counseled. Additionally, engineering personnel were briefed on the incident and the responsibilities of technical reviewers were emphasized.
IV.
Corrective Steps to be Taken to Preclude Further Violations Further evaluations are in progress at this time to determine appropriate corrective actions for the identifed cause. These evauations are being tracked by our plant corrective action process.
V.
Date of Full Compliance Will be Achieved The above evaluations are scheduled to be completed by March 31,1994.
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