ML20058G619
| ML20058G619 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 12/02/1993 |
| From: | Hutchinson C ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GNRO-93-00147, GNRO-93-147, NUDOCS 9312100005 | |
| Download: ML20058G619 (6) | |
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'M Entergy Operations,inc.
- ENTERGY mum i
Pyt G nm MG 391f4 Te 631437 2F.00 l
C. R. Hutchinson l
December 2, 1993 yl%f' u,mnm: m f
U.S. Nuclear Regulatory Commission Mail Station P1-137 Washington, D.C.
20555 Attention:
Document Control Desk i
Subject:
Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 I
License No. NPF-29 Follow-up Response to Violation for Inadequate
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Procedure Results in RCIC Injection Report No. 50-416/93-14, dated 10/08/93 (GNRI-93/00179)
GNRO-93/00147
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Gentlemen:
t Entergy Operations, Inc. hereby submits a follow-up response to i
the Notice of Violation 50-416/93-14-01.
l In the above mentioned inspection report, you noted concerns regarding certain similarities between this and a previous t
violation (50-416/92-18-01).
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In the previous violation which occurred during sensor replacement activities, the Reactor Core Isolation Cooling (RCIC) system steam supply valve received an automatic c?osure signal.
t That ESF actuation occurred due to a maintenance 71anner
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specifying an incorrect value for simulating an untr'pped condition to the associated master and slave trip units. The
-i cause was determined to be a misleading descriptica of the slave trip unit in the plant component database (CDB) which resulted in the input values, specified to block the instruments from tripping, not being verified.
In the current violation, an incorrect setpoint for a slaved trip unit also led to a system actuation.
In this case; however, the setpoint was incorrectly specified in a procedure which had l
received an inadequate technical review.
l To determine whether events are similar or repetitive, we employ
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the same approach as that used by the NRC.
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l 9312100005 931202 P
PDR ADOCK 05000416 I l
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K December 2, 1993 GNRO-93/00147 i
Page 2 of 4 Appendix C to 10CFR2 describes these terms as follows:
"The term j
" repetitive violation" or "similar violation" as used in this policy statement, means a violation that reasonably could have t
been prevented by a licensee's corrective action for a previous violation".
Our procedures define corrective action to be those actions necessary to prevent the root cause(s) of an event from recurring.
In other words, the corrective action we develop in response to a quality deficiency is i direct function of the root cause of the event rather than the characteristics of the event.
itself.
Therefore, similar events such as an automatic equipment actuation can have widely differing corrective actions depending i
on whether the cause of the event was personnel error, inadequate procedure, inadequate training, design deficiencies, etc.
Consequently, similar or repetitive events are those in which the root causes are similar --
i.e.,
the later event should not have occurred if corrective action had been effective in preventing the root cause from recurring.
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In this context, the current violation and the previous violation are not similar even though both involved incorrect slave unit setpoints.
The earlier event involved incorrect information in j
the CDB, misleading a maintenance work planner sufficiently to cause a mistake on a work order.
The current event's root cause is substantially different in that inadequate engineering review led to the incorporation of an incorrect setpoint into a procedure.
Similarly, the corrective actions for the two events are substantially different and those actions implemented for one event could not have prevented the other.
We share your concern for repetitive /similar events because they can indicate that corrective action has been ineffective.
It is for that very reason that last year, in revising our corrective action program, we explicitly identified repetitive events as significant and deserving of increased scrutiny.
However, for the reasons discussed above, we do not believe that the events cited in Inspection Report 50-416/93-14 meet that criterion.
Yours t ly F,
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attachment cc:
See next page
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.December 2, 1993 GNRO-93/00147 Page 3 of 4 l
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't cc:
Mr.
R. H. Bernhard(w/a)
Mr.
H.
W. Keiser(w/a) i Mr. R. B. McGehee (w/a) l Mr. N.
S. Reynolds (w/a) i Mr.
H. L. Thomas (w/o)
Mr. Stewart D. Ebneter (w/a) l Regional Administrator U.S. Nuclear Regulatory Commission Region II 101 Marietta St.,
N.W.,
Suite 2900 Atlanta, Georgia 30323 Mr.
P. W.
O'Connor i
Office of Nuclear Reactor Regulation l
U.S. Nuclear Regulatory Commission i
Mail Stop 13H3 Washington, D.C.
20555 l
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Attachment Io GNRO-93/00147 l
Page1of3 Notice of Violation 93-14-01 l
l Technical Specification 6.8.1.c requires that written procedures be established, implemented, and maintained covering the applicable procedures recommended in Appendix 'A' of Regulatory Guide 1.33, Revision 2. Regulatory Guide 1.33 recommends that procedures for performing maintenance which can affect the performance of safety related equipment should be properly preplanned and performed in accordance with written procedures and documented instructions.
l 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 3
Cooling (RCIC) injection on September 14,1993.
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Admission or Denial of the Allened Violation i
Entergy Operations, Inc. admits to this violation.
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The Reason for the Violation,if Admitted The plant was in OPERATIONAL CONDITION 3. Prep rations were in progress to l
place shutdown cooling in ser ice.
l In response to NRC Bulletin (NRCB) 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 purge the instrument reference leg associated with reactor steam condensing pot D004B.
.j 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 perturbation:,
j on the reference leg during the purge, a RCIC initiation would have been prevented due to i
one channel being placed in CALIBRATE (CAL).
j Pnor to purgmg the reference leg associated with condensing pot D004B, master inp unit (MTU) 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 MTU receives the output of an internal power source from the associated calibration station. The MTU, in turn feeds slave trip unit (STU) B21N692B. This STU provides an initiation signal for half of the RCIC control logic.
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Attachment to GNRO-93/00147 i
Page 2 of 3 l
~ The output of the internal power source is adjusted by turning the CAL dial located on the calibration station. The output of the power source is increased until it matches an output that does not generate a trip signal.
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On September 14,1993 during the manual purge of the reference leg associated with D004B, the input to MTU B21N691B was adjusted by turning the CAL dial three (3) turns from fully counter-clockwise. The three turns were adequate to prevent a trip from the MTU; however, this adjustment did not provide an adequate output signal to STU B21N692B. The procedure did not require the STU to be checked to ensure no tripped l
condition existed after placing the MTU in CAL. This was identified as a contributing j
factor to the event.
l The master and slave trip units are on the same panel, but B21N692B is not located where l
personnel would readily notice its condition (c. g. tripped) when adjusting B21N691B.
l Therefore, personnel were not aware of the tripped condition of the slave unit.
Plant personnel began purging the reference leg for D004B using a hand operated pump.
Pump operation caused pressure perturbations on the reference leg and resulted in i
B21N692F generating a low water level signal to the RCIC control logic. The existing trip i
on the "B" channel along with the trip on the "F" channel caused an initiation and injection of the RCIC system.
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i The system injected for approximately two minutes at a flow rate of 800 gpm. Reactor 3
level increased approximately 20 inches. The calibration station output to the MTU was increased to reset STU B21N692B, which prevented further RCIC initiations during the purging evolution.
An investigation was initiated to determine the cause of this occurrence. The investigation l
. revealed that the technical review of the instruction for the reference leg purge was inadequate. The reviewer failed to identify that the output adjustment for the MTU was insufficient to reset both the MTU and STU.
l Following the response to GL 92-04 and NRCB 93-03, the procedure was issued for use l
in the field. It had not been performed prior to use on September 14.
i The design configuration of the RCIC low water level instrumentation is such that penurbation on a single reference leg can cause system initiations. This was also identified as a contributing factor to the event.
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Attachment to GNRO-93/00147 l
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Page 3 of 3 JII. < ~ Corrective Steps Which Ilave Heen Taken and Results Achieved i
instruction 07-S-13-60, Reactor Vessel Reference Leg Purge, was changed to correct the CAL setting for B21N691 A, B, E and F. The change also specifies the value of the setting instead of the number of turns of the dial.
l The engineer responsible for the procedure's technical review was counselled.
Additionally, engineering personnel were briefed on the incident and the responsibilities of j
technical reviewers were emphasized.
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IV.
Corrective Steps to be Taken to Preclude Further Violations The above corrective actions are adequate to preclude recurrence.
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