ML20137U320
| ML20137U320 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 04/14/1997 |
| From: | Terry C, Walker R TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TXX-97061, NUDOCS 9704160353 | |
| Download: ML20137U320 (5) | |
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gg Log- # TXX-97061 1
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File # 10130 C
C IR 96-04 Ref. # 10CFR2.201 lilELECTRIC' April 14, 1997 i
C. Lance Terry I
Gmup Mce President j
U. S. Nuclear Regulatory Commission Attn:
Document Control Desk Washington, D.C.
20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET NO. 50-445 and 50-446 NRC INSPECTION REPORT NOS. 50-445/96-17 and 50-446/96-17 i
RESPONSE TO NOTICE OF VIOLATION i
i TV Electric has reviewed the NRC's letter dated March 7, 1997, concerning the inspection conducted by your staff which was completed on February 1, 1997.
The subject inspection report enclosed a Notice of l
Violation.
The NRC inspection report 50-445(446)/96-17 states that the corrective actions taken to prevent repetition of the April 4, 1993, Unit 2 grid synchronization event were not effective.
TV Electric wishes to note that i
the 1993 event transpired two years prior to the current violation, and during that time no violations have occurred which could have reasonably been expected to have been prevented by our corrective actions for the 1993 I
event.
NUREG-1600, " General Statement of Policy and Procedures for NRC Enforcement Actions," at S VII.B.2.(b) for " mitigation" appears to accept i
two years or two inspection periods in which no violations occur that could have been prevented by licensee's corrective action as a period that 4
substantiates effective corrective actions.
Given the referenced NUREG, TU Electric's corrective actions for the 1993 event appear to be effective.
Notwithstanding, via Attachment 1, TV Electric accepts the violation and is j
j responding to the specific Notice of Violation (445/9617-01).
l The response to the subject inspection report was due on April 7, 1997:
however, TV Electric requested an extension until April 14, 1997.
The i
extension was discussed with Mr. Larry Yandell of the NRC Region IV staff.
4D,, i 9704160353 970414 C
PDR ADOCK 05000445' O
PDR _
1G0058 1815555M5P5.E5 P. O. Box IGJ2 Glen Rose Texas 7600
T)0(-97061 Page 2 of 2 Should you have any comments or require additional information, please do not hesitate to contact Obaid Bhatty at (817)-897-5839 to coordinate this effort.
Sincerely, e,% Q C. L. Terry By:
Roger D. Walker Regulatory Affairs Manager OB:ob Attachment cc: Mr. E. W. Merschoff, Region IV Mr. J. I. Tapia. Region IV Resident Inspectors
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At'tachm'ent to TXX 97061 Page 1 of 3 RESPONSE TO THE NOTICE OF VIOLATION
]
RESTATEMENT OF THE VIOLATION t
(50 445(446)/9617 01) 1 10 CFR Part 50, Appendix B, Criterion XVI, states, in part, that measures shall be established to assure that significant conditions adverse to quality are promptly identified and corrected and that the cause of the condition is determined and corrective action taken to preclude repetition.
Contrary to the above, the corrective actions taken to prevent repetition of a 1993. Unit 2 grid synchronization event were not effective.
The resultant reactor coolant system transient resulted in plant operation below the minimum temperature for criticality. A similar event, involving Unit 1, occurred November 16, 1996.
RESPONSE TO THE VIOLATION (50-445(446)/9617-01)
TV Electric accepts the violaticn and the requested information is provided herein.
1.
Reason for Violation Event description:
On November 16, 1996. Comanche Peak Steam Electric Station (CPSES)
Unit I was in Mode 1 after completing its refueling outage number 5 (1RF05).
Reactor power was between 6% and 10%.
Shift Operations completed the preparatory steps to synchronize the main generator according to procedure IP0-003A " Power Operations" step 5.1.28.
The task was classified as an infrequent evolution.
The Unit Supervisor (US) performed a general pre-job brief on the evolution for synchronizing the main generator and initiating loading.
The brief discussed the governing procedure.
Neither the US nor the BOP Operator had plant experience initiating a generator load with a new core.
The US had performed the task once at core mid-life. The 80P Operator experience was based on simulator training during initial license training.
The BOP Operator's task was to establish turbine speed at 1800 RPM, place the generator voltage regulator in service, energize the generator synchroscope and adjust turbine speed to obtain synchroscope rotation at 2-4 rpm in the fast direction, close one generator output breaker when the synchroscope reached the 12 o' clock
E l
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At'tachm'ent to TXX 97061 j.
Page 2 of 3 i
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position, raise the speed reference device until a positive increase c
in turbine megawatts (MW) was observed, adjust reactive load by i
raising the generator voltage regulator reference value, then loading i
the main turbine to between 30 MW and 100 MW by raising the speed l
reference device. These actions were outlined in procedure IP0-003A i
j step 5.1.29.
At approximately 9:22 p.m., on November 16, 1996, after closing the i
generator outpu breaker, the 80P Operator started initiating a load i
increase by depressing the speed reference device. About 10 feet j
away, the US was observing the plant computer monitor for MWs.
After i
t approximately 15 seconds the 80P Operator noticed no MW increase.
It j
should be noted that on the simulator (as experienced by the B0P Operator) the effects of the push-button speed reference device were seen witnin a few seconds.
Since the BOP Operator was concerned about having a generator reverse power trip, he depressed the MW raise button on the speed reference device once more and watched for i
j a MW increase.
After approximately 10 seconds, again the 80P j
Operator noticed no MW increase and depressed the MW raise button one more time.
I After several seconds, load began responding to the B0P Operator's l
action. MW load rapidly increased to about 150 MW with a 1
corresponding Reactor Coolant System (RCS) response and alarms.
RCS temperature, pressure, and pressurizer level decreased rapidly to j
below 551*F the minimum temperature for critical operation per j
Technical Specification (TS) 3.1.1.4, 2219 psi, and 17% level respectively.
Chemical and Volume System (CVCS) letdown flow i
automatically isolated due to low pressurizer level.
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The US directed reduction of MW load.
The 80P Operator lowered I
turbine load to about 40 MW for the next three minutes.
In parallel, rod withdrawal was initiated in increments to restore RCS-temperature.
The extra R0s took control of Steam Generator Level Control-(SGWLC) and rod control and monitored RCS parameters, At approximately 9:30 p.m. on November 16, 1996, normal RCS parameters were restored, the TS 3.1.1.4 action statement was exited and CVCS letdown was restored.
TU Electric Analysis:
TV Electric believes that the corrective actions for the previous event were effective, this conclusion is based on the several successful restarts since the 1993 event.
However, the corrective actions for the previous events did not adequately consider the consequences of having a person whose experience and training are solely based on the simulator perform a sensitive task without being directly observed by a person experienced in the evolution. While Operating procedure IP0-003A contained cautions and direction on turbine loading as a result of the previous event, simulator and classroom training did not adequately prepare Operators to anticipate and respond to potential transient situations encountered during beginning-of-life startups.
' Attachment to TXX 97061 Page 3 of 3 2.
Corrective Steos Taken and Results Achieved The US directed the reduction of turbine load and Main Feedwater flow.
The 80P Operator lowered turbine load to about 40 MW.
At approximately 9:30 p.m., on November 16, 1996, normal RCS parameters were restored, the TS 3.1.1.4 action statement was exited and CVCS letdown was restored.
3.
Corrective Actions Taken to Preclude Recurrence The applicable procedure which provides guidance for synchronizing the main generator to the grid has been further enhanced to include cautions for beginning of life operations to minimize temperature transients induced in the RCS.
A Simulator Action Request (SAR) was initiated and implemented to add a new temperature control (TC) malfunction to allow control of turbine load using the Speed Reference Device.
The Turbine Generator model was modified to provide an approximate 20 second time delay from the time the speed reference raise push-button is depressed until the time load is actually increased. All crews have been trained on this event.
TV Electric believes that these action will minimize the potential for recurrence.
4.
Date of Full Comoliance TU Electric is in full compliance.
5.
Additional Information CPSES TS 3.1.1.4 states that the RCS lowest operating loop i
temperature shall be greater than or equal to 551*F.
The required i
action is to restore temperatu:e within its limit within 15 minutes or be in Hot Standby within the next 15 minutes.
During this incident. CPSES was within the TS limiting condition for operation as i
RCS temperature was restored to greater than 551*F in less than 15 l
minutes.
CPSES has been analyzed for a number of events which postulate an j
increase in heat removal from the RCS by the secondary system.
This event is bounded by the more severe limiting RCS cooldown events presented in FSAR Section 15.1 " Increase in Heat Removal by the Secondary System.' Had the turbine loading continued the reactor would have eventually been tripped by the High Power Range Neutron l
Flux - Low reactor trip function prior to the time that any fuel 1
damage would have been predicted.
Hence, this transient had no impact on the public health and safety.