ML20058K310
| ML20058K310 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 12/10/1993 |
| From: | Gipson D DETROIT EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CON-NRC-93-0126, CON-NRC-93-126 NUDOCS 9312150125 | |
| Download: ML20058K310 (6) | |
Text
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Douglas R Gipson 4
benu W e Present
%tient Generabon Detroit Edison :bommDme*@*at:m :-""
December 10, 1993 r
U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C.
20555
References:
- 1) Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43
- 2) NRC Inspection Report No. 50-341/93018 (DRP), dated November 10, 1993 i
- 3) Notice of Violation, (NRC Inspection Report 50-341/93018(DRP)), dated November 10, 1993
- 4) HRC-93-0092, Licensing Event Report (LER) No.93-010, dated September 13, 1993
Subject:
Reply to Notice of Violation 93018-01 Enclosed is Detroit Edison's response to Notice of Violation 93018-01 which is contained in Reference 3 This violation was the result of a failure to follow Alarm Response Procedure (ARP) 4D40, " Gland Steam Pressure High/ Low" subsequent to a reactor scram on August 13, 1993 Failure to follow the ARP resulted in the closure of the Main Steam Isolation Valves which resulted in a loss of the main condenser as a heat sink and the need to use the reactor safety relief valves to control reactor pressure.
In addition, as requested in Reference 2, Detroit Edison has addressed what actions have been taken and are planned to ensure that conditions in the simulator training sessions accurately reflect actual plant conditions.
Should you have any questions regarding this response, please contact Mr. John A. Tibal, Compliance Engineer at (313) 586-4289 i
Sincerely, Enclosure cc:
T. G. Colburn W. J. Kropp J. B. Martin M. P. Phillips Region III v312150125 931210 5
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I, DOUGLAS R. GIPSON, do hereby affirm that the foregoing
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statements are based on facts and circumstances which are true and accurate to the best of my knowledge and belief.
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i DOUGLAS R. GIPSON
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Senior Vice President j
On this II day of
/pxM.41993, before me pers9nally appeared Douglas R. Gipson, being first duly sworn and l
says that he executed the foregoing as his free act and deed.
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- Enclosure to NRC-93-0126 Page 1 Background Information:
On August 13, 1993 while performing routine reactor building rounds, a Nuclear Power Plant Operator (NPPO) noticed some tape on a valve handle on a manifold to instrument B21-R004B " Reactor Vessel Division 2 Pressure Indicator." This instrument is located on reactor vessel level and pressure instrument rack H21-P005 While the NPPO was attempting to remove the tape and some residual adhesive material he noticed a pressure spike on instrument B21-R004B and heard the scram pilot valves vent. He called the main control room and was informed that an automatic reactor shutdown had occurred.
9 Subsequent investigation determined that while the NPPO was attempting to remove the tape material from the valve handle the valve was inadvertently unseated. This induced a pressure transient into a common header shared by other instruments. The NPPO was not aware of the hydraulic interface between the valve he was working on and other instruments on this rack. The pressure transient created a false high reactor water level signal. This false signal caused the main turbine generator and both reactor feed pumps to trip off line.
These steam driven components trip when reactor pressure vessel high water level is sensed to protect the associated turbines from any potential water impingement.
All group isolations and safety system actuations occurred as expected.
t While recovering from the automatic reactor shutdown, main condenser vacuum was lost resulting in a group 1 isolation. This isolation group includes the main steam isolation valves (MSIVs). Condenser vacuum was lost after the turbine tripped because the start-up gland supply steam header was isolated and operator action was required to maintain the system in service. Without the turbine gland seal system the sealing mechanism for the turbine seals was lost resulting in air in-leakage. The decrease in main condenser vacuum cuased the group 1 isolaticn.
Following closure of the HSIVs, reactor pressure was controlled by manual operation of the safety relief valves. Both divisions of the residual heat removal system were placed in the suppression pool cooling mode. Reactor level was controlled by the standby feedwater and condensate systems.
Specific details of this event are contained in Licensing Event Report (LER)93-010.
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Enclosure to NRC-93-0126 Page 2 Statement of the Violation:
10 CFR Part 50, Appendix B, criterion V, requires, in part, that activities affecting quality be prescribed by documented instructions, procedures, or drawings of a type appropriate to the circumstances, and be accomplished in accordance with these instructions, procedures, or drawings.
Annunciator Response Procedure (ARP) 4D40, " Gland Steam Pressure High/ Low," initial response section, required operators to throttle open valve N30F603, Gland Steam Supply Regulator Bypass Valve, to maintain gland seal steam pressure at 2 to 3 psig when a low gland steam pressure alarm exists.
I Contrary to the above, on August 13, 1993, the operators failed to implement ARP 4D40 when the low gland steam pressure annunciator alarm was received subsequent to a reactor trip at 9:46 a.m.
A subsequent high condenser pressure annunciator alarm was received at 9:50 a.m.
when gland steam pressure was not restored by the operators.
The Main Steam Isolation Valves automatically closed at 0:03 a.m. due to the high condenser pressure. The closing of the MSIVs resulted in the loss of the main condenser as a heat sink and the manual use of the Automatic Depressurization System reactor safety relief valves E, J, P, and R to control reactor pressure.
l The Reason For The Violation:
The reason for this violation was personnel error in that the control
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room operators failed to observe and respond to the audible and visual i
alarm associated with annunciator 4D40. Several factors contributed l
to this violation:
1.
There was a high degree of activity in the control room following the reactor scram and loss of the reactor feedwater pumps. This distracted the Operators from acknowledging and acting upon alarm 4D40.
2.
Manual operation on the gland seal system was not addressed In either the abnormal operating procedure for a reactor i
scram or main turbine trip.
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The Fermi 2 simulator did not model the manual operation of j
the gland sealing system. The simulator modeled the gland seal system automatic operation, which is as designed, and therefore it did not challenge the operators to manually restore gland sealing steam after a turbine trip.
Enclosure to NRC-93-0126 Page 3 1he Corrective Steps 1 hat llave Been Taken And 1he Results Achieved:
1.
The gland seal steam system control instrumentation was adjusted so that the steam regulating valves from the 52" manifold will remain in automatic. These steam regulating valves will close at high power when the high pressure turbine supplies the gland seals, but they open if the turbine gland seal packing line pressure decreases i.e., on a turbine trip. However, manual operation of the dump bypass valve is still required to maintain proper system pressure.
2.
Abnormal Operating Procedures 20.000.21, "Heactor Scram", and 20.109.01, " Turbine / Generator Trip" have been revised to verify proper operation of the gland seal system.
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3 Licensed Operator Training for all shifts was completed on December 3, 1993 to address numerous issues associated with this event. One of those issues was the importance of acknowledging all annunciators in the control room as soon as possible.
Ilowever, it is clearly understood that operators are responsible l
for determining when conditions are sufficiently stable co address panels with " Balance of Plant" annunciators.
i Management expectations concerning panel awareness during transients were clearly expressed to the operators.
l 4.
Other automatic systems which require manual control during transients were reviewed. Compensatory measures were instituted, including changes in procedures and training where appropriate, i
Long term corrective actions have been planned and are being tracked in accordance with the Corrective Action Program.
I 1he Corrective Steps 1 hat Will Be Taken To Avoid Further Violations:
1.
The gland seal system will be modified in the next refuel outage to correct the design deficiency. This will be accomplished through Engineering Design Package EDP-10257 which was scheduled for implementation in the next refuel outage prior to the event.
l Subsequent to the implementation, the procedures cited above will j
be revised to reflect the system's new configuration.
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Enclosure to NRC-93-0126 Page 4 2.
With respect to simulator fidelity, Detroit Edison remains f
committed to ANSI standard ANSI /ANS 3.5-1985, " Nuclear Power i
Plant Simulators for use in Operator Training."
As required by ANSI /ANS 3.5-1985, modifications to the plant are reviewed at least annually and the simulator is updated as
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appropriate based on engineering and training value assessments.
Detroit Edison strives to ensure simulator fidelity with actual plant conditions. This is accomplished through various methods.
l Currently, Nuclear Training personnel obtain plant status information through mechanisms such as-t 1.
Feedback from operating crews during simulator training.
2.
Review of the Equipment Concerns List. This is a routinely published list of equipment performance concerns identified through routine and diagnostic assessments or concerns that have the potential to significantly affect system or component availability or reliability.
Different means of obtaining plant status information may be utilized in the future.
e When differences between the plant and simulator are identified, an evaluation is conducted and, if determined to be appropriate, the simulator will be modeled to reflect that plant condition.
A current list of differences between the simulator and the plant is maintained at the simulator. This list is reviewed with simulator trainees on a regular basis.
The Date When Full Compliance Will Be Achieved:
Detroit Edison is in full compliance.
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