ML20138F264
| ML20138F264 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 10/11/1985 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 5211-85-2171, NUDOCS 8510250226 | |
| Download: ML20138F264 (2) | |
Text
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GPU Nuclear Corporation Nuclear
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Middletown, Pennsylvania 17057 0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number:
October 11, 1985 5211-85-2171 Dr. Thomas E. Murley Region I, Regional Administrator U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, Pa.
19406
Dear Dr. Murley:
Three Mile Island Nuclear Station Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 EFW Turbine Inlet Relief Valve Lift During Turbine Operation This is to document GPUN's commitments to remedy problems which resulted in lifting the Emergency Feedwater Pump (EF-P1) turbine main steam inlet relief valves MS-V22A/B during automatic starting of EF-P1 as part of the Startup Test Procedure TP 700/2. The setpoints of relief valves MS-V22A/B are 200 psig and 220 psig. Although EF-P1 operation was steady with a relief valve not completely closed, operations personnel were able to reseat the relief valve by gradually reducing the setpoint (thumbwheel) of the pressure controller (MS-PCS), and then returning the setpoint to normal (150 psig) after the relief valve closed. The relief valve lifting problem did not prevent EF-P1 from functioning normally and it remained operational throughout the test. The redundant motor driven EFW pumps EF-P2A and B were unaffected.
The cause(s) of the relief valve lif ting and actions to be taken to prevent recurrence are currently under design review and investigation. Based on our current understanding of the problem, interim guidance has been provided for the operators. It is a condition of operation imposed by the NRC in the restart proceedings that until the EFW System is made fully safety-grade, an auxiliary operator shall be dispatched to the EFW flow control valve area, upon any EFW auto-start condition, in order to take normal control of the valves if needed (Condition of Operation 1.P from NRC's letter of October 2, 1985).
In accordance with the specific interim guidance which has now been provided, if MS-V22A or B should lift during operation of EF-P1, the operator is required to assure the motor driven IFW pumps have automatically started if EFW system operation is required and to notify the Shift Supervisor.
Instructions are provided on how to reseat the relief valve; and in the event that MS-V22A or B cannot be reseated, instructions are provided on how to take EF-P1 out of service without interrupting motor driven EFW Further guidance is also provided under which, during an emergency, pump flow.
EF-P1 may be 8510250226 851011 PDR ADOCK 05000209 9
PDR GPU Nuclear corporation is a subsidiary of the General Public Utilities Corporation P q!
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5211-85-2171 October 11, 1985 operated with a relief valve MS-V22A or B leaking or gagged closed.
Preliminary design calculations have indicated that adequate steam capacity can be provided to operate EF-Pl with one MS-V22 relief valve full open.
Before returning to 100% power operation following the verification of plant response to a turbine / reactor trip at 100% power, at the end of the Restart Power Ascension Test Program, GPUN will complete the design and operational review to determine any actions that may be necessary to prevent recurrence of MS-V22A/B lif ting during EF-P1 automatic starting operation.
If further design and/or procedural changes are found to be required and it is feasible to do so at post 100% trip plant conditions, they will be implemented prior to returning the unit to power.
In any event, however, the results of our investigation will be available for NRC review at that time along with an implementation schedule for completing any additional actions which may be required, and the basis for continued operation until the actions are completed.
As described above, GPUN has established sufficient administrative controls to assure proper operations of the turbine driven EFW pump in the unlikely event of EFW actuation followed by a failure of one of the MS-V22 valves to reseat.
Therefore, TMI-1 remains within the licensing basis of the plant and the safety of the plant is assured.
Sincerely,
. D. I ill Director, TMI-l cc: W. F. Kane J.
Thoma HDH/MRK/emw 0383A l