ML20207F897
| ML20207F897 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/15/1988 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| C311-88-2107, IEB-88-004, IEB-88-4, NUDOCS 8808230271 | |
| Download: ML20207F897 (3) | |
Text
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GPU Nuclear Corporstlor
- Nuclear
- =,omgreo Middletown, Pennsylvania 17057 0191 717 944 7621 TELEX 84 2386 Writer's Direct Olal Number
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Atgust 15, 1988 5
C311-88-2107 h
U. S. Nuclear Regulatory Commission L
Attn:
Document Control Desk Washington, DC 20555
Dear Sir:
Three Mile Island Nuclear Station, Unit 1 (TMI-1)
=
Operating 1.icense No. DPR-50 Docket No. 50-289 GPUN Response to NRC Bulletin 88-04 y
"Potential Safety Related Pump Loss" g
Decay Heat Removal (OHR) System r
GPUN's letter of July 8,1988 provided a response to NRC Bulletin 88-04, "Potential Safety Related Pump Loss" and addressed all safety-related systems with the exception of the DHR System.
Due to the volume of work related to the current outage, our schedule for this r
submittal was revised as; discussed in our letter of August 1,1988.
This letter provides the information requested by NRC Bulletin 88-04 for the Decay Heat Removal System.
The DHR System has two DHR pumps with independent trains such thF* the resulting piping system configuration precludes pump to pump interaction during miniflow operation.
Cross connections between the two trains can be used 1) for controlling boron concentration or 2) in the event of a break in the Core Flood System piping.
For those two situations, the interaction of concern at minimum flow operation cannot occur. Therefore, items 1 and 2 of the subject bulletin are not applicable to the TMI-l DHR System.
Each DHR Pump is provided with a separate minimum recirculation line including a manual locked-open valve (DH-V56A/B). Originally, each r
L recirculation line was provided with a 0.6" orifice.
Later the orifices were removed as recommended by the pump manufacturer. With the orifices removed, the DHR Pumps now have a minimum flow of approximately 125 gpm.
8808230271 880815 gDR ADOCK 05000289 PNU r6Il GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation g
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C311-88-2107 August 15, 1988 GPUN has investigated the various situations where the DHR Pumps wculd be operated under minimum flow conditions.
The most limiting case would be the small break loss of coolant accident (SBLOCA).
In this case the DHR pumps could operate at minimum flow for some period of time for the SBLOCA that is covered by the High Pressure Injection (HPI) System. The actual time would depend on the size of the break and the inventory of the BWST.
The maximum time that the DHR Pumps would operate under minimum flow conditions in this situation is judged to be no more than 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
Special tests and analyses were performed in July, 1988 to evaluate the acceptability of operating the DHR Pumps for at least 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> at 125 gpm.
Local vibration data were taken and the data were analyzed.
These data indicate that both DHR Pumps are in good mechanical balance and that the vibration levels that were obtained are acceptable for operation for at least 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
Our review of the DHR Pump operating and test procedures has resulted in the following olanned actions:
- 1) In order to enhance our ability to trend DHR Pump vibration data, procedural changes will be made to include additional periodic vibration readings in conjunction with the existing surveillance test procedures.
- 2) GPUN will review the adequacy of the current DHR Pump vibration monitoring instrumentation sotpoints and the guidance provided to evaluato and take action under alarm conditions. This review may involve changes to the setpoints as well as the procedures.
Our current evaluations of the DHR Pumps indicate that adequate minimum recirculation capacity is provided to ensure that pump operability is not affected by minimum recirculation operation. The procedural changes discussed above including any setpoint changes will be incorporated by January, 1989.
This concludes our evaluation of the DHR Pumps as requested by NRC Bulletin 88-04 cxcept for the actions discussed above.
Also, as discussed in our letter of July 8,1988, GPUN has requested information f rom the pump manuf acturers.
If the information roccived from the manuf acturers does not confirm our own evaluations and conclusions,
i C311-88-2107 August 15, 1988 GPUN will inform the NRC by letter of any additional short term or long term actions that may be required.
Sincerely,
/,. '
.D.
i1 Vice President and Director, TMI-1 HDH/MRK cc:
J. Stolz R. Conte R. Hernan W. Russell sworn and subscribed to before mc this
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