ML20039G857
| ML20039G857 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 01/07/1982 |
| From: | Mayer L NORTHERN STATES POWER CO. |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8201190226 | |
| Download: ML20039G857 (2) | |
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Not thern States Power Company
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414 NicoHet Matt Minneapoks Minnesota 55401 Teiephone (612) 330-5500 January 7, 1982
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Director s
Of fice of Nuclear Reactor Regulation
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Attn: Document Control Desk 9-4 d5N7a.
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' " k2 U S Nuclear Regulatory Commission Washington, DC 20555 N.- y PRAIRIE ISLAND NUCLEAR GENERATING PLANT h
[qipM Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 Modification to Provide Auxiliary Feedwater Pump Protection in our letters dated February 4,1981 and November 24, 1981 we committed to install loss of suction protection for all four auxiliary feedwater pumps at Prairie Island. We originally planned to implement this protection using pump discharge pressure switches. Following discussions with members of the NRC Staf f and the pump vendor, we have revised our plans for this modi f icat ion.
The purpose of this letter is to provide, for ?he information of the Staf f, a description of our revised plans and our scAdule for implement ing them.
Protection of all four auxiliary feedwatet-pumps will be accomplished by installing both suction and discharge pressure switches. The /uction pressure switch will protect against valving errors (loss of pump suction caused by closed or partially closed suction valves) and loss of level in the condensate storage tanks. The discharge pressure switch will protect against pump damage due to excessive flow (run-out) or inadequate pump vent ing.
The suction pressure switch setpoint will be based on the pressure at the pump when the supply piping from the condensate storage tanks begins to drain at zero flow conditions. This pressure corresponds to approximately the top of the condensate storage tank suction nozzle at design flow conditions (220 gpm).
This setting will also trip the pump prior to f alling below the minimum required NPSit at design flow and 100 F suction temperature. The discharge pressure switch will be set below the minimum TDH for the pumps of 887 psig. A 100 - 150 psi margin below th9 TDH will 00 prevent spurious trips. Actual setpoints will be selected following 3
installation and testing. A Technical Specification change will be proposed governing the surveillance and operability of the protection logic within D
90 days of completion.
Pressure switches and other components will be environmentally qualified.
The requirements of IEEE-323-1974 and IEEE-344-1975 will be satisfied, 8201190226 820101 PDR ADOCK 05000282 p
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XX NORTHERN 'CTATED POWER COMPANY Director of NRR January 7,1982 Page 2 The suct ion and discharge pressure switches installed on the steam driven auxiliary feedwater pumps will trip the steam inlet valve closed. On the motor driven pumps, these switches will trip the motor breaker open.
In both instances the pump will stop and the control room operator will receive an alarm. The alarm response procedues will direct the operator to take corrective action to restore pump suction or limit pump discharge flow as applicable. When the problem has been corrected, the operator will be directed to reset the steam inlet valve (locally at the pump) or restart the motor (from the control room or locally).
The modification will be completed prior to startup following the next refueling outage of each unit.
The next refueling outage of Unit 1 is currently scheduled for November, 1982. The next refueling outage of Unit 2 is currently scheduled for August 1982.
Plesse contact us if you have any questions concerning the information we have provided.
s L 0 Maye r, PF Manager of Neelear Support Services LOM/DMM/jh cc Regional Director, III, USNRC NRR Project Manager, USNRC Resident Inspector, USNRC G Charnoff
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