ML20137Y664
| ML20137Y664 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 11/25/1985 |
| From: | Diianni D NRC |
| To: | NRC |
| References | |
| NUDOCS 8512110102 | |
| Download: ML20137Y664 (17) | |
Text
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November 25 1985 Docket Nos. 50-282 and 50-306 Facility: Prairie Island Nuclear Generating Plant Units Nos. I and 2
Subject:
SUMMARY
OF NOVEMBER 6, 1985 MEETING REGARDING THE l RELIABILITY OF AUXILIARY FEEDWATER SYSTEM On November 6,1985 the NRC staff met with Northern States Power Company, the licensee for the Prairie Island Nuclear Generating Plant Unit Nos. I and 2.
The meeting was requested by the staff as a vehicle for information exchange to establish the level of reliability of the auxiliary feedwater systems at the Prairie Island Nuclear Generating Plant. A list of attendees is enclosed Enclosure 1 ). Co les of the licensee's viewgraphs are also enclosed Enclosures 2 and 3 .
In the opening remarks, the staff informed the licensee that all licensees would be requigd to show that reliability of the auxiliary feedwater systems ranges from 10 to 10 - per demand, meeting the criteria of section 10.4.9 of SRP and the Branch technical position ASB 10-1. In showing the level of l reliability for auxiliary feedwater system, it was recomend that the reliability I analysis should be performed in two phases. The first phase would be similar to I the generic methods pertaining to probability assessments in NUREG-0611 and would include system modifications that were completed since the publication (1981)ofNUREG-0611. This phase would serve as a bench mark for comparing the Prairie Island system with other PWRs. The second phase of the analysis would apply specifically to Prairie Island considering operating experience during the past 10 years for both units, operator actions and component failure estimates based on operating experience.
l The licensee described the design and the operating experience of the auxiliary feedwater system (Enclosures 2 and 3). The auxiliary feedwater system for each unit consists of one turbine driven and one motor driven pump for each unit. In addition, cross tie lines exist between the two motor driven pumps (i.e., one for each unit) so that both pumps can furnish coolant to either unit. Detailed operating procedures for operating cross tie valves (normally closed) do not exist but the plant staff is aware of the existence of these valves. The licensee comitted to develop an operating procedure for emergency operation of the cross tie valves when both auxiliary feedwater pumps of one unit become inopersble and the operation of the motor driven pump of the other unit is required. The piping design of the system permits the water supply from condensate tanks from either unit, with the Mississippi River water as a final backup to be furnished to any of the steam generators of both units.
The power supply regarding source, redundancy and level of safety to the motor driven auxiliary feedwater pumps is equivalent to the power supply furnished I to the pumps in the ECCS.
- The licensee has established a reliability analysis group to determine the reliability of various plant systems. The auxiliary feedwater system is the i
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first system being worked on and the licensee has contracted with Delian 1 Corporation to assist in performing the analysis. The licensee committed '
to submit the results of this analysis within 100 days from the meeting date.
The licensee comitted tg show ghat either the existing system meets the reliability level of 10- or identify necessary plant changes necessary to meet this reliability.
Dominic C. Di Ianni, Project Manager Operating Reactors Branch #3, DL
Enclosure:
As stated r) i Dominic C. Di Ianni, Project Manager Operating Reactors Branch #3, DL
Enclosure:
As stated l
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Enclosure 1 t
< v PRAIRIE ISLAND MEETING ON AUXILIARY FEEDWATER NORTHERN STATES POWER NOVEMBER 6, 1985 ATTENDEES Ed-Butcher NRC/DL/0RB#3 Gus Lainas NRC/DL Gordon'E. Edison. NRC/0RB#4
' Ashok Thadani NRC/ DST Frank Congel NRC/NRR Olan Parr- NRC/DSI/ASB
'J.S. Wermiel NRC/NRR/DSI/ASB Lynn Lieder NRC/0RB#3 Lester-S. Rubenstein , NRC/ CPS Dave Rautmann NSP/SUP Safety Analysis Richard P. Pearson NSP/Sr. Prod. Engineer, P. I.
- David Musolf NSP Chuck Hsu AE0D/NRC M Stuart Rubin AE0D Bob Borsum B&W for AP&L R. Wessman f!RR/DL A. EL-Bassioni NRR/RRAB/ DST Faust Rosa NRR/DSI/ICSB Conrad McCracken NRR/DL Dom Di Ianni NRR/DL/0RB#3
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Enclosure 2 <
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NORTHERN STATES. POWER COMPANY - NRC STAFF MEETING i TO DISCUSS PRAIRIE ISLAND AUXILIARY FEEDWATER l SYSTEM RELIABILITY NOVEMBER 6, 1985 1PM P422, PHILLIPS BUILDING, BETHESDA, MARYLAND NSP REPRESENTATIVES:
Richard Pearson Senior Production Engineer i Prairie Island Plant David Rautman Supt Safety. Analysis Nuclear Analysis Department i David Musolf Manager Nuclear Support Services .
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,y Prairie Island Feedwater System ~ Design Features Two electric motor-driven main feedwater pumps per unit
- One electric motor-driven auxiliary feedwater pump per' unit
. One turbine-driven auxiliary _feedwater pump per unit.
Ability to manually cross-connect motor-driven auxiliary feedwater pumps from one unit to other
- unit by manual operation (5 - 10 minutes).- This time is short compared to "dryout" times predicted for Westinghouse designed steam generators.
Summary -
Three motor-driven feedwater pumps immediately available to each unit.
~
One turbine-driven (AC free) feedwater pump immediately available'to eachtunit.
One-additional motor-driven pump available to each unit from the other unit in.a short period of time.
Low reliance on steam driven feedwater pumps.
Excellent history of main and auxiliary feedwater-system reliability.
l Plan of Attack for Resolving NRC Concerns
- Plant specific PRA of Prairie Island Auxiliary Feedwater System for comparision to NUREG-0611 results.
-PRA to identify " weak links" in auxiliary feedwater system.
-Alternatives to improve reliability will be tested using PRA
-NSP will demonstrate compliance with NRC criterion of E-4 to E-5~ unavailability per demand.
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'Y Response'to NRC Concerns Related to Auxiliary Feedwater System at Prairie Island -
NRC SER on NUREG-0737, Items II.E.1.1 and II.E.1.2
- issued on 3-22-82 confirmed TMI Action Plan requirements met.
Improvements:
Separation of' condensate tank level channels between Units 1 and 2 Suction and discharge pressure switch protection provided for run out and loss of suction 3
Turbine-driven auxiliary feedwater pumps modified to be totally AC-free (pre lube system and air operated steam admission valves).
Other Upgrades:
NRC SER related to seismic qualification of auxiliary feedwater system issued on 6-16-83.
Seismic capability of system confirmed.
Recent Upgrades to-turbine driven pumps to improve steam trap and drain' design and relocate stop valve l outside of pump room (environmental qualification '
requirements).'
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. i s; NSP Questions
-Credit for manual operation (for example, cross connection of motor-driven pumps)
-Credit for main feedwater system reliability?
Total reliability = main feedwater system reliability X
auxiliary feedwater system reliability -
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PRAIRIE ISLAND AUXILIARY FEEDWATER SYSTEM f Four' Pumps 4
1-Turbine Driven ~ Pump per Unit 1 Motor Driven Pump per Unit Power Source TD - respective unit's main steam header upstream of MSIV's MD - safeguards 4160V busses, 300 HP Major Valves .
~2 Normally open MOV's to each steam generator (one from each pump) 1- Normally open, locked open containment isolation MOV for each steam generator N) 2 Suction supplies for each pump 1
Normally open - condensate storage tanks ,
Normally closed - cooling water (safeguards supply) 2 Normally open steam supply MOV's for each turbine i 1 Steam control valve (air operated, open) for each turbine -l l
1 Trip / throttle valve (normally open) for each turbine ;
1 1 Recirculation control valve for each pump i 1 Oil' cooler supply control valve for each pump ,;
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Motor Driven Pump Auto Starts I Steam generator lo lo level (13%)
Safety injection Both MFW pump breakers. trip with AFW selector switch in Auto
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p is-) Turbine Driven Pump Auto starts Steam generator lo lo level Safety injection Loss of both MFW pumps Undervoltage on both MFW pump busses Aux Feedwater Pump Trips Load rejection (motor driven only)
Low discharge pressure - 500# (200#.TD)
Low suction pressure - 4 inches Hg Mechanical overspeed (turbine driven only)
Scart of Aux Feedwater Pump causes:
SGBD isolation
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) Normal and emergency condensate makeup isolation Stand by_hydrazine pump start
- Valve close to condenser
- Valves open to AFW Local heat removal ventilation starts (motor driven only)
Cooling water supply to lube oil cooler opens Recire valve opens Computer alarm l
Discharge of motor driven pumps can be manually cross connected.
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.AUXlLIARY FEEJWATER
-f ID v-CHEMISTRY RECORDER (NOT REQUIRED) 2000 AFW DISCH.
PRESS. 0-2000 -
0-200 0-200 AFW FLOW (2 AFW CONT. ISO.
2) 11 S/G 12 s/G 11 S/G 12 s'/G (21) (22) (21) (22) 11 (21) AFW TO: 12 (22) AFW TO:
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F y ,- 11 12 STMISO.TO TD AFW PUMP SHUTDOWN AUTO AFW PUMP " "^ '
MANUAL MANUAL UTO MODE SELECT AUTO
. 11/22 12/21 TD MC STAR T STAR T STOP STOP CO JTROL (NOT REQUIRED)
' ' CONDENSATE SUCTION ISOLATION VALVES 11 11 12 12 (22) (22) (21] (21]
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COOLING WATER SUCTION ISOLATION VALVES M.A. GardzinSki P8180L-007
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PRAIRIE ISLAND MAIN CONDENSATE AND FEEDWATER 3 Condensate. Pumps per Unit 5650 gpm at 410 psig Shutoff. head - 550 psig.
~4160 volt motors - 1750 horsepower eight stage.
-centrifugal ~ pump
- 2. Main Feedwater Pumps per Unit 8600 GPM at:900 psig Shutoff head '1440 psig -
4160 volt' motors - 5000 horsepower single stage i
centrifugal pump, 5082 rpm O
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LOSS OF PDIPING CAPASILITIC Plant Lead 1 70% Plant Load 1 CD, 1 W. 1 Mtr Drn pyog Pump Operettag 2 CD, 2 FW, 2 Etr Dra Pupe Operating i I l l l l I I I
.. l I 14 3 af Loss of lose of Btr loss of Loss of Loss of 1 loss of 2 CD Pump N Pup Drn Pup 1 CD Pup 1 N Pop _ Ntr Dra Pep lose of 2 loss of 2 CD Pape _ m Pops Etr Dra Papa
- Stby CD - Stby CD Pup Start -
Pee Star s - Stby Htr Turbine Aus N Dra Pmp 1 Below ~
Trip Start Turbina Aux W lose of *" q*"any May W Pup 4 l . Start Trip Trip Start #11I21] l See Note See Note yv p , ., 3 Below 1 Below '
i l.ose of Eti Dru Paps See Note i I 2 Below Turbina Aun W Restart #11 See Trto Start Note 3 loss of 811 121]
[21] TWP Ef #12 122] FWP may g , ,g Possible Below trip if STRY CD Refer to Steps 3 and 4 Her Drn Pap fails to start Losa af Pup Mtr Dra l .
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Rafar to Steps Refer to Steps 3 and 4 3 and 4 pote la A standby heater drain pump will start automatically. Condensate injection to k' heate'r drain pump may open upon standby p o p start. If a standby psamp cannot be e, started, refer to Note 2 below, pote 2:
Condensate low pressure heater bypass valve CV-31087 [CV-31088] will open. Reduce plant load at the maximum controllable rate. Possible plant trip, refer to steps 3 and 4 of the general procedure. Spen the following pump valves to the condensert CV-31040 (CV-310561 heater drain tank, CV-31024 [CV-31062],15A [25A] Heater, CV-31026 [CV-31351] Heater, CV-31029 (CV-31065] fla Reheater, CV-31035 [CV-31071]
- 1A Reheater, CV-31032 [CV-31068] #25 Reheater, and CV-31038 [CV-31074] #2A Reheater.
Note 3t Reduce plant load at the naminum controllable rate. Possible plant trip, refer to steps 3 and 4 of the general procedure, ,
b Figure E5-1
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MEETING
SUMMARY
DISTRIBUTION Licensee: Northern States Power l
- Copies also sent to.those people on service (cc) list for subject plant (s).
Decket:Fi1E.
ORB #3 Rdg
- g DDilanni EButcher BGrimes- ,
OELD EJordan, IE ACRS-10, NRC Meeting
Participants:
Glear Glainas GEdison AThadani FCongel OParr JWenniel LLieder LRubenstein RWessman AElBassioni FRosa CMcCracken ,
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