ML20237B067

Summary of 851106 Meeting W/Util Re Reliability of Auxiliary Feedwater Sys.List of Attendees & Licensee Viewgraphs Encl

ML20237B067
Person / Time
Site:	Prairie Island
Issue date:	11/25/1985
From:	Diianni D Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
TAC-61519, TAC-61520, NUDOCS 8712150463
Download: ML20237B067 (18)

Text

l 1

- November 25, 1985 Docket Nos. 50-282 and 50-306 l i i

Facility: Prairie Island Nuclear Generating Plant Units Nos. I and 2 l

SUMMARY

OF NOVEMBER 6, 1985 MEETING REGARDING THE 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 ). Copies of the licensee's viewgraphs are also enclosed  !

(Enclosures 2 and 3). ,

In the opening remarks, the staff informed the licensee that all licensees j would be required to shog 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 reliability for auxiliary feedwater system, it was recommend that the reliability analysis should be performed in two phases. The first phase would' be similar to j the generic methods pertaining to probability assessments in NUREG-0611 and l would include system modifications that were completed since the publication (1981) of NUREG-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.

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 l (normally closed) do not exist but the plant staff is aware of the existence of these valves. The licensee committed to develop an operating procedure for emergency operation of the cross tie valves when both auxiliary feedwater pumps of one unit become inoperable 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 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 8712150463 851125 PDR ADOCK 05000282 P PDR

. 2-first system being worked on and the licensee has contracted with Delian Corporation to assist in performing the analysis. The licensee committed to submit the results of this analysis within 100 days from the meeting date.

Thelicenseecommittedtgshowghateithertheexistingsystemmeetsthe reliability level of 10~ - 10- or identify necessary plant changes necessary to meet this reliability.

Dominic C. Di Ianni, Project Manager Operating Reactors Branch #3, DL I

Enclosure:

As stated 3

1 w Dominic C. Di Ianni, Project Manager Operating Reactors Branch #3, DL

Enclosure:

As stated l t

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N ORB #3;DL ORB #3:DL 0[# L P.6%ytzer DDi Ianni:dd E48u her U/j /85 11/2i/85 11/f,/85

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l Mr. D. M. Musolf Prairie Island Nuclear Generating Northern States Power Company Plant

'cc :

-Gerald Charnoff, Esq.

Shaw, Pittman, Potts and Trowbridge 1800 M-Street, NW Washington, DC 20036 Executive Director Minnesota Pollution Control Agency 1935 W. County Road, B2 Roseville, Minnesota 55113 Mr. E. L. Watzl, Plant Manager '

Prairie Island Nuclear Generating Plant Northern States Power Company Route 2 Welch, Minnesota 55089 Jocelyn F. Olson, Esq.

Special Assistant Attorney General Minnesota Pollution Control Agency 1935 W. County Road, B2 Roseville, Minnesota 55113 U.S. Nuclear Regulatory Commission l Resident Inspector's Office Route #2, Box 500A Welch, Minnesota 55089 Regional Administrator, Region .JII U.S. Nuclear Regulatory Commission Office of Executive Director for Operations 799 Roosevelt Road Glen Ellyn, Illinois 60137 Mr. William Miller, Auditor l

Goodhue County Courthouse Red Wing, Minnesota 55066 i

- - - - - - - - - -------__---___u__-__

a Enclosure 1 PRAIRIE ISLAND MEETING ON AUXILIARY FEEDWATER NORTHERN STATES POWER NOVEMBER 6, 198S ATTENDEES I

l Ed Butcher NRC/DL/ ORB #3 Gus Lainas NRC/DL I Gordon E. Edison NRC/0RBf4 l 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 l Chuck Hsu AEOD/NRC Stuart Rubin AEOD ,

Bob Borsum B&W for AP&L l R. Wessman NRR/DL A. EL-Bassioni NRR/RRAB/ DST Faust Rosa NRR/DSI/ICSB Conrad McCracken NRR/DL Dom Di Ianni NRR/DL/0RB#3 ,

1 I

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. . ,, Enclosure 2 NORTHERN STATES POWER COMPANY - NRC STAFF MEETING TO DISCUSS PRAIRIE ISLAND AUXILIARY FEEDWATER SYSTEM RELIABILITY -

NOVEMBER 6, 1985 IPM P422, PHILLIPS BUILDING, BETHESDA, MARYLAND NSF REPRESENTATIVES:

Richard Pearson Senior Production Engineer Prairie Island Plant David Rautman Supt Safety Analysis Nuclear Analysis Department David Musolf Manager Nuclear Support Services t

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f Prairie Island Feedwater System Design Features Two electric motor-driven main feedwater pumps l 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.

I Summary -

Three motor-driven feedwater pumps immediately available to each unit.

One turbine-driven (AC free) feedwater pump immediately available to each unit. ,

j 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.

t Excellent history of main and auxiliary feedwater system reliability.

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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Response to NRC Concerns Related to Auxiliary Feedwater System at Prairie Island l

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. 1 Improvements:

Separation of condensate tank level channels i between Units 1 and 2 Suction and discharge pressure switch protection provided for run out and loss of suction i l

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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. j Seismic capability of system confirmed. '

, Recent Upgrades to turbine driven pumps to improve I

steam trap and drain design and relocate stop valve t outside of pump room (environmental qualification requirements).

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-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

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PRAIRlE ISLAND AUXILIARY FEEDWATER SYSTEM Four Pumps 1 Turbine Driven Pump per Unit 1 Motor Driven Pump per Unit Power Source TD - respective unit's main steam header upstream of MSlV's MD - safeguards 4160V busses, 300 HP Major Valves 2 Normally open MOV's to each steam generator (one from each pump) -

1 NormcIly open, locked open containment isolation MOV for each steam generator

( 2 Suction supplies for each pump Normally open - condensate storage tanks Normally closed - cooling water (safeguards supply) t

, 2 Normally open steam supply MOV's for each turbine

_ 1 Steam control valve (air operated, open) for each turbine 1 Trip / throttle valve (normally open) for each turbine 1 Recirculation control valve for each pump 1 Oil cooler supply control valve for each pump .

Motor Driven Pump Auto Starts steam generator lo lo level (13%)

Safety injection

'Both MFW pump breakers trip with AFW selector switch in Auto

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i Turbine Driven Pump Auto Starts Steam generator lo lo level Safety injection Loss of both MFW pumps Undervoltage on both MFW pump busses i

Aux Feedwater Pump Trips k Load rejection (motor driven only)

Low discharge pressure - 500# (200# TD)

Low suction pressure - 4 inches Hg Mechanical overspeed (turbine driven only)

Start of Aux Feedwater Pump causes:

SGBD isolation Normal and emergency condensate makeup isolation Stand by hydrazine pump start

- Valve close to condenser

- Valves open to AFW

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I local heat removal ventilation starts (motor driven only) i j

Cooling water supply to lube oil cooler opens Recirc valve opens Computer alarm '

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Discharge of motor driven pumps can be manually cross connected.  !

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AUX 1_lA RY FEE JWATE 9

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CHEMISTRY RECORDER (NOT REQUIRE 6) 0-2000 AFW OLSCH.

PRESS. 0-2000 0-200 Apw ptow 0-200 i

AFW CONT. ISO. 8 (2 3 22) 11 S/C 12 S/c It S/c 12s*/G (21) (22) (21) (22) 11 (21) AFW TO: 12 (22) AFW TO:

<. f 11 12 STfI ISO. TO TO AFW PUMP SHUTCCWN AUTO AFW PUMP SHUTDOWN AUTO MANUAL MANUAL AUTO AUTO

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' ' CONDE'NSATE SUCTION ISOLATION VALVES 11 11

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COOLING WATER d'JCTION

, _ ISOLATION VALVES M.A. Cardzinski 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 j 4160 volt motors - 1750 horsepower eight stage.

centrifugal pump j 2 Main Feedwater Pumps per Unit-8600 GPM at 900 psig Shutoff head - 1440 psig .

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1 4160 volt motors - 5000 horsepower single stage centrifugal pump, 5082 rpm 1

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MEETING

SUMMARY

DISTRIBUTION Licensee: Northern States Power

• Copies also sent to those people on service (cc) list for subject plant (s).

L Docket File NRC POR L POR ORB *3 Rdg 00ilanni EButcher BGrimes OELD EJordan, IE ACRS-10 NRC Meeting

Participants:

Glear GLainas GEdison AThadani FCongel 0Parr JWemiel

- LLieder LRubenstein e  !

RWesstran H Ul f/ -

AElBassioni 'l FRosa n ('j CMcCracken p

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