ML17340A679
| ML17340A679 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 02/03/1981 |
| From: | Robert E. Uhrig FLORIDA POWER & LIGHT CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML17340A680 | List: |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.E.1.2, TASK-TM L-81-36, NUDOCS 8102090398 | |
| Download: ML17340A679 (30) | |
Text
REGULATORY RMATION DISTRIBUTION SYS (RIDS)
ACCESSION~ NBR'! 8102090398 DOC ~ DATE: 81'/02'/03 NOTARIZED:
NO DOCKEiT FACIL:5 Turkey Point Planti Uni.t 3z Florida Power and Light C
05000250 0-25 Turkey Point,Pl ant'i Uni t 4i Florida Power and Light C
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- Power, 8 Light Co, REC IP ~ NAMK!
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FLORIOA POWER IIL LIGHTCOMPANY February 3, 1981 L-,81-'36 Office of Nuclear Reactor Regulation Attention:
Mr. Darrell
'G. Eisenhut, Director Division of Licensing U.'S. Nuclear Regulatory Commission Washington, D.
C.
20555
Dear Mr; Eisenhut:
$$ c55 RE:
Turkey Point Units 3
& 4 Docket Nos. '50-250 and 50-251 NUREG 0737 Item II.E'.1.2'Auxiliar Feedwater S stem)
Our report on Parts 1 and '2 of NUREG'737 Item II.E.1.2 (Auxiliary Feedwater System Automatic Initiation and Fl'ow Indication) is attached.
If you or your staff should have any questions on this report, we would be glad to arrange a meeting to provide clarification.,
Very truly yours,.
ob rt E. Uhrig e President Advanced Systems
& Technology REU/PLP/ras Attachment cc:
J.
P. O'Reilly, Region II Harold F. Reis, Esquire g(02.090398 PEOPLE... SERVING PEOPLE
~p,g Agg(
C'+i:i jI
'a
/g/7 1~t~4 UNITEDSTATES UCLEAR'REGULATORYCOMMISSIO WASHINGTON, D. C. 20566 i~IEMOKQGNPiI FOR-TERA CORPORATZON FROM:
.US NRC/TZDC/DOCUMKfT NANAGEaMNT BRANCH SIJB DEC'T:
a.
Special Document Handling Requirements Please use the following special disa'bution lisz for the at~ached document.
The attached document requires the fol'owing spec'al l
considerations:
C3 Do not send oversize enclosures to the 'iKC PDR.
Only one oversize enclosure was received please return for gegulatory File storage. ~~~ g~i ea~si~
+~remi~
Q proprietary.information send only non-oroprietary port" ons to the,MC PDR.
EI Other: (specify) cc:
DMB F'les TZDC/DMB Authorized Signa"ure
ATTACHMENT Re: 'urkey Point Units 3
& 4 Docket Nos.. 50-250, 50-251 NUREG 0737 Item II.E. 1.2 (Parts 1 and 2)
S stem Automatic and Flow Indication Function of AFW System The function of the Turkey Point Plant AFW System is to supply auxil'iary feedwater to the steam generators in case of loss of the normal feedwater, in order to keep the unit in hot standby for a limited period or to lower the reactor coolant temperature and pressure to levels where the Residual Heat Removal (RHR) system can be put into operation to take the unit to cold'hutdown.
2.
Sys tern.Description, As shown on the attached: sketch, three steam turbine driven Auxiliary Feedwater pumps are aligned to deliver feedwater to the three steam generators o'f either unit.
(One pump is normally aligned to each unit and the third is a shared, standby for either unit).
Under a design basis accid'ent only one pump would'e required to cool the unit down to a condition where the RHR system could be put into operation.
These pumps take suction from the 250,000 gallon, seismic Category I, Condensate Storage Water Tanks.
Water is also available from the Water 'Treatment System and'rom the Main Feed Systems of units 1 and:2 (non-nuclear)..
The turbine driven pumps are supplied with steam from the main steam line of either or both units upstream of the MSIV.
The AFW auto initiation system selects the steam supply from the uni't which has lost its normal feedwater supply.
The turbines have an atmosphere exhaust.
Steam can also be manually supplied from the unit having normal feedwater supply and from an auxiliary steam system connection to Units 1
& 2.
The turbine driven pump steam supply line has a
normally closed AC motor operated valve in series with a normally closed DC solenoid air operated pr'essure control valve.
Two of the three AC,motor operated steam supply valves will be changed'o DC power.
The pump discharge control valves are DC,solenoid/air operated valves.
The air supply for all valves are, backed by a seismically qualified nitrogen supply that automatically initiates on loss of,normal air supply.
All three AFW pumps, will automatically start by any of the following signals:
(a) safety injection (b) low-low water level in any of the three steam generators (c) loss of voltage on both 4160V buses (d) loss of both main feedwater pumps Any one of,these signals, will automatically open the normally closed
Any one of these signals will automatically open the normally closed motor operated valve and air operated pressure control valve in series which isolate the main steam lines from the steam supply header of each AFW 'pump turbine.
Air to operate the AFW flow control system to the steam generators is supplied when the steam supply valves commence opening..
The AFWS can also be started manually in the control room or from the local station.
3.
Documentation The following enclosures are attached as documentation of the indicated NUREG requirements.
1,.
Sketch of AFW system 2.
Part 1
IEEE 279-1'971 discussion 3.
Part 1
System design description 4.
AFW flow initiation and-control PAID (Drawing 5117-110-H-1) 5.
Part 2
Westinghouse plant discussion 6.
Part 2
IEEE 279-1971 discussion 7.
Part 2
System design description 8.
Diagrams a.
Elementary Diagram AFW'low control and indication (5177-109-E-05 Sheets 1,. A, B) b.
Connection Diagram AFW flow'ontrol and containment pressure monitor racks and junction boxes Unit 3 (5177-109-E-07) c.
Connection Diagx'am AFW flow control and contaimnent pressure monitor racks and junction boxes Unit 4 (5177-109-E-09) d.
Connection Diagram AFW flow control and indication control panel 3C02 and missc.
components.
Unit 3 (5177-109-E-08) e.
Connection Diagram AFW flow control and indication control panel 4C02 and mi'sc. components.
Unit 4 (5177-109-E-10)
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ENCLOSURE 2 Page 1 of 2 NUREG Item II.E.1.2 Part 1
Com liance with IEEE-279-1971 The following discussions are keyed to Section 4 of IEEE Std. 279-1971 and demonstrate compliance with the above mentioned standard.
1.
General Function Requirements
- The auxiliary feedwater initiation and control system will, with precision and reliability~automatically perform its protective function whenever the station conditions, as described in FSAR Table 7.2-1, reach preset levels.
.2.
Single Failure Criterion - Ho single failure can prevent the auxiliary feedwater initiation and control system from performing its protective function.
3.
Qualification of Components and htodules - The auxiliary feedwater initiation and control system consists of high quality components and modules with.minimum maintenance requirements and low failure rates.
Quality control procedures were used during fabrication and testing to verify compliance with the requirements specified,.
for the equipment.
,4.
Equipment Qualification - Type test data is available to verify that the auxiliary feedwater initiation and control equipment meet, on a continuing basis, the performance requirements.
6.
Channel Independence
- Each auxiliary logic channel are located in separate a barrier against fire and mechanical'he cabinets are located in the cable environmental and missile protection.
feedwater initiation and control cabinets.
The cabinets act as damage from jexternal sources.
spreading room which offexs 7.
Control and Protection System Interaction-a.
Classification of Equipment - Equipment that is used for protection and control function is cl'assified as part of the protection system and meets the requirements of IEEE-279-1971.
b.
Isolation 'devices -'he auxiliary feedwater initiation and control system is considered a complete protection system and'o isolation devices are utilized between signal and control.
Page 2 of 2 Co Single Random Failure - A single random failure resulting in a control system action, simultaneously causing a channel failure and a station condition requiring protective.
action is considered incredible.
d.
Multiple Failures Resulting from a Credible Single Event-
,No control system action can result in a condition requiring
,protective action and can concurrently prevent the protective action of the auxiliary,feedwater initiation and control system.
9.
Capability of Sensor Checks - The initiating parameters are monitored in the control room which permits cross checking between channels.
10.
Capability for Test and Calibration - Manual testing is provided for each initiating parameter.
Manual calibration is provided for at the auxiliary feedwater flow transmitters which can be independently isolated and simulated process parameters applied to check calibration.
ll.
Channel Bypasses or Removal from Operation
>> Maintenance is permissible to each separate, independent logic system without the necessity, for bypasses.
Removing one logic system will remove one initiating channel.to provide a two out of two logic in lieu of the two out of three as stated in the FSAR Table 7.2-1.
12.
Operating Bypasses
- Operating bypasses are not provided.
13.
Indication of Bypasses
- Since no operating bypasses are provided, there is no indication of bypasses necessary.
17.
Manual Initiation - Manual initiation is provided, at a system level from the main control console by means of hand switches to: open the auxiliary feedwater pump turbine steam immission valves and hand control-lers to manually open the auxiliary feedwater valves.
Enclosure 3
SYSTEM DESCRIPTION r
FOR AUXILIARYFEEDWATER FLOW INITIATIONAND CONTROL (SAFETY GRADE)
'TABLE OF CONTENTS
~Pa e
1.0 Function 2.0.
Design Bases 2.1 Safety Design Bases 2 ~ 2 Power Generation Design Bases Table 2.1 Codes and Standards 3.0 Description 3.1 General Description 3.2'ys tern,Operation 3.'3 Component Description 6
6 7
9
'4. 0
.References
1.0 FUNCTION The auxiliary, feedwater flow controllers hold the pump;discharge flowrate to a maximum of.200'PM per loop on ini.tial pump start up.
Changes in flowrate can be accomplished if required by operator
,manipulation of the flowrate setpoint in the control room..
3
2.0 DESIGN BASES 2.1 Safet Desi n Bases T
, The auxiliary feed'water flow control system is designed in accordance with safety-grade requirements
.as shown in Table 2'. 1.
Automatic or manual initiation of the auxili'ary feedwater system will automatical'ly initiate the flow control system.
Control circuitry is powered from the emergency buses.
Single failure design criteria is inherent in the design of the steam generator'ystem, and is therefore met in the design of the flow control system by applying a separate control loop to each of the three steam generators.
The flow transmitters form part. of the steam generator pressure
- boundary, and are therefore qualified to meet the acceptance criterion for Qp devices, which is, that they maintain their structural integrity, leaktightness and
,operability during and after a seismic event.
2.2'ower Generation Desi n: Bases Each fl'ow controller is a rack mounted proportional plus reset controller with a.manual set point received from a control room control station.
The control'ler output drives existing flow control valves.
The electrical signals received by,and transmitted from the control system. are 4-20.milliamps.
4'
TABLE 2.1 Codes and Standards SPONSOR NUMBER SUBJECT ANSI B2.1-1968 Pipe Threads (except Dryseal) lb ANSI B16.5-1973
'Steel Pipe Flanges and Flanged Fittings
'ANSI
. B16.1'1-1973 Threading Forged Steel Fittings, Socket Welding and IEEE 323-1974 General Guide for Qualifying Class 1E Electric Equipment for Nuclear Power Generating Stations IEEE 344-1975 IEE Recommended Practices for Seismic Qualification of Class 1E Equipment for Nuclear Power Generating 'Stations NEMA e
ICS-1970 Industrial Controls and Systems NEHA WC5-1973 Standard for Thermoplastic Insul'ated Wire and Cable for the Transmission and Distribution of Electric Energy 5
3.0 DESCRIPTION
3.1 General Descri tion The auxiliary feedwater flow, initiation and control loops are shown on P&ID 5177-110-M-1.
The electronic flow control system totally replaces a pneumatic flow control system up to the exisitng solenoid valves mounted'n the flow control valves.
The hand indicating controllers mounted on the main control consoles 3
and 4 C02, provide indications for auxilary feedwater flow, flow controller setpoint and flow controller output signal..
The flow measurement and setpoint scales.are 0 to 300 gallons per minute.
The control'ler output scale is 0 to 1'00% of valve opening signal.
The flow measurement pointer is red while the set point and output pointers are black.
A setpoint knob on the hand controller adjusts the control loop setpoint.
A mode transfer switchalso exists on the hand contoller.
This lever selects the control 1'oop operating mode:
automatic or manual.
Output adjustments may be made by moving this lever up or down in the "M",slot.
The actual control function circuitry for the system is in racks 3QR80 and 4QR80 located in the lower cable spreading room.
The hand contoller communicates to the rack mounted control function card by 0 to 10 volt signals via a 30-conductor cable.
A's all signals within the rack mounted control system are 0'o 10 volts, converters are used to interface the controller and signal processing electronics with the 4 to 20 milliamp signals in.the field.
A 4 to 20 millamp signal is developed by the associated feedwater line flow transmitter.
This signal is converted'o
- 0. to 10 volts 6
3.1 continued at the control system rack where it is then processed by a square root converter.
The control function card then uses the set point from the hand'ontroller 'and the measurement from the flow transmitter to develop a 0 to 10 volt control signal.
'The 0 to 10 volt control signal is then converted to a 4 'to 20 milliamp signal which drives an I/P transducer mounted adjacent to each control valve.
Upon initiation of the auxiliary feedwater
- system, the turbine steam isolation valves open-and.actuate position switches that energize the solenoid valves mounted on the auxiliary feedwater control valves to
.permit the instrument air control signal to modulate the control valve as required by the flow control signal.
3.2 S stem 0 eration When the auxiliary feedwater system is in standby
- mode, the main control console mounted hand indicating controller is preset to 200 GPM.
However,,
the controller output is disconnected from the control valves by the solenoid valves.
With no signal coming from the controller, the control valves will be driven to a closed position.
Also, since a long term.er'ror signal is produced.between the 200 GPM setpoint and the 0
GPM flow measurement,
.the proportional plus reset controller wil'l "wind up", charging the, reset circuitry with a signal sufficient to drive the control valves fully open.
On an auxiliary feedwater initiation signal,.
steam is applied to the auxiliary feedwater pump turbines.
An initiation signal is also applied to the feedwater.flow control solenoid valves which then permits instrument air to be supplied to the flow control valves.
The full,output signal from the controll'er is then applied to the control valves driving them wide open.
Under normal conditions the check valve in the feedwater discharge line will remain closed until the turbine has developed sufficient shaft horsepower to enable the pumphead to overcome the head'n the steam generator.
At that point the check valve will then open and feedwater will begin, to flow to the steam generator.
The increasing flowrate will be sensed by the flow transmitter and its output signal will increase affecting the controller balance and unwinding the reset.
The controller will initially over shoot then decay to control flow at 200 'GPM The operator may change the auxiliary feedwater flow to any desired value by changing the flow controller set point from the main control console.
For 'a description of the flow transmi'tters see the System Description for the Auxiliary Feedwater Flow Indication at Enclosure 7.
Manual position of the control valves can be accomplished in the control room by taking the hand indicating controller out of the automatic mode and putting it in the manual mode.
The driving signal to the valve, which is indicated on the hand controller by a 0 to 100% scale, can be increased or decreased by
3.2 (continued) moving the manual adjustment level up or down in the manual slot.
While in the manual mode the control unit holds the last output value until the operator changes it.
Swi'tching from manual to automatic and back to manual is a bumpless, balanceless type of switching procedure.
In order,to assure a greater degree.of system operability during maintenance, the automatic and manual circuitry for the controller has been placed on two separate rack mounted cards.
In this type of arrangement, if the control loop is on manual the automatic card may be removed and replaced without interruption to the system.
If the loop is on automatic, the manual card may be removed and changed without interruption to the system.
If the look is on automatic and the automatic card is removed, the loop will switch,to manual.
To avoid' sudden upset of the output signal when replacing unplugged cards, the following steps must be taken:
(1) When replacing the removal manual unit, put the transfer switch on the hand controller in automatic ("A").
(2) When replacing the automatic proportional reset control unit, put the transfer switch in manual ("M").
3.3 Com onent Descri tion Hand Indicating Controllers:
Foxboro Series N-250 H Model 8N-250HM-M2NH-F Range:
0-10 volts DC
3.3 (Continued)
Control Units:
Foxboro Model N-2AC D + A4 + RM Includes removable manual unit in dual module
.Range:
0-10 vols DC
'Proporational:
2-500%
Reset:
0.01-60 minutes/repeat Square Root Converters:
Foxboro Model N-2AP + SQE Range:
0-10 volts 'DC Current to Voltage Converters:
Foxboro Model N-2AI-I2V Input Signal:
4-20 milliamps DC Output Signal:
0-10 volts DC Converter contains a 24 volt DC power supply for.the flow transmitters
~
'oltage to 'Current Converters:
Foxboro Model N-2AO-V3I Input Signal:
~
0-10 volts DC Output Signal':
4-20 milliamps DC Control Valve Positioners:.
Transducer Model (number not available)
Input Signal:
4-20 milliamps DC Output Signal:
3-15 PSIG Positioner Model (number not available)
Input Signal:
3-15 PSIG Output Signal (as required by valve)
Max.
70 PSIG 4.'O'EFERENCES 10
4.0-REFERENCES 4,.1 P&ID 5177-110-M-1 4.2 System Description Auxiliary Feedwater Flow Indication 5177-110-J001 (Enclosure 7) 4.3 NUREG 0578'tem 2.1.7A
ENCLOSURE 5 NUREG ITEM'I.E.1.2 (Part 2)'UXILIARY FEEDWATER'YSTEM FLOWRATE INDICATION 2)
For Westin house Plant (a)
To satisfy these requirements, Westinghouse plants must provide as a minimum one auxiliary feedwater flowrate indicator and one wide-range steam-generator level indicator for each steam generator or two flow-rate indicators.
The system is designed with two flow rate indications.
Narrow range and wide range level are presently available.'b)
The fl'ow indication system should'e:
(i) environmentally qualified.
The system is qualified to IREE 323-1974 and IEEE 344-1974',
(ii) powered from "highly,reliable, battery;backed non-Class 1E power source.
The system is po'wered from the vital bus system which is. a Class IE power'ource.
(iii) periodically testable The system is testable.
One channel can be tested'ith the other in service.
(iv)
,part of plant, quality.assurance program The system is part of the program.
2)
Westin house Plant (continued)
(v) capable at display on demand.
System will display at all times there is flow.
The addition of this equipment will not increase the potential for operator error because this addition will only replace existing equipment.
It actually reduces the possibility of operator error with the additional channel of indication.
0 ENCLOSURE 6
Page 1 of
'2 NUREG Item XX.E.1.2 Part 2
Com liance with IEEE-279-1971 The following discussions axe keyed to Section 4 of IEEE-279-1971 and demonstrate compliance with the above mentioned standard.
1.
General Function Requirements
- The auxiliary feedwater flow indication system will>with precision and reliabilityzprovide both remote and local auxiliaxy feedwater flow indication whenever the station con-ditions as described in FSAR Table 7.2-1 reach
.preset levels thereby initiating auxiliary feedwater flow to the steam generators.
2.
Single Failure Criterion - No single failure can prevent the auxiliary feedwater flow indication system from providing the opera-tor with auxiliary feedwater flow indication to all three steam generators.
3.
Qualification of Components and Modules - The auxiliary feedwater flow indication system consists of high quality components and modules with minimum maintenance requirements and low failure rates.
Quality control proceduxes were used during fabrication and testing to verify compliance with the requirements specified for the equipment.
4.
Equipment Qualification - Type test data is available to verify that the auxiliary feedwater flow indication equipment meets, on a con-tinuing basis, the performance requirements.
6.
Channel Independence
- Each auxiliary feedwater flow indication logic channel is located in separate cabinets.
These cabinets act as a barrier against fire and mechanical damage from external sources.
These cabinets are located in the cable spreading room which offers environmental and missile protection.
7.
Control and Protection System Interaction-a.
Classification of.Equipment - Equipment for the auxiliary feedwater f'low indication is classified as part of the auxiliary feedwater initiation and control and meets the requirements of IEEE-279-1971.
b.
Isolation devices - The auxiliary feedwater flow indication system's considered as part of the auxiliary feedwater initiation and control system and no isolation devices are utilized between signal and control.
0 0
Page I,:2-of g'.
Single Random Failure - A single random failure resulting in a control system action, simultaneously causing a
channel failure and a station condition requiring protective action is considered incredible.
- d..Multiple Failures Resulting from a Credible Single Event-Ho control system action can result in a condition requiring protecive action and can concurrently prevent the auxiliary feedwater flow indication system from providing the indication required.
9.
Capability of Sensor Checks - The auxiliary feedwater flow indication system has multiple readouts in the control room which permits cross checking between channels and other feedwater parameters.
10.
Capability for Test and Calibration - Manual testing and calibration is provided for each auxiliary feedwater flow transmitter which can be independently isolated and simulated process parameters applied'o check reponse and calibration.
ENCLOSURE 7
SYSTEM, DESCRIPTION FOR AUXILIARYFEEDWATER FLOW INDICATION (SAFETY,GRADE)
TABLE OF'ONTENTS PAGE l.O'unction
'.0 Design Bases 3
2.1 Safety Design Bases 2.2
'Power Generation Design Bases Table 2.1 Codes and Standards 3.0 Description 3.1 General Description 3.2 Component Description 4.0 References
'1. 0 FUNCTION The auxiliary feedwa'ter flow indication instrument loops provide the operator, with redundant flow ind'ication from the auxiliary feedwater pumps to each steam generator.
- 2. 0 DESIGN
'BASES'.1 Safet Desi n Bases The auxiliary feedwater flow indication system is designed in accordance with safety-grade requirements,
.as shown in Table 2.1.
Indication circuitry is powered from the emergency buses.
Redundant measurement and indication is provided for each auxiliary feedwater li'ne.
The flow:transmitters; form part of,the steam generator pressure boundary and are therefore qualified to meet the acceptance criterion for Qp devices, which is, that they maintain their structural integrity, leaktightness and operability,.during, and after,a seismic event.
2.2 Power Generation Desi n Bases Each steam, generator auxiliary feedwater line has one flow element (orifice plate).
The normal signal transmission will be 4-20 milliamps DC.
TABLE 2.1 Codes and Standards SPONSOR NUMBER SUBJECT ANSI B2.1-1968 Pipe Threads (except Dryseal)
ANSI B16.5-1973 Steel; Pipe Flanges an Flanged Fittings ANSI B16.11-1973 Forged Steel Fittings, Socket Welding and Threading ANSI C39.1-1972 Requirements for Electrical Analog Indicating Instruments ANSI C39.5-1'964 Electrical Safety Requirements for Measuring and Controlling Instrumentation IEEE 323-1974 General Guide for Qualifying Class 1E Electric Equipment for Nuclear Power Generating Stations IEEE 344-1975 IEEE Recommended Practices for Seismic Qualificati'on of Class 1E Equipment for Nuclear Power Generating Stations NEMA WC5-1973 Standard for Thermoplastic Insulated Wire and Cable for the Transmission and Distribution of Electrical Energy
- 3. 0 DESCRIPT ION 3.1 General Descri tion The auxiliary feedwater flow indication loops are'hown on PAID 5177-110-M-1.
Each steam generator auxiliary feedwater line has two redundant feedwater flow indication loops.
Both loops on each feedwater line share a common flow element.
Redundant
,.flow transmitters have common, taps on the feedwater line.
Signal conditioning is provided, by an electronic square root extractor to give linear flow indication.
Redundant indi'cation is given in the control room and locally at the auxiliary feedwater control valve location.
The signal conditioning and control room indication, of one of the redundant feedwater.flow loops occurs within the auxiliary feedwater flow control system.
The square root extraction for this particular loop takes place in racks 3QR80 and 4QR80 located in,the lower cable, spreading room.
The indication for this loop is contained within the hand indicati'ng controllers for the auxiliary feedwater flow control system located on the main control consoles 3C02 an 4C02.
The square root extraction for,the.other flow indication loops is done in redundant racks 3QR80 and 4QR80 located in the lower cable spreading room.
Control room indication for th'is loop appears on vertical panels 3C04 an 4C04.
The 'required 24 volt DC power supplies for the flow transmitters are contained within current to voltage convertors located in the same racks as the square root extractors.
3.1 (continued)
For a description of the signal conditioning electronics see the System Description for Auxiliary Feedater Flow Initiation and 'Control at Enclosure 3.
3.2 Com onent Descri tion Flow Elements: Orifice Plates Flow Transmitters:Westinghouse Model (number not available)
Calibration Range:200" WC Differential Pressure Output Range:
4 20 milliamps DC Flow Indicators:Sigma Model 1151/1251 Vertically mounted edgewise indicator Input Range:
4 20'illiamps DC Scale Range:
0 300 GPM
4.0'EFERENCES 4.1 P&ID 5177-110-N-1 4.2 System Description for Auxil'iary Feedwater Flow Initiation and Control 5177'-109-J002 (Enclosure 3) 4.3 NUREG 0578 Item 2.1.7B