ML20090B009
| ML20090B009 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 04/22/1981 |
| From: | CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| Shared Package | |
| ML17198A223 | List:
|
| References | |
| CON-BOX-13, FOIA-84-96 NUDOCS 8104280609 | |
| Download: ML20090B009 (150) | |
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MIDLAND PLAPT UNITS 1 AND 2
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DESIGN RF/IEW PirsthTATION,
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AUXILDutf FEEDATIR SYSTEM CESIG REVIDi PRESENDLTION DBt2 & CINTDTTS E231 1.0 INrno0UCTIW 1-1 1.1 PURPOSE & PRE 5errATION 1-1 12 PRESENmTION PUDWT l-1 1.3 INr200tITICH T SPEAKERS 1-1 2.0 IESIN BASES 2-1 2.1 SMT1Y IESIN BASES 2-1 2.2 POWER GNERATICE CESIG BASES 2-2 2.3 CXES AND SDMARDS 2-2 3.0 SYSTEM CESIG AND CPERATICN 3-1 3.1 AFW SUPRX PIPIE AND RCTION SOURCES 3-1 3.2 APW PLMP5 3-2 3.3 APW DISCHUCE PIPIE 1
3-3 3.4 OPERATDC MXES 3-4 3.5 AFW ACItATICN 3-5 3.6 POWER 51PPLY 3-4 3.7 IMrrRLMI2frATION AND GNTRCEE 3-8 4.0 STSM GENERA 1tR CENTRO!/ SYSTEM RESP 0 TEE 4-1 4.1 frDM 22 ERA 2tR ISTL CCtfrNL 4-1 4.2 FEID CHLY GOCD GENDATUt INTERDCK 4-5 4.3 STDM G2ERATUt CVERFI!L PRC7TIETION 4-6 i
M 5.0 AFW SYSTDI RELIABILTfY 5-1 6.0 IESIG EWIATION/REI;UI.ATIOeB 6-1 6.1 SMT!Y EVAUATIm 6-1 6.2 GENERAL EESIW OtITMIA 6-3 6.3 RIEULAN GUIIES 6-5 6.4 BRANCH 1ENNICAL POSITICBS 6-7 6.5 CnHER RFUr3Am gettmcg 6-8 LIST T AIMMEVIATICbE
'!NEZS FIGlRES APICCIX A:
MItXAND PLANT AFW SYSTDt REI,IABILf!T ANM,YSIS SYNOPSIS APPUCIX B:
ISAR APP 10A APPENDIX C:
TEDINICAL SPECITICATION 16.3/4.7.1.2 APPENDIX Dr NURID-0667 RESPONSG, REED 9ENIATIOta 9,10, 21 APPINDIX E FSAR GJESTION 211.184 APPENDIX F:
FSAR ORPTER 7 (SEIKTED SELTICES) d'
D001gn Reviser PrOOOnthtion
1.0 INTRODUCTION
1.1 PURPOSE OF PRESENTATIO!
- 1. 2 PRESENTATIC2; FOPEAT
1.3 INTRODUCTION
OF SPEAKERS O
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2.0 DESIGN BASES l'Theauxiliaryfeedwater 2
once-through steam generators (OTSGs) during normal plant startup, cooldown, and hot standby conditions.
The AFW system is not required during normal plant power operation, but remains in the standby mode.
During emergency conditions, also designed to automatically supply feedwater to the OTSCsthe AFW system is allowing the removal of decay heat from the reactor coolant i
system (RCS) through the secondary system to a point at which the 4
decay heat removal system can be placed in operation.
In general, the AFW system consists of diverse feedwater supplies, two AFW pumps, a double crossover discharge piping arrangement, and level control logic.
the AFW system is provided as Figure 2-1.A simplified diagram of 4
2.1 SAFETY DESIGN SA5ES The following AFW system safety design bases were determined to be required to meet regulatory criteria and to directly or indirectly ensure the health and safety of the public.
2.1.1 safety Design Basis one
.j The AFW system provides feedwater for the removal of reactor core decay heat to preclude damage to the reactor core following a loss of main feedwater. and to ensure the reactor coolant temperature can be reduced to the point at which the decay heat
=
removal system may be placed in operation.
i; 2.1.2 safety Desian Basis Two The AFW and supporting systems ensure the required flow to the steam generators in the event of a sing 1s active failure.
2.1.3 Safety Design Basis Three j
the AFW system is operated from the auxiliary shutdown 3j 2.1.4 Safety Design Basis Four k
The AFW system, designed to remain functional following the safe shutdownincludin b
2 2.1.5 safety Design Basis Five The AFW system is designed with two independent full-capacit a
systems, each with diverse motive and control power sources.y complete loss of ac power. (station blackout), the turbine-driven On j
2-1 2
5 i _
AFW pump io ccpablo cf meating tha fecdwetor requirements for o cinimum of 2 hsura.
2.1.6 Safety Desien Basis Six The AFW system is designed to avoid the effects of hydraulic instability (water hammer).
2.2 POWER GENERATION DESIGN BASES 2.2.1 Power Generation Design Basis one The ATV system may be used to supply feedwater to the steam generators during startup, cooldown, and hot standby.
2.3 CODES AND STAICARDS Codes and standards applicable to the AFW system are listed in
. Table 2-1.
The AFw system is designed and constructed in accordance with quality Group C requirements up to the containment isolation valves, requirements within the containment.and with quality Group B I
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Decign RSvicw Prc3cntation 3.0 SYSTEM DESIGN AND OPERATION 3.1 AUXILIARY FEEDWATER SUPPLY FIPING AND SUCTION SOURCES The auxiliary feedwater ( AFW) pumps take suction from the sources described in subsections 3.1.1 and 3.1.2 below.
3.1.1 Nonsafety-Crade Sources The normal water source of the AFW system is the non-Seismic
.S Category I, 300,000-gallon condensate storage tank (CST).
The i
CST is sized to accommodate the plant at hot shutdown for approximately 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> followed by a 6-hour cooldown to 280F.
Alternate water sources for the AFW system are the deaerator storage tanks and the condenser hotwell.
Water from the deaerator storage tanks is normally used during hot standby or normal plant cooldown to minimize thermal shock to the once-through steam generators (OTscs). Water from the condenser hotwell is considered to be a backup source to be used if water from the deserators and the CST is unavailable.
3.1.2 safety-Crade source A Seismic Category I supply to the AFW pump suction is provided by the Lervice water system (SWs) to supply feedwater in the that the CST or other sources of water are not available.
event 3.1.3 Suction Pipino Configuration The AFW suction piping, as shown in Figure 3-1, is arranged to enable the motor-driven AFW pump to operate independently of the turbine-driven AFW pump.
Normal alignment of the AFW suction is from the non-Seismic Category I CST when the AFW system is in standby.
All suction valves required for system initiation and control are power operated.
Suction can be aligned either to the deaerators or the condenser hotwell by opening or closing remote manual valves operated from the main control room (MCR).
Each AFW pump train connects to the SWS through two motor-opsrated, automatically actuated butterfly valves in series.
Switchover of the AFW pump suction to the SW5 is accomplished automatically using a two-out-of-four low pump suction pressure logic concurrent with the presence of an AFW actuation signal (AFWAS).
Upon actuation of this switchover, the nonsafety suction sources are isolated and the two butterfly valves to each service water train are opened.
To prevent spurious opening of the service water valves due to normal transients, the low suction pressure must persist for 4 seconds before the transfer is initiated.
The valves admitting ser.* ice water can also be 3-1
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Design Coview Frecentation cpened frco the control room or auxiliary shutdown panel in response to an alarm of low AFW pump suction pressure.
3.2 AUXILIARY FEEDWATER FUMPS There are two safety-grade AFW pumps, one motor-driven and one turbine-driven, for each of the two units.
Each pump is a horizontal centrifugal unit rated at 885 gym and 2,700 feet total developed head.
The discharge head is sufficient to establish the necessary flowrate against a steam generator pressure corresponding to the lowest pressure setpoint of the main steam safety valves.
The ficwrate of each AFW pump is equal to, or greater than, the flowrate required to remove the decay heat generated at 40 seconds into the transient.
The 40-second time was chosen to allow the AFW system to inject feedwater and begin increasing OTSG 1evel to the 50% operating range level, required for natural circulation, prior to completing reactor coolant pump coastdown.
The motor-driven AFW pump associated with each unit is supplied with power from the Class lE ac power system.
Following initiation of an ANAS, the motor-driven AFW pump is capable of supplying feedwater to the steam generators within 40 seconds, including an allowance of 10 seconds for starting the emergency diesel generators.
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The turbine-driven AFW pump associated with each unit provides system redundancy of AW supply and diversity of motive pumping power.
Steam supply piping to the turbine driver, as shown in Figure 3-2, is taken from each of the main steam lines inside the containment.
A line from each steam generator, equipped with a normally closed de motor-operated isolation valve, supplies steam to a common header.
containment isolation valve and throttle trip valve.This header leads to the t The steam lines are designed to prevent the accumulation of condensate in the lines.
The turbine driver can operate with steam inlet pressures ranging from 45 to 1,160 peig.
Exhaust steam fs., the building roof. turbine driver is vented to the atmosphere above the auxiliary Cocling for the turbine-driven AFW pump bearings and the turbine lubricating oil is provided by internt.1 recirculation of the pumped fluid through the pump seal coolers and the turbine primary lube oil cooler.
This system is designed to provide sufficient cooling with pumpage tempwratures at or below 130F, and satisfies cooling requirements when suction is taken from either the CST or SW5.
Though not intended for normal use, but provided to allow further operating flexibility, a secondary cooler using service water is used when suction is desired from I-the deserators.
Valves and controla necessary for the function of the turbine-driven pump and its associated equipment are 3-2
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........,.........as.m Design C view Proccntoticn anergized by Class 1E de power supplied as discussed in Section 3.5.
Following initiation of an AFWAS, steam is admitted to the turbine-driven AFW pump.
The feed-only-good generator (FOGG) signals are provided to the steam supply isolation valves of both steam generators, ensuring that only the good steam generator provides motive steam to the turbine driver by closure of the steam isolation valves from the faulted steam generator.
This ensures a steam supply to the AFW pump turbine driver.
The time required to open the steam supply isolation valve and bring the turbine-driven pump to speed is less than 40 seconds.
The AFW pumps are located in separate flood-protected rooms at al 584'-0* of the auxiliary building.
Each AFW pump room is provided with an engineered safety features (ESF) unit cooler to control room temperature at a level consistant with environmental requirements for proper operation of the AFW system components.
The ESF coolers begin operation in conjunction with the pump they cool, and stop when the corresponding pump stops and the room temperature is reduced below the room thermostat control setpoint.
The fan of each unit cooler is powered from the same train as the pump with which it is associated.
When the pump served by the unit cooler is off, the unit cooler fan is controlled by the pump room thermostat.
3.3 AUXILIARY FEEDWATER DISCHARGE PIPING The AFW pump discharge headers, as shown in Figure 3-3, are provided with a double crossover piping arrangement for system redundancy.
Each discharge header splits into two lines:
line for the lead-level control valve of the associated steam one generator and another line for the crossover redundant-level centrol valve of the other steam generator.
The level control valve in the crossover piping normally remains closed as long as the lead valve is functioning properly.
If either the AFW pump or the lead-level control valve of one train fails to supply the necessary feedwater to its associated steam generator, the AFW pump of the other train would then supply feedwater via the crossover piping.
Parallel containment isolation valves are provided on the discharge piping to each steam generator.
One of the parallel valves is ac powered and the other is de powered.
The AFW pump discharge headers are also provided with minimum recirculation and test lines.
The discharge flowpath is to the condensate storage tank or the cooling pond, depending on the suction source.
When AFW suction is taken from the deaerators, minimum pump recirculation flow is satisfied by recircul. tion to the deaerator storage tanks through the auxiliary-to-sain feedwater system crosstie.
3-3
Design Rhview Prcocntbtion 3.4 OPERATING MODES 3.4.1 Plant Startup
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During startup, the motor-driven AW pumps may be used to supply feedwater from the deserating storage tank to the steam generators.
3.4.2 Normal Plant Operation The A W system is not activated during normal power generation.
The pumps are placed in the standby saode and aru lined up to take auction from the CST if this becomes necessary.
3.4.3 Hot Standby During hot standby, the AW system may be used to provide water to each steam generator to maintain the water level.
Auxiliary feedwater pump suction may be taken from the deaerator storage tanks, which maintain the temperature at approximately 229F.
Feedwater flow would be pumped into the mair. feedwater nozzles of the steam generator via the auxiliary-to-main feedwater system cross tie.
3.4.4 Normal Plant Cooldown During cooldown, the motor-driven Arv pump may be used to supply water to the steam generators from the deaerator storage tanks, CST, or the condenser hotwell.
The deaerator storage tanks would be the primary suurce of this water to minimize thermal shock to the steam generators.
steam generated during normal cooldown is bypassed to the main condenser.
The A W pump may be used until the reactor coolant (RC) temperature drops to approximately 280F, at which point the decay heat removal (DER) system is activated.
After the DER system is placed in operation, the OTscs are placed in a wet layup condition by using the AW system.
During wet layup, all required AW components will be manually controlled to accomplish OTSG filling.
3.4.5 Shutdown After High-Energy I,ine Breaks The events following a postulated break in AFW piping depend upon the plant conditions at the time of break.
The technical specifications will not permit using the turbine-driven AW pump during hot standby except in emergencies.
In the event of a postulated failure in the piping associated with the electric-driven pump, the break is isolated and the turbine-driven pump is started.
Because the turbine-generator is not paralleled to the offsite grid during hot standby, availability of offsite power is 3-4
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Design R;vicw ProCCntaticn cccused.
This permits use of the main feedwater pumps in the event that the turbine-driven AFW pump fails to start.
Emergency shutdown is not required following a failure outside the containment in the AFW system during normal or hot standby operation.
3.4.6 Emereency Operation The AWAS automatically starts both AFW pumps in less than 40 seconds.
These pumps continuously supply the required feedwater to the steam generators until the flow is terminated by operator a&sinistrative control.
Urder emergency conditions, heat is removed from the RC system (RCS) by boiling the feedwater in the steam generators and venting the steam to the atmosphere through the power-operated atmospheric vent valves and/or the main steam safety valves.
If the main steam isolation valves are open, steam may be relieved via the turbine bypass system if a condenser is available, or through the modulating atmospheric dump valves, if the condenser is unavailable.
Either method is capable of lowering the RCS temperature to a point where the DHR5 can be placed in operation.
3.5 AUXILIARY FEEDWATER' ACTUATION The safety-grade AFWAS automatically starts both the turbine-driven and motor-driven AW pumps.
AWAS also automatically l
positions the AFW valves both to mitigate the consequences of a loss of main feedwater or loss nf offsite power incident and to provide feedwater to allow primary heat removal through the steam generators.
The ANAS will automatically start the AW pumps under any of the following conditions:
Low pressure in either OTsc a.
b.
Low level in either OTSG Class IE bus undervoltage c.
d.
Loss of reactor coolant flow indicated by loss of power to three out of four reactor coolant pumps Loss of both main feedwater pumps e.
f.
Emergency core cooling actuation signal (ECCAS)
In addition to automatic initiation, AFW equipment may be manually actuated from the control room or from the auxiliary shutdown panel.
3-5 m
Decign RGvicw Procontation 3.5.1 Byennnnn A bypass is provided to avoid actuation of both the AWAS and the main steam line isolation signal (MSLIS) systems by a low steam generator pressure during normal startup and shutdown conditions.
Bypasses are also provided to avoid actuation of AWAS either by loss of the main feed pump trip signal or by loss of three out of fo : reactor coolant pumps during normal startup and shutdown.
3.5.2 Interlocks The AFW system is equipped with a FOGG control system which operates to terminate AW flow to a faulted steam generator.
The FOGC system continuously monitors the differential pressure between the steam ganerators.
When a preselected differential pressure is Jensed, FCCC automatically closes the following:
The An isolation and control valves supplying the lower a.
pressure OTSG b.
The steam valve supplying the turbine-driven AW pump from the lower pressure OTSG The continuous intezrogation feature of this system permits isola *. ion any time during a secondary pressure transient and allows the lower pressure OTSG to be returned to service should the pressure differential be reduced by corrective action, such as main steam and feedwater line isolation.
The OTSCs are protected from overfilling by automatic closure of both the AW level control and isolation valves feeding the affected oTSC on high-high level.
3.6 POWER SUPPLY 3.6.1 Normal Operation The AW system power supplies are derived from Class 1E sources.
Each AW train (A and B) is fed from entirely independent Class lE sources.
These sources include:
AC components are fed frem trains A and B Class IE ac a.
buses.
b.
DC components are fed frem trains A and B Class lE de buses.
DC buswa are normally fed through rectifiers from their c.
respective ac buses.
d.
Station batteries feed the de buses whenever ac power is unavailable.
3-6
Design Rovicw Fraccntaticn 3.6.2 Trnin A The train A AFW system consists of the motor-driven AW pump and its related components.
class IE power supplies as follows: Major components of the system receive Motor-driven AFW pump - ac power a.
b.
Room cooler fans - ac power Level control valves - ac power through inverters from c.
the de bus d.
Parallel containment isolation valves - ac power to one valve, de power to one valve Other valves - ac power e.
3.6.3 Train B The train B AFW system consists of the turbine-driven AW pump and its related components.
Major components of the system receive Class lE power supplies as follows:
Turbine-driven AW pump controls - de power a.
b.
Room cooler fans - ac power Turbine steam supply isolation and control valves - de c.
power / hydraulic
. d.
Level control valves - ac power through inverters from the de bus Parallel containment isolation valves - ac power to one e.
valve, de power to one valve f.
Other valves - ac power 3. 6. 4 Loss of offsite Power Upon loss of offsite power, all components in trains A and B receive power from the trains A and B emergency diesel' generators.
To provide further AFW system flexibility, the motor-driven AW pump and associated components (train A) are capable of being fed off o' the train B diesel generator by manually switching the power supply breakers via mechanical interlocks.
3-7
auxAAlory rocawotor SyctC:3 Design Rcvicw Proccntation 3.6.5 Station Blackout Upon loss of all ac power (station blackout), the train B A W system will operate using 125V de class lE battery-backed sources.
In such an event, the batteries will supply de power to the components listed above and will provide ac power, through inverters, to the ac-powered AFW 1evel control valves.
System alignment is such that other ac powered valves do not need to operate following the blackout.
The de system has sufficient capability to supply the required power for AW system operation during station blackout for at least 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
3.7 INSTRUMENTATION AND CONTROLS Instrumentation for the control and monitoring of the AFW system is located in the MCR.
Instrumentation for A W system operation needed to achieve plant safe shutdown is also contained on the auxiliary shutdown panel (ASP) and may be used in the event the control room is evacuated.
Manual control of any equipment at the ASP overrides the automatic and manual contro; capabilities of that equipment in the MCR.
This allows full control from the ASP regardless of the mode selected in the MCR.
The manual status of the controls at the ASP is indicated by lights on the MCR panel.
The following controls are provided both in the MCR and on the ASP:
a.
Motor-driven A W pump (start /stop) b.
Turbine-driven AW pump (start /stop)
A W level control valve position c.
d.
Service water supply isolation valve position (open/close)
Essential power-operated valves in system (open/close) e.
f.
AW pump turbine speed control valve position Alarms are provided in the MCR for the following:
Condensate storage tank sinimum level a.
b.
AW pumps low suction pressure Remote control'being overridden by local control c.
d.
Service water supply isolation valves and CST recirculation block valves open simultaneously e.
A W low flow 3-8
Design Asview Pro 0Gntation The following parameters are indicated both in the MCR and on the ASP:
a.
OTSG water level b.
OTsG pressure c.
AFW pump suction pressure Moter-driven AFW pump (running / stopped)
Turbine-driven AFW pump (running / stopped)
AFW pump discharge pressure 6.
9 AFW flowrate to each OTSG h.
Turbine driver steam inlet pressure i.
Condensate storage tank level j.
Position indicators for 1.
All AfW power-operated isolation and control valves (open/ closed) 2.
Service water supply and co..uensate storage supply isolation valves (open/ closed) 3.
Turbine driver steam inlet isolation valves (open/ closed) 4.
Essential manually operated valves in the recirculation line (open/ closed) 3-9
pu,dland Plant Units 1 and 2 Auxiliary Feedwator Sycten Decign Review Prccentatien 4.0 STEAM GENERATOR CONTROL / SYSTEM RESPONSE 4.1 STEAM GENERATOR LEVEL CONTROL
=.l.1 Purpose Auxiliary feedwater (AFE is initiated by the auxiliary feedwater actuation system (AFWAS).
Initiation of AFW occurs under two conditions:
- 1) loss of main feedwater and 2) loss of forced circulation on the primary system.
The' primary means of detecting a loss of main feedwater is low water level in either steam generator.
This signal detects a loss of feedwater from any cause.
In addition to low steam generator level, a loss r f main feedwater is also detected by a loss of both main feed. eater pumps, low pressure in either steam generator, or an emergency core cooling atuation signal (ECCAS).
The low steam generator pressure and 4CCAS signals are used to isolate main feedwater and, therefore, the signal is also used as an anticipatory start for the APW.
A loss of both main feed pumps' signal, though not Class IE, is also used as an saticipatory start for the AFW.
While these anticipatory start signals will not detect all loss of feedwater events, they will provide an earlier initiation of AFW for those events that are detected.
When forced circulation is lost in the primary system, auxiliary feedwater is used to obtain natural circulation.
The primary signal used to detect this condition is the loss of three out of four reactor coolant pumps.
In addition to this signal, Class 1E bus undervoltage signal is used to detect a loss of a
offsite power.
Either signal will initiate AFW.
Once the Ara system is ini u ated, it is controlled to a level that is dependent on plant conditions.
If more than one reactor coolant pump is running, the AFW is controlled tc approximately a 2-foot level.
If forced circulation is lost in the primary system, the level is raised to approximately 20 feet to establish a high thermal center for natural circulation.
In the event of a small break LOCA, the operator must take manual control of the system and taise the level to approximately 30 feet to establish steam condensation natural circulation.
i Initiating full AFW flow and rapidly filling the system to 20 feet can result 'a a large cooldown of the primary system.
This cooldown could cause a loss of indicated pressurizer level I
and possible actuation of the ECCAS because of a low re coolant (RC) pressure.
To minimize the potential for th apid r
cooldown, a level rate control system has been implemented.
4-1
l Midland Plant Unita 1 and 2 Auxilicry F edwatcr Syctco De3ign Review PrOcCntation The design objectives of this control system are to:
Minimize operator sction needed to prevent:
a.
j 1.
Loss of indicated pressuri:er level 2.
Low pressure engineered safety features actuation system (ESFAS) actrat:lon b.
Allow a minimum of 10 minutes prior to requiring operator action to prevent loss of pressurizer level indication i
4.1.2 Input / Output
)
7 The functional design for accomplishing thess objectives is as i
follows.
I Following AFW actuation, control of steam generator level is accomplished using AFW control valves in each AW loop.
Control signals for each AFW level cout rol valve are supplied by redundant and independent C2 ass 1E level transmitters on the
)
associated steam generators.
Figure 4-1 provides a simplified
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diagram illustrating the inattilation of these transmitters.
Controllers for each valve are 1xated in the main control room l
(MCR) and on the auxiliary shutdown control panel ( ASP).
i In addition to autcmatic actuation by the APMAS, manual control of the AFW level control valves for startup, shutdown, or emergency operations can be initiated using these controllers.
Auxiliary feedwater level control signals are continuously being generated by level controllers for the associatert steam generator but are blocked from reaching the associated normally closed valve.
Upon AFWAS actuation, the signal blocks are automatically removed and AFW level control commences.
Dual level setpoints are used for level control.
A low-level setpoint is utilized when more than one of the reactor coolant pumps (RCPs) is
}3 operating (signifying forced circulation) and a high-level setpoint is used when three out of four RCPs are tripped
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(anticipating natural circulation).
The setpoint switchover is achieved by a safety-grade auctioneering device which senses RCP status.
In addition, when the plant changes from forced circulation to natural circulation, the low-level setpoint is ramped at a controlled rate to the high-level setpoint to preclude ov ccooling of the primary loop.
The function of the ramp generator is put on hold when either of the control stations is put in the manual mode.
generator is provided in the MCR and on the ASP.A reset pushbutton for each ramp Manual activation of this pushbutton allows the level setpoint to drop to 2 feet, at which point the ramp function is restarted automatically.
A simplified diagras of the level control scheme is provided in Figure 4-2.
4-2
Midland Plant Unita 1 and 2 Auxiliery Focdwater System Decign R0vicv Proccntaticn The APW level control valve control systems are redundant.
These mystems include redundant class 3E level transmitters on the steam generator and redundant Class 1E level controllers on the main and auxiliary shutdown control panels.
Power for the AfW level control system and control valve is from the class 1E 120 V ac preferred power power supplies (battery-backed).
In the event of level transmitter failure, the APW control valves may be manually controlled by placing the controller to the AFW control valve in manual.
In this mode, the level setpoint can be manually changed for manual level control.
The transfer to manual control from the ASP overrides automatic control capabilities and removes manual operation from the control room.
This allows full control from the ASP regardless of the mode selected in the control room.
Manual status of the ASP controller is displayed by an indicating light on the control room panel.
This indicating light is used to bring attention to en abnormal condition affecting the associated controls.
The following conditions are used as bases for level control system design.
Maintenance of safe shutdown capability using the a.
l auxiliary feedwater system is required.
b.
4 Steam generator level is required to be sonitored to 2
provide AFW eystem control.
)
steam generator level, isolation and control valve j.
c.
positions, AFW pump operation and AFV flow are the
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minimum indications necessary,to adequately monitor AfW l
4 operation.
4 I
d.
The normal operating wr.ter level for the steam generators is 2 feet during forced circulation and 20 feet during natural circulation.
l i
The :aaximum and minimum design water levels for the e.
steam generators are approximately 36.5 feet and 1 foot j
above the bottom tubesheet, respectively.
4 f.
Auxiliary feedwater actuation signal response time (not including sensors or actuated devices) is less than 500 millise=onds.
5@ sequent to establishing A3W flow,
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the level in the steam generators can be allowed to vary somewhat during safe shutdown; therefore, reesponse time i
for AFW level control is not critical for performance.
Auxiliary feedwater operation is initiated by the AFWAS when steam generator level reaches 1 foot.
Auxiliary feedwater level controllers are preset to automatically 4-3
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.1 M
Midland Plant Units 1 and 2 Auxiliary Feedwater Syctea Design R; view PrcCantatien control steam generator level at 20 feet during natural i
circulation and at 2 feet during forced circulation.
l l
Applicable design bases are also given in Section 2.0.
g.
i 4.1.3 System Response The high AFW injection point provides sufficient heat transfer high in the steam generator to establish natural circulation.
Because of this high injection point, a rapid filling of the steam generator is not required.
A conceptual study of level rate control was performed prior to the development of a specific hardware design.
This conceptual study confirmed that the level rate control concept is viable and established a preliminary AFV fill rate.
.9 both high and low decay heat cases.This level rate limit was established by ex
- i When the initial decay heat level is low and all RCPs are off (i.e., no pump heat is available) almost any rate of once-through 2,
steam generator (OTSG) level increase, however small, will result in cooling of the RCS.
i the need for higher fill rates.At the same time, other factors dictate
- (;
First, if one fill rate limit is to be used for all initial conditions, then it must provide adequate coolant at high decay heat levels.
Second, the time required to reach the high-level setpoint must be the minimum practical to ensure adequate natural circulation flow is established.
And finally, the rate limit chosen sust be of a large enough sagnitude te allow smooth control by the electronic circuitry.
Two bounding conditions were chosen as the criteria for rate selection:
1) cooling with 100% decay heat,the rate must be high enough to prcvide adequatej to provide a minimum of 10 minutes for operator action with 15%and !
decay heat.
these conditions.A level rate limit of 4 inches per minute satisfied
)
Figures 4-3 through 4-5 depict the results of the 15, 40, 100% power cases using a 4-inch-per-minute level rate.
and l
feedwater flowrate to each steam generator was varied from aboutAuxiliary I
180 gpm to about 200 gpa to achieve the leveLrate of 4 inches per minute for the various decay heat levels.
The 15% case resulted in the most rapid cooldown, with pressurizer level going off-scale at about 890 seconds l
(14.8 minutes) into the transient.
At that time, OTSG levels were about 4 inches on the startup range; would be required before 14.8 minutes to maintain indicatedthus, operator action pressurizer level.
The 40% case does not show pressurizer L: vel going off-scale, but extrapolation of the rate of pressurizer level decrease with the 4-4
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Midland Plant Units 1 and 2 Auxilicry Feedw ter System Design R'3 view PrecGnteticn i
rate of CTsc level increase indicates operator action would be required before approximately 21 minutes into the transient.
I i
The 100% case ebows a very gradual RCS cooldown and thus, a very gradual loss in indicated pressurizer level.
This case is not expected to result in the need for operator action; i.e., the 240-inch level setpoint would be reached before indicated pressurizer level is lost.
Figure 4-6 provides a graphic representation of time available for operator action vsraus initial decay heat level using a 4-inch-per-minute fill rate.
{
This graph shows that a minimum of i
10 minutes will be available for all initial conditions and, for initial decay heat levels 2.90L no operator action is required.
Thus, a fill rate on the order of 4 inches per minute satisfies both criteria of providing at least 10 minutes for operator action to preclude loss of indicated pressurizer level ano providing adequate cooling for maximum decay heat levels.
4.2 FEED-ONLY-GOCD GENERATOR INTERLOCK
{
i 4.2.1 Purpose i
j i
The AFW system is equipped with a feed-only-good generator (FOGG) i interlock which operates to terminate AIV flow to a faulted steam generator.
Following a steam line or feedwater line break, the
]'
heat removal from the primary system must be controlled to.svoid excessive overcooling resulting in a possible return to power.
Continued feeding of AFW to a depressurized steam generator creates the potential for this overcooling.
In addition, if the i
break is inside the reactor building, ccntinued feeding of the faulted steam generator can result in excessive mass and energy l
release to the reactor building.
The F0GG system is intended to detect the steam generator with the break and to isolate AFW to that steam generator for those breaks where prompt automatic i
action is required.
A second consideration in the FOGG design is to ensure that continued heat removal is always available through at least one steam generator.
As a result, the FOGG system can isolate AFW to either steam generator A or 8, but cannot isolate feedwater to both steam generators.
l The method for detecting the steam generator with the break is to measure the pressure diffe. suce between the two steam generators.
j When the pressure difference escoeds a setpoint, AFW is
(
termina,ted to the low-pressure steam generator.
If this pressure difference is the result of a break in the system, then the low-pressure steam generator will continue to depressurize as the remaining inventory in the steam generator is lost through the break.
J If the pressure difference was caused by some unexpected system perturbation or if the break is isolated, the steam generator would repressurize.
When this happens, the pressure 1
i 1
Midland Plant Unita 1 and 2 Auxiliary Fosdwster Syctas Design Review Proccntation differential between the two steam generators would be reduced below the setpoint.
The FOGG system would then reestablish AFW flow to both steam generators.
4.2.2 Input / output The FOGG system continuously monitors the differential pressure between the steam generators.
When a predetermined differential pressure is sensed FOGG automatically closes the AFW isolatice ana control valves supplying the lower pressure OTSG and the steam supply valve from the lower pressure OTsc to the ateam turbine-driven AFW pump.
The FOGG logic is developed as part of the plant ESFAS.
The continuous interrogation feature of this system permits isolation any time during a secondary pressure transient and allows the lower pressure OTSG to be returned to service should the pressure differential be reduced by corrective action (i.e., main steam and feedwater line isolation).
In addition, manual actuation / block of FOGG is provided for the operator to feed the good generator during a tube break in the other steam generator.
is provided in Figure 4-7.A simplified diagram of the FOGG system Redundant actuation and controls are provided throughout the AfvAS on a one-to-one basis with mechanical equipment trains to ensure the required flow to both steam generators in the event of a single failure.
}
4.2.3 System Response A typical system response to a steam line break is shown in Figure 4-8.
This case is a 2.0 square foot steam line break which has been determined to be the worst case overcooling transient.
For this case, both steam generators rapidly depressurize and are isolated by a low RC system pressure ECCAS signal which results in closure of the main steam and main feedwater isolation valves.
AFW to the affected steam generator.The FOcG system will also isolate As can be seen from the plots, the steam generator with the break will continue to depressurize while the depressurization on the other steam generator is stopped.
The pressure in the unaffected steam generator is then controlled by the temperature in the primary system.
That is, the steam generator will repressurize to the saturation pressure corresponding to the temperature in the I
primary system.
If this case were calculated further out in time, decay heat would gradually heat up the primary system and
(
the steam generators would then repressurize to the atmospheric dump valve or safety valve setpoint.
4-6 l
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Midicnd Plant Units I cnd 2 Auxilicry Fcedw0 tor Syctem Design Acview PrOccntation 4.3 STEAM GENERATOR OVERFILL PROTECTION 4.3.1 Purpose Overfilling of a steam generator that causes liquid carry-over I
into the steam lines has several potentially serious consequences.
Potential consequences include:
- 1) steam-water hammer can impose excessive thrust loads on valves, piping, and supports, and 2) two-phase flow to the turbine-driven AFW pump can damage the controls or turbine preventing its operation.
For these reasons, an AFW overfill protection system has been implemented to automatically terminate AFW flow when an overfill condition is imminent.
This overfill protection system uses a high-high level signal in the steam generators to terminate feedwater and allows a return to normal AW 1evel control when the level falls below a predetermined setpoint.
4.3.2 Input / output steam generat.or high-high level signals are developed tw wide-range steam generator level transmitters.
as These are the same transmitters that are used for the AFW level control system.
Interlocks are provided to demand closure of level control and isolation valves to prohibit AW flow to a steam generator if the level has reached the high-high level setpoint.
A demand closure signal to the valve will remain active until the steam generator level drops to 10% of the transmitter span below the high-high level setpoint.
As the demand closure signal is re aved, the normal AFV control system will regain control of the AFW system.
4.3.3 System Response Ah auxiliary feedwater overfill transient occurs much slower than a main feedwater overfill transient because of the lower flow capability of the AFW system.
As a result, specific simulations of an AFW overfill event have not been performed.
1
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Auxiliary Feedw0 tor SyGtcm D3cign R5 view PrecOntaticn 5.0 AFW SYSTEM RELIABILITY The Midland Plant Auxiliary Feedwater System Reliability Analysis Synopsis, prepa red by Pickard, Lowe, and Ga rrick, Inc., is provided in Appendix A.
)
i 9
e 5-1 1
Midland Plant Units 1 and 2 Auxiliary Feedwater system Design Review Presentation 6.0 DESIGN EVALUATION /*F"3TATIONS This section provides the muziliary feedwater (A"V) system safety evaluation and compliance with the Standard Revie.t Plan 10.4.9 Acceptance criteria (including general design criteria / regulatory guides / branch technical positions) and other regulatory guidance.
(Refer to Figure 6-1. )
Whsrever " position" or " guideline" statements appear in the following section, the words have been paraphrased from the referenced regulatory document for the purpose of brevity. Nidland-specific terminology has replaced generic designations where appropriate.
6.1 SAFETY EVALUATION The following safety evaluations correspond to the similarly numbered safety design bases as given in section 2.1.
6.1.1 safety Evaluation one The Afw systess, in conjunction with the condensate storage tank (cst) [or the service water systems (SWS) if the CST is unavailable]. provides a means of pumping sufficient feedwater to prevent damage to the reactor following a loss-of-main feedwater incident.
The AFW system can also cool the reactor coolant system (RCS) at a maximum rate of 100F per hour (via the turbine bypass system) if the main condenser and circulating water systems are available.
During normal cooldown with the condenser available, the motor-driven pump reduces the reactor coolant temperature directly to 280F, at which point the decay heat removal system is initiated.
During an abnormal cooldown, i.e., a loss of offsite ac power, unavailability of the main condenser, or loss of the motor-driven AFW pump, the turbine-driven AFW pump is capableSfgucing the temperature of secondary system once-through steam generator (OT50) to approximately 310F.
However, under these conditions, the decay heat removal system is capable of being initiated at 325F, instead of the normal 200F, to further cool down the RCS.
Fump capacities are discussed in Section 3.2.
The capacity of the AfW pump equals the flow at 105F which, when injected in the steam generator, will offset by evaporation the decay heat released following a reactor trip from full power (as determined by using the method prescribed in Branch Technical Position AFCSB-9.2 for calculating decay heat generation).
The pus;p discharge head sufficiently establishes the necessary flowrate against a steam generator pressure corresponding to the lowest pressure setpoint of the main steam safety valves.
The minimum condensate storage tank volume adequately accosusodates the plant at het standby for approximately 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> followed by a 6-hour cooldown to 280F.
6-1
Cidland Plant Unita 1 and 2 Auxiliary Feedw0ter Sy3 tem Design Review Presentation 6.1.2 Safety Evaluation Two The AFW system provides a redundant and diverse means of l
supplying feedwater to the steam generators for cooling the RCS under emergency conditions.
Either pump has the capability of supplying 100% of the feedwater requirements for safe cooldown of the RC3.
Complete physical and electrical separation is maintained throughout the pump controls, control signals, j
electrical power supplies, and instrumentation for each AFW pump.
The AFW system can perform its safety-related function assuming any single active component failure coincident with loss of offsite power.
6.1.3 Safety Evaluation Three Instrumentation and controls are provided that enable operation of the pumps at the auxiliary shutdown panel (ASP) in the event of control room evacuation.
Instruments provided at the ASP are described in section 3.7.
6.1.4 Safety Evaluation Four The Arv system is designed to meet seismic category I regairements.
l The AFW pumps take emergency suction from two sources.
The normal source is the non-Seismic Category I CST.
If the CST is unavailable due to a tornado or seismic event, the operator is j
notified by low-pressure alarus on the pump suction, and an i
automatic switchover to the seismic Category I tornado-protected SW5 occurs.
One service water train supplies each AFV pump.
Upon initiation of service water, the affected AFW train is autoanatically isolated by power-operated valver from the non-Seismic Category I piping leading to the CST, condenser hotwell, and deserstor storage tank.
Check valves are also provided to prevent backflow to the CST, condenser hotwell, and demerstors.
Each SW5 train is isolated from the other so that failure of one does not affect the other.
6.1.5 Safety Evaluation Five Diversity is provided in the type and number of pumps, sources of water supply, power supplies, and arrangement of piping and pump and valve controls, so that any single failure will not negate the AFV system's ability to perform its safety function.
The motor-driven pump and associated equipment are powered by Class 1E ac power supplies.
The turbine-driven pump receives i
steam from either or both main steam lines before they leave the containment.
valves and controls necessary for the function of the turbine-driven pump and its associated equipment are energized by Class 1E de power supplies.
6-2
Midland F1 cut Units 1 and 2 Auxiliary Feedwater system Design Review Presentation Assuming a temporary loss of all offsite, normal onsite, and emergency onsite ac power (station blackout), the AFW system is designed tc. perform its safety function for at least 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
The steam turbine-driven Arw pump provides the required feedwater to both steam generators during station blackout. -
4.1.6 Safety Evaluation six The AFW system incorporates the following design features to minimize the effects of hydraulic instability (water hammer):
a.
AFW piping rises vertically to the OTSG AFW nozzle to prevent drainage of the lines into the OTSGs.
b.
AFW lines have check valves to prevent back drainage of the lines.
I,ow-temperature AFw is fed directly at the upper section c.
of the OTSCs into the tube bundle, independent of the main feedwater nozzles, so that the injected water is heated to within a few degrees of raturation prior to pooling above the lower tubesheet.
6.2 CENERAL DES!CN CRITERIA The ATW system conforms to the general design criteria (GDC) provided in 10 CFR 50, Appendix A, og discussed below.
6.2.1 CDC 2, Design Bases for Protection Against Natural Phenomena Guideline:
structures, systems, and components important to s
safety shall be designed to withstand the effects of natural phenomena such as earthquakes, tornados, hurricanes, floods, tsunami, and seiches without loss of capability to perform their safety functions.
Design:
Structures, systems, and components required for A!W system performance are designed to meet seismic Category I l
requirements and to withstand the effects of other credible natural phenomena such as tornados and floods.
The natural phenomena and their magnitudes are selected in accordance with their probability of occurrence at the Midland site.
6.2.2 GDC 4, Environmental and Missile Desian Bases cuideliner structures, systems, and components important to safety shall be designed for the environmental conditions associated with normal operation, maintenance, tasting, and postulated accidents, including loss-of-coolant accidents.
They shall be appropriately protected against dynnaic effects, including the effects of sissiles, pipe whipping, and discharging 6-3
Midland Flant Units 1 and 2 Auxiliary Fccdw3 tar system Design Review Presentation fluids, that may result from equipment failures and from events and conditions outside the nuclear power unit.
Design:
Tbs AFW system design includes two redundant, independent, safety-grade AFw trains that ensure the system function will not be compromised by postulated environmental conditions and dynamic effecta.
Further details, including environmental qualification, are provided in FSAR Chapter 3.0.
6.2.3 CDC 5, sharine of structures, systems, and components Guideline:
structures, systems, and components important to safety shall not be shared among nuclear power units unless it can be shown that this sharing will not significantly impair their ability to perfotu safety functions, including, in the event of an accident in one unit, an orderly shutdown and cooldown of the remaining units.
l Design:
The only shared system / component in the AFW system is the backup safety-grade sks.
The Sws, while shared between units, concains two redundant independent trains.
Each 5'tS train is capable of simultaneously supplying the emergency feedwater recruirements of both unita.
6.2.4 CPC 19, Control Room Guideline A control room shall be provided from which actions can be taken to operate the nuclear power unit safely under normal condations and to maintain it in a safe condition un.:t accident cone.tions.
Equipment shall also be provided at appropriate locations outside the control room with a capability for prompt hot standby, maintaining a safe condition during hot standby, and with a potential capahnlity for subenquent cold shutdown.
Design:
Instrumentation and controls required for operating and monitoring the ATW system are provided in the main control room and on the ASP.
Further detail is provided in section 3.7.
4.2.5
@C 44, Cooline Water Guideline:
A system shall be provided to transfer the combtned heat Isad from structures, systems, and components important to safety to an ultimate heat sink under normal operating and accident conditions, suitable redundancy in components and features, and suitable interconnections, leak detection, and isolation capabilities shall be provided to ensure that for onsite electric power system operation (assuming offsits powec is not available) and for oftsite electric power system operataon (assuming onsite power is i'
64 4
- - - - - - - - ~ ~ - - - - - - - - - - - - - - - - - - - ' - - - -
a
2 Midland Plant Units 1 and 2 Auxilicry Feedwater System Design Review Presentation l
l not available) the system safety function can be accomplished,
' assuming a single failure.
Design:
The AFW system provides sufficient feedwater to the OTsGa to transfer the RCs decay heat loads to the main condenser er, if the condenser is unavailable, to the atmosphere through the atmospheric dump valves, power-operated atmospheric vent valves, and/or the main steam safety valves.
The AFW system is designed with redundant isolatable trains that ensure its safety function will not be compromised, assuming any single active failure concurrent with a loss of offsite power.
4.2.4 GDC 45, Inspection of coolina water system Guideline The cooling water system shall be designed to permit appropriate periodic inspection of important components, such as heat enchangers and piping, to assure the integrity and aapability of the system.
Design:
The AFW system design allows inspection of components essential to the system's safety function in accordance with the ASME Boiler and Pressure Vessel Code,Section XI.
6.2.7 CDC 46, Testing of coolina Water System Guideline:
The cooling water system shall be designed to permit appropriate periodic pressure and functional testing to assure
- 1) the structural and leaktight integrity of its components.
- 2) the operability and the performance of the active components of the system, and 3) the openability of the system as a whole and, under conditions as close to design as practical, the performance of the full operational sequence that brings the system into operation for reactor shutdown and for loss-of-coolant accidents, including operation of applicable portions of the protection system and the transfer between normal and emergency power sources.
Design:
The AFW systes design allows testing of the AsME components in accordance with ASME Code Section XI.
The AFW system instrumentation design allows testing in accordance,with section 4.10 of IEEE standard 279-1971.
~
4.3 REGULATORY CUIDES The AFW systes conforms to the applicable regulatory guides as discussed below.
4.3.1 peauhetory Guide L.26, Quality creup classifiestion and 9tandards (6/YS)
Position:
Fortions of the AFW system extending from and including the secondary side of steam generators up to and 6-5
r.
Midland Plant Units 1 and 2
-i Auxiliary Feedwater System i.
Design Review Presentation o
including the outermost containment isolation valves and connected piping up to'.and including the first valve (including a U
safety or relief valve) that is either normally closed or capable of automatic closure durinr all acdes' of normal reactor operation j
shall meet the requirements of-ASME Code Section III, Class 2.
Design:
The, AFW syntes piping and valves that are part of the containment pressure boundary meet the requirements of ASME Code Section III, Class 2.
Position:
Portions of the AFW system important to safety, but not included in the guideline above, shall meet the requirements of ASME Code Section III, Class 3.
Design:
AFV system components important to safety meet J1e requirements of ASME Code Section III, Class 3.
6.3.2 Regulatory Guide 1.29, Seismic Design Classification J 8/73 )
Positfon:
The AFw system shall be desig.ated as Seir ic Category I, designed to withstand the effects of the safe shutdown earthquake and to remain functional, and meet the q"ality assurance requirementa of 10 CFR 50, Appendix B.
Design:
The cortions of the AFW system required for its safety function are designed to meet Seismic Category I requirements
~
and are housed in Seismic Category I structures.
6.3.3 Regulatorv Cuide 1.62, Manual Initiation of Protective Actions (10/73) 2 Position:
The AFW system shall be capable of manual initiation at the system level, from ths control room, and perform all actions performed by automatic initiation.
Design:
Each train of the AFW actuation signal can be manually initiated from the control room and results in the same system response as automatic initiation.
Position:
Equipment common to both' manual and automatic initiation shall be minimized.
Design:
The number of AEW components common to both manual and automatic initiation has been minimized to the extent practicable.
No single failure in either the manual or automatic controls will preclude operation of the AFW system.
r 6-6 m.
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-6 "M
6"
, _ _ T ".'
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Midland Plant Units 1 and 2 Auxiliary Feedwater System Design Review Presentation Position:
Equipseat required to manually initiate protective actions shall be minim 4 zed.
Design:
A single pushbutton on the main centrol boards is capable of initiating each AFW train (two trains per unit).
6.3.4 Regulatory Guide 1.102, Flood Protection for Nuclear Power Plants (9/76)
Position:
The AFW system should be designed to withstand the most severe flood conditions postulated to occur due to severe hydrometeorological conditions, seismic activity, or both.
Design:
The safety-related structures housing the AFW system are capable of protecting the system from the effects of the probable maximum flood, including maximum water level concurrent with wind wave activity.
6.3.5 Reculatory Guide 1.117, Tornado Design Classification (4/78)
I
~
Position:
The AFW system should be designed to withstand the effects of the design basis tornado (DST).
Design:
The AFW system can withstand the DBT including tornado-generated missiles, and maintain its safety function.
6.4 BRANCE TECHNICAL POSITICNS 6.4.1 BTP APCSS 3-1, Protection Acainst Postulated Piping Failures In Fluid Systems Cutside Containment /
BTF MES 3-1, Postulated Break and I,eakage Locations In Fluid System P1 Ding Outside Containment AFw system compliance with the applicable portions of BTP APCSS 3-1 and BTP MEB 3-1 is described in Section 3.4.5.
A detailed discussion of high-and moderate-energy pipe failure protection is provided in FSAR Section 3.6.
6.4.2 BTP A35 10-1-(Revision 1), Design cuidelines for Auxiliary Teodwater System PE=a Optve and Power Supply Diversity for PwRs cuideline:
The AFW system should consist of at least two full-capacity. independent systems that include diverse power sources.
Design:
The Midland design contains two full-capacity, independent Alv trains, each capable of supplying the feedwater 3
=i requirements for a safe cooldown of the RCS.
One train contains H
a motor-driven pump. the other a turbine-driven pump.
Redundant and diverse Class lE power sources supply the pumps and valves.
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i Midland Plant Unito 1 and 2 l
Auxilicry Focdwatcr Systes l
Design Review Presentation Redundant class lE power sources are provided for the controls and instrumentation required to operate and monitor the AW system.
Refer to Sections 3.0 and 4.0 for further detail.
Cuideline Other powered components of the AEW system should also use the concept of separate and multiple sources of motive energy.
Design:
Refer to the previous design response paragraph.
Guideline:
The AFW intake and discharge piping arrangement for each train should permit the pumps to supply feedwater to any combination of steam generators.
The Midland AFW system piping arrangement is capable of supplying feedwater to any steam generator considering any single active component, power supply, or control system failure.
The suction piping arrangement enables independent operation of each AFW pump.
The discharge piping arrangement includes a crossover design allowing each puso to feed either steam generator.
Each train is fed by independant, diverse power sources and is capable of remote manual / automatic control.
Refer to Section 3.0 for further detail.
Guideline:
The AFW system should be designed to offset a single active component failure.
Design:
The AFW systes is designed to withstand any single active failure coincident with a loss of offsite power.
Cuideline:
When considering a high-energy line break, the systes should be so arranged to assure the capability to supply necessary emergency feedwater to the steam generators, despite the postulated rupture of any high-energy section of the system, assuming a concurrent single active failure.
Design:
Normal operation of the electric-driven AFW pump occurs during periods when the turbine-generator is not paralleled to the offsite grid.
Operation of the turbine-driven AFW pump for any norinal operation is precluded by USAR Technical
-Specification 16.3/4.7.1.2.
Under any potential operating condition for which a high-energy line rupture must be postulated, availability of offsite power is assumed.
There fore, in the event of a high-energy line rupture at the discharge of one pump (worst case) and a single active failure of the other pump, the main feed pumps are available as a water-injection source.
6-8
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a
- - - -_a Midland Plant Units 1 and 2 Ausiliary Feeduster Sy0tas Dec1gn Review PrOcentatica 6.5 OTEER REGULATORY GUIDANCE l
The following section discusses the conformance of the AFW system to applicable regulatory guidance not covered in sections 6.2 through 6.4.
6.5.1 NRC 10 CFR 50.54( f) Request, B&W System Sensitivity Formal responses to the R&W system sensitivity concerns were provided by Consumers Power Company in letters to the WRC from S.R. Howell to R.R. Denton, dated November 30 and December 4, 1979, and April 1, 1940.
The following itaans are applicable to the AFw system.
The responses to these items is as referenced below.
Item 5, Fully Safety Grade AFW System - Refer to Sections 3.0, 6.0, and 6.5.4.1 Item 6, FOOG System - Refer to sections 4.2 and 6.5.4.3 Item 9a, Reliability Analysis - Refer to Section 5.0 Item 9b, Flow Indication Upgrade - Refer to Section 6.5.5.2 Item 9c, Piping Modifications - Refer to section 3.0 Item 10, Improved AFW Flow Control - Refer to Sections 3.0, 4.0.
and 6.5.6 6.5.2 AFW System Flow Requirements Responses to the requests for information regarding the basis for Arw system flow requirements, transmitted in Enclosure 2 of 1
D.F. Ross, Jr. 's letter to S.R. Bowell of April 24, 1940, is l
provided in Section 10A.4 of Appendix 3.
[
l 6.5.3 NUREC-0611, Generic Evaluation of Feedwater Transients and Seell-Break LOCAs in Westinehouse-Designed Operating Plantis A comparison of the Midland AFW systes design with the recommendations of NUREG-0611, Appendix III, is provided in Section 10A.3 of Appendia 5.
The preliminary Midland Technical Specification 16.3/4.7.1.2, AFW Systes, is provided as Appendix C for information.
6.5.4 NURIC-0667. Transient Response of B&W-Designed Reactors The following recossendations correspond numerically to the recommendations contained in Section 2.2 of NUREG-0667 6-9
Midland Plant Units 1 and 2 Auxiliary Fccdwetar Systca De31gn Rcview Frccentation 6.5.4.1 Recsemendation 1, AFW System Upgrade Position:
The AFW systra should meet safety-grade requirements.
Design:
All essential portions of the AFW system are safety-grade and designed to me et seismic category I requirements.
4.5.4.2 Recommendation 2, AFW System Initiation and Control Positiont The AFW system should be automatically initiated and controlled by safety-grade systems independent of the integrated control system (ICs), nonnuclear instrumentation (NNI), and other nonsafety systems.
Design:
The AFW system is automatically initiated by the safety-grade AFW actuation signal (APWAS).
Automatic alignment and/or modulation of AFW-related valves is accomplished with safety-grade controls.
Both the automatic initiation and control functions are independent of the ICS, NNI, and other nonsafety systems.
6.5.4.3 Recommendation 4, Steam Line Break Detection and Mitigation Position:
The steam line break detection and mitigation system should eliminate adverse interactions between it and the AFW system.
It should be capable of differentiating between an actual steam line break and undercooling or overcooling events caused by feudwater transients.
Design:
The feed-only-good generator (FOCG) control system operates to terminate AFW flow to the lower pressure OTSG when the differential pressure between the two steam generators exceeds a predetermined value.
This system allows the higher pressure OrSG to remain in service at all times for decay heat removal duty.
Therefore, positive differentiation between steam or feed stor line breaks and feedwater transients is not required.
6.5.4.4 Recommendation 9, Post-Trip Pressure and Level Response Position:
Following a reactor trip, pressurizer level should remain on scale, and system pressure should remain above the high-pressure injection actuation setpoint.
The system response (e.g., secondary pressure) should be modified to meet thes== two objectives.
Meeting these objectives should be independent of all manual operator actions.
Design:
A response to this position is provided in Appendix D.
6-10
Midicnd Plant Units 1 and 2 Auriliary Foodwater System Design Review Presentation
- 6. 5. 4. 5 Recomsendation 10, Sensitivity Studies to Reduce OTSG
Response
Position:
B&W licensees should perform sensitivity studies of possible modifications which would reduce the response of the OTSG to secondary coolant flow perturbations.
Both passive and active measures should be investigated to mitigate overcooling and undercooling events.
Design:
A response to this position is provided in Appendix D.
- 6. 5.4. 6 Recommendation 21, Reevaluation of AFW System Injection Point Position:
The need to introduce AFW through the top spray sparger during anticipated transients shall be evaluated.
The reduced depressurization response if AFW could be introduced through the main feedwater nozzle and could enter the tube region from the bottom of the unit shall be considered.
Design:
A response to this position is provided in Appendix D.
6.5.5 NUREG-0737, Clarification of TMI Action Plan Requirements The following items correspond with the ATW-related items provided in NUREG-073 7.
6.5.5.1 Item II.E.1.1, AFW Sys tem Initiation Pos it ion s An AFW system reliability analysis shall be provided to determine the potential for AFW system f ailure.
Design:
The Midland Plant Auxiliary Feedwater Reliability Analysis, performed by Pickard, Lowe, and Garrick, Inc., has been forwarded to the NRC by letter f rom J.W. Cook to B. R. Denton, Serial 11223, dated February 23, 1981.
A synopsis of the analysis is presented in Section 5.0.
Position:
An evaluation of the AFW systen using tne acceptance criteria of SRP 10.4.9 shall be provided.
Design:
An evaluation is provided above in Section 6.0, aloco with design details provided in Sections 3.0 and
- 4. 0.
Position:
The AFW system flowrate design bases and criteria shall be reevaluated.
Design:
Refer to Section 10A.4 of Appendix B.
6 -11
Midland Plant Units 1 cnd 2 Auxiliary Fosdwater Systcm Design Review Prosentation 6.5.5.2 Item II.E.1.2, AFW System Automatic Initiation and Flow Indication Position:
Safety-grade automatic initiation of the AFW system anJ safety-grade flow indication to each steam generator shall be
{
provided.
Design:
The AFW system design incorporates safety-grade automatic system initiation and flow indication as described in Sections 3.0 and 4.0.
As a result of clarifications to the requirements associated with this item, the Midland design will be revised to incorporate two safety-grade flowrate indicators in the main control room for each steam gensrator.
6.5.5.3 Item II.K.2.2, Initiation and Control of AFW Independent of the Integrated Control System Position:
Procedures and training to initiate and control the AFW system independent of the integrated control system (ICS) shall be provided.
Design:
The AFW system is independent of the ICS.
Procedures and training associated with AFW initiation and control are being developed to comply with the above guidelines.
6.5.6 Open Items Associated with Staf f Peview of Midland Plants (NRC Letter, 3/30/79; Meetings of 4/16'-11/ 79 and 4/19-20/791 6.5.6.1 RS B-4 Guidelines This open item expresses concern about primary system ovescooling when using AFW to control OTSG level during loss-of-offsite-power events.
The Midland design incorporates a level rate limiting circuit in the contrc'. logic of the AFW flow control valves.
This feature minimizes AFW-induced overcooling of the RCS and permits the pressurizer level to remain in the indicating range following reactor trips.
Analyses of plant performance during such events are provided in the response to F3AR Question 211.194 (Appendix E).
Section 4.1 provides furtner detail.
4.5.6.2 ICSB-11 Guideltne:
This open item requests further information on tre instrumentation end controls for automatte switchever of the AFh pump suction f rom the nonsafety condensate storsqe tank to the safety-grade SWS.
6-12
Midicnd Plant Units 1 and 2 Auxilicry Focdwetor Systcm Decign R3 view Pros 3ntatiCn Design:
Appropriate portions of FSAR Chapter 7 have been revised to address this concern.
Refer to Appendix F.
i e
O l
t 6-13
Midland Plant Units 1 cnd 2 Auxiliary Focdwator Syoten Decign R3 view Procontation LIST OF ABBREVIATIONS i
AFW Auxiliary feedwater ArWAS Auxiliary feedwater actuation signal ASP Auxiliary shutdown panel CST Condensate storage tank LHR Decay heat removal ECCAS Emergency core cooling actuation system ESTAS Emergency safety features actuation system FOGG Feed-only-good generator MCR Main control room OTSG Once-through steam generator RC Reactor coolant RCP Reactor coolant pu=ps RCS Reactor coolant system SWS Service water system 4
I 4
,n.- - - -., -,
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TABLES l
O e
b
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Midland Plant Units 1 and 2 Auxilicry Feedwater Systwa Design Review Procentatien TABLE 2-1 AUXILIARY FEEDWATER SYSTEM CODES AND STANDARDS l
Quality Code /
Seismic Component Location GroupHi Standardm Category W _
Turbine-driven Aux C
III-3 I
AFW pump Motor-driven Aux C
III-3 I
AFW pump AFW pump turbine Aux NA NA I
AFW pump motor Aux NA IEEE 323/344 I
Piping and valves Aux C
III-3 I
to penetration Piping and valves Cont B
III-2 I
to OTSC
"'C.B:
Quality group classification as defined in Regulatory Guide 1.26 m III.2, III-3:
ASME Soiler and Pressure Vessel Code, i
Section III, Class 2, 3
- 1:
t Construction in accordance with seismic requirements of Regulatory 1.29 and Appendix A to 10 CFR 100 i
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i AUXILIARY FEEDWATER CONTROL SYSTEM DESIGN i
OBJECTIVES l
j e MINIMlZE OPERATOR ACTION NEEDED TO PREVENT l
. Loss of Indicated Pressurizer Level f
i
. Low-Pressure ECCAS Actuation l
e ALLOW M!NIMUM OF 10 MIMUTES PRIOR TO REQUIRING OPERATOR ACTION TO PREVENT LOSS OF PRESSURIZER LEVEL INDICATION G 154 F O F i
i 1
AUXILIARY FEEDWATER CONCEPTUAL DESIGN STUDY RESULTS e CONTROL OF AFW ADDITION IS NOT REQUIRED WHEN FILLING TO 2-FOOT 2
SETPOINT j
e CONTROL OF AFW ADDITION AT RATE OF l
3 TO 4 INCHES PER MINUTE IS SUFFICIENT TO l
PROVIDE ADEQUATE HEAT REMOVAL FOR i
NATURAL CIRCULATION FOR MAXIMUM DECAY l
HEAT; AND WILL MINIMlZE OVERCOOLING FOR l
MINIMUM DECAY HEAT
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, 50 a
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FIGURE 4-6 j
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a i
L AUXILIARY FEEDWATER FEED-ONLV-GOOD GENERATOR
{
LOGIC 5
L i
L PURPOSE
?
{
. Limit Reactor Coolant System Overcooling l
e Limit Mass and Energy Releases to Reactor j
Building
. Ensure Heat Removal ls Always Available i
Through Minimum of One OTSG i
s.
i AUXILIARY FEEDWATER FOGG LOGIC FEED FEED BOTH OTSG A FEED OTSGs OTSG 8
=
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4 AUXILIARY FEEDWATER OTSG OVERFILL PROTECTION e DETECTION l
- High OTSG Level
?
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- ACTION 1
. Allow AFW System to Regain Control When l
OTSG Level Has Dropped Below Setpoint l
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APPENDIX A t
MIDLAND PLANT AUXILIARY FEEDWATER SYSTEM RELIABILITY ANALYSIS SYNOPSIS 1
l
^
PLG-0166 I
I I
i MIDLAND PLANT AUI!LIARY FREDWATER SYSTDI RELIABILIYY ANALYSIS SYNOPSIS bY Dennis C. Bley Carroll L. Cote i
Daniel W. Stillwell B. John Ostrick i
i l
l
{
Prepared for l
CONSUMEAS PCWER COMPANY Jackson, MicNgan
(,
March,1941 l
PICK ARO. LOWE AND GARRICK. INC.-
consultants - NUCLEAM POWS Invi8st CALWOmMA WA%46N0f0N. O C.
l TAsr.: or comnes
_sts11m Zan 1
STATSMWT OF 70R7068 1
i suMM4AY 2
3 M Tu0o0 LOGY 12 4
SYSTEM Aaut.fsts is 4.1 Systes Models 16 4.1.1 Stapitiied systee Piping Diagrame 16 4.1. 2 Funetional 81ock Otagrame 14 4.1. 3 Systen Fault free 16 4.1. 4 Computer Progrsas 17 4.1. 5 Data 17 4.2 Aanden Failures 17 43 Test and Maintenance le 4.3 1 Testing 18
- i 4.3.2 Maintenance 13 4.4 sumen !nteraction 20 4.4.1 Kuman Interaction /Recoveracle Fa11Jtes 23 4.4.2 Muman Error / Testing 21
- 4. 4.1 uuman Error--Common Cause 21 4.5 Common Cause Analysts 22
- 4. S.1 The First Cratac ton 23 i
- 4. 5. 2 The second centerion 23
- 4. S. 3 Assults of Common Cause Analysts 23 4.6 Svent free Analysis 25 5
R35UI.?S 35 S.1 pessits of Systee Analysis 35 S.2 Aeeults of Event free Analysis 37 6
REFEARMCES 53 i
l l
__,-.,..-,..,,.,..___.m,
l 1.
STATDerr CF PURPOSE A study was made of the reliability of the Midland auxiliary feedwater system for Consumere Power Company (CPCo) of Jactaon, Michigan. The purpose of the study wee tot e
Provide a thorough and comprehend 1ble assessment of the overall reliability of tae system.
Identify important contributore to unseliability.
o Compere three alternative pump coefigeration designs.
e A principal als of the study was to use the most applicable data in the analysis with due regard for the true range of ancer~cainty in this information. Ze addition, to mete camperisons with NRC analyses more directly vielble, calculations using the standard NRC data base have been included.
1
2.
SUMemRY The emergency functio., of the snaillary feedwater system (AFNS) is to provide beat removal for the priaae system when the main feedwater systes is not available.
Water is supplied from the condensate storage tank (CST) or service water ayates through two pumps to each of two steam generators.
The AFWS aust proeide this function during small loss of coolant accidents (LOCA) as well as following transients that lead to a loss of asis feedwater.
The AFuS provides initial cooling to prevent ourpressurisation of the primary systes and has sufficient preferred
, ater supply to,F.anintain hot standby conditions for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> followed by a w
cooldown to 320 The system is also used Juring normal plant startup, shutdown, and het standby conditions. Requirements for success under emergency conditione are that flow from a least one pump de delivered to at least one steam generator immediately following initial demand.
The system analysis determines the system hardware sintasi est sets, i.e., the smallest groupe of combined component failure modes that lead to eystem failure.
It further estalogs the causes for specific croponent failure modes and evaluates their likelihood of occurrence.The causes considered includes Aandom independent failures e
e Test and asintenance e
Eumen error Common cause failures.
o Two sets of data are used in a rate quantifications. The NBC point estimate data from utp5C-0411l I is identified here as NaC Data.
Data meet applicaele to the Midland AFws that includee uncertainty has been identified as Plant-Specific Deta.
described in M135G-0811 are analys ed:
The three specific casee 1.
LMFw - tranatent initta'ed by interruption of the main feedwater system (reactor trip caurs) and of fette AC power remaine avelleele.
2.
IMw/140P - transient initiated by loss of of fsite AC power and reactor trip occura lasin feedvetor eyetee is interrupted by tBe less of offelte powerl.
Onette esergency AC power sowscos ero trseted prosaelltetically.
3.
1Mw/only DC power ave 11aele - transient is lattiated as in iten e stowe but onette emergency AC power eeurces are unavallaele.
mote that these essee leed to condittoast weave 11sttlity calculations that are co pled with spoettic states of elsettic power.
12 *eaa tseai st 2
.. ~.. _. _.
......__.. _ _. ~.
Three alternative pony configuration designs are analysed. Their block diagrass are shown in Figure la 3a.
Double Croaaover (DCD) - one 1000 actor-driven pump and one 1004 turbine-driven pump. This option has oeen selected by Cpco for installation at asidland.
It permits each pump to supply either or both steam generators. Each crossover path is controlled by the same electrical supply as the asecciated pop.
3b.
asse case - one 1004 ester-driven pump and one 1004 turbine-driven pump. This option was the original Midland design. It permits sect pump to supply either or both steam generators.
3c.
Three pump - two 50% actor-dsiven pumpe and one 1004 turbine-delven pump. This design la similar to that used at some other (SW) plaats and is included for comparison purseses only.
nesults for the aco design are displayed in Table 1 for each of the three transient cases and each data set.
The results using the NBC Data for each of the three cases are plotted in Figure 2 along with similar results t 21 for other matcoca and W11cos (Boul plants. Nidland appears to be one of the better performing SW auxiliary feedwater systeta.
l Tables 2 and 3 present the resulta using plant-specific Gata for comparisene of the base case and the three pump designs against the DCD.
The taee Case and the DCD have nearly identical reltamility results.
The DCQ to clea 1y better than the Three Pump design analysed. These results, including the effects of uncertainty, are placed ;1 better perspective by the cuaves of Figure 3.
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- 1. 2 E -4 to t t al 1.4 8 4 3.8 8 4 1.e 8*3 1.983 senese efetse festesee 43.9 8-et it.l S-13 11.9 $=4s eenen ettet stoet-testere to S. 3 8-e 3.7 s*4 18 E=6 138-)
318**
3184 stese fe!! f&es teet ee& eel 81.1 8*131 43.8 8*91 13.3 8*?l Ceemen eseee Ifw!& flee 0.4 E-4 S. 4 E *4 8.4 8 4 8484 8.4 B-4 8.48-4 test vetee spea ef ter teet) 41.9 B tas 15.9 8 186 19.9 8 131 yyy 8
9 tvetoe Tese&
meam 3.8 E-4 1.8 t*1 4.784 3.3 B*3 geesense li e.
6.8 S=4 8.78*4 3.48-l Sgts 4 1 S.1 3.18*3 S.884 steesen 3.8 8 3 4.8 E 3 L. 4 4 **
1.38-4 488**
- 5. 5 8 **
488*3 1.38*8
'The tesel emete 61346160 lee se se&& es tee Lad &endes& emmtf 6eutgame ggeen La teae tes&e age met ame.e.teestatsee out ete egetae etevestettettee omn464temet en seeen f aa states ed e6eettas poses se is6 esteen systee IJnFW 3ffette AC peset to essetanuemeny even.aole.
6ewei L eer'.309 Of fette 4C pomov as eneestleete--iteest genesetes e any og LJePWLeee of ela eCe eef we secept need.
448 aC posee se enevesteeses 3C posee se sees.eele.
- wneventees& sty se see freetten et tseos tne eroise e644 set peefste sie temeteem enea teesseed.
't.8 8-t toed f.8 e 40*l.
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t
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e ete tenee
- 8eessicos tae apread of tae seeette eseus one apen.
l 14efe48)ett/t P00R ORIGINAL
t l
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=
i i
9068 2.
Staeahar OP 88 8611.75 CDuetT1ce46* alem!LASIL87tst** OF TIE 6 &#tes (Plant Spes<e Satel e
Less of scene Lese of stone f.eos ed feste hee =eter resenetet pocheese he to lese eed Lees et Ala ac posee Centenantess to et offette posee onese6&estisty tenete snee asete been anonle base Cessessee Case Caesemose Caos Csesseese Cees
)
Aseeen festesse 7.0 8-l*
7.3 s.9 8.6 3 4 4.4 E 4 1.181 1.683 111848 (1.9 8=88 10.4 8.es (3.3 5 4#
41.3 8-48 f f.) t-Is Itet and estateneese end 1.3 3 4 1.3 E.4 3.4 8 4 3.4 8 4 S.9 g-3
- 1. 9 t - 3 senese system fentette (3.9 tatt (1.3818 14.5 8.?1 8 3. 3 E.76 11.9 Sees f1.t s-ei hoon erree stee'-fe6tese te, 4.384 4.4 t-4 1.8 8.$
1.0 E.9 3 1 E-4 3.1 t - 4 eleoe te&& fim..eet es!*ee 41.4 8.Lal 13.4 E.648 83.8 8 93 st.J 8 486 tl.3 8.?
(5.3 8 ee Comene seems efell flae 3.4 t*4
- 8. 4 S -4 S.4 E.4 0.4 8 4
- 8. 4 S.4
- 4. e 8-4 test eense spee e4 tee testa el.9 E tes 19.9 8.*3s el.9 t-168 (1.9 5 14e 8 9. 9 8.'.4e E1.0 E.'Js etter g
a t
a 4
i Systee Meet steen 3.934 3.1 t-4 1.883 1.s 8 3 3.3 s.3
- 3. 3 s.3 Utenesee 4.184 1.1 S.9 4.9 8 =4 3.9 4-4
- 6. ' t.4 4.8 8 e tem 3.4 t-4
- 1. 9 t+1 418-9 f.9 8 5 3.183 3.54-3 tite 1.0 8 4 f.4 t*4 3.4 5+ 3 3.188 4.0 t=3 9.88 3 8tedase 1.48-4 1.1 B+4 4.0 t=4 9.3 E*4 1.683
- 1. 3 E 3 m..etoi eee.ie..liti.e se asi
- e. too e.....sel.ons,ime.ene. ee
.a.e.e.e.4e e,e met ameeesleestat see est ese erstee eteeestee set ase eenestnesol en speetise etetoe of essetese pomos se fe 4e est.e a,e..
Weeve Jf fsete 4C posee le contee swelp evealee6e.
s
.e.
Wurtarbase 3(teate AC posse to emeestleeleM6eset gemesetees any se esy ws W4P8/ Lees ed all AC.
seeste need.
All af posee te enesellee.es SC poser se eve 4 &oe44
- emecenteesintf IF tee f teettee e( tleet Lee eysees es11 ese pe#fece see feestsee sogeneed.
- 1.0 0-l toes
'.8 e Le*%.
( l sessemeo. eyesensee see speeed of tee seeegeo eenet see esea.
lettestsett/4 P00R ORIGINAL
l 1haLS 3.
84Better Or 4880s.?5 ORISt? tossed.e taanga:LAstLg71ss** OF M 433Lhste Aftre (Plent Spectite Setet Iees of sense lese ei stein tese of stein Foedoetee resemetee Foodneter lhee to taae end tese of 411 AC powee et Of f ente Poues i
Contatteeeve ta the4*etiess14ty
]
"'" W C
- ause C
e Ce e
Readas fastutee 1.4 5.l*
e.1 set 4.4 E.4 3.0 E.3 tt83 1.' E.1 111846 t1.e 5 48 (8.4 8 48 (1.1 8.ls 11.3 8 4s 13.6 8 18 het one estatensame and
- 1. 3 E -e 4.9 s.4 3.e 8-4 9.3 E.4 S.t E.)
- 1. 9 t. 3 toades efetoa te6&ette 83.9 5 4e (1.4871 64.5 E-78 43.* 1 48 (1. 9 E.48 11.9 1.es ik.esa es tee steet-fest.ee to 4.3 8 4 3.881 1.485 4.9 s-1 3 1 E-4 3.1 f.e stese te&& flee teet esteet 11.1 s tas 43.8 a.9s 13.3 8 93 (0.8 3 46 8 3.3 s.f t gl.3 g.to 4
Commme casse (falt tie.
g.e s.4 3.s34 g,g g.4 g,a g.4 g,a g,4 g, g,,,,,
4*et ee&ee spoe af tet testa ll.D E*&8i 45.6 S.101 tl.9 8 133 (1.9 3 13 (1.3 g*184 (1.6 C'!Gt t
0 e
t t
Systee 4tet samen 3.8 a.e 1.383 1.0 t.3 3.0 3 3 3383 3.3 E.8 Massaee 4.9 Set 3.4 E.9 6.884 1.385 4.934 3.3 f 4 len 3.43-l 3.384 4.181 4.a s.e 3.1 E.1 0.38 3 l
tite
$.0 3-4 3.883 3.483 9.8 f.3 4.4 E.)
- 1. 3 t.3 seedsen 1.e 8 4 9.3 E.4 4.384
- 8. 9 C.5 1.483 3.3 s.3 g
7
- 1he totel e=evealeestessee se se61 es tee endtese e4 contasemanene geen ta test teele are not esteen eyesee eneeelleesisties met see efetoe enesentessettee so46taeast en speesite statee et eteetsse panee se to.as.o.
nArte s Of fsato aC poses le sentamwomely eseaWo.
I Leeme%J0Fs of teste et paese to enesenteele 4tesen geneesteve sey et eer est seeepe need.
4dru/ Lees of ett 6Ce 441 ac pomos se e eees.seles BC posee to seesteene.
m
- 14teess & eel & l t s to the f e as t ice of t e nse see eyotes v e n t met pe e f oe s s e e f ae t sen enen s eq.i r ed.
- ?.8 $*l seed 9.8 e te*l.
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Three Pump FIGURE 1.
BICCE DIACRAMS Of THREE AI.TCPNATIVE P'MF CQ4 FIGURATION DESICIS FCS THE MIDLAND P! ANT Ard SY1 TEM P00R ORSM.
t 6 5 MIN i
O i5 win O 20 Hlu inc EAsins Aren0x.HAr. r0n O cn 'oEntso nELiA81LITY TWO TRAIN SY5TEH*
I I
RANCHO SEC2 O
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'UPPE4 LINIT 13 OlFFERINT FOR RinCH3 SECO SECL' 3E OF Tite HULTI-DRIVE PU!!P.
J FIGI,*RI 2.
COMPAR:3CN Cr RI' ABILITY (MPC DATAI OF ATWAS CC:035 IN PIMTS 'J3:NC Th*E S&W N555 (T?.ts f agvre, en:ept for Midland, was taken from Meterence 2. )
rigure 2ial
!JfW
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is Mix Q 30 MIN INCREA$ LNG APPR0X. MAX. FOR WIK
~
g CN 00%ND aELIAstLITy Two inAls sys' I
RANCM0 SEC0 O
l b _J CCONEE I,II,III 6
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'hMIRE C4E TRAIN is ELECTtIC P0wt2E0 FRCH A DIE![L GESERAT t I
(IE.,EICLUDING DAVl3-sEs;[ 1).
LlHIT 15 OlFFEtENT FOR RA.1CHO 3ECO SECAUSE OF TM[ Mutil.0tivE PUAP.
r! CURE 2.
COMPAD:50M Cr str'.!As!:.ITY (WC CATA) CF ATWA5 DES!CNS IN PLAffr$ U$!NC THE D4W NS$$
i (This figure, except for Midland, was t ske from Reference 2. )
T::URE 2th): LMFW/LCCP 9
i
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- - - * ' - ' ' ' * " ~ ~ ~ - ' " - - ~ ~ ^ ^ - - ~ ~ - ^ ~ ~ ~ ^ - ~ '
6 5 MIN O is als b a ulN wlanaii..-[urwxlau0s INenust rw ruin srstEr c,,
i RANCM0 SECO OCCNEE-I.U E I
CRYSTAL RIVER-3 I
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THREE MILE ISLAND *l b
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l M!CL A ;01 & 2 l
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-5 Log $cale -
- WERE ONE ftAIN l$ ELECillC 70wCRED FICH A DIESEL GENE 4170R
(!!.. CICLU3!MG DAvl3 IE13E-1)
FI"' AE 2.
COMPAA!5CN OF RELIASILITY (NPC DATA) CF ATWAS W
DESIGNS IN FIAlffS USING TIE BW NS53 (This figure, except for Midland. was taken from Reference 2. )
FICURE 2(c) : tJ9Fw/LCAC r
en
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8E?IDOMOCT l
l The approach taken in this stady is to separate the reliability peoelen into two legioelly distinct endules - determination of einimal entsets of envissent failure sedes and deterstaation of cause sets, i.e.,
3333g that can bring atout failures of the equipment outeets.
N first stop is to deoelop a detailed fault tree of the systen.
ht tree is developed down to the level of hesic component failure l
modes, such as **elve Nov 3470A falls to opes.' Thss uhen the minimal
.cateets of this feelt tree are determined, they represent groupe of
!g equipment functional failure modes that must occur together if the systes l!
is to fall. Those cutsets are characteristic of the systen hardware i
alone.
A stay 11 tied fault tree for the Nadland AFWS is shown in Figure 4.
I N TCP eeent, "ano Or Insufficient Fles (N0!F) To Soth Steen Generators,'
I can only occur if there is N0!F from the actor pump section AND from the turbine pump section. ac!F free a pump section can only occur or. NCIF from all water sources or failures witSin the pump sectione. The l
detailed fault trees are sheen in the main Soport 1161 for tbs base case, double crossover, and three pump designe respectively.
The second step is to tatulate the possible cassee for each f ailure mode. A single equipment functional failure mode any be caused by randoe tndependent fsults, test and meintenance, common or independent human j
interactions, common environmental conditions such as high temperature or flooding, aging, etc. Eatire cutsets any fall due to any single cause or
]
coincident comoinations of causes.
I The cause tree for the Midland AFWS, Figure 5, lays out the overall solution approach of this report. 180!F to both steen generators can only l
occur if one or more fatture mode cutsets are failed. Such failures must j
be caused by:
?
Randon Independent Failures on Independent Rosen Errors CR
)
Test and Maintenance in conjunction with other causes CR Common cause Failures I
CR Other Failure Causes.
l l
12 l
- =-
i i
l I
If time is avellable to recover from systie fa11ere, then recoverable random fallarse only need to erstem failure when combined with benen inaction - husen failure to recover. Seek cases were met eeneidered in this analysia because, tened on ave 11able information, system success requires immediate operation.
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=osa e none tvaa.no O*vt#8%W GAsvtm punse sa m on enorts petion stopsi 8 war seetiese q%,,
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4.
SYSTEN ANALYSIS 4.1 SYST94 nom 1J 4.1.1 Sinalified system Pinig Diserase piplog diagrane for each of the three proposed designs are pteensted here os Rose Case Figure 6. Double Croseone, Ptgure 7, and Three Pump, l
Piquee 8.
These etaplified 762De are graphical models of the tapertent floupethe and ce penents is tae AFus. These diagress. al with other
, pertinent decir aforestion diceveaed in the main Report i 6), serve se the heels fo. all furthee modeling and analyssa.
4.1.2 Punctiocal Bloco Steerase The bloca diagrene samme earlier as Figure 1 provide etaple understanding of the funct2anel connectten among anjos system congenent groups. The overall reliastitty logic boccese clear as well.
4 1.3 Sveteo Fault tree i
The fault tree modele the fattures that must occur to prevent auccessful systee operatice. The TCP event le defined es 'No 0:
Insuf ficient flow To both $ team Generatore.' Succese le defined se -the flow from et least one puep trein delivered to et least one stese j
i generator.
The step 11f ted fault tree of Figure 4 showed that for the eyetoe to fall we suet fall to delawr owlf tclent flow to both eteem i
generatore.
In each case tala requires that there te no or ineuff tetent I
flee through the steen generator inlet velve section et that there is ne et insuf ficient flow delivered to that sect ton. Seeendly, se swet how i
1, no er taewff tetent flee free the meter drtoes peep (either avat f all to the three pump etternetteel and no or insufficient flee from the terstae driven pump.
Finally, there to no water free any of the potential water sources.
The complete feelt tree modele are presented in Appeedtcee 4 S. and C of the main hopert for the beoe case, dowele croceewr. and three pvar etternatives respectively, where the syntes le modeled to the ten t of major compemente.
tactuded are the pumps, selves, electrical j
supply, seter operatore, eed termine and eentrel nochantees.
sent modeled are drain lines, deele valseo, piptag, ned connected lines which are 3
l emell in else, t.e., eyetes components whose fatture rates are wry low compared to the ones inelweed le tM model.
yhe Afwa flowpeth to modeled free the water eeurces to the steen generatore. 81ectsteolly, the systee 1e modeled free th toe to the eyetes.
(note thet for the case *>e t
Of fente Power Asella41e,' the diesel generatore are treeted proemet tlis tlee tly.)
Veristlene on the adia models were mede depending upon the inttlet condit tene of the scenerlo.
These verlattens were mode at the teetc event level and ceneisted of changee to the failure pro 644ttity for the heele event.
Ao esemples, eenender the feilentogs to run the sedel for the ease
- Lees of Offette Pe=er,' tM fellwre probeellittee for tN AC 1)gdAd1944t /1
- - ~~~-~'-
- - ~ ~ ~
~
i heese eere leereseed to 'the value of the promeh111ty of fattere of a diesel generator to starts to staulate the senditten of metatenance on a peep teate, the peep fallere probability see cheoged to one (which ledicates a fatted susponent) etich rosesited in a new 11stlag of mieteue esteets for eyeten failure. In thle senaer, the boele tree developed fet d portlester eresas deelgo con correctly evaluate erotes fatture for i
l
- etyleg lettial conditlene.
4.1.4 Canoetar Freerone i
1 j
the computer peograms that ee.e used to proeess infoemetten in 1
,eystaa rollentlity analysee are le the pesh11e dessie and are avellable through the Argonne code Center. The codes are the aset eerrect versione of eseputer pechages that have been la ese for eeny years.
nest of the seipeter peegrees sete used in support of the heaetor Safety Study.
taas-1400, end have been endified as deoelopsonte are ande to reduee oneputer emot et lepesee set t presentattees. The eespeter egrees used on thte peeject are SAS 113. COntAsrII All2I. and noCAast{33 4.1.5 ggg The coepiste data besee used in the study are given in tse meta Report.
i sec Dete.
The data 4esd for the point settaste geantification se roguested by the mac le tasen from hppendis !!! of MusSG-4411.
[
The eensce toe that dets wee primertly tansa-14041143 In some cases sweh generte data eterepresente egulpeeat actua!!r taetalled in a epeetf ac plant.
Dennq pelas cettnetoe aseos the pleet-to-9laat verish111ty as the prtaeay source ef useoeta4ety le the dote se emed in unas. lees.
i Geaeric sad Plant-leecifle Data. A plant-speelfle data best for Nidland wee prepeted.
The seet evettaale data to deserthe the speettle egulpesat an place et Radisad to taetuded. It to beoed upes generte dets that taelvdes a wide wacertainty head to aceewet for pleetate-plant i
i vertentlity and wheee sufficient sletaae opeelf te date le avelleele these gewe te diet:16vinome teeve toea updated to secount for the spoetite ogwipseat and preettree in place at Midlead.
i 42 ppm 00m rnf14* TEA Raades systee retteres refleet the eyotee mettvaet tone that seest se a reevnt of reaese compeacet fetteree. The estacident fellere of each esapeaoat la sa ares esteet seevite in a readas systee fatteve.
Thle etteet ten deee not laclud., and should be et tforentiated from teet and me1at**enee. eeseen asuae, and Ind, pendent husen et tate. The seet tea sa i
hensa iatereetien eisentttee en the sehjeet of f ete**ty af the eyetse by
- ope a t or oper a tet setton.
l
~... _, _, -.. _ _ _
. ~
i 4.3 1887 WD M&LetBIARCE i
4.3 1 fastina i
The Am8 and ate espporttag systees are tested pertedically to i
settsfy plant teensteal sweettleettee regelsesents. This testing ensures that these systems e111 he t,erante ones regelred by certeus plant senditions.
The plaat seensiaal spoetflaettens alas 11 sit the slee taet l
eystone. er porttees of systems, any be est ed aereise and identify special teettee regstremente esseeeery to emoure plant esfety we11e these i
eut-of-servlee systees er sempeneste are teams repaired.
plant precedures enneernist taas toraaleet epocif teettee testant j
were est yet seeilatie for tais aselyelse toerefore, ellgat ditierensee totwoon the estaal test estaede and the geoetal estaede dissuesed to taas l
seesten mer esist.
I A M psmes.
The een111ery footseter peeps are tested mentaly en a staggered tests.
j This test requires that tae Arw pump succeaefully pese
{
lon of too reestred flew tareega the pues test typese line at the required pump disenaste toed. Te develop the required pressure. the pumpe were seeM to se isolated from the ANS et the level control
{
valves durtag tate felt (Lov testing. Dorteig the test. if the APW8 as required to operate, the ope <ater at tae teet typeas eelve must slese i
tata vain te allow AFW flow to feed tae ate.
I
\\
Every la eentne, the see111ary foodwater puepe are shocked te ensere that they start upon reseapt ed an eestatary feedwater estaetion algael.
i gWw valeen.
All assual, poweraeperatede er auteestie selves that are n<,' leased, seeled. et otherwise pseused in poettien age serified in i
the cot reet poettaen mentaly. ftta test ta eseemed to to a etauel eheen j
ratner name a velve eye 11ag steet.
j
)
tvery 10 eenths seen auteestteetly operated volve is choosed to ensure the velee eyeles to the eerrect posatten wron revelpt of an austa tary feedweter actuetten signals the e.st.Lary feedweter steam i'
generator Level eenttst valves are sheeted to eneere tMy esintain etees generatet weter Leests and tae sentainment toelatton and the level eenteel valvea are checeed te eneere tasy eyete enut upon reestyt of a angs len1 La the assestated stees tenerater.
Aust11arv Feedwater 4stantian Irates.
The seatitary feedweter i
estuat ten system (Aldadi ne fanettenally coected eenthly. Channel checes are performed at toast every 11 hausse are salterated at least every le sentne.and the toetrumeetetten channela 1
_ _ _ _ _. ~. -. _ _ _ _ _ _ _ _.,., _ _ _ _.. _ _, _ - - -.
3 l
i Condensate Stortee Tene_.
vesified at toest every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Level in the condensate storage tant te With oes of the two condensate storage taste inoperante, as amtiliary feedwater pump supply flowpath is desenstrated to be operable at laaet daily.
Service water System.
Service water valves (manual, autcastic, or pomer-operated) which service safety-related equipment are verified to be 1e the eerrect peettien monthly if the valves are not lected, sealed, or l
othecwise assured la peettien.
Every 18 monthe each automatic velve la wrified to actuate to ite
. correct peettien upon receipt of an essential safeguards features actuetten signal (ESFA4) and eact service water pump la verified to start i
on an R$FAS test signal.
4.3.2 fraintenancq All system componenta were reviewed for puethis contribution to maintenance unevetlantlity.
with thte component review to teentify prevalentGeneric data wee reviewed in conjunctio fa11ure modes and the ef fect of the associated meinteneece on systee operation.
j to a brief discueston of the resulte of this review.
The following Nordware r tlures (nec*enical Cc+ w entet.
e Feceing replacement and ad}we tseat is the dontnant cause of asinteneece on valves.
In most i
cases. tale estatonance can be performed with the valve in the correct peestaan for eyetes operatsoe Itally open er fully eloeodi.
Valve repetre requiring disassemely of the velve, although not frequently securring, any neve a me}or tapeet en systes eve 11a4111ty dee to system laelattee reqvtresente neccesary to safety perform this maintenance.
These volves valen togstre fell ADE shutdeun in order for repelt also
)
require a plant aneteewe (per technical specttteattenel med, therefore, i
de not sentrisute to the meintenance unavettehility of the Ams.
velves regeitinq meintonence vaich only need a a1ngle AFw pump train to f*ose be shut down de centriewte to meintenance unevelleellity of the AMS.
valves whien are perledically eycled, ettet have a throttling action, or vales are in a high energy system are the destaaet contsthutore to thte enevettaatitty.
These velves are inelvded in th pump train maintenance uneve t taat t i ty.
pway esintenance constate of a raege of acttone free major l
diesesseely to ps ting adjustment.
per the AFW pumpe, meet asintenance i
performed regwires teetetten of the pump from the systes end, therefore, sentributes to the seintenance unevetlant1 tty of the puey train.
i the saintenance on large entore reage face inopoetton eed cleaning i
te me}er dieeeeeeely.
selet regeltes peet tet disassemely of the actor.The prevelent fatture mode le bearin All saintenance of t N AFw pop seter sentributes to seintenance unevellshtitty end le included La too pop train naintenance unavailaellsty.
19 4
13944433401/1
1 l
Turbine maintenesee een ramte from eleple adjustmesta te mejor
- lleeseemely.
i A revise W !.isoneee twent Asperta free January 1971 to i
49:11 1970 revealed en4y one tapetted fattere of a tertime in as AFue.
tale failure sea due to a emeing steen 1eet discovered eartag startup ettet touttae maintenesse had been perfotood.
i forbine fatture le i
N1uded in the asintenance sentratutten to uneestlability of the turbine defven pw:ap trata.
1 31eetrieal Failures (centrat=. eted,. notee operated volw (MOV, 14WI centret eticult fattures oseus vita moderate frequeney.
j aspelre gonetally comeiee of aremeleeheeting and defeetise eesponent aspiacement j
.or repair.
In eene seees, the ceasetated velve any be placed in the desired peettien priot to commensing repetra en the sentiel circuit.
i The lent conteet velves (teol for each pump train, and the SS AFtr leeletten valves (two per SGt were een41dered for their meistenance centribetten to systen unavetla4111tys benever, their individual centrihetten te maintenance wave 11att11ty to less then 19 ei the sentributten of the indivtdual pump traine to meistenesee unevettability.
i l
The A#it pump motor treamer and centrol ettstwit requires periodic neintenance and repeir.
Escause the 4,160V treeters are interchargeatle j
Mtwen 4.14CV cuticles, and opere treaters are avelistle, mejor treater repair le not treluded in the estatsnance unavellaallity of the actordriven pump train.
All other centeel and broeter esintenance le I
included in the unave14ast11ty of tne motor-driven AFW pump train.
[e_t g.
plant hintetical receede for metatenance settens were i
avallatie for this analyster however, eecause the plant la not ret operatteg, this data was not used in determinte) the maintenance l
unavaita'attity of the ettformat peep traine, insteed generic valaes free MASN-1400, the Beester Sofety Study, were used.
Free $t451-1400, the espected fregeeney of pump asintenance le one set enry 4.$ nonths.
the driver (turetne er meter), and assectated centrel cirnage.Thte meinton The setntenance duration reeged from a few minutes to severas days.
plant technical specifications !!sts tale metatenence duratten toThe 72 heure.
i The legeefset mean maintenance act duration to 19 heute.
Saeed upon the provedtog dieeueston, Totte 4 presente the i
I asintenance unave11a4111ty centsibuttene for AFW pump traine.
4.4 WnAo left4C7!0e 1
4.4.1 Punen Interartloc/keoverable Failures for the purpeees of this analyste, due to the e%ert period r,f time i
between f411wre of the Me8 to start and lose of tte See due to Jryout, ne operator eetice to rece,er the Arws vee considered.
TPts conservattee eeuld to ellaineted it more definttive calculatione for timing of afet sta r ting a r e nede.
i l
I
>i 139ene13eet/t
~
i There are same system failures free which the operator seuld sesseer.
The aset significant of these la a tushine-driven ausiliary foe k ter pump tt'p.
The dominant eestributes to tushine driven aest11ery feedmeter pumpe faltere to start en deoend is a fatture of the tuattne sentrole, primer 11y due to turbine trip en overspeed during I
stattup.
The operater any seneally reset the e,orspeed trip, or taae eenteel of the tuttine-dciven APW pump if, during a demand, this pop did j
not operate.
4.4 2 Euaan trror/Testine During the aanthly full flew testing of the AM pumps, an operater l
to stationed at the full flew test bypass valve.
After the pump la j
statted, thte operates throttles open the full flow test velve to achle w l
rated pump flew and discharge head. Stewld ;he ApWS be aetaated by a
)
plant teenstent, this operator amat cleos the full flew teet eaave to allow the Apu pump to feed the see.
3 l
!aat 15 minutes por Li.att.
The full flow teet la aseuned to Pump unevallantlity des to this teet is equal to i
15 etnutes, so minutes, i20 hours hour sonth i
menta a 3.S a 10*4 j
fu operator error, falltag to act estrectly during the first $ etnutes af ter the oneet of an entremely h194 attees situatten to 0 9.
i l
The unevettat:11ty of a pug trata en demand due to this failure is l
I 3.1 a 10-4 i
t 4.4.3 Numaa trror -- Cassee came l
i A sessen eawee hennen erree hoe been identified for the Ape.
The error can eseur af ter the pump aanthly fles *estieg. Senentially, after each pump teet, the aust11ery plant apetetet esat elece the full f1Jw test velve.
I The pumps theneelves are sentre11od fees she main centrol board, and positten indication to available for the full flew test ve1w at the esin centret board.
If the pumps are tested segwentially t1.e.,
one pump la tested and at the completten of thle test the other pump to tested) common human ettet et cemelnattena of ettete le pesettle.
These ervere constet of tM auctitary plant operator festing to eleee the
)
full flow teet valve fee the first pump and fatning te eleee the oevend
)
pump's full f!ce test valve (elee, eospling is asemed):
and the main control heard operatet falling to nettee the vain poettien indlestion fee the full flow teet wtwo en the meta eentret heard falan elese coupled if the f atet velve poettien ladicatten is eleoed).
]
The recovery time fee this fativie to based upon 'he 9tetentltty of the improper valm eminen meln, dioce,ered dering.htri enan,e.*en ih. aee.ing and offgelag opetetote ' welt down* the main eenteel teet4e free susc-0411.
fatte !!!=3, the point value estimate for this potential husen error le i
1 a 10*8 with en eettanted erret faster of 10.
i thah th i
4 aseed upon diaeussions with the plast operators. the followirq recovery histogree sea cometrooted.
t 1
, o.75
~
=
1 g
_0._2C i
0.0s n
0 2 7
30 Days he asean value face this nietogree for recovery is 2.53 days and'the ver1ance la 13.7 days.
The probaa111ty for fatture on demand for this common cause husen i
error is then (if one assumes chat the error has occurred)
Q,* 1 actuatton a 1?-4 senth Pif) x 2.52 days a _30 days h
gy 3.4 jg-6 with a variance of 6.7 x 10*IO.
4.S Case 0N CActs AseALT115 The method used to perfore the osamon cause failure analysis is based on the systee logic model. ' Qualitative failure characteristics are identified for eeth beste event.
1 thee comeinstions of basic events tnat' result in systen failure andA sea share qualitative failure characteristics.
I Barriers beter,en components, both phyeleal and administrative, are considered,in the shalysis.
rescita of the caumon cause search are groups of cutsets identified by The common failure cherectoristice and abeence of barriers.
There is en estresely large array of failure covees that must be considered in a croprehenelve common cesse fe11ere analyste.
failure causes have been grouped into two mejor categories and these two These categories have been further subdivided.
Por each subdivision a generic cause of failure hoe been identsfied..Me first division la made on the beeis of barriers that can be erected to the cause of failure in order to prevent it from failing _the entire'systse.
The barriers that esist are of either procedural or pavysica.'. ' The failure causes, also called qualitative failure characteristias of the basic event er
- oueceptibilities* are catogaris ed by criterion based'~ en barriers to the failure cause.
y, h
l
^
! l-
[l
e The senceptibility sedes for the easees of failure considered in this analysis are given in Tekle S.
Due to the limits of the available teformation, amoumptions were made concerning maintenaaee actione, test preesdures, and manufacturers.
for different generis composants.These links are assumed to be different l
4.5.1 The First criterien i
& qualitative failure eheracteristic, or a susceptibility, is a
{
enumen link when physical barriera cannot he erected to present the propagation of the failuses, and procedural barriers saat then be Typical common links used la a common cause analysis ares
, erected.
t e
nonefacturer e
Test /Meintenance e
Operator
)
e nottee poo.c l
e Instrument power e
Installation e
Calibration e
similar parts i
t The common linha of ma3ufacturer and similar parts were used in this
)
analysis.
4.5.2 The second Criterion i
The coding of failure sonettivity to causes of failure are given for i
each generic component type in Tatie 4.
The final information that i
needs to be ceded for the AMS season cause analyste la the physical i
location of the beste events.
Table 7 is the reference used in location definition.
The exhibit identifies the equipment locations used in the study.
Seen fault tree beste event was assigned ta its appropriate location.
- 4. 5. 3 Results of Cosumon cause Analveis All cutsets with common susceptib111tice were found to be in the same location, CIfV, the area of the ausiliary building outside the An pump acome.
Moleture, grit, and impect we e found in this locatton.
i l
number and order (number of beste evente in the cutset)
The i
for each of these causes of failure are given in Totle 8.
Moteture was found to be a common susceptitility for the four level control valves and for four twet cutsete in the pop evetion lines (conaletint of the pump emetton MOVs and variove cochinations of the service water supply MCVs).
The design of these valves protects the motor operators free high humidity and other siner ooerces of water.
Flooding or pipe rupture could, however, prevent these valves f tem operating when demanded.
level control selvee are the soet susceptible to We cause because they The avet save from their normally closed poettion to Minit AM flow to the steam generators.
The auction velves are only taired to operate in the eeent of les pressure at the pump section and a coincident Aruna signal.
l Fres v155-1400, the probability of a pipe rupture is 1 a 10-4 per reactor year of operation, Somever, this erstes la celled upon to operate (and therefore pressorised) 16 times per year (sia setuations and tee startup/ shutdowns). The average run time la about two hours. The resulting probaaility of failure is 4 a 10*7 wisich ta significantly less than the comman cause beanen error identified in Section 4.4 but was fosad to be a common susceptibility for the same estests as moisture.
Motor operated valve design protects the mator operators from the normal sources of airtstrie grit c*r dust during plaat operation. During asiatenance periods, the plant general asintenance procedures limit the sources et grit as a general houseteeping practice. This practice in
. conjunction with the safety system testing that occurs prior to plant operation results la a large reduction in the probability of failure due to grit because of asintenance.
In edittion, because failure due to grit is not an inatantaneous failure, but rather a slow degradation in oporation, say aman cause fsiluroa wtil mont litoly be detocted and
'j oorrected as a result of normal testing and preventive maintenance.
,t
]
accouse of the above reasons, 'the peobaatlity of systee failure due to the common cause susceptibility - grit ~~ is very much less than the ccanon cause human error identified earlier in section 4.4.
Ispact is identified as a common cause susceptibility for 51 three-event cutsets in the pump suction paping,16 three-event cutsets in the pump discharge piping, and 451 four-event cutsets in the purp discharge piping.
Thre is no high energy piping in the immediate vicinity of the pump suct*on piping, thus eliminating pipe whip as an impact source.
The only other possible sources of impact in this area are due to estJrnal causes such as emplosion.
Plant procedures limit the form an administraties barrier to emplosion as a cause of impa The pump discharge piping is a high energy system when the AFW systee la in eperation and is the only high energy system in the vicinity.
ta conservative assumption considering piping support designi,If l
impact as a source of common cause failure can be no acre severe than moisture as a source which has been discussed above.
Therefore, the probability of failure due to impect is less than 4 s 10*I, which is significantly less than the common cause human error identified in Section 4.4.
Common linse were found in 274 cutseta, identifying those cutsets as common cause candidates.
during surveillance tests and normal operations, and are maintainedSin l
j regularly, they should have shaken out most manufacturer-related problema.
Furthermore, the components are tricated in different areas of the plant and are therefore subjected to different environments.
ee
-l
(
l 1 l'
)
4.6 EvtWT TILE AMAMSIS l 1 Time sequential teneolee, key systes f:pf=tes, and reduced erotus perfeteamee states can be modeled using event tree eethods.
The evoet tree of Figure 9 lays out such a modal for the Midland Flast easiliary femenetec erstem.
i Bere, the lattiating event le se aust11 sty i
feedwater eetwatlas signal.
Aest, the guestion of ' good
- end
- bed
- stese j
generatore. la addressed.
eith a stema breat that has not been teolated.We have defined a bed steam gene failure rate as 1 e 18*4 NASM-1400 gives the j
per year for pipes, purther containment and steam generatos emelysee coeld lead to a revised definitaon, t
I i
Nort ta the tree ooms the questione eeneerning the asellability of
)
electric power.
Withest DC pomer the entire system east fall.
i AC pones, the tesbane-driven pump trate say still operate.
without I
l The seat taree evente define neocesefel start of the AFut.
hertine train staste, turbine restarta after tuttine trip, and meter train star t a.
Pretehilities of successful starting will be derived free i
deccepositione of the system feelt tree.
start path, the systee falle ce deseed.
unthout succese in et least one wher. eene electric poser la avellaele we suat now sak if the FOGC system operates.
i For cases vita a eingle bed stone generator. FOGC suet seep ausiliary feedwater teolated j
from that stees Teaerator and oust perett flow to a good stese generator.
Secting a final FOGG system design, we have seeigned a l
reasoneele uneve11at111ty of 10*4 quality actuatica systems in sensa-1400.per deeend per train taaed on htgh 4
i l
Given that the systee has started, we nest een if the failsce in tha level control erstes leeds to j
overecoling in either steen generator.
Ageln lacaing esoplete level j
control systee information, we have seeigned a proteat tity of fatture of 10~8 per desead.
Finally, given a successful statt, we est if sne eystes coatinees te too sucesestully for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
j i
8even final systes states have been identified on the tree.
stande for eemplete sucesse, State-8 overcool, one contieues to run fee 8 heers.yhe systes starte successfully does not failures the system does not State-F1 to immediate
)
start on demand. state-F2 se taittal i
coolings the syntes starts successfully but long-torn f allare end v t
overcooling.
starte and continues to run successfully not level control s i
{
leeds to overosoling in one steen generator.
State-F4 4e early j
overeocling in one stese geaerators the systes starte successfully Out falle to run for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and level osetrol selfunction leads to j
overecoling in one stone generator.
k State-FS is over-cooltr.g in both stese generatores the eyeten otette successfully and coatinues to run for l
i In teth stene generatore med failure to run for 4 heu successfully starts but selfumettone lead te overcooltag in noth stese generator e.falle to r l
!1 r
/
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TAA12 4.
PUMP fttist Utt4VRILA8!LITT CtX TO TEST &a0 Mh!Irtsakam 1
1 l
Q asiatenance turtime
- 4 5 mentas"I*** " a
--
- 1.1 a 10~I actuation : 720 howts l
1 ******I"" a D *' '
C meintenance asses 720 mouss
- S.9 a 10*3 s
4.5 mentas actuetten
. i g test tweetne
- M eta ntes, 60 minutes, 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br />,,,,, 3,3, gg.4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> apath (operates segrett aseth l
Q test entor
- li sta 4
n
\\
nt ee,
our _
oceen teperator ersogi to stautes, 720 howse--- a 0. 9
- 3.1 e M
- 8 aoata i
i Syatee Onevaalasi11ty See te feet and as1ateneses i
9 systomy.g
- tC meinteneme= tushlae + 0 test teettael (G eystem wits tusklee pump demel
!Q malatenance notee a g test aseov)
+
($ syetse wIta ustee pump doses l
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.....,____,...____m.
4..r_,,-
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TAetJ 5.
8ttsG PftstLITY CCCES l
i First Cricetten 1
meinteneste Aetton
- gg gg sg gg m2 m) me feet Ptesoawe
" ?! M T3 T4 TO 15 TF TG 11 T2 Tx TL TII TF TS TT TV T*/
Tis j
8teaufset wegs A*Ost Cee11sq
.g Byaon Jec.ec,
. gg Can aoa r.- ;:,;,
.g
..?,, e u u.it s.
T98 ry ha a gn,
. y; UH w istastse i
. gg g; gg,,
Casgenents CdW El af as it9 ether!
IWeed filterlea tape <,
vawetten sla g sq.g e
,g Offt
.g Streee
.g
= - -
i i
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taata s.
amenze cceecaners Amo Turra amarmens a rarm
- D Special Condition a^::n o th111ty Level Velve e,y y a y g menval vel,,
gy y,
g,
M T n g y Twessa.1:ael e..
n y
controtal M C CentMt ce y
Ciftutt Steeeeg c3 y
! Y m 4 I
Contgot case,gg y,
! V A Q I
I V N C Centest clecoge cg y,
! V N C 8t*tet Vales av g,
41.y as y
! V N G c m e vot,,
cy 7,
1 8 n G l
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m
- Mu
[
24312 7.
NysgCAL SAAA223 IgrtMBRT!0st S ulpenet besattene Ceed in the Midland Am Systes Aaalyets t
A1SA R12
- 1aside reester hullding.
280C P!88
- e*11asy be11 dias pipe stese.
M
- esallery telldiag osta4de AFtr pump rsees.
M
- enallery te11 ding mete, deg,en peer rees.
7344 - eastlary besidgn, twentne 4, s YARD - estarieg of n g gggo,,,
SAAA - 414.*V4C settehgear room A.
SASA -
esqNnC eettchgear some A.
3AAA
- e# W owitetigeen room 3 AAAa - 125teC tettery reos A. penet 1211.
t 4440 - 121gec settery some 8, Feast 1821.
9444 - setetes meter pump room 4 75a4 - noenee setes pg room e.
00l4 - 18F estwetLee - Atwas cesaae& A.
I.
OCES - SSF attwetIse - AFW casene1 8.
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5.
1ESULTs The resulta presented is this section show that in the emergency mode the Midland plant AFWS is eery reliable.
- ' - 'rg, separation, and availability during testing are applied in oostinations that aske the systes quite sound. The resulta presented here follow from the detailed foolt trees, the data, and the analysta described la section 4.
They are beoed on failure of the auxiliary feedmater system to deliver sufficient flow f amediately upos demand to at least one SE therefore, human intervention to recover from some system failures is not considered.
If
,further analyses of the asu nuclear plant demosatrate that a time window exists dating which actuation of the soziliary feedwater system can provide adequate core cooling, then the affects of operator latervention to restore system function should laproee the system reliability.
Sech considerations will require reviewing emergsney procedures to determine the likelihood of successful operator action.
S.1 leset.Ts or STsTen AaALYsts The resulta fer all three initiating event cases from WURG-0611 are given in Tables 1, 2, and 3 shown earlier.
In Table 1, the point values based on NCREG-0611 data are tabulated along with means and variances based on plant-specific data for the double crossover design.
In Table 2, means and variances based on plant-specific data are provided for the double croaaowe and the base case designs.
In Table 3, means and variances based on plant-specific data are provided for the double crossover and the three pump designs.
Test and asintenance in ceabination with randos system failures are the dominant contributces to unavailability.
failures alone, busan error, and common human error in importance.They are the three pump design and 'in all cases gives a loss of all AC powerFor random independent failures are the dominant contributors.
The dominant random independent failure contributions are associated with the pumps:
either the pumps themselves, their prime movers ~ seters or tarBines, and the power supply to the actor-drives pumps.
Dominent homeo errors are associated with failure of the operator to close the full flow recirculation test valve either during a test when the system is demanded to function, or following a test in which the valve is lef t in the wrong position.
Tables 9 thecugh 20 deactibe the dominant contributions to i
conditional unavailability for each of the four situations described in Tables 1, 2, and 3.
\\
l The dominant contributors tw the double crossover design systee
{
esing NBC data are given in Tables 9,19, and 11 for the three rases of NUEEG-0611.
In each case, maintenance on the turbine-driven ausiliary feedwater pump combined with random failures in the motor pump train is the dominant contributor.
For the loss of main feedwater case, meintenance on the motor-driven aus111ary feedwater pump comenned with randon failures in the turbine train canas second.
In the other two l
1390A433081/1 35
cases, this failure mode is not as important because of the reduced l
l availability of AC electrical power. Dent in all cases is tarbine or turbine control failure coupled with failure of the motor-delwee pump motor.
Usiag plant-specific data for the double crossover erstem, Tables 12,13, and 14 show the same dominant contributors appear with tone changes in ordering.
Dominant contributors for the tase case design using plant-specific data are presented in Tables 15,16, and 17.
These results are very sisilar to the double croaaover case salag plant-specific data both in l
I the rank order of the individual contributors and in the quantification.
,Tahlos 18,19, and 20 present the dominant contributors for the three pump desige using plant-opecific data. The overall resulta of this design are not sa good as for the douele crossover or base caos designs.
Although there are three pumpe, success requires either the turbine pump operating or both 50% actos pumps operating.
The leading contributor for i
the cases when hc power may be ave 11able is maintenance of the turbinedriven aus111ary feedwater pump cometaed with renden fa11eres in the motor-driven per traine.
Essever, the large summer of fairly important contributors due to randon failures throughout the systes leads; to the owrall effect that combined random failures provide the dominant contribution to systen unavailaeility.
Such randos fattures include fatlure of the turbine or turesne controls centined with single actor pump train level control valve f ailing, failure of the turbine-driven pump comeined with failure of power to either electrically driven pump, turbine or turbine control failure and a single pressure control valve in a motordriven pump train f ailing, and failure of the turbine-driven pump cemeined with failure of a actor-operated valve in either motor-driven Pump train.
This design suffers from the fact that success, given a failure in a turbine pump train, requires that two complete trains of actor-driven pumps operate.
The selected design, the douele crossover system, boa very low unavailability.
newetheless, it is instructive to list possible system modifications that have potential to further reMe that unave11ae111ty.
To improve unavaila4111ty, the endifications aust attaca dominant contributors of yattee 9 through 14.
dennanant contr1butore and the poseible modi!Ications thee might add thee.
Maintenance of the turbine-driven auztliary feed pop and o
l system failure on demand without this pump - reduce the frequency of pump maintenance by carefully eltainating any nonessential asintenance, consolidating meintenance, etc., and reduce the duration of pump maintenance outages through additional preplanning, training, etc.
Maintenance of the actor-driven sumi11ary feed =eter pump and s
random failures in the turbine-driven pump train - same as for turbine maintenance.
13gSA033001/1 I
1 Turtles or tuttine controle fall combined with raedom fa11eres e
l in the actor-drives pump trata ~ modifications to Saprove reliability of turbine controls, perbepe provisione for preheeting control fluid and positive identification that the testine trip le reeet.
)
sienen errors associated with the full recircolation flow valve e
1 i
during and followleg pump test ~ carefully written test procedures to eseure the selves are reclosed, staggered teetteg ta ave &d esquesttal highly coupled humaa ia1luros, autamatic cloetog of these test valves when an Afuks le present.
1 These contribetors are responsible for approsimetely 80% of the total unevetlantlity of tee semillary feedmeter system.
Thus.
imptovements could hese a setetanttal effoct on tne owerall unavaila4111ty. Bowever, a word of wereing la appropriate. It te posenble that eene of these ceanees could create more proeless then they solve.
For eaample, a redeelped turbiae centrol system sight not perform hetter then the one alteedy installed. Also, for any of these i
optione aimed at the single cause of failure, accomplistuneet of any one enormously decreases the value of those esmetning.
Finally, the systes la already very soltable and ne serious deficiencies have been Ldenttfted.
Any changes conandered anos1d only be made af ter a careful evaluatton of all costs and besef tte including the chance that a change
{
aimed at improving rettact11ty could actually degrade it.
l 5.2 Risut.73 CF t'asr? Tert amy,ysis i
TN event trse analyeie descr1 bed in Sect 1on 4 has been performed for the douele creseover system (see Figure 91.
A de-:-,::1 tion of tt:e 1
double erossover eyetes evont trse and time dependent calculatione have been seed to quantify the syntes evoet tree.rel1 ability Proaseilities have been calculated for each sequence in Figure 9.
3 have summarised those calculattons in the following brief table.
We l
l notative systee state
'**Y Follow 1og Demand 1.
Immediate fatture 4 a 10-5 J.
Initial cooling. long-ters 1 a 10*3 failure 3.
Succesafel operation but 2 e 10*4 overcooling an at least one SG 4.
Initial overeocling and 2 a 10*'
long-tors failure 1390A033081/1
State 3, overcooling, any not be a serloom contributor to public riot.
Recent calculatione show that natural circulation cooling can to effective even with two phase conditions in the primary as long as the core receine covered.
Overcooling caneet abrink the primary coolant enough to uncover the core. States 2 and 4 - tattial cooling but leet-tera failure are auch less serlaus than State 1 ~ immediate failure.
They have renewed initial decay heat, permitted some cooldown, and have allowed poser to decay. noch more time is available for recovery.
The e,eet tree developed in this study een provide a tesis for
.reetoed analyses la the fature. As more details on FCGG and the level costrel system become ave 11aele, they can be ese11y ancloded.
- also, additional thinking on good and had SGa can be incorporated.
f 13904813441/1 le
i taar2 9.
Donraurt cowTa.taercas 20 comorTrouAZ, tasavn!IA!At.1TT l
I i
i, IDES OF MkIN M DMA M i
l Doutte crossover (mac Deta) i t
Raat Event Description Uneve11a4111ty i
i 1
Maintenance of turbine-driven AFtm an system 3.5 m 10*S failure on demand without this pump.
2 Asiatenaneo of motor 4 rives ANP and system 3.4 a 10-5 fa11ere on demand without stia pump.
3 Turbine or testine controla fall and MSA 1.6 x 10-5 motor fails to start.
i 4
rw cause--human error-full flow test 6.4310-6 valves open after test.
5 Turbine or tuttiine controla fall and MSA 4.C a 10*4 fails to deltvar sufficient water.
6 I
MS4 falla to deliver sufficieet water and 4.0 a 10*'
PC!A motor fatte to starr.
7 M$s test valve le open and MSA motor fails 2.0 x 10~0 i
to start.
i 8
Turbine or turbine controle fail and Mia l
2.0 a 10'0 test valve is open.
{
i MSa in test (operator error) and system 1.9 a 10~4 j
failure on demand without this pump.
10 MSA in test (operator erroel and system 1.9 a 10-4 fa11ere on demand without tale peop.
I 1407A033041/1
4 i
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thata 10. DOMIRArt CouT3tISUMRS M CDWDITIOuhL UNAVAIIABILITY 1483 OF MRIE FEEDumTER EDE M 1 DSS OF orFSITE 80e33 I
I Doubl* Crossover (sec Detal 1
i 88%
Event DescriptPm gnavailability 1
maintenance of turbing-driven AFWF and systee 2.5 a 10~4 failure on demand without this pump.
2 j
Turbine or tuttine controls fall and 4,164v 1.5 a 10-4 bus 1A45 fails to supply power.
3 3
M5a falla to deliver sufficient water and 3.7 a 10-5 4,140V bus 1Aa5 fails to supply power.
4 heintenance of motor-driven AFWP and system 3.4 a 10-5 3
fatlure on demand without this pump.
3
{
i MSR test valve open and 4,160V bus 1A05 1.0 a 10-5 fails to supply power.
6 i
Turbine or tartine controls fall and M5A 1.6 s 10-5 j
actor fails to start.
1 7
MSB in test (operator error) and systes
- 1. 3 a 10-5 fatlure on demand without this pump.
8 Common cause--tumen error ~ full flow test 8.4 s 10~4 valves open after test.
l 9
T'arbane or turbane controls fail and MSA 4.0 a 10-6 i
l fails to deliver sufficient water.
10 MS3 fails to supply sufficient water and 4.0 a 10*'
MSA motor fatta to start.
11 MSA in test (operator error) and systee 1.4 a 10~0 l
! allure on demand without this pump.
1
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That2 11. DCat!Eluff CONTRIRUTCAS TO CCIEITICelAL ENihVRIEA81LITY East 0F ALL AC Double CrosaWTer (NRC Deta) i Sana Event Descriptiew Oneve11ab111ty 1
Maintenwce of turbine-driven AFwF.
S.9 x 10-3 2
TurbA e or turbine controls fall.
4.0 m 10*3 3
MSS fatis to deliver sufficient water.
1.0 m 10-3 4
M5a la test (operator ersor).
3.1 a 10-4 S
M5a teet selve open.
1.0 a 10*4 5
MSS suctiam valve transfers closed.
1.0 x 10*4 7
Velve M03124 transfers closed.
1.0 a 1:*4 8
Svetion hesaer cross-connect valve n00683 1.0 a 10-4 transfers elemed.
9 Valve MC3856 transfers closed.
1.0 a 10**
10 CST isolation valve 037 transfers c!c..ad.
1.0 x 1C*4 11 CST outlet chect valve 024 fails citx44.
1.0 a 10**
12 Common cause--human error-Iull floe teet 8.4 a 10*'
valves open after test.
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l 1407A433431/1 41
I 1
TRAIR 12.
OlbtZllAR COpfRIBUTOM TO CCte!?IONAL tRIAWRIIABILITY ISBS W akIs Frtens1233
{
i Double Crosaceer (Plant-Specific nota) l Anak 3,ent Beeceiption Daese11ata11ty 1
meistenance of noter-driven AF'!rP and system S.3 a 10*I i
failure os demand withest tale pump.
i 2
Tuttime se testin6 controls fail and MSA 3 3 a 18*S l
fails to delivet esificient water.
3 maintenance of tuttine-driven APWF and system 2.4 a 10*S fa11ere en demand without tale pop.
l 4
MSS falla to deliver oeff acient water and 1.5 m 10-5 fails to deliver sufficien
)
Common cas:: ' - error-t water.
{
5 full flow test 4.4 a 10*4 valves spee after test.
4 Turnine or turnine controls fall and MSA actor falls to start.
5.8 m 10*8 7
MSA la test leperator error) and system 4.9 a 10**
t fa11ere on demand without tale pump.
4 Turbane or turbine controls fail and MSA 3.5 m 10*4 asser breater esse not close.
9 MSS falla to deliver sufficiens water and 2.6 a 10*8 l
POSA motoc fails to start 10 MSS falls to de11eer sufficient water and 1.4 a 10-8 POSA estor tresser does not close.
11 Turbine or testine controla fait and AftrP 1.5 a 13*4 relay R1111 (POSA) falls open.
12 M58 in test (operator error) and systes 1.4 a 10-4 failure on demand without this pump.
1 i
1 14e?ne33eg1/1
I 1
1 i
Taal2 13.
DCst2RAst CtarTRIAtrfcas 10 00 set?!CenL gmHRifA32LITT IDES OF MAIN FEEDNATEA DER TO 1488 0F OPPSITE POIER Deeble Crossover (Plaat-Specific Detal Asnt teent Deseription Oneve11ah111ty 1
hetine er tuttine controls fall and 4164v 3.9 a 10~4 tus 1 ASS falls to supply power.
2 meintenamee of test 1Msivon AMP and systes 2.4 a 10*4 ts11ere en deanne enthout tate pump.
3 MSS fails to delleer aufficient water and 1.4 a 10-4 i
4,164V bee 1A0$ falls to supply power.
4 Meantenance of actor-driven APWF and systee 9.3 a 10*I failure on 4*esed without this pmap.
h:4 tee or tuttine controls fell and POSA 3.3 s 10-5 I
f ails to deliver sofficient unter.
Mia in teet (operator er ror) and syntes 1.3 a 10-5 1
failure om demand esthout Common cowoo--w error this pump.
1 full flow test 4.4 a 10*4 i
valves open af ter test.
4 MM in test i
facerator error) and syntes 4.9 s 10*4 fanlure on demand without tats pump.
{
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l 14474433601/1 0'
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11382 14.
Dem11 mart CDerf5L!agneS M CDMD!?!CemL OuhVA3!ASILITT 1488 QF ALL AC touble Croaaover (Plast-Specific Dete) i sena 3,ent seeceiption Unavallatility 1
Tuttine or termine controle fall.
1.1 : Id*3 i
a metateaene..f seemt erte.e uw.
s.s lo-3 3
MSS f alle ta eeltver soff tetent water.
4.7 a 18*3
)
4 MSa in teet taperato, error).
3.1 s 19*4 S
Common esehuman error-full flow teet e.4 a 13*8 velves open after test.
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118E2 15.
DCut2NMrP GurFRIBUTOR$ 10 CM2710IIAL Ott4VAILA31LAT less 0F a42N FREDem153 Base Came (Plant-Specifte Detal l
i Rent Roset Seeestyttan Onesellability i
1 Natetenenee of ester-ettoon Arte and syetes 9.4 s 10*S fa11ere en demand without this pump.
2 Mth fails to delivet suffletest esser end 3.3 a 10*8 tae*1ae er testime sentrole fall.
3 metatenamee of testineMatten afts and systen 2.4 s 10*5
]
fa11ste se deemed attaout this pony.
4 MSA fails to deliver suffleteet ester and 1.5 a 10*I JOSS falla te deliver suffleteet water.
S Commen caute-4 men errot-full flee test valves open after teet.
8.4 m 10*4
{
4 M u notor fatte to stort and t.stine or 3.0 a 10-4 tuttame conteele faal.
7 Mu in teet (operatet e,rreal and ersten 5.0 a 10*'
fattere se demand witbest thte pump.
8 70% antaa treater does ces close and twettee3.5 a 10**
er teretne centrols fall.
9 Peu setor falta to start end MSS falle to 3.0 a 18*4 delleet eeff teleet estet.
10 s
MM estee treates done see elone and P014 fable to del 1*ee esitteleet water.
1.6 a 13"O 11 Aries relay 81111 (Mul feita open and testine et tuttime centrols fail.
1.5 a it*'
12 M1a in teet topsestos errect ame efetsa 1.4 s 1 *4 f a t tere en deoend en thout t h t e pump.
1847A43 30 81/1 45 i
l thaLE 16.
Dest 2nharr CONTRIsomis to countyrcNAL OueVAtus21.2TT i-..- -
tsee Caos (Plant-specific Deta)
Rena 3,eet beesription One,ellang g gty 1
Turttae se teettae sentrola fell and 4.164V 3.9 a 14*4 noe lael falle to espply poser.
3 metatasance et tartaae-esiven Afur and erotem 3.4 a 18-4 fa11ste en deseed oltreut tAie pump.
3 MSS talla to dellwer estfielent eater and 1.7 a 18"4 4.1609 Dee taal felle to supply power.
4 notatasance of motor-driven Apur and system 9.4 a 10-5 tallute on demand ete %.t tale pop.
5 Turbine et turbine <.ontrols fall and PC$a 3.3 a 14*S fails to deliver so ff aelent meter.
i 6
MSS falle to dell' or sufficient meter and
- 1. 4 a 10-5 M SA falle to delt et suffleteet ester.
1 MSS la teet loperstor ettori and system
- 1. 3 a 18-5 fa11eae on deseed '1tho conson cauee--namen s..w.t this pump.
4
- full time test 4.4 m 10-4 valwee open after tes:
9 MSA is teet leposata erto.,.m2 systee S.8 a 18*4 i
fallese en demand eith w a i
ae M.
1 l
14474433441/1
- - ~.-
l marmer commamens to commoman, omavast.assi.m
- 'a It.
4 l
1000 0F As.L ac i
1 Sees case (plant-speegige geg.3
~
i 8w at Doesttytaen g
gg.nggggy 1
hettae or tuttime sentrols fail.
1 L.L a 10-2 3
i metatenease et teeMetven Afur.
l.9 s 10-3 l'
3 MW falla to de24,ee soffietent notes.
4.7 a 10*3 4
MM la teet (operater errer).
3.1 a 10*4 i
1 Commen someo--hunne error-tell flow test veloos open after teet.
a.4 a to*8 i
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r 14efae3Movt 47
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1n882 18. StettaMrr CCarfRISOTORS 10 C3EDITINU, ORAva!!Aa!LITr fMS OF NRIN FREcemy33 three Pump (plant-Specifte Catal Stat Beest b eeription Omeve11 set 11ty t
1 notatemence of testinNriven IJet and eyecae 2.9 a 18-4 failsee en demand without LAle pump.
2 hatine et terbine eisteels fall and Lv387531 1.5 m 10-4 treasters cloeod (eentrols).
3 metatemenee se ester-esteen Aswp (MSal and 9.8 s 10-5 erstee is11aes an eenend witheet this pug.
d metatemenee se estat4rteen Arup ir05C) and 9.8 a 14-8 ersteen faalste en deseed wit *oet tais pump.
S MSS fasts to deliver evif tetent water and 8.9s1r5 Lv347S41 tramafesa cleoed (eentrelas.
4 hetime se tarttae ccattels fell and LV3875A1 1.5 s 1r5 treaefers closed (controls).
g 5
7 hetino or tatt.tne controls fall and pressure S.8 ITS 1
contest velse 0300 falla elooed.
a hrelse og testine oestret f all and pcseawe 1.4 a 1r5 easteel selve slam falla eloeod.
9 hreine et tuttae eestrels faal and 8038?ft 3.7 a la-S aster operatet fatta.
10 hastmo et tettlee controls fati and se03ei4A 3.7 a 1t*5 aseos operates fenle.
11 hrstae er tuttae teatrols fall and MSC 3.3 a Irl
+
falla to dellror eeffletant water.
12 heelee er twaine controla fatt and POSA 3.3 trS fatta to deliver soffletent wecer.
13 MSS fe11e te deliver esittetent water and 3.4 a 18-8 LV341SA1 traeefere elooed (controls).
14 MSS falla to deliver eefficient water and 2.6atrS preeeere eentrel volve 43c8 fa11e etened.
15 Mia fatta te deliver eeff teient weter and 1.6airl processe sentret volve 630A falle elooed.
16 Mla falla to deliver suffletent weter med 1.7 s trS molette actor operatet fails.
17 MSS fails to deliver estfleient water e4 1.7 e irl N01stta enter operater fatic.
It M13 la test leperatet errer) and systes 1.4 a 14-1 fattere se denend eithmet thAs pump.
19 MS4 fasts to deliver' owf f tetent water eM 1.1 a 10*S M9C fatte to deliver esffielent weter.
s u u..
. o.
HaLS 18. DonIleMrt CCIPt280TURS 10 m!?!ceM. Dunvn!!As!LITY (sectinued)
Less op anga yngnages Three Pusp (Plast-8;ocific Data)
Rent tweet Beeceiption Unavailability 20 I
POSS fails to deliver sufficient unter and 1.5 a 10*S P354 fails te deliver suff!cient unter.
21 Common cause--human erree-full flew teet 4.4 a 10*'
velves spee after test.
j 33 TurStae et ternise controle fell and level 6.1 a 10*8 mostrol valve LV347581 falla slooed.
23 Turbine or turbine sentrols fail and MSC 5.8 a 10*8 meter falla ta start.
14 Tuttine er tuttine controls fail and MSA S.8 a 10*8 ester fails to start.
l 25 MSA in teet (operater error) and ersten 5.3 m 10*'
failure on demand without tais pee.
24 MSC in test (operator error) and systen 5.3 a 10*'
j j
failure on deoend without this Fusy.
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14476433 egg /g 49
i-I i
TsaLE 19. DentmNrr omrfmIMToms to como!TIoanL UnAVAJ1AaILITT tage or anIN FEEnunTat nas to Loss or CPts!'s POWR Three Past (Plant-Specific Deta)
Anna Beent Deecription Unavailability 1
Meistenance of tuttine-driven ArtrP and system 7.2 m 10-4 fa11ere en demand without this pump.
2 Turbine or tu bine controle fail and 4,160V 3.9 x 10-4 bas 1A0$ fails to supp1f poser.
3 Turtime or turbine ocetrels fail and 4,164v 3.9 s 10-4
-has 1406 falla to segyly poset.
4 POSS fails to deliver suff1= lent water and 1.7 x 10-4 4,1847 t>us LAGS fails to supply power.
5 PO5a fails to deltwc sufficient water and 1.7 x 10 4 4,1687 bus 1A06 fatle to supply power.
6 Turbine or turbine controls fail and LV3075aA 1.5 x 10*8 transfers e!csed.
7 Maintenance on meter-driven APWP (POSA) and 9.4 m 10-5 systes'f411ere on demand without this pump.
8 Maintenance en actor-driven AFWP (PCSC' and 9.8 x 10*S system fallare on eenend without this pump.
S 705A fails to delawr suffielent water and '
4.9 a 10-5 LV387582 transfers elooed.
10 Tustino or ~ turbine controls fail and Lv387541 5.9 a 10-5 transfers closed.
11 Turbine or turbine controls fail and pressure 1.8 a 10-5 control valw 020s fails'elooed.
12 Turbine or turbine controis fall and pressure S.8 x 10~S concret ve19e 020A fails elooed.
13 70$a to test foyerator error) evid system 3.8 a 10-5 failure on demand without this pump.
14 Turnie, or turbine controls' fail and Mo3870s 1.7 a 10-5 actor operator falla (and controtel.
15 Turblae or turbine controla fell and Mo3877 1.7 3 10-5 I
setor coeratar fails (and controlsl.
16 Turbise or turbine controls fail and I.*f4 1.1
- it-S fails to deliver sufficieet water.
17 Turbins' or terbine controls f all and POSA 3.3 s it-S fails to deliver sufficient water.
lt 7654 'fs11a to deliver suiticient water and 2.4 a 1C*S LV3875&1 tranetera ricead.
19 POSS falla to deliver auf ttrient water and 2.4 x 10-5 preesese control valve 0208 falle closed..
n I
1464&Atinet#9
l Tha13 19.
Amm8F COEfR280 TORS TO CORDITICERL URIATAILABILITY (continued) 1488 cr saIn FERDenTER DER 10 1488 0F CrF8Its possa l
Three Pump (Plaat-Specific Data)
Rank Event Description havailability 20 M58 fails to deliver sofficient water and 2.6 s 10-5 pressure control velee 020A fails closed.
11 M58 fails to deliver sofficient water and 1.7 x 10-5 MO34708 operator fails (and controla).
22 M54 fails to delleer entficient water and 1.7 a 10-5 M03870A operator falla (and controle).
23 M58 fails to deliver sufficient water and 1.5 x 10-5 M5C fails to delver sufficient water.
24 Common cause--busan error ~ fall flow test 4.4 x 10-8 velves open af ter test.
25 MSA in test (operator error) and systen 5.2 x 10~6 f a11 ore on demand without this pump.
26 M5C in test (operator error) and evetem 5.2 x 10-6 failure on demand without this pump.
D I1
i I
28882 28.
00N!alAarf CIIrfRISCTOR$ TO CORDITICIIAL GMAVAIIABILITY ICSS OF ALL AC Three Fusp (Plant-Specific Deta) j Aant Event Description Uneve11atility 1
1 Turbine or turbine controls fall.
1.1 x 10-2 i
2 Meletenance of turbine-driven AFWP.
5.* a 10*3 3
M5a fails to deliver sufficient unter.
4.7.x 10-3
)
j 4
M SS in test (operator error).
3 1 x 10*4 S
1 POSS discharge valve transfera closed.
2.9 a 10*4 4
LV347542 transfers closed (controls) and 2.2 x 10*4 LY3s?SA2 transfers closed (controls).
7 LV3875A8 transfers closed (controle) and 2.1 m 10*4 NO38708 fails closed.
8 LY347552 transfers closed (controls) and 2.1 m 10-4 NO3870A fails closed.
9 Common cause--buaan error-full flow test 4.4 x 10-4 velves open after test.
f l
l I
1407A433001/1 52
i j
i 1
b M ENCES l
1.
U.S. Nuclear Regulatory Commission, " Generic Evaluation of Foodneter Tranetests and Small treek Imes of Coolant Accidents la Westingheese Designed operating Plants," 5038G-0611, January 1984.
2.
Weaver, W. W., R. 3. assnes, R. S. Isminna, *Aus111ary Feedeater Systems molian111ty Analysee: A Generle Report for senseen and Wiloca-Designed Plants,* Ratcott and Wilsee, Decemeer 1979.
, 3.
U.S. nWear Regulatory Commisalon, " Transient Response of Setcott i
and #11cou-Oesigned Erwtors
- EUREG-0447, Ney 1944.
i 4.
Midland Final Safety Analysis Asport, Chapters 8 and 9.
i S.
'Stadland Pa!Ds foe Aemiliary Feedmeter, Main Steen, Condeseate and
, Feeduster, and Service Water Systeme.*
6.
- Midland Scheestics for AFW Pumps and Motor =Cperated Valves.*
7.
"Midlard Technical Specificatione for Aus111ary Feeduster, Conder.4 ate Storage Tant, Electric Pomer, Service Mater, and Instrumentation Systees.*
'AFW System operating, Emergency and Surveillance Procedures."
8.
9.
- Discussions with mesters of the Midland Plant Staff in the Operattons, Maintenance, Startup, and Technical Groups.*
10.
Su111ren, T.
S., J. P. Eindinger 'AF4 Systee configuration and Control Taa4 *= h ation,* Caneumors power Ceepany Internal Correspondence, Eind S-80, April 9,1940.
11.
" User's Gelde for the Reliability Analysis Systee IRA 8) Computer Code,* TIEE-1119, developed by BC64, IDAED, Inc., at the Idene motional Bagineering Leboratory (Ilsu, Septoster 1977.
12.
- WAN !!-A, A Computer Program for Automated Common cause Failure AnalyCs," TIEE-1361, developed by EC44, IDAND, Inc., at the Idaho actiona ' Engineering Laboratory (DEM, May 1979.
- 13. *mcCAas:
A Monte Carlo Code for Determiniaq the Distribution and Simulation Limits.* Scott D. Mathews, developed by IC64,10A50, Inc., July 1977 14.
U.S. Nuclear 3egulatory Cossaission.
- Reactor Safety Study:An Assesament of Accident Riats in U.S. Commercial Nuclear Power Plant s,' la8N-1409, 1975.
13944433001/1 53 L
i I
I 13.
U.S. auteer astulatory Countselen, ' Staff hopeat en the Geneste Aseeeement of Feedseter Traceteets la Preeserised noter noectore belN W the Seteosa and utlaos Cap.ny.' WUlme-0340, may 1973, 14.
Stey, S. C., C. L. Cato, D. u. settleell, S. J. Cer riet, "Ilidland l
Plant Assiliary Fehter syntes nellatility Analysis,* PW147, estater 1946.
/
tieaan staan n
$4 h..._
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l T
niotm e lo2-rsAn tea.3 cosernalsons or ins miouwe Aurluaar rarouArra sysTrn DEsscu wlTH THE. SECtegeEMDATION or numsc-os:1._ Arptseta_lLL icontinued: necommemietten nesoone. (2) The lacensee should propose Technical See Subsectson 16.3/4.7.1.2. Spectfacetsons to eseure that, prior to plant etertup folio.alng an estended cold shutdown, a flow teet would be performed to verify the nessel flew path (sue the paseery A N system water sousce to the steam generators. The flow test. should be conducted wath A N systee watwee in thear moreal aligriment. Sques peelistIL94 The Itcensee eheute verify that See Lbe response to Accommendation GL-1. automatic steif AFW eystem saenale and associated carcuatry are safety-gsede. If thae connot be worafted. the new erstem outuestac anttaation erstem ehuute be meda taed in the ehes t-tesle to meet the functional ~ regaarementa lasted below. For the longer-terin. the automatac anitaetson eignete and circuate should be napstated to meet safety-grade requisemente, se Andicated in necommendation CL-S. 10 (1) The deelgen eheuld provide for the automette anatsation of the Ant system flow. (2) ine automette anatistion signato and carcuite eheuld be desagned so that a sangle feature wall not result an the loss of AN system functaen. (3) Testabality of the snitiatana signals and carrmane shalt be e teeture of Ene dessen. (4) The snittetaeen algnale and carcuite should he powered from the emergency buses. (S) stenenal capaba14ty to snitiate the AW eystem free the control room should be retaaned and should be septemented so that e single fe11ere an the manual carcuate wall not result an the loes of erotem functaon. (6) The oc motor-driven pumps and watwee an the Afw system should be ancluded an tJoe automatic actuetaan geneuttaneous and/or seguentaal) of 10A-4 Bewesten 30 80/#o r
CibtAae IS2-FSAs 164.3 casenatsras or Tor w otaae Atfurt. AaY FYrDesATER S CwumEj-59L~4fliisuji'1TT hat tputa!-~ ~YSTEM DESIGN trITH THEJf,CWWg3EATION ~-~ ~ ~ ~ E'CORB'8M$aE8on Ses m ee the leeds to the emergency twees. (7) The autome t t e a na t s at t ost esgnale and carcuate shell be desagemed so that these fattuse e444 emot result an the 8ves of messual capahala t y to saataate the Arw system from the control race. aecommendetion cs-e - The Iacenses shoutd ane ei1 e Est e ~~t o 4Jt & Gee n s y see ahe e es.onee o secommendet on co-:. instsete Arw system re w. Yhse syste neee not me eerety-ge.ases he wer, an the sort-tere, at shoeste meet the crater te 14ete f belser, which are sanaler to itse 2.1.7.a of NumEG-ob74. For the longer-tere, the autometse anstaatson eagnate eed casewate should me = pes ded to meet safety-grade reguaramente, as asedacated an accomunendation CL-1. 34 (1) The doesgut should proeide for the automette anatsatson es the Arw erstem flees. (2) The autemetac inittetaan esgesate and circuite should be desagseed se that a single feature wall not result 4m the looe of AFW erstee finns t a an. (3) Testabiltty of the instaatang sagunale and 2 carcuate should be a feature of the doengue. (4) The anttistang si p le and circulta should be pausered f eame tine seergency busee. (S) 80enwel cepehtlity to ant tlate tage AFW syetee from the control room shoes!d be retasated and should saplemented so that a single faalute an the manual carcuits us!! not result an the lose of eyetse fu.ireson_ (4) The oc motor-drtven pumps and welwee nn the AFw system should be ancluded am the automatte actuatnon (etenaltaneous and/or segnsent aal) of the Io de to the emergency buses. (7) The automatac initiatsoi signels and estrutte t 30a-0 mevasson 34 10/80
cipfAam 162-fsaa 1o4.5 of 8067.c-o61.1.AtrSNni m 1ILL semi Assie31somramisces or tur usouue Auxst.:Aar ranzannTra sr_sTos_ocsjcm 1 tecommendetaon Geoponse should be desagned so that thear fealute wall not result an the toes of manual capabaltty to anstaate the AFw system from the centsel race. >L 194.3.2 Addatsonal short-Tere Receemendationes bec - ndetsen et. The lacensee should prownde A deses aptaon of the condensate storage tent. Ste r edusssant leveTa nda ce t s on and low level alaree in take be f awn.3 opetetson, and the sastrumentat aen provsded for at cast 4 control rose for the AFw system pramery water supply, an Subsectase 9.2.4.2. to allow the operator to antac apate the steed to sete asp water or transfer to an alternate water supply and Crevent a low puey suc t a on ps esou r e cond a t a ca f r om occustang. The now level alarm setposat should allow at least 20 saneates for operater act&on, asseastag that the j lasgeet capacaty Arw pump as oposatang. I seconeeendat son e2 - The lacensee should perform a t h ur A 72 hout endusence test en at t Arw systee pesapo, af such endurence test of 18te Arw peamps wall t>e l contanasoese persod of operataea has not been conducted dursng the inattet testang program. le O test et accompt aottedw.to date. yalIawang ahe 72 heve p.asse e tese. me. 3 4 s,e.h t do n d cooied doen and then g sesearted and rien fos one hour. Test acceptance crataraa should asaclande demonstratareg that the pumpe ..ee.a. wa tsa n doe s a is.ste wath ree ect to tsa r asegAmear a ng e s t toeperatesgos and vabretten and that l pump room amhaent condatsene gtemperature, beanadaty) 40 eiet escoed envasesumental gnsais f acetsoa t aalts fos" l CCfety-related sp apanent as the room. secomumendersom e1 - 7the lacensee should Saylement EM follonsang repa remente se speca sted by stem 2.1. M om i page a.32 et asL w oS78: I1) Safety-grade asedacetsoa of AFw flow to each Safety grade flow and4cattosa of t8es AFw flow to each steen generatos should be provaded &n the once-throuqtt steam generatos (OTSC) as provaded at control room i Madlerat an accordance w& th IsWREG-OS78 Recomumendetson 2-8.7.b. Redundancy as provaded througsa safety gaede (28 The AFW flow a ns t r nament channele should be level a sula c ot t on o f each CFr5G. poweses free the emeegency bween cenasetent wata sataafyang the emergency poses dawersaty requatemente f or the And eyeten set forth as A sa n t a ae y systees se mach Technacal Pesatson i 10A.IO Sevasson 30 10/80 I
CIOLAIS &&2-FSAR 1 taA.3 carneis,c= or ws aaot.ame aos oF M8m465411_. ' Anbess m @:a. ey m ruwe dg-gro sysTot racs cm w Tae ma eaccesecamer om mecommendeeasa Be*e~ise i Is-1 et t.he standard moview Flen. Sectaast &c.4.g. a.rresumendetsee #4 Lacensees wa tan plants wensch reguare The Mailand procederee for periodac surveallesece Tipcel semesel s e el a gsument of valves to condect $4esnoene t est stig of AW wa !! sectende provaa.aosse for operator toe t s on osse Ans sys tem t r e a n ene$ wen s c h hewe only eene trasmun e re t s on w a t h Lane sent s ol s eem any t ame em Arts eemeinsne saw trean eventee,se res o,,e. e s a es es t e esean se j' propose Techseacet specafacettesse to psovide that a removed free servsce for testang. dedaceted andawadisal who se an commesnacetaea ma th the centros reen se statnoned et the menwel wolves. Upon snetruction face tJoe contret room. thae operator womand re-olagun the welwee an the A#w eyetse tems tAe teet mm de tm ate aperettostal e14gmeest. ISA.3.3 taAg M 85 h e t&ehS a.commendet tee ct.- t - res plante wa tan a menwet stertang autemetac esfety < trade inteistloa of Arts se prepW14ed at 30 M ietee. the laceasee oliens&d smote 14 e system to M141and. A detailed deecript8ea of the AFtsM and a estaaetacelly amatsete the AFtf system floor. Thaa system lasting of the antaletime signale een he fee =4 an and eseocaeted aestaaet ac sea t set son e agnale eatsns44 he St.been son 7.3.3.3.6. eenagreed and seeteated te meet eefear-grade empu a r enen te, stonese1 AFtr ayetem oter t arid coatrel cepebalaty samoisId he reteamed wath semesel etert servang as hectup to eestaaet3c AFW erstem Saattatsen. secoemender son CL Lacemoees watJa paamt doesgne as wesach all dyr amery esad etternetal water easept see to LJee Perellel papang se provided an the Madland AFw system Artf systems pese through welwee na a sangle flow path for the prasary and secondary water seesrces (see Chould saatell redisedent perellet flew pathe Spapang Fagieres 10.4-10 sheet 2 and 10.4-13 Sheet 2). and weIweep, l i ge$essmeade_taen Ct. AE 8 e se t *** AF* e ye tem pump 4*4 The etees tusbame erteen AFW peep ae cepehle ef i a te es ecc a e t ed flow potas and essest n e l snete e ntetson supptyang f eedwat e r to tame e t ese gene r s t ore for et cano 4 4 automet ace 4 a y saaesete Asv syetem flow and a e 4eest J housa f attomang a lose of 411 oc penser se cepeale et means operated andependently of eary ec power dascussed an Sieheectaea &G.4.g.3. eow2ce for et neeet t we sieur e. casevere aom of ec po* ea to ec power as acceptehle. e c==m _adessen - ca. 4 t.a cemeaen hevane plaats wath Frotect son of the Medies a Arw pumpe agesnet a tese of I empsetected normeF AFw egetae water e=4 place show&d t he pa ames y water notarce (Condeneste otorage tene) cwetanate the drenge of their Atw systems to detesesse p r ov s ded try en automatic ewatchower to tame eefety grade se i af autamette protectaan of the p w e se necessary servace water system. See suan sec t a ese 10. 4. g. 3. \\ 494-12 Dev t e 40s 30 le/se
scrouum is.2-rsan 1M 3 nuttaal W OF THE mit4AJe_ 6e inngd:wi co,.,% g j,44JRit.I Aar f ttbuATER SYST1A 145tcm wlTH THE ettXuggumattoes ,m_,3,--- Receemendetaom sesponae followang e seassac event or tornede The teme avestense nerose y, same,e.ac.a. eterme.no andacatione avestemae to t e cont r a s r oom c,s.o r.t e r. en.s the tame nece s se t y for as t a on ehees 44 De cone a do r edsameneang the prettee end tetang ne an determanareg whether oper ater oct aon can be sel sed cui to prevent p g deseqe Comenderatson shew!d be gaves to prova.3ang Pump protect aen by asene e ch se evt netas ovatchever of the m sectaone to the etternate setety-gsade sousce of water, esteestac p g taspe se too auctsema psesoure, et upgredang the normal source of water to meet seassac category I and seenees protecenoe e gene monte meccomenwsee aon Ct-S - The 1sconeee sheu14 mpgrese the See t r>e ree:=ocse eo secommmendet ton cL-3. I 33 AfW eyetee L temutic anstaatsoa signale and cascuate to meet eetety-grade segwasemoets. 30 \\ 804-12 888** 33 8e ! 4/
'~ ~ - ~ ~ ~ ~ ~ -~ cantase aa2-naa r i asA e essecessgs_to,nse orp ssrs,ros m, . et, s..__s ar samn71.m._~s maam a mi rna, eAs s s, wa_a m l 3e ama, oa Ms s sa___p rtys to t w, .eth,_aretL_,ge n= o s. 1. D****8** Seest a.= lea, e
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se saA S.a a teeneery one ese.. e..aese=e .-e e<cament c am a.se s ee... t so s a h a ng arws u.e enna. aweasseer reedwater erstem (Arws faowrate <==eeta.o. was set ty functaonal regisaremente. That fleurate was flow s egn a g emeent e, a nc 3 edaag trae fellwwang t hen was a f sed to be acceptable we a ng Stae trans s ent eeente-li which w*wle regesee the eseatest afwe flow. Tsee t s e.es s ee.t e 3a twee of smaam Feed (IM) cone s eer ed wer e ana l ysed sad ar e 3de st a f s ed an table 40A-1. The evoets l a s ted sa LAn s gues t a ess we,a s h ese e.v t saateded sa Tette sea-8 wa8.' aloe 8,e 3e sJerw w/ lees er estese* A power e.baseated 3) EJerw w/3ese er enes te sad of tma te Ac T?ne functaonal segestreseets for the AswS fleurate are power to remove the decay heat generated af ter a reacter ebuteuws: el Fleast coeldews and to provaes a emooth reactor coolant gjens j tsansatson fram forced carceslet ten to natisaat c a t culat s on sha,wid a lose et of fen te power (140r) 53 Turname te sp wath and watJmoest hypsee occur es**lten*owsty wath tame need ter Aew. Tsne functaenet op amean steam asotatsen valve closure re9waramente resulted an an AFws flowrate of 859 esa to t,e delasered to the steam generator within to e cora. et the anstaatsen saysas. Tame tame et 73 sam a n f.ee same tresa 2 40 seren.se wee chooem to allow the Arws to assect 33 te eneses en sam a n st e em tane pseaa one began sacreassne steme peesseter Jewel to the Sol opesatang range level, reqasted for natiscal casculataan, praer to cesplesson et the reector coelaat pway 48 Smel! bream ODcA s eas t down at that tame. Lane dessem tiewrote was eesected to be equel to er greater thaan tame decay tiest toe other tramesent er acesenet cond s t s osee generatson tate. met 8aete4 ansve Dercawee decay heat rate changes wsth tame. ether va4weo thasa ee seconde and aSe gre cow 4e sneve been meed and been eccep0mble. I These pasamsters were thee used sa trametent arid occseent eweleatsuno. The toes of feedwetes (thewt trenement so the moet tasatang ser Arms taew. The ensaymas soewoptaone ter tante event are addreseed an tame senyonee to gue sta osa 3 8A.4.2. All ether trenesents wh 4 c h e s tr.e t r eqw a r e or aseesmo take avs a l ah t i t ty o f AFw an the eately ana l ye s e use same 3es a gst vetees derawed fees tAe twytsonal s egnsa reement s. The evente S a e t ed a n Eac t eenste 2 e f the D. F. Sees. Jr., i 1 84A=&S Se e s e lost 13 4/98 . -. - - - - - - - - - - - - ' ^ ^ ^ ^ ^ ^ ^ ^
^ Cste.asso SAJ-ream sea.4 asse.esg>_Yp_ M esga u ts_ rue srsTrsts rtone agesamMs rQ_ seeaservesneTjos etcAepassc_;sec SAs s ton Arw k_fJ!sEJLtsTTEe_TTLL L8*MqL Afa a1_f4, aseo2_of He a en,aser a testat. 88 gy N oneetson ee = se settee to s se se e33 dated apea4 24 Seee, wenscan are nt sac 4 eed en Teasle 804-8. ese dascussed belone: toes or nasa readmeter (tserwp wit en tone or onette end es f os s7W'Le JThte event is not's desi9n beel'e~of tie ~pTeKt' ee=T cc,neeweetly as not sneladed an Chapter Ib esowev er, followine e temporary toes of att oc s==er. the steem turt,ane deseen ArW pway can 8,e used to sups,1y sa f f $ c t en.t..feedemeter to both eteeen generatore ee di.co...d an ,e.cEs.e 1e.e...s. re.at~ coo 4 n - piant ide .a u. erv. e rect e olled e~went watn decay meet levels equel to or lowes then an the emergency conds tson identa tted as the desaen tree e event Ytne desaen basae event bewsnds thee case toe erw flow requased. cretectsesi egegnet potentset arv overcouisag is provsded by the AFtf level teentrol erstem deses sbed in senteectaea Is.o.g. tee ss ane ve op us es* end w8 thout Sygese - This event 33 4.,re~ ant offeet. i.e A 6 eTs afi~feile, in edisch c a se t e.e t>erw event s,reviously addressed would e. ad e s., arse. desegn. I stesa Steam Isolatlon Welwe c1 eu g - A eta, taste event 9 6 h e not dsrectt esecwesed eneve.y effect the AtwS entese SWW te loot es
- =*I breet teme-of-Cootent Acendent Tt.e 'AYu Totiers'e~esAemed for t G even(taraj.
t are 4,ecratse4 ac Tos. scal Aeport SAas-100%2 updated by lesser rep =*rt. J.n. Taylot (86W) to S.A, Verage sensses, 1/18/18, and the recently s eettled 86W t es.oe t eatatted t welwetiosi of Tr enesent Seheesor ena smets meector foulemt Systes steeks an the 111 F A plant. S/01/79 These documente discues t he arws itoerete end show t ha t es utal not teed tre the e so n ee se== of tse ecceptance crtterte. D. Descranne the plant p r ot ec t s oen e.ceptance The plant protection ecs.epteence craterse for each es s ter s e e.id ces s esporesa ng t echn ace s, beses es t adent ese lasted an Tehle 404-4 along watas the weed for e a ss enetsetang event seestarsed techascal 4. ease for each acceptance cratersen. The etewe The ecceptern e es s ter se ottoeld addrese tsenesent evente adentsfied an Questien 3 weisch are not 104-84 Sev 8 sions 33 4/a3 I
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plaat I saa te eac h es. sewleded an Te2.le 10A-I ese not towndsag evente. have r.s. t been ene6paed. and me seech de seet have ecceptance shoeseuss SCS preeemse (polar og estety e a st es se The we8*e actestsea) esseptance etstesse for e emelt bace4 14( A ase a nc l uded sa tame docessente adents faed Se s c open. to 9weetsee Se. that temperature er denege taaste (LeNE. STT. messemi feel centret m g r ec t., ge,. gent eyotes (er s 3 coas t s ong rete le
- "pe r e t#r o l sms a laest re8etswe to aces 4ent acceptance craterte.
W sh a f e t y least for all teenssents utasch use AFW acs coettag sete lamat to evond fue estegetson as that the rose reeels cos.2ed trat96 eecesesse coelaat shasatego witamate errestence ersteria besag these addresse8 ,, g,,, g, s an g, y,,, e e ane sent e me. scan seewst en ses samum e t een gene r a t or 3 eve l te ersonsas tree ,5,tesour t ser oc for weitch not iscal eseure eettacaeet steam geneester ,,,,,g,,,,,, ,,go,,g,, g,g,,,,,,,g, ,,,g g.gg,, heat Stemeret ses4 f ece to reepwe ,, g,,,esweseer level and subcoolanag ta eccemplisted escay heat and/or cooleeum the t,y swe l l e en*3 due to Core heat t apest end &meentory pasmery erstem. a ce s es e s a n== any hsgh-Sereesere anjection. steen generater sewel 4e met beood en decer heet 33 e =wea rete or coeldsmus capabs t sty. steen generater leven an eer sable dependtag es the plant comes taese. Ttue tevet se noreetly low eenen remowang decer heet wsth terced orseesy carculetsen. vme s eve s s e seeme s t y hs ges we en e ..,.e eecer sneet watas noteral carculettoes. It as also set ksges for anell loca es deecrated ass tapacen sepest saw soesa. and se the amar report. stweleetsen et Tsenesent pehawser eend ame&& meector coolesst systee 1 tseete 184 0 2 i mesceame the ' tec ensn a ce t one4yees and ese g taone and correependaag Aa <* a scuemed sa ehe resposee to theeetIem Ie above, tSee sosta t scets oa eseed wa th pleet conda t ases d*ssga beese event conesented an 1.e. ehowe seclodsag. u0tSch werIfles 40be APWS destga
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The analyin.s ses.mpeonas for taas seemt are Isoned below gneyed to 93-setters at e r-e etwe st tem s. Correspondenes tecknical bas e a t scat ar*a. wobere not erecifscelly issted beloer, s o t ened c.a 5 l acene snee regnestement e and poussent enganeer-se e s.Seeeat et r ese t one o f t he emelyess. The infor-me t : >= se..<> e se vad*** f ee e ste other evenes 84enteised sa On.eet s. a le sad facele 34A-8 taecanese teme lose-o(~ fee 4*eter event as 84 e meet 13matlag. 304-3% l aevision 33 4/8! l - - - - - - - - ' - - ~ ~ '~- ~ ~
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l 'I 'l r APPENDII C i I TECENICAL SPECIFICATION 14.3/4.7. 1.2 i ( f I i l J i i 4 .~._,-.~..__...._._ _____________ _ __ _ __
i N!D3 jus 182-FSAR B.Mrf sYsTaps amtILImat_rzame.?mt mm2m f m'Mme ent-top som wucu e a l I 3.7.1.2 Two independent steam generator asuttiary feedwater pumpe and associated flowpathe shall be oftmasu with: che aus111ary feedweter pamp capatie of belag s. i powered from an CPERA33 eastgency bus. b. One ammillary feedwater psay onpsble of being powered free an CPERAELI steam supply system. I Operation of the essas driven ausiliary feedwater e. pump for McCES 1, 2, J, and 4. eucept for serve 111ance and testing nquirements and waan { actuated by station emergency conditions, is l i prohihited anlass tne electzte drima feedwer pump is inoperable. i 1 APPLICAafmY3 MODEB 1, 2, and J. AS11GE8 i i with one ausiliary feedieter eyetna inoperable, i a restore the inoperable system to oppAzu statue witala 72 hours or be in alof SMUTDOWN within the 12 hours. next l EUpVfft'2"CF RECUIREMENTS i 4.7.1.2 rach semiliary feeduster syster shall be demonstrated CPDAaLu At least once per 31 ' days on a STAGGERED TEST FASta a. kS Y 1. Verifying that the steam turbine driven pump develops a discharge paseure of 4 1,160 peig above svetion pressure at a flow of & 054 gpe den the secondary stese supply pressure is greater than 485 psig een tested as required by specification e.0.5. Revision 5 16.3/4.7-4 2/78
l i MIDfJus 1&2-PSAR Pt.Mff STETINS l " W at M_ M 11;- _-1; (-x ce4 - :S 2. Verifying that the actor driven pump develops a discharge pressure of 1 (t.Afth) peig at a flew of.1 (IATER) p when tested se required by specification 4.0.5. 3. Verifying that each valve (manual, power operated, or automatic) in the flowpath that ta ret locked, sealed er otherwise secured in peettles, is in its correct position. l 4. Entry inte stede 3 is allowed for the purpose of perferning surveillease testing 20 Requirenas 4.7.1.2.a.1. f h. At least ease per la meaths, during shutdown, by: i 1. Verifying that each automatie valve in the flewpath actuates to its correct position on an aum111ery feedwater actuation test signal. { 2. Veritytag that each pump starta automatically upon receipt of an ausiliary feedwater actuatten teet signal. 3. Vertlytag that the aus111ary feedwater staan generatar level control valves maintain a steam generat&T level of (IATsa). 4. Verifyias that dbe aus111ary feedwater pump i etops and the esm111ery feedwater creestte l valve closee automatically upon a high level in the assectated loop steam generator of (LATER) feet concurrent with an ausiliary feedwater actuation test signal. i S. Verifying that the nuailtary feedwater pump 'estarts when the associated steam t...rator level falla below (t.ATER) feet from the high levet in Itan 4 above, coecurrent with an aust11ary feedvater actuatten test signal. Devision 29 14.3/4.7.S
- gj7,
1. I l l I APPEND 3 D i i i i l NUREG-0667 RESPONSES, i 4 l RECOMMENDATIONS 9,10,21 1 a I l 4 I i I l l' l i i \\ j \\ l i 4 i i 1 \\ l 1 l l l l l a 1 ? -~~-.--..c,v+--,... - ~--, - - +
- ~ ' ' ~- NIDIAND 1&2-FSAk RESPONSES TO 708T-1N1-2 ISSUES A85 EVENTS ( PART !!! NUR30-0647 RESPCNSES Recoussendation 9 - Post-trip Pressure and !avel Response i Resoonse the fellowinn performance criteria for acceptable normal post-trip plant response have been developed: Reactor coolant system (Rcs) pressere remains above the a. setpoint for automatic high-pressure injection (EFI) actuatien. b. RCs pressure remains below the setpoint for Ac8 code safety valve actuation. Ac5 tasperature decrease does not ascoed technical c. specification limits ( 100F decrease in 1 hour). d. Reactor coolant is contained within the primary RCS and quench ta.%. Indicated pressurizer level remains on scale. e. ( f. Ind2cated staan generator level remains on scale. These criteria are based on measured plant variables and reflect 30 the expected Midland response for normal reactor trips. A review of resctor trip data identified several instances where perforwance criteria were not met. The causas of these abnormal responses and the Midland design features espected to prevent these ocentrences are addressed below: IXCessive Main Feedwater d. improper control of main feedwater etter a reactor trip can lead to 'vercooling of the primary system with a potential for loss of pressuriser leva' indication and caa11enge to t W MFI system. Even ually, control problems could lead to once-throutrh steam enerator (OT5G) overfill. with respect to this concern.The Midland design has been reviewed A failure modes and effects analysis (FMEA) was conducted on-the integrated control system (ICs) and is being completed et the main feedwater system. It is anticipated that these studies will verify the capability to automatically control the post-trip main feedwater flow tv ensure ecceptable plant response. A review of the main fee &ater overfill concern has led to a recommiended design modification 5 !!!-13 Revision 30 10/80 l
Ninum la2-r*An RESMEBSIS 10 p0ST-1NI-2 L!tES Am EVENTS PART !!! E! REG 4647 BEspGrSES which will be implemented to ensure feedwater la i terminated before the OTsc is filled. b.' Excessive Auxiliary Feedwater In the event of a reactor trip coincident with loss of main feedwater, auxiliary feedwater (AFW) provides the source of cooling water used to remove decay heat. Under these circumstances, improper control of AFW may lead to overcooling or overfill probines similar to those of main feedwater as discusred above. Due to the importance of proper APW control, several desip features exist or will be incorporated by amendment within the Midland desip. First, the AFW 1evel control system is being modified to provide for the addition of AFW at a prograsused rate. This rate will be sufficient to ensure establishment and maintenance of natural circulation while limiting the extent to which the BCS is cooled. The result will be a smoother and dampened post-trip response. Secondly OTsc overfill due to improper AFW control is precluded by existing plant features whic!. terminate AFW injection before the steam generator is filled. Asalysis of the plant performance during such events is provided in the Response to IRC Question 3C 211.184. A description of the AFW 1evel control system is provided in subsections 10.4.9 7.3.3.2.6. and 7.4.1.1.1. Final 1F, the acceptability of the entire AFW system, including its control systems, is being evaluated through the preparation of an estensive AFW reliability analysis. . design deficiencies identified by this study will beAlthough not anticipated, an satisfactorily remedied. OTSG Underfeeding Due to 14ss of Main Feedwater and c. Delayed Auxiliary Feedwater The potential for this concern is affected by the ' reliability of both the main and auxiliary feedwater systems. Evaluation of these reliabilities, and improvements where necessary, are being addressed through FIEA and reliability analyses and design changes discussed in Itsas a and b above. In addition to these studies and improvements, additional modifications are being made to the AfW system which are espected to improve its reliability. Specifically, changes are being made to the AFW suction piping to remove system interconnections and therefore unitise the systems. The discharge piping is also being modified to provide !!!-14 Revision 30 10/80
l NIDLAls 1&2-F5Ak RESPCNSES TO P087-TN!-2 ISSUES Alm ETENTS r l PART !!! 5U33D-0447 RESPONSE 3 redundant flow paths from each Afw pump to each steam generator. 'these efforts, to be docinsented through the use of rtetA and reliability analysis techniques, are espected to reeuit in highhy re11able systans for assuming timely sad adequate secondary neat removal. d. Excessive steam as11ef 1 l Improper control of secondary system pressure afte'r a reactor trip can result in overcoeling of the primary system and undesirable primary pressure / temperature response. To prevent this occurrence, the ICS must be te.:,:! for proper speration of the turbine bypass system and the list and blowdown setpoints of the main steam safety valves must be adjustad correctly. Careful attention will be paid to these requirements during preoperational testing to ensure proper system operation. Stuck-open Power operated Relief valve e. Excessive primary system blowdown reau.1. ting from failure be prevented bof the power operated relief valve (FORV) to reseat will ( block valves. y automatic isolation by the two FORV An isolation signal will be transmitted when coincident logic of PCRV open position and low RCS pressure is satisfied. This design feature will ensure that, for anticipattd transient or accident conditions 30 calling for PCav actuation, the failura of the PCRV to aitigated. reseat or improper blowdown will be automatically f. Racessive Nigh-Pressure InjenWn Fluid valves may be challenged by the prolonged operation the MP! systam. Termination of NP! flow requires t satisfaction of certain small break operator guidelines and, therefore, relies upon reliable and sufficient indication of plant status. Midland plant operators will be provided with indication of pressuriser level, hot-les temperature, RCS pressure and saturation margin independent of nonneclear instrumentation or ICS availability. With this instrumentation available to the operator, termination of EP! flow, when warranted, can occur on a timely basis. k !!!-15 Revision 30 10/M I - - - ~ ~ ~ ~ ~ ~ ~' ~ ~ ~
N!DEAS 142-FSAR RESMMBES TO 7087-1581-2 !$8UBS AND r/Ilrfs FART !!! NURREN M47 RESFtNSES These design features are sapested to ensure satisfaction of the established post-trip response performance critaria. No 30 immediate operstar action will be necessary. l , i l 1 1 1 4 4 f I i l !!!-16 Revision 30 10/80 ---w ,,--,+ ,e
Nr0 LAID 142-FSAR j RBspcusES TO 7087-TW1-2 Issass AaB E W rfs PART !!! N 0647 REspcusts l '
- r.-detion 10 - Sensitivity studies to.5% of50 Ressoggt SE-ESSE 90E.1 A review of plant trip data compiled far the estreat SW operating plants has identified several causes for overcooling I
and undercooling events. These causes, and the design features esisting er planned for Nidland plaat Unita 1 and 2 that address 1 M them, are presented in the response ta necesseadation 9. Jo general, features currently asist or are being added ts essere Addittomaily, proper feedwater and steam pressure centrol.instruesatation will be provided to allow the operator to properly and promptly interfeco with autamatic plant features. Finally, a failure modes and effecto analyste and reliability analyses are being cemencted to answo that systems called upon to prevent er reopend to secondary l coolant flow perturbations meet design critaria requirements. fI I. it A 1 k !!!al? Revtaton 30 10/80 I ~~ ~ ~ ' ~ ~ v w
- - - - - ~ - ~ ~ ~ ~ ~ ~ ~ ~ ~ ' ' ~ ~ ' ~ ~ 1 NIDA. AID 142-FSAR REspostas 10 Post TMI-2 !$3UES Alm IVEarf3 PART !!! WURSO-4647 REspCpsts Recommendation 21 - Reevolustico of Anillery rwdweter systes Iniection Feist Resannat Introducties of emaillary feeheter (Afd) threegh the top spray operger wee a conscious essign decastem ataed at improving natural circulatten flow capellities ' whale sintaining the i poteetken for thermal eheck concerne. The elevated injectaan point la of pertacular Nf at sn:'er condatione during which reactor emelant pumpe are usavailable eresting a lar drivimp head la the steen generater and, therefore, ger thermal improved 38 natura., citestatase flew. In addittee, for autamet.ic Ard initiation ene to lose of esta feedwater, the elevated AFW additlen aantaines thermal shock of the steam generater vessel well and lower tee sheet. The concern that laattated this recommendation to overcoelang of the reactor coolant eyetse due to Arv snjection. pelocating tAs Atw injection potnt will provide mantaal rettet. Overcoelang dwe te Arw injectise aan be psoperly and adequately prevented tAreegh the proper toetzol of Atv flow. The Nadland AFw level (flewl control desus is discussed an the neopease to WUREG-0M7 secommendation 2. I I I l Ill 20 sevleton 30 10f 00 i . _, - - - - - - - - - - - - - - - - - - - - - - - - - - ~ ~ ~ ~ ~ ~ ~ - " ~ ~ ~ ~ " ~ " ~ ~ ~ ~
.. ~..__.. -. _ -- ---_- _ _- - - - _ - - - - _ _ _ _ _ _ _ - - - - - - - - - _ - - - _ _ - _ _ _ - - - - - - - - - - - - - - - - - 1 AstruoI2 e FSMt gJEst!Ci 211.144 t i 9 e l l l l
- -- ' - - - - - - - ~ - ~ ~ toepsmoes te lac geestions Ridland 1A2 l thaasgion 21L1H (15.2) amaring the resset revise of the locy of-effsite-power prosperative tatt proceders for anewsr Omat, a concern arose regardtag tas omstrel of OTSC leM1 by the aus111ary feedwater system daring the west. specific 417, evercoeling of the primary system eseld result from fondiwJ the OtsG with the cold anna 111ary faseseta. 'the coeldews sauld be large enough to empty the presseriser asid cause a staan huhele ta fMs in the het leg h&WL pelata, metica emeld impede nataral circulation and core n emellag. Address this concere for the Nadland units. Provide the resulta of an analyste of a looe-of-effetta power sesuming the weret-esse tat tial condat.sene (lee power appears to be worst stace programmed staae 9eneratar level is loweet). laciude plots of steam generatet leven, reactor emelsat systan temperature, and presournaar lese).. Discuss your assumptione regarding auallaary foodneter centrel. Shoe that IE3fta will remain above 1.30 and sare emellag will est he impaired. ' i e,q,ne, operatang espertence at other tw planta has clearly demonstrated I the potentn al far sua 11ary feedwater ( AFW) anduced Jvercooling evvets during law decay heat load candstaans. An investigetton j of petential modtf1 cations wfisch weeld reduce the likalthood of even eventa at 2141and has been condected by SW, As a result of the study, the fe!! awing features have toes tacorporated into the des 1gn ef the as41and Asw level contial eyetame: Dual stoes generater level setpeists of appremisately 4. 2 feet when forced circulat.Los is available and 20 feet when forced circulattaa is met avan 14 ale have oeen added to the Arw level control syntes. The lower level setpetat providee adogsate decay heat reeeval without evercooling uten t2e reacter ceetant pumps 4f4CFsI ate ruaming, and the higher level setpoint ensurita the establishment of Satural circulation in the reactor 30 coolant systas (act) when et least three of fevr acte l are eff. The AFw level control erstan will oonttot the etatwe of all acts and avtametically select the appsopriate setpoint. b. After the correct setpoint to 4eterataed the Arw level control valves will reopend la propertion to the errer between the actual level and the settsint to maintain a cenetant once-through ateam generator level. However. logic het been added to the controle of each AFw level control velve which will automatically limit the rate of increase of the steam generator != vel to a value which prevents escoselve heat teenval free the acs and rapid ehrinnege of the reacter coolant. Devision jo 96E ll.2-22 lofeo
~ ~ ~ ~ l ampo e to une anatione nadiand 142 4 ( The Arw level sentrol systes, including the abese modifications, l is safety grade, as discussed la FSAA Subsections 7.4.1.1.1 and 10 4.s. i The anstmum allowable rate of steam genvator level increase under worst case conditione has been cale. 21sted by SMt to be 4 approstaataly 4 inches per minute. asweven praeperatiemal and post-fuel toed tests will "se conducted ta wify that the setpotata and flowrates utilised la tAAs leve; control system are adequate to malatain the reactor in het standby. j The 36W investigation of Atw induced overcoeling transienta indicated that a loss-of-offsite power (1407) event at low reactor r levels would produce the yeatest potential for evercool ag. Analyses of predacted midland perfe 1mance following a 1407 have been perforined using a e inch per ataute rate limit 1 on steam generator level and the resulta are shown for inattel power levels of 1001, 40%, and 15% in Fifaree 15.2-11, 15.2-12 and 15.2-13. respectively. These analyses were perterined with the AUX-1 computer code developed by SMd for use in analyzing steam generator perforwace following AFM syntan actuation. 15% anstial power case shows that the indicated pressurizer level The reaches sero at approstaately 14.4 minutes into the transtant. Wowever. this analysts was performed ustng the following conservative assu.sptions: C. set makeup flow into the RCS is sero. a. I b. Ae indicated pressuriser range of 320 iaches was used N instead of the actual 400 inch range. taltial pressuriser level was set at les inches. c. The improved safety grade AFw level control system. combined with Midland's eatended pressurt:er level indicating range and the operator's amtlity to establien makeup flow, will provide adequate protection against AFw induced overcooling transtants. For event scenarios which include energency core cooltag actuation systee actuation, priority will be given to maintaining AFW flow regardless of indicated pressuriser level. nucleate belling retto (Duna)F1AA subsection 15.3.1 shows that the m 1.4 seconds after the less of all BCPs.is reached approntastely During this brief time. of AfW eystem operation and depends only on the coastdo and the initial inventory of water in the steam generators, same elight effects due to variations la RCS pressure or stone pressure. In addition. AUX 1 and the data on wh.ich it is benchmarked show that maximum overcooling (and minimus k lt Q6A 15.2-23 Pevision 30 1 10/80 ^ - ' ~
i i .) aseyeeses to unc Geestions midland 1s2 pressuriser level) occurs 5 mimetes er nors into the 2007 event. Herefore, there is no potential for reaching utnimamm DNBa duriat AM induced overcooling transients. 30 I j 1 1 I i l Osa 15.2-24 nevision 30 10/80
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l i t I i l l APPEND H F t I FSAR CFJWTR 7 l (SELECTED SICTIONS) I i 1 1 l I I i i I i I l 1 i i l r
NIDIAlm 2&2-FSAR anvenmaury. The equipment and systems actuated by NSLIS are of sh====1ves independent and redundant (escept the main staan line inelation valve described in Section 10.3). Independent actuation channels are provided on a one-to-one basis with the mechanical equipment trains to be controlled. Redundant actnation sipals from two independent actuation channels are isolated, then combined using ca logic on the main staan imetation valve actuator. 1 Through a hydraulic testing mechanism one actuation channel may be tested through its output device to partially stroke the main steen line isolation valve without the loss of the protection function. During such testing, the ca logic on the main steam isolation valve actuator converts to AND logic and energency closure will occur when both actuation channels are actuated 4 either manually 3r automatically, when valve test is completed the actuator logic reverts automatically to normal ca logic. The testing sequence of the final output device is continuously = = aciated in the main control room. DIVSa3ITY - Diversity of the sensed variables which initiate MSLIS is provided by the use of either an ECCAS actuation, or low l32 stems generator pressure in either steam generator to sense a main steam line or steam generator rupture. ACTt!ATED DEVICES - Table 7.3-3 shows the devices actuated by MSLIS. DESIGN BASES - The design bases for MSLIS are the process system requirements listed in Subsection 6.2.4 and additional actuation system requirements are etiscussed in Subsection 7.3.3.3. 7.3.3.2.6 Auaillary Feedwater Actuation System The purpose of the AFWAS is te laitiate the supply of ausiliary feedwater to the steam generators to allow primary heat removal through the steam generators following a loss of main feedwater 33 or a loss of offsite power incidset. AFWAS automatically starts bota the turbine driven and motor drivan AFW pumps and correctly positions the AFW valves. The AFw system is described in subsection 10.4.g. In addition to conformance with the general description of the ~' owner supplied ESFAS subsystems (see subsection 7.3.3.1), the AFWAs also has the following special features. INITIATING CIRCUIT 5 - AFWAS will be initiated by any of several possible input signals: low pressure in either steam generator, a low water level in either steam generator, loss of three out of l30 t four reactor coolant pumps, loss of both main feed pumps 133 class 1E bus undervoltage, presence of emergency core coo, ling a 30 actuation signal, or a manual trip. Setpoints, ranges, and the locatione of the sensort may be found in Table 7.3-2. !33 Revision 33 7.3-28 4/81 l l
MIDLAS 1&2-FSAR IACIC - The logic for AFwAS is shown in Figurs 7.3-4. l 33 STPASS - The integrated leak rate test bypass is discusset with RBIS-1 in subsection 7.3.3.2.1. A bypass of NSLIS is provided to avoid actuation of both the [ 33 l AFus and the MsLIS systans by a low steam generator pressure i during normal startup and shutdown conditions as described in the i MSLIS subsection. Bypasses are also provided to avoid actuation of AFMAS by loss of both sain feed pusps trip signal and by loss i of three out of four reactor coolant puspa signal during normal startup and shutdown. Indicattom of the systes bypasses is 4 described in Section 7.5. INTERICKS - The Midland AFW systems are aquipped with a feed-only-good generator (Focc) control system which operatas to telainate Arw flow to a faulted steam generator. The FOGG system continuously monitors the differential pressure between the steam generators. When a differential pressure of (by -admaat) or greater is sensed, FOGG automatically closes the AFw isolation and control valves supplying the lower pressure once-through 30 steam generator (OTSC) and the steam supply valve from the lower pressure OTSC to the steam turbine driven AFW pump. The continuous interrogation feature of this system permits isolation any time during a secondary pressure transient and allows the lower pressure CTsc to be returned to service should the differential pressure difference be reduced by corrective a.ction (i.e., main steam and feedwater line isolation). The valves actuated by FCCG are indicated in the F00G section of Table 7.3-3. The logics are shown in Figures 7.3-3, 7. 3-4, and 7.3-9. REDUNDANCY - Redundant actuation and controls are provided throughout the AFwAS on a one-to-one basis with mechanical equipment trains to ensure the required flow to both steam generators is the event of a single failure. DIvtaSITT - The AFwAs is diversified by utilising steam driven pumps with de train 3 control and 120Vac preferred power level l32 control valves, and motor drives pusps with 120Vac preferred Power level control valves. Diversity in the actuation signals 30 is provided by the sensing of multiple parameters (see Initiating Circuita above) any of which will cause Arw actuation if an abnormal condition is detected. provided at the subsystes level. In addition, manual actuation is AC7JATED DEVICES - Table 7.3-3 abows the devices actuated by AFWAS and their characteristics. DESIGN BASES - The design bases of the AFwA5 are the process system requirements listed in subeection 10.4.9.1 and the i specific actuation system requirements listed is subsection 7.3.3.3. Revision 33 7.3-29 4/31
NIDrase lat-FRAR i Main steam isolatica valve (ISIV) and main foodwater s. isolation valve (NFIV) controls b. Ammiliary feedwatar (ArW) osotrol Auxiliary feedwater supply switsbevor c. ' d. sain steam safety valves (no remote control required) e. Essential service water system controls f. Essential componest cooling water systas controls The following instrumentatiac capability is provided ta eenitor adequate tamperature contzol Wring safe shutdowns a. acs het and esid leg tasperature h. acs flowrata Once-through atmas generator (OTsG) pressure c. d. OTSC level e. Arw flowrata 33 7.4.1.1.3.1 Main steam Isolation Valve and Main reedwatar !aelation Valve Control controlled beat transfer from the acs to the secondary side of the steam generator must be established for coeldown. To ensure control of heat removal, the MsIve and NFIVs can be elooed maanally from the centrol room. In addition, the ms!To and ur!?s close automatically on low pressure in either staae gneerster or on an tecAs algaal, se described la subsection 7.3.3.2.5. IWIVs also close on high orso level to prevent overfill. i 7.4.1.1.3.2 Aus111ary Feedwater control on loss of sein feedwater, feedwater le automatically supplied to the steam generators from the AFW systas. The mechanical and aatcty aspects of the ArW aystem are discussed in detail in subsectica 10.4.9. Automatic actuation is from the AfW actuation system (Arms) which is one of the engineered safety features actuation systems. la subsection 7.3.3.2.4.A complete discussion of the Arths is given l37 subsequent to AFw actuation, control of level in the steen generators is accomplished using the Arw control valves la mach 133 Arv loop. Control signals for each Arw level control valve are supplied by redundant and independent class IK 1evel transmitters 30 on the associated stans generators. Controllers for each valve seviaise 33 7.4-7 4/91 1
E!DEAIS 1&2-F54R are located in the asia oestrol room and as the muziliary i abutdoes panel. Ta addition to estematic actuation by the ANAS. control to the AN level oestrel valves for startup, shutdown, or amargoesy operations can be ialtiated using these oestro11ere. INITIATTIM ClacutTS - AN level oestrol sipals are continuously generated by level osotrollers for the associated steam generater 33 but are blocked free reaching the associated aermally closed volve. Open ANAs actuation, the signal blocks are outematically removed and Ap level control aseenances. Daal level setpointe are need for level osotrol. A low level setpelat le stilised eben more than ene of the reacter coolant pumpe (RCPe) is operating (signifying ferood circulation) and a high level eetpoint is used when three out of fear acte are tripped i (anticipattag natural circulaties). The setpoint switchever is 30 achieved by a safety grade sectioneering device idLich sensee BCP etatus. In addition, when the plast changes frem forced circulaties te natural circulaties, the low level setpoint is ramped at a oestrolled rate to the high level se: point to prohibit everoseling of the primary leep. l IActe - fa the event of level transmitter failure, the AW osotrol valves may be maneelly controlled by r. mans of the bypass provisione discussed below. STPAssEs - typass of the ArwAs faitiatlag logic is discussed in subsection 7.3.3.2.4. aypass of automatic level control may be 127 accomplished by plectag the controller to the Arw control valve 130 in the manual mode. In this mode, the level setpoint can be manually changed for saaval level control. .) The transfer to manual control from the aus111ary shutdown panel l33 overrides automatic control capabilities and removes assual operation from the oestrol room. This allose fell control frne the auxiliary shutdoon panel regardless of the mode selected in the control rose. Auto /massal states of the ausiliary shutdoen 33 panel controller is displayed by indicating lights on the centrol room controller. These indicating lights are seed to bring attention to' an abnormal condittee affecting the associated i controle. For design beste inferination for the easiliary shutdown panel see tubeection 7.4.3.1.3. IltfTRI4cKs - AW control laterlecha are discessed in Subsectice 7.3.3.2.4. I l RCUNDANCY - The AW level control valve coittel systems are lIl redundant. These systems include redundant cleaa 13 level transmitters on the steam generater and redundant class 1E level controllers on the sain and emaillary shutdown panels, 30 DIVER $iTY = The AW level centrol velve control systems are net diverse. novision 33 7.4-4 4/31
CIDLA m 1A2-rsAR ACTUATED INVICSS - The AFW 1evel centrol valves are the actuated devices. SUPfCETIM STr!Eles - Power for the AFW 1evel costrel system is free the claea la 12Syde syntaa. Power for the AFW 1evel oestrel 33 valve is from the class 15 L20Vec preferred power eigglise (see l30 subeecties e.3.2.1). PCerYICNS pct asguttsD Fos SAFETT = All pertices of the AFW 1evel central system are required for safety. DEstcar basts !sFossETICM - The doetgm besee of the AN 1evel oestrel system (per Secties 3 of IIII std 279-1971) arms a. The generating staties condition wedch requirse protective actise le the meistaeance of pafe shetdown uslag the esalliasy feedwater eyetas, b. The generettag station variable that la required ta be asaltared le order to provide eestrel of the AFW ersten is staan generator level, c. steen ponerator level, toelation ard centrol valve 130 poettions, AFW pump operaties, and AFW flowrote are the 133 mislanas indicatione necessary to adequately seniter AFW operaties. 4. The normal operattog water level for the etsam generaters is 2 foot euttag forced circulatten, 20 feet 31 during natural streelaties. J(, i e. The easine and stalum design water levele for the l etoes generatare are opprestaately So feet and 1 feet above the betten tueesheet. f. The AN level controla are doetgned for the l33 envireamental conditions stated la Secties 3.11. The range of the environmental parameters for the electrical power supplice le diocessed la chapter 4. g. The AfW controle are designed to withstand the ef fecte of the oefe shuteswa earthpake without lose of operettee. The velves and centrole are located ta provoet lose of functica free elastle damme. i 1 b. AFuu reopense time (met including eeneers or actuated l devices, i. iees t .u.ee,een te pi establishing AFW flow, the level in the steen generaters can be ellowed ta ver" semewhat during sefe shutdowns therefore, toeposee thee for AFW 1eveo eemtrol to est critical for performance. ArW operation le inattated t,y (33 the Amka oben eteas generatar level reaches 1 foot (see subsection 7.3. 3 ). AFW 1evel centre 11ere are preset to auteewtically centzel steem generater level et 30 feet 130 Sovielen 33 7.4 9 4/s1 i
f HID MIS 143-FRAR I enring antaral circulaties and at 2 feet during farced circulation. 30 In addition to the AFW 1evel centrole described above, the AFW erstaan has the fellowing class II omstrels and switches to act as a backup to the level control systme: e. staan gemarator h1 gh level AFW 1evel centrol and isolation valve tr switches 30 h. Arw pump turbine speed controla c. AFW estar driven peep ee-off centrola d. AFW eystem actor operated egly feelatias valve eentrale enAW11BGB = 1,ogic diagrams will be submitted by emanheats P&IDe, ese Figaree 10.4-10 and 10.4-13; electrical schematice, see ) E-153, 3-154, and E-154 (submitted with drawings listed in Table 1.7-15); control boards will be submitted by hat. i 7.4.1.1.3.3 Aus111ary Feedwater Supply switchever Feedwater le normally supplied to AFW pump suction from the nonseismic Category I condeaeste storage tank. If the condensate storage tank or other ocurces of water are act available, a seismic Category I makeup supply from the service water system is provided. When required, the AFW pump suction will automatically switch over to the servtce water system, which will supply feedwater through two redundaat tralas. Concurrent with this switchever menselenic catagory I portione of the AFW eystem 33 sucties piping are isolated. INIT!ATING CISCUITS - Astamatio switchever to service water le initiated by an Aruns signal combined with a two-oet-of-four AFW l pump low section pressure. To prevent spurious opening of the service water supply valves because of normal pep start transients, the low evetion pressure must persist for 4 seconds before initiattag opentag of these valves. A completa discueston of the AFWAS le given la subeection 7.3.3.2.6. IACIC - There are four pressure tramaalttare on the auction side of each AFw pump. Before the service water notar operated valves are actuated, there must be as AF443 eignal concurrent with low pressure sipale free two of the four pressure transmitters and these signale oust persist for 4 secoede. MANUAI. CONTROL - The service water empply valves can be manually 120 opened from the nata control room or the aum111ary shutdown panels. For design beste information for the ses111ery shutdown pesel, see Subsectice 7.4.3.1.3. A i Sevision 33 7.4 10 4/81 1 - - -. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~ ~
NIDLAS 1&2-FSAR 2NTERIACK3 - AFW supply automatic switchover actuation is interlocked with the AFW pep low suctica pressure to avoid any spurious actuation of tbs switchover. 33 errunmawy. modundant AFW suction pressure instrumentation has l been used to provide a reliabis system. DI"Eas!Ty - The AFW supply switchover control systems are not 20 diverse. ACTUATED DEVICES - The service water and the condensate storage water supply valves are the actuated devices. DRA'JINGS - Zagic diagrams, see Drawings J-227 and J-252 (submitted with drawings listed in Table 1.7-11), and J-299 (Figures 7.3-2 through 7.3-9); loop diagrams, see Drawings J-337 i and J-334 (submitted with drawings listed in Table 1.7-12); electrical schematics, see Drawing E-158 (submitted with drawings listed in Table 1.7-15): centrol boards, see Drawings J-726 J-908, and J-909 (submitted with drawings listed in Table 1.7-9); and P& ids, see Figures 10.4-10 and 10.4-13. l 7.4.1.1.3.4 Main Steam safety Valves t The relief function of the sain steam safety valves is entirely mechanical and takes place automatically on high sain steam line pressure. There are no control systems. A complete discussion l of the main steam system and the main steam safety valves is i given in section 10.3. Additional steam relief capability is provided by the power operated atmospheric vent (FOAV) valves as 33 described la subsectise 7. 4.1. 2. 3. 2. 7.4.1.1.3.5 Essential Service Water System controls The essential service water system controls are discussed in l Subsection 9.2.1. 7.4.1.1.3.6 Essential Component Cooling Water System Controls The essential component cooling water system controls are discussed in subsection 9.2.2. 7.4.1.1.4 supporting systems for safe shutdown Instrumentation and Contsol Syataas The sumiliary support systems required for the operation of the safe shutdown instrumentation and control systans described in subsections 7.4.1.1.1, 7.4.1.1.2, and 7.4.1.1.3 are sa follows : a. Class 1E Power System Revision 33 7.4 11 4/s1
N!DEAMD 1&2-FSAR 7.4.2.1.3.2 Anziliary Feedwater control This section will address only AFW 1evel control. A complete analysis of the AnfA8 controls is included in the engineered safety features actuation system analysis (subsection 7.3.3.4). CCNFORMANCE TO IEEE STD 279-1971 - The AFW 1evel controls cogly with the following applicable portions of IEZI Std 279-1971: 33 s. Single-Failure Criterica - Any single failure in the AFW now controls will not prevent proper initiation of safety fanctions. This is acccaplished through the use of completely independent controls for each of the two AFW supply systems and redundant control loops for the AFW 1evel control valves. b. geality of Components and Modules - Equipment annufacturers are required to use high qualf.ty components and modules in equipment construction. Quality control procedures, use<* enring fabrication nrd testing, verify compliance with ~.his requirement. Equipment Qualification - Type tat.t data are available c. to verify that the AFW 1evel control equipment meets the l33 perfoznance requirements necessary for achieving the required system response. d. Chaanel Independence - Each level control channel is powered from an independent Class II power supply. In order to prevent interaction between redundant systems, the controls are wired independently and separated, with no electrical interconnections. system Interaction - The transmission of signals from e. nonsafety equipment to the AFW control system is l33 huffered by Class IE, seismically qualified isolators t which ensure that failure of the nonsafety equipment will not prevent the protection system from meeting the minimum performance requirements specified in the design bases. f. Capability for Test and Calibratica - Manual testing facilities have been built into the auxiliary feedwater controls for preoperational and online testing. g. Information Readout - The following are indicated on the main control panels and on the auxiliary shutdown panels l33 1. steam generator level l 1 2. AFW flow 3. AFW pumps rurmhg A Sevision 33 7.4-23 4/31
MIDfJutD 1&2-FSAR i ( 4. AFW isolation and e :pply valve positions l33 h. Identification - Physical identification of safety grade i power supplies and safety-related signal channals is done as described in subsection 8.3.1.3. 7.4.2.1. 3. 3 Auxiliary Feedwater Supply Switchover Control 33 Because a complete analysis of the AFWAS controls is included in the ESFAS analysis (subsection 7.3.3.4), this section will address normal AFW supply switchover to service water supply 20 controls only. CONFORMANCE TO IEEE STD 279-1971 - The AFW supply switchever controls comply with the following applicable portions of IEEE std 279-1971. single-Failure criterion - Any single failure in the AFW a. supply switchover control will not prevent proper 33 initiation of safety 1%netions. This is accomplished through the use of completely independent controls for each of the two AFW supply systems and redundant presst.re transmitters for the AFW supply switchover to service water. i b. Quality of components and Modules - Equipment manufacturers are required to use high quality components in equipment construction. Quality 20 construction procedures used during fabrication sad testing verify compliance with this requirement. System Interactica - The transmission of signals friar c. nonsafety equipment to the AFW control system is huffored by class 1E seismically qualified isolators 133 stuch that no failure of the nonsafety equipment will prevent the protection system from meeting the minimum performance requirements specified in the design bases. 20 d. Information Readout - The following are indicated on the sain control panels and on tbs auziff ary shutdown panel 1. AFW pump suction pressure e 2. AFW flow 3. AFV pump running 33 Arv isolation and supply valve position 4. CONFCSMANCE TO IEEE STD 323-1971 - conformance to this standard ~ for electronic transmitters is discussed in Table 3.11-4. Devisioc 33 7.4-24 4/81 ,m_ _. _,, ._.,-,,___,-..._...-_,,,-..-.,_._,-m
MIDLAND 1&2-F5AR l i CONFORMANCE 20 IEEE SD 344-1975 - Conformance to this standard I for electronic transmitters is discussed in Subsection 3.10.4.1.41. 33 CCatFORMANCE TO IEEE SS 323-1971 - Conformance to this standard -) is discussed in Table 3.11-4 for safety-related control systans 1 equipment. CCarFORMANCE TO IEEE STD 344-1971 - Conformance to this standard 20 is discussed in subsection 3.10.4.1.14 for instrussut racks, rack mounted instruments, and power supplies. 1 7.4.2.1.3.4 Main steam safety Valves The safety-related function of atmospheric steam relief is satisfied by the main steam safety valves, which are entirely 1 mechanical. The discussion of these valves is found in section 10.3. Monsafety atmospheric steam relief is diecussed in subsection 7.7.1.7. Cold shutdown can be achieved using the safety grade PCAV valves. These valves are discussed in subsections 10.3.2 and 7.4.1.2.3.2. 7.4.2.1.3.5 other controls Required for Safe Shutdown Essential portions of the service water system and component cooling water syntaa that are safety-related are initiated by one of the engineered safety features actuation system (ESFAS) syshaystems. in subsection 7.3.3.4.A complete analysis of ESTAS controls is presented i 33 l 7.4.1.2.4 Supporting Systems for Safe shutdown Instrumentation i and Control systems Subsection 7.4.1.1.4 references FSAR subsections which discuss all the auxiliary support systems for the instrumentation and control systems required for safe shutdown. These discussions include analyses of the austriary support systems. 7.4.2.2 Cold Shutdown Systems Analysis _ 7.4.2.2.1 Reactivity and Inventory Instrumentation and Cont. col Systans Except for CFT isolation, no control systems and instrumentation in addition to that described in subsection 7.4.1.1.1 are required to maintain reactivity and inventory control while achieving and maintaining cold shutdown. Analyses for tbs systems described in subsection 7.4.1.1.1 are provided in subsection 7.4.2.1.1. As analysis of all the controls used to Revision 33 7.4-25 4/s1 .}}