Saftey Injection(SI) Flashcards
What provides capability for Reactivity Control of Core on the Safety Injection system ?
-HPSI
-LPSI
-Safety Injection Tank(SITs)
How does the Safety Injection provide short term and long term Heat removal ?
-HPSI
-LPSI
-Shutdown Cooling system
-Containment spray
How does the Safety Injection provide Pressure & inventory control ?
-HPSI
-LPSI
-Safety Injection Tanks (SITs)
What does Safety Injection provider for containment ?
Iodine removal
How does Safety Injection provide RCS inventory control during Station Blackout ?
-HPSI
How does Safety Injection prevent hydrogen build up in containment post-LOCA ?
Uses containment spray to reduce hydrogen build up
What events will cause Safety Injection system to be used ?
-Loss of Coolant Accident(LOCA)
-Control Element Assembly Ejection Accident
-Loss of secondary coolant including uncontrolled steam release or loss of Feedwater
-Steam Generator Tube Rupture
What are the Active Injection Equipment ?
-HPSI pumps
-LPSI pumps
What is the Passive Injection Equipment ?
Safety Injection Tanks
What kind of water is injected by the Safety Injection into the RCS ?
Borated water
SIAS ensures acceptable consequences during what kind of emergency events ?
-Loss of Coolant Accident( LOCA)
-Control Element Assembly ejection accident
-Steam Generator Tube Rupture(SGTR)
-Main Steam Line Breaks(MSLB) inside containment
ESFAS initiates a SIAS to actuate Saftey Injection when which 2-out-of-4 signals are met ?
-PZR pressure low 1837psia
-Containment Pressure high 3psig
How much time do the Refueling Water Tanks contain to maintain full safety injection flow ?
Has enough borated water for 20 minutes of injection flow with all pump on both trains operating at runout with 10% margin
When a SIAS is generated how much time does it take to deliver borated water to the core ?
Within a maximum of 29 seconds after SIAS
Which RCS legs do the HPSI pumps inject borated water into ?
HPSI injects water into all 4 cold legs
Which RCS legs do the LPSI pumps inject borated water into ?
Injects borated water into 2 RCS cold legs
When will all 4 Safety Injection Tanks inject into the RCS ?
They will inject when RCS Pressure drops below Safety Injection Tank Pressure
What happens when Refueling Water Tank reaches 9.4% ?
-A Recirculation Actuation Signal is actuated
-Containment Recirc. Sump Isolation valves will automatically open to supply both trains of HPSI pumps
What valves automatically close when a RAS actuates? What valves must be manually closed on a RAS ?
-All safety Injection Pump Recirculation valves close
-RWT outlet valves must be manually closed by the control room following a RAS
Post LOCA initiation how long will it take to establish Long Term Core Cooling ?
2-3 hours Long Term Cooling will be Established
What flow paths does Long Term Cooling use ?
1.)Containment Recirc. pump supplies both train HPSI pumps
2.) HPSI pumps discharge flow is split 50% to 4 Cold Legs; 50% Hot Leg
How is the HPSI flow discharge split during Active Injection Long Term Cooling ?
The control room manually operates MOVs to split the flow 50/50 between the cold legs and hot leg by
Why is there a 50/50 split of flow between the 4 cold legs & the hot leg during Long Term Cooling ?
-Maintains subcooling
-Insures flushing to prevent boiling induced boron precipitation in Reactor Core, which could cause heat removal to be diminished
What happens to Safety Injection Pump Recirc. Valves during a RAS ?
All safety Injection Pump Recirculation valves are closed
What two functions do the LPSI pumps serve ?
-Inject Large quantities of borated water into RCS in event of LOCA
-Provides shutdown cooling flow through Reactor Core and Shutdown Cooling heat exchangers for normal plant shutdown cooling
What do the HPSI pumps do for RCS during a LOCA ?
-Prevent fuel cladding failure during injection mode following small LOCA
-Provides continuous flow during LOCA after SITs emptied
How fast do LPSI pump motors get up to designed running speed under load ?
They can get up to designed running speed within 5 seconds, while underload
What is the rated flow for LPSI pump ?
4300GPM
What is the runout flow for LPSI pump ?
5500GPM
What is the shutoff head for LPSI pump ?
210psig is shutoff head
What is the sizing of the LPSI pump governed by?
-Governed by shutdown cooling function
-Single LPSI pump is able to maintain delta T at an acceptable level at initiation of shutdown cooling
What’re LPSI pumps normal condition ?
-Maintained in standby condition
Locked open:
-Motor operated suction valve
-Manually operated discharge valve
Isolated from RCS by motor operated loop injection valves
What signals will LPSI pumps auto start on ?
-SIAS
-CSAS
What happens to LPSI pump when a RAS happens ?
-LPSI pump will shuts off
-Both LPSI Recirc. & safety injection trains common Recirc. Header solenoid operated valve to the RWT
Where do LPSI pumps received power from ?
Class 4.16kv buses PBA-S03 & PBB-S04
What is the LPSI pumps Rumble Region ?
-2500-3500gpm
-Rumble Region should be avoided
What does HPSI pump provide ?
-RCS injection flow to reactor core following small break LOCA
-Flow exceeds decay heat boil-off rate
-Long Term Cooling for reactor core cooling & flushing to prevent boron precipitation
-Able to fill B train only SIT
How fast can HPSI pumps get up to designed speeds under load ?
Within 5 seconds
What HPSI pump flow rated for ?
-900GPM
What is the HPSI pump runout flow ?
1130GPM
What is the minimum shutoff head for the HPSI pump ?
Shutoff head is 1775psig
What’re the HPSI pumps sized for ?
Sized for one HPSI pump to supply adequate water to match Decay-heat boil off rates soon enough to minimize core uncover
What’re the HPSI pumps normal conditions ?
-Maintained in standby
-Manually operated suction & discharge isolation valves that are normally locked
-Isolated from RCS motor operated loop injection valves, which automatically open on SIAS
How is Long Term Core Cooling established with the HPSI pumps ?
-It’s established 2-3 hours post LOCA
-Manually realigning HPSI discharge for simultaneous cold legs and hot leg
What’re the automatic actuations for the HPSI pumps ?
Auto starts upon receipts of:
-SIAS
-CSAS
What happens to HPSI Recirc. Valve and SI Train Common Recirc. Header to the RWT ?
These valves BOTH close going back to the RWT
Where does HPSI pump receive power from ?
CLASS 4.16 KV; PBA-S03 & PBB-S04
What is the purpose of Safety Injection Tanks ?
Passives means to flood core during a Large LOCA, UNTIL Safety Injection pumps are available
How much water does each SIT contain ? How much is it pressurized ?
-Contains 140,000 gallons of borated water
-Pressurized by nitrogen to 600psig
What is supposed to be assumed about the SIT when cold leg breaks ?
Entire contents of one SIT is supposed to be assumed completely lost
Why does SIT have MOV & two check valves ?
They’re used for isolation of the RCS
During SIT normal operation what position is the MOV in ?
MOV is open & with its power removed to prevent inadvertent closure
When will SIT inject water into RCS Cold Leg ?
SIT will automatically inject into cold leg when RCS pressure drops below SIT pressure
Why does SIT provide the sole source of makeup water to RCS during a LOCA & LOOP at the same time ?
This is because LPSI & HPSI pumps can’t provide flow until the diesel generators startup
During a controlled cooldown what is the RCS depressurized to? What happens to SIT tanks during a controlled cooldown ?
The RCS is depressurized to 750psia, then SIT pressure is lowered to 300psig by venting nitrogen to containment
During a controlled cooldown and depressurization what must happen to SIT MOVs when RCS pressure is <430psia ?
SIT MOVs may be closed to isolate them from being discharged into RCS during a RCS cooldown & depressurization
What is done to the SIT MOVs during a controlled heat up & pressurization ?
When RCS pressure is raised above 430psia, then SIT MOVs will be opened, power removed, & breakers locked open
What is the interlock between SIT MOVs & PZR pressure ?
Ensure MOVs will open automatically as RCS pressure increases above SIT pressure & prevents closure
What are the Recirculation Sumps used for ?
Collects water released into containment from a break in the RCS & recirculates back into RCS
Which pumps are used during Recirculation Mode ?
-HPSI to cool and cover reactor core
-Containment spray to cool containment
Which pumps will trip on a RAS ? What valves are closed on a RAS ?
-LPSI pump will trip to ensure NPSH to the HPSI & CS pumps
-All SI pump recirculation valves to the RWT will be closed to prevent RWT from being contaminated
What is used to prevent blockage of the ESF components inside the Recirculation Sump ?
Baffles and intake screen limit Max. particle size entering the Recirc. Sump
What is the purpose of Containment Spray ?
Sprays cool borated water into containment
When does containment spray have to be used ?
-LOCA
-Main Steam Line Break(MSLB)
-Main Feedwater Line Break(MFLB)
What’re the affects when containment spray is used during an accident ?
-Rapidly reduced containment press. & temp. below containment design
-Rapidly reduces iodine concentrations in containment
-Reduces DP between containment atmosphere & external environment
How do Containment Spray interface with Trisodium Phosphate(TSP) ?
-TSP mixed with water in Containment Recirc Sump & achieves uniform PH
-Hydrogen mixes within containment to prevent localized accumulations of hydrogen
What accidents will actuate a CSAS ?
-LOCA
-Main Steam Line Break(MSLB) inside containment
-Feedwater Line Breaks(FWLB) inside containment
When will ESFAS initiate a CSAS ?
2 out of 4 signals of containment press high-high at 8.5 psig
What is Shutdown cooling Heat Exchanger normally lined up with ?
Normally lined up for containment spray
What happens to containment spray system when SIAS start ?
-Containment spray pump starts
-Containment isolation valve remains shut
-CS pump will operate with Min. flow from the RWT & Recirc. back RWT
What happens when Containment spray when CSAS initiates ?
-Containment Spray isolation valve will open and allow flow to spray nozzle
-Recirc valves remain open to allow minimum flow to recirculate back to RWT
What happens for Injection Mode on CSAS & RAS ?
-Containment spray will collect in Recirc. Sump and send it back through CS pump, SDC heat exchanger, back to CS nozzles
-CS pump Recirc valves will close to prevent contaminating RWT
What functions do the Containment Spray pumps provide ?
-Pumps water into containment spray header to cool/depressurize containment
-Provides shutdown cooling flow during normal cooldowns
-Provides SFP cooling during outages
How fast the the Containment spray pumps be brought up to designed speed under load ?
Will get up to speed in 6seconds
What’re the Containment Spray Pumps flow rates ?
Rated flow:3890GPM
Runout flow: 5200GPM
What is normal operation alignment for Containment Spray Pump ?
-Valve supplying water from RWT is locked open
-Other suction valve from SDC line is normally locked closed
-Containment spray pumps are isolated from containment & spray nozzles
What is done to CS pumps when RCS temp is below 200, during shutdown cooling augment ?
CS pumps will realign and start in parallel with LPSI pump to provide more flow through SDC Heat Exchanger
What is used to cool down spent fuel pool when SFP pumps can’t maintain temperature ?
Containment Spray pumps will be realigned and started for additional SFP cooling through SDC HEX
What will automatically start Containment Spray Pumps ?
-SIAS
-CSAS
What happens to recirculation valves for both CS pumps on RAS ?
All recirculation valves will close upon a RAS
Where do Containment Spray Pumps receive there power from ?
Class 4.16KV PBA-S03 & PBB-S04
What is the Rumble Region for Containment Spray Pump ?
1800-2800GPM should be avoided
What is the SDC HEX used for ?
-Heat rejection for RCS temp in post shutdown for refueling temp & maintaining fuel temp
-Heat rejection for cooling plant to cold shutdown
-Heat rejection for SFP cooling system during refueling
-Heat rejection during Recirc. Mode following LOCA for containment heat removal
What cooling water is sent through HEX to cool primary side ?
-Essential cooling water is sent through shell side of HEX
-Then Essential Cooling water sends the heat to the Essential Spray Ponds
How is the temperature of the RCS controlled during shutdown cooling ?
Control room operator throttling SI side SDC HEX bypass valve
How is the temperature of the RCS controlled during shutdown cooling ?
Control Room Operator throttles SI side of SDC HEX bypass valve
What is the backup cooling water for SDC HEX if essential cooling water is unavailable?
Nuclear cooling water can be crossed tied to support essential cooling water when its unavailable
What is the purpose of Shutdown Cooling subsystem ?
-Reduces RCS temp at a controlled rate
-Not to exceed 75F per hour
-Maintains proper RCS temperature during refueling
What temperature does RCS get brought down to during Shutdown Cooling ?
-From 350F to a refueling temp of 135F
What does Shutdown Cooling do during plant heat up ?
Maintains flow through core during plant heat up
What’re the shutdown cooling system major components ?
-RCS & containment Isolation Valves
-Low Temp. Over-pressure relief valves( LTOPS)
-LPSI pumps
-Containment Spray(CS) Pumps
-Shutdown Cooling Heat Exchanger
When does Shutdown Cooling get put into operation ?
-RCS temperature is reduced to 350F
-RCS pressure is reduced to 400psia
Which pump initially accomplishes reducing RCS temp & pressure to refueling temperature ?
LPSI pump will initially accomplish
What happens when RCS temperature is reduced to less than 200F during shutdown cooling ?
Containment Spray pump is realigned and started to provide additional Shutdown cooling flow to maintain cooldown rate and temperature
How is cooldown rate controlled ?
Controlled by adjusting flow through SDC HEX
During shutdown cooling which pump is used? Where is the suction drawn from ?
-LPSI pump is used
-Gets its suction water from the RCS Hot Leg from the Shutdown cooling isolation valves
Where does the LPSI pump discharge inject to during shutdown cooling ?
It’s injected into ONE of the RCS cold legs
What’re the Shutdown Cooling Isolation Valves serve as ?
-RCS pressure boundaries
-Containment Isolation
What’re the first two in line Shutdown Cooling Isolation Valves ?
Double valve RCS pressure boundaries
What’re the middle in line Isolation Valves serve as ?
-Containment Isolations
-RCS pressure boundaries
What’re the last three in line Isolation Valves used for ?
Containment Isolation Valves
What must be done to the suction line three motor operated isolation valves in series for shutdown cooling ?
All three MOV isolations must be opened to initiate shutdown cooling
What is the interlock between RCS & Shutdown Cooling Suction Isolation Valves ?
If RCS pressure exceeds 410psia, the interlock will prevent SDC Suction Isolation Valves from being opened to prevent SDC over pressurization
What’re the power supplies to SIA-UV-651 & SIA-UV-655 ? What’re the power supplies to SIB-UV-652 & SIB-UV-656 ?
Class 480 load centers
What powers SIC-UV-653 & SID-UV-654?
Class 125 VDC control power
Through inverters, PKC-N43 & PKD-N44, which output 480 VAC to motor actuators
What is the purpose of the Low Temperature Over Pressure Protection Relief Valves(LTOPS) ?
Prevents overpressure of RCS during low temperature conditions, with water solid conditions during either energy or mass input transients
What’re Energy Input Transients ?
-Start of idle RCP with SG water temp 100F higher than RCS temp. in reactor vessel
-Inadvertent actuation of PZR heaters
What’re Mass Input Transients ?
-Inadvertent SIAS causing two HPSI pumps to inject
-Three charging pumps injecting with letdown isolated
What is the LTOP valve setpoint ? What is the relieving of the a LTOP capability ?
-Setpoint is 467 psig
-One LTOP has relieving capability of to prevent over pressurization
Where do the LTOP valve relieve too?
They’re relieve to the associated trains Containment Recirculation Pump
What do the LTOP relief valves provide to RCS when they’re opened?
-RCS/Shutdown cooling intersystem leak relief
-RCS Low Temperature Over Pressure Relief
How does SI system Interface with PB system ?
Class 4.16kv(PB) provides power to:
-HPSI pumps
-LPSI pumps
-CS pumps
How does SI interface with PH ?
Class 480 MCC supplies power to:
-SI system valves
How does SI interface with PK system ?
PK provides power to SI system valves
How does SI system interface with Class Instrument power(PN) system ?
PN supplies power to SI instrumentation and valve position indicator circuits
How does SI interface with Diesel Generators(DG)?
DGs provide emergency standby power for Safety Injection Pumps & Valves
How does SI system interface with SBOGS?
SBOG can provide emergency standby power for SI pumps & valves during a Station Blackout
How does SI interface with NN?
NN provides non class miscellaneous instrumentation for SI system
How does SI interface with Chemical & Volume Control(CH) system ?
-RWT in the CH system provide the borated water for the SI pumps
-CH provides shutdown of water during Shutdown Cooling
-SI relief valves outside containment discharge to equipment drain tank(EDT)
-SI relief valves inside containment discharge to reactor drain tank(RDT)
-SI tank can be drained to RWT or RDT
How does SI interface with Essential Cooling Water(EW)?
EW supplies cooling water to Shutdown Cooling Heat Exchanger
How does SI interface with Service Gases(GA) ?
Nitrogen supplies gas pressure into Safety Injection Tanks(SITs)
How does SI system interface with Instrument Air(IA) ?
Provides air supply to pneumatic operators,instruments, & controls
How does SI interface with ESFAS ?
SI receives ESFAS signals to initiate:
-SIAS
-CSAS
-RAS
How does SI system interface with BOP ESFAS ?
SI pumps & valves receive Loss of Power, Load Shed, & Load Sequencing signals from BOP ESFAS
How does SI system interface with Aux. Building HVAC ?
-Normal vent. provides cooling to room containing SI system equipment
-Essential vent. provides room specific essential air cooling units to cool SI Pump Room to maintain pump operability
What happens to SI system on a loss of Essential Cooling Water(EW)?
Would make shutdown cooling heat exchanger inoperable
What happens when Shutdown cooling heat Exchanger becomes inoperable ?
-At power Containment Spray becomes inoperable
-Shutdown cooling system becomes inoperable
How would a loss of instrument air affect the SI system ?
Inability to fill/drain Safety Injection Tanks from/to RWT
How does loss of Aux. HVAC affect SI system ?
-Loss of normal HVAC would require starting ESF air cooling units(ACU) to maintain operability
-Loss of Essential HVAC would result in associated room becoming inoperable
Will a loss of a single SI train prevent plant from safely shutting down ?
No, SI system is designed to be able to perform its function in safely shutting down plant on just one SI train
What happens if one or both trains or individual components of SI system become inoperable ?
A plant shutdown may be required
What is Mission Time ?
Is the amount of time a safety component is able to perform before it needs to stop,repair, or restart the SSC
When’re reasonable operator actions allowed ?
They’re allows after 30 minutes into Design Basis Accident(DBA)
What’re examples of operator action ?
Addition of consumables such as oil,fuel,& water
What components for the SI system have a mission time of 30 days?
-HPSI pumps
-Containment Spray Pumps
-Shutdown Cooling Heat Exchanger
Which component has an administrative Mission Time of 30 days & why that component?
-LPSI pump for extended Emergency Core Cooling functions
What would challenge the 30 day operability for required mission time ?
-An oil leak could challenge the required mission time
-AO must identify anything that could change mission time and report to control room supervisor
How many SIT are required by Tech Spec ?
4 SIT must be operable to ensure 100% content of Three SITs will reach core during LOCA
For a SIT to be considered operable what must happen ?
Motor operate isolation valve must be fully open, power removed, boron concentration, & nitrogen cover press.
For a SIT tank to be considered operable during Shutdown what must happen ?
Isolation valve fully open when press. >430psia, power removed when PZR press. is >1500psia, Boron concentration, Nitrogen cover gas
What is the LCO for Emergency Core Cooling Systems(ECCS) when plant is operating ?
-Two ECCS trains shall be operable during modes 1& 2
-Must be operable in Mode 3 with PZR
press. >1837psia or with RCS Tc>485F
What is the LCO for Emergency Core Cooling System during shutdown ?
-One HPSI train shall be operable in mode 3 PZR press. <1837psia and with RCS Tc<485F & Mode 4
Why must there be an adequate supply of borated water in the RWT ?
-To cool & depressurize containment in event of Design Basis Accident
-To cool and cover core during LOCA to remain subcritical following DBA
-Provide adequate water level in Containment Recirc. Dump to support ESF pump in Recirc. mode
To consider RWT operable what limits must be established ?
-temperature
-Boron concentration
-Water Volume
What is the LCO for ECCS TSP ?
TSP baskets shall contain >524ft^3 of active TSP during modes 1,2,& 3
Why is TSP required ?
-It’s required to adjust PH of Recirc. water to >7.0 after a LOCA
Why must Recirc. Water be maintained at 7.0 PH after a LOCA?
-Prevents iodine from dissolving into Recirc. water and converting into a volatile form
