Isolation Condenser Flashcards
What is the purpose of the Isolation Condenser?
Core Decay Heat Removal following Reactor Isolation from Main Condenser and Reactor Scram.
Heat Removal capacity sufficient to remove decay heat at ~530seconds following Rx Scram
What is the available initial runtime and temp design of the Iso Condenser
Maintains shell <210F to ensure 20 minutes of sufficient cooling with no makeup (B3.5.3)
What power source is required for IC function?
Completely independent of AC power
How does IC associate with PRA?
PRA important operator action to initiate shell side makeup within 20 minutes to minimize core damage. Allows IC to function and conserve vessel inventory.
How quickly is IC shell makeup required to be aligned?
20 minutes
What is unique about IC pressure control function?
Allows for no Pressure Relief Valve inventory lost
How much heat removal is the IC capable of?
74MWth or 2.5-3%
Which IC valves are normally open? Closed?
1,2,4,17,20 NO
3NC
Where does IC discharge return to?
A recirc loop
Which IC valve is normally closed and what is its power source?
3 vlv - powered by RB 250vdc
What is the preferred order of IC Makeup water to shell side?
IC Makeup Pp
Clean Demin
Fire Main
Condensate Transfer
Where does IC drain to?
RBFDS - loop seal maintains secondary containment
What is the pressure rating of the IC?
1250psig because it is a primary system boundary
What must be done to IC if manways are open and IC drained?
Plates installed on vent pipes to maintain secondary containment
What powers the main valves?
1&4 - AC - norm 28-1/ alt 38-1
2&3 - DC - 250VDC RB Bus
How are the IC 1&4 valves swapped to alt power supply? What happens when this occurs and how can this be isolated?
Can be swapped from panel in 2/3 EDG room.
If this is done, MCR indication and control is lost and will not respond to Grp 5 isolation.
Panels in U2SDC and U3TIP used to isolate power to 2/3EDG IC panel in case of fire.
What alarm is in if IC control swapped to alt power supply?
“ISOL CONDR VLVS OFF NORM”
How is IC Vlv 3 operated on loss 250vdc?
manually - MOV - declutch
What does the PTL position do to the IC 3 vlv?
PTL Position will override initiation signal and close the valve
What is position of valves on initiation signal?
1,2,3,4 Open; 1,2,4 should be open already
17,20 close
3 vlv full open is really only 10% open
Can the IC 3 vlv be throttled with an initiation signal present?
No It should not be throttled
What causes a failure of the IC Vent Line Valves and what position do they fail to?
Loss of IB or IA - fail closed
What are the positions of IC Vlvs on Grp 5 isolation?
All close, REGARDLESS OF CONTROL SWITCH POSITION
What causes IC System Isolation?
De-energize to Actuate
Hi Steam or Condensate Flow (300%) causes isolation signal - all vlvs go closed
Loss of either DC logic Division causes isolation (either 2A-1 or 2B-1)
What powers IC Logic?
Div I 2A-1; Div II 2B-1
Which overrides the other: Initiation or Isolation?
ISOLATION TRUMPS INITIATION!!
What shares the same penetrations as the IC?
U2: Return line shares with SDC into A RR Loop
U3: Suction connected at same penetation; RWCU must be secured before IC initiates to prevent cold water from IC thermally stressing RWCU suction piping
What is automatic initiation signal for IC?
RPV Pressure for 1055psig for 12 seconds
What signal is sent to 1,2,& 4 valves upon initiation?
No open signal sent….
What happens on a IC Tube leak?
Shell Side Temp Increase
Shell Level Increase
Vent Rad Increase
Shell side vent loop seal maintains secondary containment
What is the RPV Pressure Control Prefference?
IC w/ IC Makeup Pps IC w/ Clean Demin HPCI in Press Control Mode IC w/ Fire Water ERVs IC w/ Contaminated Demin
What is the IC initation logic Scheme?
De-energize to actuate: Div 1 powered from 125vdc 2A-1 Div 2 powered from 125vdc 2B-1 Both divisions required to initiate Loss of either causes isolation
What is the difference of U2 to U3 IC Pressure sensing elements?
U2 is Elbow sensing on condensate return
U3 was replaced with Annubar flow elements - has time delay due to spurious signals from sensitive elements.
What is required on an IC INOP CONDITION?
Must IMMEDIATELY verify HPCI available administratively for pressure control
What provides make-up fuel fill to IC Make-up Pump Day tank?
U2 EDG Storage Tank - EDG INOP DURING FILL
