Ts, Ps, and Cs Flashcards
Describe a bistable
Compares input signal to a set point
If OK, power supplies to downstream relay
If not OK, power removed from relay causing trip
What are OTDT and OPDT trip logic?
2/4 above the loop specific setpoint
What feeds the OPDT and OTDT bistables?
OPDT
Loop-specific setpoint
Loop-specific delta-T
OTDT
Same
OTDT inputs?
PZR pressure (one P transmitter for each loop)
Loop-specific AFD
Loop-specific Tavg
OPDT inputs?
Loop-specific Tavg
What is C3? C4?
C3 is for OTDT
C4 is for OPDT
2/4 are 3% less than setpoint
Blocks outward rod motion
Turbine runback until signal clears
P12?
Low-low Tavg
Closes SDs when 2/4 Tavg < 550
Where does PZR send protection signals?
PZR high level trip
PZR high P trip
PZR low P trip
P11 block
PZR low P SI
OTDT
P7?
Enabled if getting P10 or P13
Flow trips enabled
PZR high level enabled
PZR low pressure enabled
P13?
1/2 turbine channels > 10%
Feeds P7 when met
What PZR trips are blocked when below P7?
PZR high level
PZR low pressure
What causes FW isolation (FWIS)?
SIS
P14 (2/4 > 78% on 1/4 SG)
SG lo-lo level on 2/4 in 1/4 SG
Low Tavg (P4 plus 2/4 Tavg < 564)
What will trip the FW pumps? (differs from FWIS)
SIS
P14 (2/4 > 78% in 1/4 SG)
All condensate pumps tripped
High discharge P
List C1 - C5
C1: stops outward rod motion when 1 IR > 20%
C2: stops outward rod motion when 1 PR > 103%
C3 & C4: runback when OTDT orOPDT < 3%
C5: Rod withdrawal in auto is blocked when Pimp is <15%
What makes something a P or a C?
A P is generated in the SSPS and is safety grade and can be credited.
A C is outside the SSPS and is a ‘control’ grade signal.
What causes a turbine runback?
C3
C4
Loss of a circ water pump when P > 80%
Others…
What signals cause a SIS?
Low PZR P
Low steamline P
High containment P
What trips AMSAC?
What does it do?
2/2 Pimp > 40%
3/4 < 5% in 1/4 SG
Trips turbine and starts AFW (MDs and TD)
What interlocks are associated with the SD system? (Cs and Ps)
C7: Arms SDs following load rejection that exceeds 5%/min
C9: Blocks SDs if condenser not available
P4: shifts Tavg mode from load reject to plant trip
P12: closes SDs to prevent uncontrolled cooldown
List all trips (no flow or volt trips)
SR high flux. >10E5
IR, > 25%
PR low, >25%
PR high, > 109%
PR rate
OTDT
OPDT
PZR low P
PZR high P
PZR high level
SG lo-lo level
Turbine trip
SIS
What happens on SG lo-lo level?
Reactor trip -> turbine trip
FWIS
AFW
P14
SG level > 78%
Turbine trip -> reactor trip (if > P9)
FWIS
Trip MFP
Start AFW
What is P9 and why is it set at that value?
A turbine trip will cause a reactor trip when 2/4 PR > 50%.
50% is used since the SDs (40%) and rods (10%) can handle a loss of load up to 50%.
P10
2 PR > 10%
Permits block of IR trip and C1
Permits block of PR low trip
De-energizes SR
Feeds P7
P4
Caused by reactor trip
Trips turbine
Switches SD mode
Feeds low Tavg (FWIS)
