Control Flashcards
Where does loop-specific Tavg go?
OPDT
OTDT
Low Tavg (FW isolation at 2/4 < 564 and P4)
Low-low Tavg, i.e., P12 (550 on 2/4)
What is Low Tavg?
Tavg < 564 on 2/4 and P4 (trip)
Causes FW isolation
What is low-low Tavg?
Purpose?
Another name?
a.k.a P12
2/4 Tavg < 550
Blocks steam dumps
Prevents excessive cool
What uses auctioneered high Tavg?
PZR level control
Rod control
Steam dumps
PZR level control program
25% -> 61.5% as auctioneered Tavg goes from THZP to THFP
It stays constant above/below those Tavgs
PZR response to a continuous P increase
Heaters off
Sprays on
PORVS hit
Trip
Safeties hit
PZR response to continuous P decrease
Heaters on
Close PORVs
Trip (low PZR P, OTDT)
SIS
What measures FW flow for control?
Venturi
What signals feed rod control?
Tref from Pimp
Auctioneered high Tavg
Pturb from impulse P
Auctioneered high PR power
What does the SG level controller adjust?
FW control valve for flow
FW pump speed for dP across the SG
The speed controller keeps the control valve in the range where response is linear.
What does the SG controller monitor to maintain level?
Actual level vs reference level
Steam flow vs. feed flow
Should charging flow change as power goes from 0 to 100%?
No. The PZR level program was designed to match the natural expansion of water along the Tavg program.
What are the two main causes of a change in charging flow?
RCS leak (restoring VCT level)
Temp instrument failure causing Tavg / Tref deviation
Describe the SD error signal in load reject
Auctioneered high Tavg vs Tref (from Pimp)
Opens when error > 2 F
Describe the SD error signal in plant trip
Auctioneered-high Tavg vs Thzp
Opens when error > 0 F
Describe the SD error signal in steam pressure
Steam header pressure vs manually adjusted setpoint (used for heat up and cooldown)
What instrument failures would cause rod insertion?
Thot high
Tcold high
Pimp low
PR high
What system is not available if a Pimp fails?
Steam dumps
What signals do you get if a PZR P channel fails low?
An OTDT
A PZR low P trip
A SIS
A P11
What Ps, Cs, and Ts do the PRs feed?
PR low trip
PR high trip
PR rate trip
P7 - P10
C2 - C4
OTDT
OPDT
How do rods respond if Pimp fails low?
What does the operator do?
They drive in
Put rods in manual if no load rejection
How do the SDs use the Pimp transmitters in load reject mode?
PT505 feeds how much to open the SDs based on Tavg vs Tref.
PT506 senses if a >10% load reject has occurred to arm the system.
