Pzr Pressure and Lvl Control Flashcards
What is the normal Lvl, temp, and # of the PRT?
- 100°F
- 83%
- 3#
When will the PRT vent valve not open?
> 10#
What is the max # of the PRT?
- 100# (Rupture Disk)
What is the PRT designed to do?
- Condenses 110% of Pzr steam space
- Protects the Rx Vessel against brittle fracture during LTOP conditons
- Provides overpressure Protection
What are the inputs to the PRT?
- Pressurizer Safeties and PORVs
- Seal Water Return Safety
- CCP Suction Safeties
- ECCS Safeties
- RHR Suction Safety
- RHR Hot Leg Discharge Safety
- RHR hx Safeties
- PW and N2
What is the lvl per percent in the Pzr?
75gal / 1%
What is the Pzr Lvl Program based on?
Based on Auctioneered High Tave
- Unit 1 - 22% to 50% (28% diff)
- Unit 2 - 22% to 55% (33% diff)
What are the Pressure inputs for the Pzr Pressure Ctrl?
NPP-151
NPP-152
NPP-153
NPS-153
At what pressure do the Pzr Safeties lift?
2485# (SV-45A/B/C)
At what pressure do the Pzr PORVs open?
2335# (NRV-151/152/153)
Which Pzr PORVs have backup air bottles?
NRV-152/153
What supplies the PRT with water if it needs to be filled or if it gets > 126°F during normal ops?
PW
Which Safeties and PORVs have acoustic monitors?
- Safeties- 1 monitor for each safety valve (3 total)
- PORVs- 1 monitor total (combined)
What are the Lvl inputs for the Pzr Lvl Ctrl?
- NLP-151 (Ctrl Channel)
- NLP-152 (Bistable)
- NLP-153 (Either Ctrl or Bi)
- NLI-151 (cold cal)
What is the Rx Trip setpoint for Pressurizer Level?
92%
What are the Pzr Cycling Heater trips?
- Loadshed on same train
- Pzr Low Level @ 17%
- Overcurrent
- Both trains of Supply Breakers closed
- Load Con
What is the interlock associated with the Pzr Cycling Htrs? Why?
Can’t close both feeder breakers (Protects EDGs from overloading)
Which PORVs provide Cold Overpressure protection? Which pressure instruments are used?
- NRV-152 controlled by NPS-122 (Loop 1 WR)
- NRV-153 controlled by NPS-121 (Loop 2 WR)
What are the Pzr backup Heater trips?
- Loadshed on same train
- Pzr Low Level at 17%
- Overcurrent
What are the important pressure setpoints for the Pzr?
2735# - Max Limit 2485# - Safeties Open 2385# - Rx Trip 2335# - PORVS open 2235# - Normal Ops 2200# - DNB 1950# - Rx Trip 1910# - P11 Block 1775# - SI
What can happen if Channel III (NPP-153) is controlling channel for Pzr # Ctrl and it fails low?
All Pzr PORVs will be Inoperable and the only protection for Overpressure on the Pzr will be the safeties
Where does the PRT drain to?
RCDT pump Suction
With the unit at 100% power, Pressurizer level channel NLP-151 is selected for control and fails LOW. Assuming no operator action, what is the plant response?
Letdown isolates, charging flow increases, seal flow increases, actual level increases, and VCT level decreases.
- Reactor Power 97 percent
- RCS pressure 2260#
- PRZ level channel select switch in position 1 (Channel 3 control, Channel 2 bistable)
- PRZ level 53 percent
- PRZ level recorder select switch in position 1 (Channel 1)
- PRZ liquid level transmitter NLP-152 (Channel 2) fails low
WHAT is the immediate effect on the plant?
Recorder indicates level = level Ref., charging flow is unchanged, all heaters are off, all orifice isolation valves shut, QRV-111 shut
- Reactor power 99%
- Pressurizer level 33%
- Letdown flow 40 gpm
- Pressurizer level control in manual
How does the plant respond to a 20 gpm charging line leak outside containment? (Assume NO operator action.)
Pressurizer drops to 17%, …
letdown isolates and heaters turn off, reactor trips on high level
- Reactor power is at 50%
- PRZ level is stable at program level
- QRV-251 Charging Flow
- Controller is in MANUAL
- Charging and letdown are balanced
What is the effect on the plant if QRV-251 Charging Flow Controller remains in MANUAL and power is increased to 100%?
A. Charging flow will RISE.
B. Charging flow will LOWER.
C. PRZ level will LOWER.
D. PRZ level will RISE.
PRZ level will RISE.
Unit 2 was operating at 95% power when a load rejection occurred.
Shortly after the load rejection the following plant conditions exist:
RCS Tavg is 572°F
Pressurizer Level is 54%
Pressurizer vapor temperature is 650°F
Pressurizer liquid temperature is 649°F
What is the current status of the pressurizer based on these conditions?
(Reference the steam tables)
A. Pressurizer PORVs and Spray valves are full OPEN.
B. Pressurizer Spray valves are modulated OPEN.
C. Pressurizer proportional heaters are modulated ON.
D. Pressurizer Backup and proportional heaters are fully ON.
D. Pressurizer Backup and proportional heaters are fully ON.
ANSWER:
Pressurizer vapor space of 650°F equates to 2193 psig (2208 psia). This is below the 2210 psig setpoint to fully energize the backup heaters.
If PORV was leaking by and could not be isolated and the PRT rupture disk blows, what would be the ROs indication?
PORV outlet temp will lower
Which pressurizer pressure channel inputs into QMO-225 (East CCP ELO)
NPP-151 input to QMO-225 (East CCP ELO)
Which pressurizer pressure channel inputs into QMO-256 (West CCP ELO)
NPP-153 input to QMO-226 (West CCP ELO)
If controlling channel for pressurizer level fails low, what happens?
- QRV-251 throttles open to increase level
- LD Isolates (QRV-112 and all orifice isolation valves close)
- PZR Heaters Off
- Rx trips at 92% (if greater than P-7)
If contorlling channel for pressurizer level fails high, what happens?
- QRV-251 throttles closed to lower level
- PZR Heaters come on (+5% Deviation)
- Actual PZR Level decreases and at 17%
*Orifice Isolation Valves Close
*Heater off
*QRV-111 Closes - Actual level increases (min charging with no letdown)
- Rx Trips at 92% (if greater than P-7)
What happens if the bistable channel for pressurizer level fails low?
- LD Isolates (QRV-111 Closes)
- PZR Heaters off
- Pressurizer pressure decreases (heaters off)
- Actual Level increases, charging to minimum
- Rx Trips at 92% (if greater than P-7)
What failiure could cause QRV-251 to go FULL CLOSED in automatic?
QFI-200(Charging Pump Discharge Flow) fails high
Assuming NO operator action and all Systems in Auto, What happens if the controlling channel for pressurizer pressure fails High?
- All PZR Heaters Off
- Sprays full Open
- Alarm
- 1/2 Signals for NRV-152 present
- Actual PZR Pressure decreases
What happens if the bistable channel for pressurizer level control fails high?
NOTHING
Assuming NO operator action and all Systems in Auto, What happens if the controlling channel for pressurizer pressure fails Low?
- Backup Heaters in auto will turn on
- Alarm
- Cycling heaters full on
- Actual PZR Pressure goes up
- NRV-152 is INOPERABLE
Assuming NO operator action and all Systems in Auto, What happens if the bistable channel for pressurizer pressure fails High?
- Alarm
- 1/2 actuation signals present for NRV-151 and 153
Assuming NO operator action and all Systems in Auto, What happens if the controlling channel for pressurizer pressure fails Low?
- NRV-152 INOPERABLE (minimum)
- if channel 3 is controlling, all PORVs inop
Per TS 3.4.11 (PORVs), what are the actions for 1 or more PORV INOPERABLE WITH manual available?
Within 1 hour: Close the block valves and maintain power
Per TS 3.4.11 (PORVs), what are the actions for 1 or more PORV INOPERABLE WITHOUT manual available?
Within 1 hour: Close the block valves and remove power
Per TS 3.4.11 (PORVs), what are the actionf for 1 or more block valves INOPERABLE?
Place PORV in Manual within 1 hour
What is the stop for QRV-251 when in auto?
47 gpm to prevent isolating Seal Injection
