Compressed Air Flashcards
What are the PAC trips?
- Loadshed (T11/21B)
- Load Conservation (Train B)
- Motor Overload
- Lo Lube Oil Press
- Hi Lube Oil Temp
- Hi 1st & 2nd Interstage Temp
- PAC Motor Lo Current
- PAC DCCS loss of control power
- Loss of most transmitters
- Manual (Several Inputs)
When will the PAC Aux Lube Oil Pump start?
- On PAC start - remains running until > 42 psig.
- PAC is stopped (for 15 minutes)
- low lube oil press
- loss of DCCS control power
- PA header - 97# with PAC in AUTO
What are the CAC trips?
- Overload
- LO # Low (15# with 12 sec delay)
- NESW # Low (< 6# for 5 sec) (U1) (includes on start)
- NESW # Low (< 4.2 ΔP for 10 sec) (U2) (includes on start)
- Manual
Does the CAC trip on a Load Shed?
No
What are the BACPAC trips?
- Motor Overload
- LO Press low
- LO Temp High
- 1st & 2nd Stage Disch Temp high
- 2nd Stage Suction Temp hi
- Manual
What are the Compressed Air System header pressure actions?
- 97 psi = PAC Start
- 90 psi = CAC Start (WAR #)
- 85 psi = PA Hdr Isolations Close
- 80 psi = Manual Reactor Trip
What is the correct sequence of events that automatically occur in the Control and Plant Air Systems as air pressure lowers?
- 97 psig at PPS-10 (20) Standby PAC starts
- 90 psig CAS wet receiver pressure CAC starts
- 85 psig at PPS-11 (21) Plant air header isolates
What can cause PAC surge?
- Discharge Valve Closed/Blocked
- Inlet Valve Throttled too far Closed
- Insufficient Inter-stage Cooling
- Opening demister valves too quickly
- Hi System Press
What is a Surge of the PAC?
Performance characteristic of a centrifugal compressor that arises when the compressor can’t overcome the system resistance
Seal air pressurizes the PAC seals when ?
- Standby
- Start-up
- Unloaded
When loaded, the PAC seals are pressurized from?
Leakage from itself
What problem does a loss of PAC seal air cause?
May allow oil leakage from the drive casing into the compressor housing
Where does the BACPAC tie into the Air System at and why is this important?
To the Plant Air ring header between the Ring Header Isolations (ie can supply CA system directly with Plant Air Ring Header isolation valves closed)
Both Units are responding to a loss of Plant and Control Air event.
The following conditions exist: Both Unit’s PACs AND CACs have failed.
Both Unit’s PA Hdr pressures are 70 psig and lowering. Both Unit’s CA Hdr pressures are 82 psig and lowering.
An AEO has been dispatched to start the Back-up Plant Air Compressor (B/U PAC), per 01-OHP-4022-064-001, Control Air Malfunction.
What describes the B/U PAC ability to repressurize both Unit’s Control Air Systems under these conditions?
The B/U PAC will discharge to both Unit’s Control Air Systems
How does Suction Throttle Control work?
Throttles inlet valve prior to throttling the unloader valve in order to maintain discharge pressure and minimum current setpoint.
What is the purpose of the Containment Control Air Safety Valves?
50 psig header and 85 psig header SV’s are safety related and prevent overpressurization of safety related PZR PORVs
Do the Ctrl Air Containment Safety Valves have isolations?
Yes, they have manual isolations
Can the Ctrl Air Containment Safety valves be actuated locally?
Yes, the safeties have manual actuate levers
What will happen on a loss of 600v AC to PAC and CAC?
Can’t operate the PAC and CAC. Loss of Control Air will need to trip the Reactor
If you lost NESW to CAC, will the CAC still start?
No
What are the reasons for cooling the air on the PAC?
- Reduces the necessary pipe size for the system
- Causes moisture to condense so it can be removed by moisture separators
How many running PACs are required to supply both units?
1 PAC normally supplies both units
Can one CAC supply both units Control Air?
No, each CAC can only supply its own unit
Will the PAC automatically restart after a trip?
- No, The PAC will not start automatically after it has been manually shutdown or has tripped. Check for the message “Ready Auto Start”
- Must wait 2 minutes
What is the CAC flow path if the CAC is running??
- Inlet Air Filter
- CAC
- Aftercooler
- Moisture Sep
- Wet CA Receiver
- Prefilters
- Dryers
- After filters
- Dry CA Receivers
Where does Plant Air tap into the Contorl Air system?
Feeds downstream of the Wet CA receiver before the CA Prefilters
What happens on a Phase “A” signal with respect to Control Air?
The Control Air CIVs will close
When will the CAC auto start?
90# at the Wet Control Air Receiver
If all the Plant Air Header isolation valves close, will the PAC still be able to feed Control Air Header?
NO, Plant Air feeds in upstream of PRV-10/20, so if they were to isolate along with PRV-11/21, the CAC will start to supply the CA header
If you had an air leak downsteam of PA-128, what would happen?
If pressure dropped to 97 psi the stby PAC would start
When unloaded or in stby, the PAC seals are pressurized from?
Control Air system
What provides pwr to both CACs?
TRAIN A
600v AC AB-D in both units
Which PZR PORVS have backup air bottles?
NRV-152 and NRV-153
NRV-151 does NOT
What pressure is control air when it enters containment?
Enters containment at 100 psi. May be reduced to 85 psi and 50 psi once inside containment.
What is the normal air supply for Pressurizer PORVs NRV-151, 152, and 153?
85 psig containment control air header
What is needed to meet the interlocks to start the Control Air Compressor?
LO Pressure and NESW Pressure above their trip setpoints
What is the flowpath of air to the Control Air System during normal Operations
Plant air compressor, plant air receiver, air dryer pre-filters
