IA- Instrument Air/ Service Air Flashcards
1
Q
What is the purpose of the Instrument Air system?
A
Provides a continuous supply of filtered, dry, oil-free air at a pressure up to 125 psig for pneumatic instrument operation and control of pneumatic actuators
2
Q
What is the purpose of the Service Air system?
A
Supplies oil-free air at a pressure of 125 psig to service air stations located throughout the generating unit.
These stations operate pneumatic tools, resin transfer, refueling machine manual operation, and other service requirements
3
Q
How can I identify that a pneumatically operated valve has a safety function that may be required to operate to ensure a safe shutdown of the plant following an accident?
A
It will have a safety related backup air receiver
4
Q
The Instrument Air system has how many air compressors and what type of compressors are they?
A
Three 100% capacity rotary screw air compressors
5
Q
Where do the Instrument Air compressors draw air from and what pressure do they compress to?
A
Drawn from Turbine building air and compress it to 105-123 psig
6
Q
What is significant about IAA-UV-2? When will it close?
A
It’s a DC powered solenoid valve that controls Instrument Air to Containment
Closes on a CSAS (8.5 psig in Containment)
7
Q
What is the backup to Instrument Air and when will it align?
A
Low Pressure Nitrogen system will automatically align to supply the Instrument Air Header if pressure decreases to 85 psig or on a LOP
8
Q
What powers the Instrument Air and Service air compressor motors?
A
Non-class 480 VAC Power Load Center system (NG)
9
Q
What powers the Instrument Air and service air compressor motor space heaters?
A
Non-class 480 VAC Power MCC System (NH)
10
Q
What does PK system do for the Instrument Air system?
A
Provides power to the IA Containment Isolation Valve (IAA-UV-2)
11
Q
What system provides cooling to the Instrument Air Compressor Coolant Cooler and Air Aftercooler?
A
Turbine Cooling Water
12
Q
What valve opens to admit low pressure nitrogen into the Instrument Air header?
A
PV-52
13
Q
Instrument Air sends compressed gas to the Fuel Pool Cooling system for what purpose?
A
For the Spend Fuel Pool Gate Seals
14
Q
How does Instrument Air system interact with the Extraction Steam and Drain System?
A
Supplies air to the Turbine Air Relay Dump Valves (ARDVs) for Bleeder Air Valve operation.
On a turbine trip, the ARDVs close to depressurize the line and allow the BTV air cylinders to fully stroke close within two seconds
15
Q
Regarding the IA compressors, why is the Air Inlet Control Valve minimally opened during unloaded operation?
A
To maintain Separator Sump pressure
16
Q
Why is coolant (oil) sprayed into the Airend(compressor) in the IA compressors?
A
Act as an air seal
Lubricate the bearings
Remove heat from the air compression
17
Q
In the IA air compressors, when does the coolant stop solenoid open and close?
A
Opens when the compressor is started
Closes when the compressor stops
18
Q
What is the motive force for the coolant in the IA air compressors?
A
Separator Tank Pressure, normally at 60 psig
19
Q
Concerning the IA air compressors, the Temperature Control Valve regulates the TC water flow through the Coolant Cooler to maintain the coolant at what outlet temperature? What temp is maintained downstream of the thermostatic control valve after mixing with the bypass flow?
A
120F
160F
20
Q
What is the purpose of the IA Compressor Inlet Air Filters?
A
Installed on each Air Compressor to remove particulate materials and minimize compressor water
21
Q
What size particles can the IA Compressor Inlet Air filters remove and how effective are they?
A
Three microns or larger
99.9% effective
22
Q
When the IA compressor is loaded, what should the Inlet Filter DP reading be(sensed by PT-4)?
A
Less than 0.7 psi
23
Q
The local controller on the IA Air Compressor uses PT-4 Inlet Vacuum information for what purpose(s)?
A
Confirm the drive motor is rotating in the correct direction upon startup
Indicate the condition of the inlet air filter
Provide logic for positioning the inlet valve during unloaded operation based on coolant (oil) injection temperature and separator pressure
24
Q
During compressor start up, why is the Instrument Air Compressor Air Inlet Control Valve in the closed position? What happens if this valve fails to operate during the start up sequence?
A
It allows the compressor to startup with minimum current
It allows the compressor to check for proper rotation by checking that inlet vacuum is at least 1 psi within two seconds
causes an alarm
25
How is the Instrument Air Compressor Air Inlet Control Valve controlled?
Controlled by the Intellysis controller with a stepper motor
26
During unloaded operation, if plant IA air pressure drops below the pressure setpoint of 109 psig, what would I expect to occur as a result of this?
Intellisys/stepper motor opens the Inlet valve and closes the Blowdown Valve.
Compressor will then operate to deliver full capacity air to the plant system
27
During loaded operation, how will the IA system respond if plant air pressure rises to the setpoint of 119 psig?
The Inlet valve will nearly close, the blowdown valve will open (Separator Tank vented), and the compressor is operating at minimum power.
Inlet valve is slightly open to maintain the proper sump pressure to ensure positive coolant (oil) flow and smooth, quiet operation.
28
When the injected coolant temperature is less than 120F, what would I expect the Separator (Sump) pressure to be maintained at in the IA system?
45-50 psig
| system pressure plus 10-15 psi
29
When the injected coolant temperature is above 120F, what would I expect the IA receiver pressure to be maintained at?
24-34 psig
30
What is the purpose of the Instrument Air Compressor rotary screw Airend?
Single stage rotary Airend compresses air to 105-123 psig for use by the Instrument Air system
31
What are the IA Single Stage Rotary Compressors rated for?
571 CFM and 125 psig
32
Briefly describe the oil cooling utilized in the IA Rotary compressor
Oil bath compressor that has oil supplied to the inlet of the compressor for lubrication, cooling, and compressor sealing
33
How is compression accomplished in the IA Rotary Compressor?
By the meshing of two helical rotors (male and female) on parallel shafts, enclosed in a heavy-duty cast iron housing.
The grooves of the female rotor mesh with, and are driven by, the male rotor
34
In the IA system, what happens if the Airend discharge temperature exceeds 223F?
It will cause a Warning “AIREND DISCHARGE TEMP” along with a “?” and the actual discharge temperature to be displayed on the display panel.
The compressor will continue to run during a temperature warning
35
At what discharge temperature will the IA compressor trip? What is the reset temperature? What are the normal values?
228F, Alarm and trip along with “High Airend Disc Temp” along with “!”
217F, Reset temperature
185-210F, Normal values
36
Regarding the IA system, what is the back-up to the High Temperature Alarm (Trip)?
Temperature Switch High set at 245F with a 30 degree differential to reclose (215F)
37
In the IA system, if the compressor High Temperature Switch opens on high temperature, what would I expect to see on the display?
“Control Power Loss”
temperature switch is tied into the control power circuit and will open the circuit on high temp
38
What is the purpose of the IA compressor Separator Tank?
Removes the coolant (oil) from the air to provide clean air to the system while maintaining the coolant for the compressor package
39
Regarding the IA compressors, what is the coolant/air separating system composed of?
A separator with a two-stage coalescing separator element and provision for return of the separated fluid back to the compressor
40
How does oil/air separation occur in the IA compressor Separator Tanks?
Coolant and air discharging from the compressor flow into the separator and rotates around the circumference of the Separator Tank, which acts to remove some of the heavier oil from the air before it enters the coalescing separator element radially.
The mist coalesces to form droplets, which collect on the outer first stage and fall to the separator sump.
Those collected on the inner second stage collect near the outlet of the element, and are drawn back to the compressor inlet through a filter-screen and orifice fitting installed in the separator scavenge line
41
What is the purpose of the Thermostatic Control Valve In the IA compressors?
Controls how much of the coolant flows through or bypasses the Coolant Cooler.
Used as a mixing valve to provide 160F injection of oil into the Airend from the 120F outlet of the coolant cooler and the bypassed flow
42
In the IA compressors, why do we want the compressor coolant (oil) at a sufficiently high temperature?
Temperature of the discharge air and lubricant mixture will be kept above the dew point to preclude the possibility of water vapor condensing in the Air Receiver
43
Turbine cooling is normally used to remove the heat from the Instrument air compressor Coolant cooler. During a shutdown, when TC is secured, what system can be used as the heat sink? Any limitations?
Domestic Service Water (DS)
Aligned to only one instrument air compressor and one service air compressor
44
What is the purpose of the Air Aftercooler in the IA compressors?
Cools the discharge air so that much of the water vapor naturally contained in the air is condensed and eliminated from the downstream plant-piping and equipment
45
What makes up the Air Aftercooling system in the IA compressors?
Heat exchanger, a condensate separator, and an automatic drain trap
46
To what temperature does the Air Aftercooler cool the compressed instrument air to? Where is the condensate routed to?
Within 15F of Turbine cooling water inlet temperature
automatic drain traps
47
How much moisture could I see flowing out of the IA compressor aftercooler drain traps on a daily basis?
18-50 gallons
48
If Turbine Cooling is unavailable, what system can I use to remove heat from the IA compressor Air Aftercooler?
Domestic Service Water
49
What is the purpose of the Instrument Air Compressors Master Controller (IAN-PC-265)?
Can control the loading and unloading of multiple compressors to maintain IA system pressure
Controls the run sequencing of the three compressors to equalize wear
50
What commands does the IA Master Controller send to the compressors?
Only sends start/load and stop/unload commands.
Initiates trouble alarms
(The compressors will stop themselves)
51
Why will the IA Master Controller not start more than one compressor at a time?
To prevent overloading of power supplies
52
What pressure will the IA Master Controller maintain the Instrument Air system at?
114 +/- 5 psig
53
How will the master controller (IEO) respond if pressure were to rise 5 psig above the Upper Pressure limit of 119 psig in the IA header? (124 psig) If it takes less an a minute to get back to the upper pressure limit, what happens? More than a minute?
It will tell all compressors to unload at once
Reload all running compressors except the last one to load initially
only reload first compressor in sequence
54
What will happen if you try to start an IA compressor that is already running?
It will trip
55
Where is the IA Master Controller located?
Mounted on the West wall of the Turbine building 100’, behind ‘A’ Instrument Air Compressor
56
If the IA Master Controller is unavailable, what can be used to control them?
Each air compressor’s local controller
57
With the IA Master Controller unavailable, the local Intellysis controllers will take over and maintain the compressors at what pressures?
Compressor ‘A’ – 113-123 psig
Compressor ‘B’ – 109-119 psig
Compressor ‘C’ – 105-115 psig
58
What is considered the normal display for the IA compressor local controllers?
“Current Status” screen
59
Where are the IA compressors local controllers located?
On the front of each Air Compressor
60
What is the purpose of the Instrument Air Receivers? How does air get from the receivers to the IA dryers?
Provide 30 sec of storage capacity on compressor trip as well as provide pulsation dampening
a common header and a pre-filter
61
What pressure will the IA Receiver relief valves lift at?
135 psig
62
How can I remove moisture from the discharge header of each IA Receiver?
Manual drain valve which drains to a floor drain
63
Why is there a small hole in the discharge check valve flapper of the Instrument Air Receivers?
Allows system air to maintain receivers associated with non-operating compressors at full system pressure
64
Where are the IA Air Receivers located?
West end of the Turbine building, 100’, between the ‘A/B’ and ‘C’ Instrument Air Compressors
65
What is the purpose of the Instrument Air Dryer Pre-filters?
Coalescing prefilter for removing liquid aerosols
66
What size impurities can the IA Air Dryers pre-filters remove? What is in the inlet line to the pre-filters and in the pre-filters themselves that are blowndown by compressed air to the turbine building floor drain?
Down to 10 microns and oil to 1 ppm
strainers and drain traps operated by an automatic timer controlled solenoid valve
67
When placing an IA compressor pre-filter online, what could happen if I open the IA Pre-Filter Isolation Valve too quickly?
May cause damage to the Air Dryer Desiccant if the Desiccant Chambers are not at system pressure
68
Regarding the IA compressors, at what Pre-filter DP will an alarm come on in the control room? What do you do if this alarm comes in?
10 psid
swap air dryer trains
69
What is the purpose of the IA dryers?
Dehumidify IA and lower the dew point of the air to between minus 20F and minus 40F, depending on flowrate and inlet air temperature
70
How many IA drying towers are there in each IA dryer train? What happens in the IA dryers when control power is lost or interrupted?
Two (one dryer, two towers)
air flow is continuous through both desiccant chambers on each dryer
71
How is regeneration accomplished in the IA Air dryers?
By directing a portion of the flow from the discharge of the in-service tower backward through the other tower to atmosphere.
A muffler is provided to reduce noise during tower reversal
72
What is the purpose of the Instrument Dryer Air After-Filters?
A particulate filter for removing desiccant fines
73
Describe the operation of the IA Air Dryer After-filters. What is the alarm for the after-filter pressure differential switch? Where is it located?
One after-filter provided in each Air Dryer train that removes particulate down to .9 microns
10psid
100' turbine building, west side, at the IA air dryer package
74
Briefly describe what you would expect to see during normal operation of the Instrument Air system
One compressor is Running either Loaded or Unloaded while the other two compressors are in the Stopped in Auto Restart condition.
Control will be through the Master Controller, maintaining pressure at 114 +/- 5 psig
75
What will happen as IA system fails and pressure is dropping?
Pneumatic components will fail to their ‘safe position’ at different pressures
IA header pressure of less than 70 psig will affect plant power production stability
Most unstable pressure will be at 40 psig where Letdown, Reactor Makeup Water, charging, Pressurizer Spray, and Reactor Drain Tank are impacted
76
At what pressure will the IA supply be considered lost to the Spent fuel Pool Gate Seals?
36 psig
77
What if Nitrogen backup is insufficient for IA system?
FLEX connection available to install backup nitrogen bottles on the north end of the 100’ Fuel building
78
What will happen if I lose power to IAA-UV-2?
The valve will fail closed and cause a loss of Instrument Air to Containment
79
How can I align Nitrogen to IA if the Nitrogen Backup Valve fails to reposition?
A manual bypass valve can be used
80
When will the IA Nitrogen Backup Valve close?
When IA header pressure rises above 105 psig
81
What kind of compressor is used in the Service Air system?
Single two-stage, rotary screw compressor with an intake filter-silencer, intercooler, aftercooler, and moisture separator
82
What pressure is maintained by the Service Air system?
Regulates air pressure between 115 and 125 psig
83
At what pressure will the Service Air compressor trip off?
135 psig
84
Describe the flowpath of the Service Air system.
Outside air is drawn into the Service Air compressor through the intake filter. The air is compressed in the first stage then sent through the Intercooler, fed to the second stage compressor, and aftercooler. The compressor discharges to the Air Receivers. From there it flows through the Service Air Dryer and on to the system headers
85
What powers the Service Air Compressor motors?
NG
86
What powers the Service Air Compressor motor space heaters?
NH
87
In the IA system, what is the limitation of using Domestic Water in the place of Turbine Cooling water?
Limited to one Instrument Air Compressor and the Service Air Compressor
88
What components of the Service Air system are cooled by Turbine Cooling?
Service Air Compressor Intercooler, Aftercooler, Lube oil cooler, jacket water cooler and the Bleed-off cooler
89
What does the Service Air system do for the Condensate demineralizers?
Supplies air for resin fluffling during regeneration
90
What part does Service Air play in Containment Hydrogen Control (HP)?
Reduces hydrogen concentration and maintains the pressure in Containment to provide the motive force to the hydrogen purge unit
91
What service does the Service Air system provide for the Cooling Tower Make up and Blowdown system?
Provides air for cooling water makeup anti-cavitation air injection
92
What component in the Fire Protection system uses Service Air?
Fire protection Pre-action valves
93
Concerning Radwaste, what is Service Air used for?
Radwaste Concentrate Drying system and Radwaste Reduction system
94
How is the Service Air Compressor controlled?
By an On/Off unloading system operated by an air pressure switch, which senses variations in the service air header
95
Where is the Service Air Compressor located?
100’ west end of the turbine building
96
The two Service air receivers receive 125 psig air from the compressor. What protections are there for these receivers?
What do the Service Air Receivers act as? Where are they located?
Relief valve set at 150 psig and a solenoid operated moisture blowdown valve
A pressure surge chamber
100' turbine building, west end
97
What is the purpose of the Service Air Dryer? What kind of dryer is it?
Removes moisture to a dew point between 35 to 45F at 125 psig
A refrigeration type air dryer
98
What happens if the Service Air Compressor runs unloaded for 20 minutes?
It will automatically stop
99
What is the evolution with the greatest high rate usage of Service Air?
Fluffing the resin beds
100
What actions are to be taken in the event I lose Service Air?
Use of Service Air is to be minimized.
If available, a backup compressor may be used
101
What FLEX connection is installed for the Spent Fuel Pool gate seals?
connection for nitrogen backup to the Spent Fuel Pool Gate Seals
102
What is the flow path of air inside the Instrument Air compressors under loaded operation?
In the inlet air filter, through MOV inlet control valve to the Airend(compressor), through a check valve to the separator tank, through a minimum pressure check valve and to the aftercooler, through the moisture separator / drain trap, exits the compressor package
103
What is the flowpath through the IA compressors while unloaded?
MOV inlet control valve is minimally opened to maintain separator sump pressure, separator tank is vented through a blowdown solenoid operated valve to the suction of the Airend.
Minimum pressure check valve prevents backflow of air from the system into the compressor package and maintains 60 psig in the separator sump as motive force for the coolant flow through the system
104
In the IA compressors, the pressure sensed by PT-4, Inlet Vacuum, represents inlet filter cleanliness and as the filter gets dirty, less air will get through and inlet pressure will drop. How exactly do the air compressor controllers sense the pressure?
increasing inlet vacuum
105
What happens if cooling water is lost to the IA air compressors?
almost immediate trip of the compressor due to high temperatures
106
If the IA header drops to 85 psig, what does nitrogen pressurize the header to?
115 psig nitrogen will re-pressurize the IA header until header pressure reaches 105 psig, then the N2 backup supply valve will close.
(there is a manual bypass valve in the case the N2 back up supply valve does not open)
107
How often does the IA compressors master controller re-sequence?
once per week (168 hours)
108
What must be done before the X8i master controller can take control of the IA compressors?
compressors must be started (running or in a standby/ auto restart condition)
X8I will not start a compressor that is in a stopped condition
109
The IA compressors are utilized, in response to changing demand, using what type of strategy?
first in, last out
110
What happens to the X8i IA master controller if there is a power loss? What if there is a shutdown fault?
a power failure auto-restart function is enabled and will auto start when power is returned, if it was running previously
control will return to the compressors
111
What keeps the IA control cabinets cool?
air-driven vortex cooler with in-line air filter
112
What is the purpose of the green and red lights on the IA instrument air dryers? What are the acceptable colors of desiccant in the system and when would it need to be replaced?
```
green:
power on, left or right drying
red:
valve malfunction
high humidity warning
```
Blue means the air is dry
pink means the air is wet
when its any other color than pink or blue
113
What provides guidance in identifying the potential loss of plant instrument air system, actions that may need to be taken, and the restoration of impacted systems following a gradual or total loss of instrument air?
The Loss of Instrument Air procedure (40AO-9ZZ06)
114
At what pressure does the control room get an alarm on low IA header pressure?
95 psig
115
What is the flow path of the service air dryers?
air-to-air regenerative HX, precooled by exiting air, then goes through an air-to-refrigerant HX
air and condensate enter a separator tank, collecting the condensate, and then the air goes back to the air-to-air HX to cool the new incoming air before exiting the unit
separator tank drains the contents on intervals, forced out by system pressure
116
What is the purpose of the service air/instrument air cross-tie inside containment and the service air bypass line outside of containment?
provide the ability for the Service Air System to meet “Instrument Air Quality” during a failure of the IA Containment Isolation Valve JIAAUV0002.
This connection supplies continuous filtered, dry, oil-free, compressed air at required pressures and flows to safety and non-safety-related pneumatic devices (instrument and valve operators).
