AR- Condenser Air Removal Flashcards
What is the purpose of the AR system?
Establishes and helps maintain a vacuum on the shell side of the main condenser by removing air and non-condensable gases during plant startup and power operations
Reduces oxygen concentration in the condensate by deaeration to aid in water chemistry
What system cools the AR pump seal water coolers?
Plant cooling water
What system provides makeup seal water to the AR vacuum pumps?
Condensate Service Header
When would AR discharge valves realign and redirect flow through the post filter unit?
When Radiation Monitoring System detects high radiation in the AR discharge
Where are the AR pumps located?
100’ south side of the turbine building
The AR vacuum pumps are sized to lower condenser pressure to what value and in what amount of time?
5” HgA in ~1.5 hours
What powers the AR pumps?
NG
Which of the four AR pumps is the standby pump?
‘D’ Pump
What is “hogging” mode?
During plant startup operation, inlet gas is compressed in the first stage and discharged directly to the moisture separator, bypassing the second stage
A check valve in the first stage discharge line allows the vacuum pump to automatically shift to the “hogging” mode when the first stage discharge volume exceeds the capacity of the second stage
What is the purpose of the moisture separator in the AR pumps?
Separate vacuum pump discharge gas from the sealant accompanying it
Provide a surge volume and reservoir for the sealant
Where does seal water flow in the Seal Water Cooler?
Shell side
When is sealant sprayed in the inlet manifold?
During high vacuum operation to cool incoming gasses and condense any accompanying steam
Where is the post filter unit located?
140’ south side of the Turbine Building
The post filter unit consists of what components?
Moisture separators
Electric heating coil
Exhaust pre-filter (HEPA)
Activated Charcoal filter
Exhaust post-filter (HEPA)
How is the electric heating coil sized?
To reduce the exhaust gas relative humidity below 70% to maintain the charcoal filter’s absorption ability
What is required in order to enter the Post Filter Unit?
Radiation Exposure Permit
What does the NH system power?
AR pump motor space heaters
post filter blower
charcoal adsorption train heating coil
Where is the motor of the Post Filter Blower started from?
Either manually from the Control Room or automatically in response to a high radiation signal
What condenser setpoints would automatically start the ‘D’ Air removal pump?
“A” Condenser – 4.2” HgA
“B” Condenser – 4.8” HgA
“C” Condenser – 5.3” HgA
What systems must be in service prior to starting the AR system?
Plant Cooling Water, Instrument Air, Condensate Service Header, Gland Steam Seal and drain systems
What would happen up on a loss of AR?
During normal operation, would not have an immediate effect since the condensing steam will maintain vacuum
Non-condensable gases will build over time, causing a loss of vacuum that could require a turbine shutdown
Oxygen will increase in the condensate which could also require a power reduction
How long would it take before we see signs of a degraded vacuum after a loss of AR?
10-20 minutes
What three support systems are needed for AR system operation?
Plant Cooling Water, Instrument Air, and Condensate Service Header
How is the system affected by a loss of PW?
Overheating of any operating AR vacuum pumps due to buildup of excess heat
High vacuum pump seal water temperature would result in a loss of pumping capability as the seal water flashes to steam
How is the system affected by a loss of IA?
All suction isolation valves to vacuum pumps will fail closed
An effluent path will be maintained through the post filter unit, along with vented gases
How is the system affected by a loss of the Condensate Service Header?
Could result in a low level in the ‘on-skid’ moisture separator if there is insufficient moisture carryover from the main condenser
What is the normal line up for the AR pump exhaust?
bypassing the charcoal adsorption train and the post filter blower via the bypass valve and straight to the plant vent stack
How many AR pumps are used in Hogging mode to draw the initial vacuum in the condenser?
all four
There should always be some leakage from the AR pump seals. What are the two places the seal leakage can be directed to? What is the preferred line up and why?
main condenser or OW via the floor drain
OW via the floor drain because if there was an AR pump seal water cooler tube leak, PW would be introduced to the main condenser if directed there
How does the GS (Main turbine Gland steam seals and drains) system interface with the AR system?
gland sealing steam packing exhauster discharge is directed to the AR system and the drain tank vents to the AR system
How does IA interface with the AR system?
pneumatic valves
Where does each AR pump connect to the condenser?
A, B, C all connect to their respective shells and D can automatically connect to all three shells
What is “holding” mode?
inlet gas is partially compressed in the first stage and is discharged (along with the liquid sealant) to the second stage inlet. The second stage of the pump compresses the gas to slightly above atmospheric pressure, and discharges it and the liquid sealant to the moisture separator.
What is the difference between the bearings in AR pumps before and after a rebuild of the pump?
rebuilt pumps will have sealed grease bearings instead of oil lubricated bearings
sealed grease bearings should not have any evidence of leakage
Concerning the AR system, who is responsible for measuring the condenser in-leakage and how is it measured?
area operator
through a rotameter
Regarding the AR system, where does the seal water recirculation pump take suction from?
separator tank
what is the purpose of the charcoal adsorption train in the AR system? When is it used?
removes moisture, particulate contamination and gaseous iodine and methyl iodide
when high levels of radioactivity are detected in the combined air removal and gland sealing steam packing exhauster discharge
In the AR system, what will the charcoal adsorption train alarm on?
high D/P
What RU monitor is in service to monitor the exhaust of the air removal pumps during normal operation? What happens when high radiation is detected?
141
charcoal adsorption train bypass valve closes, inlet and outlet open and the post filter blower will start
What would happen on a loss of the Condensate (CD) system to the AR system?
low level in “on-skid” moisture separator (the source of water pumped into the vacuum pump spray header by the seal
water recirculation pump) if there is insufficient moisture carryover from the Main
Condenser.
What happens in the AR system when there is a loss IA?
all vacuum pump suction isolation valves will fail closed
AR pump discharge will be directed to the charcoal adsorption train
Regarding the AR system, why must the AR pumps be manually shutdown after a loss of IA?
when IA is lost, the suction valves close and there is no automatic trip for the pump
What happens in the AR system when there is a loss of GS (main turbine gland sealing steam and drains)?
excessive air intrusion into the secondary which would raise condenser pressure, start the ‘D’ AR Pump, and could threaten the Condenser AR
Pump capacity.
