AR- Condenser Air Removal Flashcards Preview

NLO Systems > AR- Condenser Air Removal > Flashcards

Flashcards in AR- Condenser Air Removal Deck (43):

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?



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?


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


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.

Decks in NLO Systems Class (63):