Instrument Air

Question 1

What trips the Instrument Air Compressor?

Answer 1

*PCIS Channel A LOCA/Hi Rad:
Low RPV Lvl 2 (-38”)
High DW Press (1.68#)
RB High Rad (1x10-3uci/cc)
RF High Rad (2x10-3uci/cc)
*Emergency Stop
Low Bearing Oil Pressure (15#)
2nd Stage Over Ratio
Starter Fault
Main Motor Overload
Remote Stop or Start Failure
Sensor Failure
High Intercooler Condensate Level
High Intercooler Pressure (43#)
High 2nd Stage Pressure (140#)
High Line Air Pressure (140#)
High 1st Stage Temperature (418F)
High 2nd Stage Temperature (461F)
High Intercooler Air Temperature (140F)
High Bearing Oil Temperature (170F)
Fan Motor Overload
Inlet Restriction

Question 2

What are the Emergency Instrument Air Compressor Auto Starts?

Answer 2

EIAC will AUTO START if it is in the AUTO control mode AND 85 psig air pressure is sensed at the emergency instrument air RECEIVER.
*RACS SV will open on EIAC start.

Question 3

What automatic actions on a slow loss of instrument air occur to attempt to stop the loss?

Answer 3

< 92# Service Air Receiver Press - Stby Service Air Compressor Starts
≤ 90# Instrument Air Header - MCR Alarm
≤ 85# Eme. Inst. Air Receiver Press - EIAC Auto Starts & RACS Demin Isol.
≤ 85# Instrument Air Header - All 3 Dryers are placed in service
≤ 70# Instrument Air Header - Service Air Isolates

Question 4

Describe what occurs in the Instrument air system when a LOCA occurs.

Answer 4

1. 1E Breaker Opens
2. 1E Breaker must be LOCALLY reset to close
3. EIAC is lost until PCIS and LOCA are reset and the 1E breaker is closed.

Question 5

Describe what occurs in the Instrument air system when a LOP occurs.

Answer 5

1. Non 1E 27 undervoltage device is disconnected: comes back on and responds to AUTO starts after bus restoration (‘A’ channel)
2. RACS to Turbine Building Isolates; however, EIAC is before the isolation valves.
3. When power is regained, compressor is available for use (auto or manual).

Question 6

Describe operations of the EIAC.

Answer 6

it will automatically start at 85 psig and unload at 100 psig in the Emergency Instrument Air Receiver. The compressor will stop after running unloaded for 15 minutes.(doesn’t every really get to the 15 min)

Question 7

What are the indications of a loss of instrument air?

Answer 7

1. Air operated valves drift as header pressure drops. Reactor will most likely scram due to low level.
2. Outboard MSIVs will close.
3. Condenser vacuum will also likely be lost – SCP and RFP min flow valves will fail open.

Question 8

What trouble alarms do you have for the instrument air dryers and what do you have to do?

Answer 8

Shutdown and transfer of in service air dryer to the standby dryer:
1. In-service dryer package high prefilter d/p – 3.25psid
2. In-service dryer package high afterfilter d/p – 3.25psid
3. In-service dyer trouble.