Gaseous Radwaste System Flashcards
What is most of the high activity waste gas?
Hydrogen and Nitrogen
Where is the gas stored prior to atmospheric discharge?
O2 free decay tank to allow isotopes to undergo radioactive decay.
What components make up the GR system?
Gas surge header
waste gas surge tank
2 waste gas compressor
3 waste gas decay tanks
Where is the decay tank gas discharged to?
the radwaste building exhaust system through 2 isolation valves, a discharge filter, a flow element, a rad monitor, and a flow control valve
What does PK supply in the GR system?
a solenoid operated containment isolation valve (UV-2)
What cools the GR gas compressors?
NC
Where does the waste gas come from?
Containment refueling failed fuel detector vent Dry sipping aux pump RDT gas stripper VCT VCT relief O2 analyzer
What does the gas surge tank do?
absorbs fluctuations in gas volume entering the system to minimize compressor run time
What will start the waste gas compressor when it’s in auto?
High surge tank pressure will start the lead compressor. Compressor auto starts on high-high pressure regardless of selected mode.
Describe the operation fo GR-34A and 34B.
pneumatically operated valves installed in series in the gas discharge line. Handswitch 34A is in the radwaste control room and 34B is in the main control room. 34B provides an open permissive signal and has the ability to close the valves. 34A will open the valves if the control room switch is in open permissive and it will close the two valves
What happens if RU-12 receives an alarm?
decay tank discharge isolation valves close and the gaseous discharge flow control valve will close
What will auto close GRV-34A & 34B?
HR system exhaust fan A & B low D/P
high waste gas discharge flow, rad level, gas discharge pressure
How are the 3 waste gas decay tanks normally used?
One receiving waste gas, one as a backup, and one holding decaying waste gas.
Why is the O2 level of the filling decay gas tank periodically checked?
Because the majority of waste gas is H2, O2 levels must be kept below the explosive limit (2% will alarm)
What happens at 3.75% O2 in the waste gas GR system?
Waste gas compressors stop, auto dilution of the system with N2 begins.
