HP- Containment hydrogen control Flashcards
What are the functions of the HP system?
Monitors hydrogen concentrations in the containment building after an accident
Maintains hydrogen concentration in the containment below the lower combustible limit of 4% by volume in air
What is the purpose of the Containment Hydrogen Monitoring subsystem? How many redundant trains are there and what does each train consist of?
Measure the hydrogen concentration at two independent locations and to alert the operator in the control room of the need to activate the hydrogen recombiners or Hydrogen Purge system
two, hydrogen sensor, electronic subassembly, local and remote readout/alarms
How are the Hydrogen Analyzers started following a LOCA?
Manually from the control room
Where is the sample line for the Hydrogen Analyzer? Where are the Hydrogen analyzers located?
Taps off the suction line to the hydrogen recombiner, which is coming from containment, passes through the analyzer and returns to the containment
aux. building
How would the Hydrogen Monitoring Subsystem be affected if HC was not in operation?
The air in containment would not be mixed well which would give a false reading when the analyzers are placed in service
Why is heat tracing used on the supply lines of the HP system?
Prevents excess condensation from developing in the lines
Concerning the Hydrogen Analyzers, what is the purpose of the Span Gas bottle?
Required for calibration of the unit
Concerning the Hydrogen Analyzers, what is required for operation of the unit? What is required for calibration?
Reagent Gas Bottle
span gas bottle
Specifically, how are the analyzers started from the control room and how long before I get accurate readings?
Control Room operator opens the containment isolation valves and selects ‘ANALYZE’ position on the control panel
30 minutes
What is the power supply for the Hydrogen Analyzers and sample pump?
PH
What system supplies control power to the Hydrogen analyzers?
PK
What is the purpose of the Hydrogen Recombiner Subsystem? What is the backup subsystem in the case that both recombiners fail?
Provides the primary means of reducing containment hydrogen concentrations after a LOCA
HP hydrogen purge exhaust
What hydrogen concentration are we trying to stay under?
4% volume, the lower combustible limit of hydrogen in air
How long do I have to connect all Hydrogen Recombiner services after a LOCA?
72 hours
How long do I have to make the Hydrogen Recombiner operable?
100 hours of the same LOCA
The system can be installed and functional before the hydrogen concentration reaches what percent volume?
3.5% volume
To what temperature is the drawn-in atmosphere in the recombiner raised to? Basis?
1300F, temperature above (1150F) which free hydrogen will recombine with oxygen to form water vapor
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What system provides for Hydrogen mixing inside containment?
[CS] Containment Spray
M
M
What is the purpose of the hydrogen purge subsystem?
Provides a backup installed capability for a controlled purge of the containment atmosphere in order to maintain the hydrogen concentration below 4% by volume following a LOCA
M
M
What is the airflow rate through the Hydrogen Purge Exhaust?
50 cfm
What powers the Hydrogen Purge Exhaust Electric Duct Heater?
NH
What system provides Service Air to the HP system for the positive pressure in Containment that is the driving force for air through the Hydrogen Purge Exhaust Unit?
Instrument Air
Where is the Hydrogen Purge Exhaust Subsystem?
Unit 1 Aux Building 100’
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Following a LOCA, what are some ways that Hydrogen is produced inside containment?
Metal-water reaction involving the zirconium fuel cladding and the reactor coolant
Radiolytic decomposition of the Post-LOCA emergency cooling solutions
Corrosion of metals and paints by solutions used for emergency cooling or containment spray
What happens if Service Air is lost?
Hydrogen Purge subsystem is rendered Non-Functional, the Recombiners will have to be used
How is containment atmosphere drawn into the hydrogen recombiner? What is the flow path through the recombiner assembly?
a gas blower
gas blower draws air in, heats it up and then flows from the heater to the reaction chamber where the conversion process occurs. reacted gas and water vapor pass through an air blast heat exchanger and then returned to containment
Where do the hydrogen recombiners receive power from? What provides the power distribution and control instrumentation and how is it connected to the recombiner?
PH and PK
power and control console
connected by portable cables
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There is an adjustable timer that disables an alarm during start up; what alarm is in when the hydrogen recombiner is starting up?
low gas temp
What is the flow path of the HP hydrogen purge subsystem? What is the purpose of the unit heater?
pressurized air flows into the hydrogen purge unit, and through a mist eliminator and unit heater. after the heater, air passes through a HEPA filter, a carbon filter, and another HEPA filter and goes to the plant vent
keep humidity below 70%
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What is the auto feature that will isolate the HP hydrogen purge exhaust subsystem?
CIAS
recombiner inlet and outlet also serve the hydrogen purge exhaust system
Concerning the hydrogen recombiners, what is the purpose of the trickle heater and how long must it be on prior to using the recombiner?
takes 24 hours to get up to 1300*F that’s required for operation
