Hydrogen Skimmer, Containment Air And Return System, And Containment Hydgrogen Sample And Purge System(VX) Flashcards
What is the purpose of the Hydrogen Skimmer System?
The Hydrogen Skimmer System mixes the containment atmosphere, eliminating localized high concentrations of hydrogen following a LOCA.
What areas are served by the Hydrogen Skimmer System?
- All four S/G compartments
- Pressurizer compartment
- Reactor compartment
- All four cold leg accumulators
- North and South fan rooms
- Incore instrumentation room
What is the purpose of the Containment Air Return System?
The Containment Air Return System ensure a rapid return of air and steam from the upper to the lower containment after initial loss of coolant accident or a main steam line break providing circulation through the ice condenser to maintain containment pressure less than design.
What is the purpose of the Hydrogen Recombiners?
The Hydrogen Recombiners combine hydrogen and oxygen following a loss of coolant accident to ensure hydrogen levels in containment are below 4%.
What is the purpose of the Containment Hydrogen Purge System?
The Containment Hydrogen Purge System provides a purge and fill of the containment atmosphere with hydrogen free Auxiliary Building air to ensure containment hydrogen is maintained below 4%.
What is the purpose of the Hydrogen Ignition System?
The Hydrogen Ignition System will provide a controlled ignition of low hydrogen concentrations, using glow coils, to ensure containment hydrogen is maintained less than 4%
What is the purpose of the Containment Hydrogen Analyzers?
The Containment Hydrogen Analyzers are available for continuous sampling with display in the control room and for sampling by RP at the Post Accident Sample Panel.
What is the system designator for the Containment Air Return and Hydrogen Skimmer System/Hydrogen Recombiners?
VX
What is the system designator for the Hydrogen Purge System/Containment Hydrogen Monitors?
VY
What is the system designator for the Hydrogen Ignition System?
EHM
What are the sources of Hydrogen following a LOCA?
- Metal steam reaction between the Zirconium fuel rod cladding and the reactor coolant
- Radiolytic decomposition of water in the reactor coolant system and the containment sump
- Hydrogen dissolved in the reactor coolant at the time of the LOCA
- Corrosion of metals exposed to containment spray and emergency core cooling systems
What is the purpose of the Backdraft Dampers on the outlet of the Air Return Fans?
They prevent the lower containment atmosphere from bypassing the ice condenser by acting like a check valve
What is the purpose of the Containment Air Return Fans?
The Containment Air Return fans return air from upper containment to the lower containment so that it can be sent back through the ice condenser for further heat removal.
What will cause the Air Return Fans to automatically start?
- 9 minutes has elapsed from receipt of Sp(Hi-Hi containment pressure >3.0psig) signal
- Greater than 0.9psig signal from CPCS(Containment Pressure Control System)
- Load group #11 from D/G sequencer has permission to start
What is required to manually start an Air Return Fan?
Greater than 0.9psig CPCS signal
What will happen to an Air Return Fan that has automatically started when pressure decreases?
When containment pressure is less than 0.35psig the fan will stop. If pressure increases to greater than 0.9psig it will start, and the cycle will continue.
What is the purpose of the Air Return Fan start delay?
The start delay of 9 minutes allows the upper and lower containment pressures to equalize and minimize the differential pressure.
What conditions will cause the Containment Air Return Dampers to automatically open?
- 10 seconds has elapsed from receipt of Sp(Hi-Hi containment pressure >3.0psig) signal
- Greater than 0.9psig from the CPCS
- Less than 0.5psid across the damper
- Load group #1 from the D/G sequencer has permission to start
What is the purpose of the <0.5psid interlock with the Containment Air Return Dampers?
The differential pressure interlock is to prevent overloading the damper motor.
What is unique about the operation of the Containment Air Return Damper following an automatic open signal?
Once the damper is open, with the signal present, the damper stays open.
What is required to manually open the Containment Air Return Damper?
- Sp signal or Air Return Fan manually ON
- > 0.9psig CPCS signal
- OPEN selected
- The time delay is bypassed
What is the purpose of the Hydrogen Skimmer Fans?
The Hydrogen Skimmer Fans take a suction on areas of hydrogen accumulation in the lower containment and discharge to the upper containment near the hydrogen recombiners.
What will cause an automatic start of the Hydrogen Skimmer Fans?
- 9 minutes has elapsed from receipt of Sp(Hi-Hi containment pressure >3.0psig) signal
- Load group #11 from the D/G sequencer has given permission to start
- The suction isolation valves are not closed
How is a Hydrogen Skimmer Fan manually started?
The Hydrogen Skimmer Fans are manually started by taking the keylock switches to ON. This will bypass any time delay.
What will cause the Hydrogen Skimmer Fan Isolation Valves to automatically open?
9 minutes has elapsed from receipt of Sp(Hi-Hi containment pressure >3.0psig) signal
What is required to manually open the Hydrogen Skimmer Fan Isolation Valves?
- Sp signal or VX fan manually on
- Open on its control switch
- Time delay is bypassed
What is the purpose of the Hydrogen Recombiners?
The Hydrogen Recombiners combine hydrogen with oxygen to ensure containment hydrogen will not exceed 4%.
Where are the Hydrogen Recombiners controlled from?
The Hydrogen Recombiners are controlled from the local control panels.
When are the Hydrogen Recombiners shutoff based on hydrogen concentration?
When hydrogen concentration reaches 6% the recombiners are secured.
How does the Hydrogen Ignition System control hydrogen concentration?
The Hydrogen Ignition System controls hydrogen by energizing glow coils and burning hydrogen in a controlled manner.
How many Hydrogen Igniters are there?
- There are 70 total hydrogen igniters, with 35 in two redundant circuits
- Locations:
A. 23 lower containment locations
B. 6 upper containment locations
C. 6 ice condenser locations
Where are the Hydrogen Igniters operated from?
The Control Room
How does the Containment Hydrogen Purge System control hydrogen concentration?
The Containment Hydrogen Purge System blows air from the Auxiliary Building into Containment, and then exhausts air from the Containment into the Annulus.
Where are the Containment Hydrogen Purge Fans and Dampers operated from?
The Control Room
Which train of Hydrogen Igniters can be operated from alternate location, and what are the indications?
- The ‘A’ train of hydrogen igniters can be operated locally following transfer of power to the alternate source.
- Control Room indication is lost and control of the igniters will be lost.
- The ON/OFF control will be performed at the local control panel(Aux Building 577 Electrical Penetration Room)
What is the power supply for the Containment Air Return Fans?
1(2)A - 1(2)EMXK
1(2)B - 1(2)EMXL
What is the power supply for the Containment Air Return Dampers?
1(2)D-2 - 1(2)EMXK
1(2)D-4 - 1(2)EMXL
What is the power supply to the Hydrogen Skimmer Fans/Valves?
1(2)A train - 1(2)EMXK
1(2)B train - 1(2)EMXL
What is the power supply to the Hydrogen Recombiners?
1(2)A - 1(2)EMXK
1(2)B - 1(2)EMXL
What is the power supply to the Hydrogen Igniters?
1(2)A - 1(2)EMXI (normal)
1(2)A - 1(2)EMXL (alternate)
1(2)B - EMXB
What is the power supply to the Containment Hydrogen Purge Fans?
Unit 1 - 1MXM
Unit 2 - 2MXM
