HC- Containment HVAC Flashcards
What is the purpose of the HC system?
Maintain temperatures and airborne activity in the containment within acceptable limits for equipment operation and personnel access
Supplies outside air to and exhausts from the MSSS in order to cool the main steam and feedwater piping penetrations
What is the purpose of the Containment Normal Air Cooling units? Flowpath?
Recirculate and cool the air inside containment
Fans take suction on 120’ Containment building and discharge to 100’ and 80’ elevations
What is used to cool the Containment Building Normal ACUs?
Each of the four units consists of three cooling coils supplied by the Normal Chilled Water System, a flow regulating valve controlling flow based on outlet temperature of ACUs fan
Cooling water is isolated when the ACU is stopped
The four Containment Normal ACU fans are powered from what system? Where are they located?
PG (PGA-> ‘A’ ‘C’, PGB-> ‘B’ ’D’)
120’ containment
When will the Containment Normal ACU dampers open and close?
When the ACU fan is started and stopped
The Containment Normal ACU heaters are installed in series with what components? What is there purpose? What is their normal status?
‘C’ and ‘D’ fans (one fan per ACU)
maintain temperature with in containment during prolonged shutdown periods
down powered
What is the interlock associated with the Containment Normal ACU heaters?
A low air flow interlock prevents operation if air flow is too low to remove the heat generated by the heating elements
During normal operations, the Containment Normal ACU has one fan running while the paired fan is secured in each duct. What will happen if an operating fan trips?
A low D/P across the fan is sensed, which starts the other fan automatically after a 60 second time delay as long as its switch is in the ‘Normal After Stop’ position
What is the purpose of the Containment Normal ACU fan 60 second time delay?
Allows the non-operating fans to come to a stop if the back draft or suction damper were leaking, which would cause the fans to spin backwards
What happens to the Containment Normal ACU fans upon a SIAS?
Stops all operating fans, can be restarted after they are in override
How are the Containment Normal ACU fans affected by a LOP?
If the fan was running prior to the LOP, the load sequencer will start the fan
When are the Containment Pre-Access AFUs operated and where are they located?
As necessary to support personnel access to the containment building during power operation and prior to opening containment for an outage
Located on the 140’ of Containment
What is the capacity of each Containment Pre-Access AFU?
50%
What components make up the Containment Pre-Access AFUs and their functions?
High efficiency bank to remove large radioactive airborne particulate material, protecting the first HEPA from excessive loading
First HEPA filter to remove smaller particles
Charcoal filter to remove fission product gases (mainly Iodine)
Second HEPA filter to remove charcoal fines
What powers the Containment Pre-Access AFU fans?
NG
What is the purpose of the Containment CEDM Normal ACUs and what do they consist of?
Keep CEDM temperatures within limitations
Consists of two CEDM Normal ACUs, each equipped with two fans for a total of four fans and set of cooling coils, ducting and dampers (on 157’ containment)
What cooling water flows through the Containment CEDM Normal ACU cooling coils and what starts it?
Nuclear Cooling Water
started automatically when an associated fan is started
Isolated when fan is stopped
Under normal conditions, how many Containment CEDM Normal ACUs are operating? Can a single fan cool the CEDMs properly?
Only one, with both of its fans running
yes
Concerning the Containment CEDM Normal ACU fans, why are there backdraft dampers installed on the discharge side?
To prevent a short circuit air flow condition during single fan operation
Where are the Containment CEDM Normal ACU fans powered from? Where are they located?
PG (PGA-> ‘A’ ‘C’, PGB-> ‘B’ ‘D’)
157’ containment
Concerning the Containment CEDM Normal ACU, what happens if a pair of operating fans tripped?
Low D/P across the fans are sensed, which will automatically start the other pair of fans after a 120 second time delay as long as its control switch is in the “Normal After Stop” position
What is the purpose of the Containment CEDM Normal ACU fan time delay?
Allows non-operating fans to come to a stop if the back draft or suction damper were leaking, which could lead to the fans spinning backwards
What happens to the Containment CEDM Normal ACU upon a receipt of a SIAS?
Stops all operating fans, which can be restarted after they are placed in override
How is the Containment CEDM Normal ACU affected by a LOP?
The pair of fans that was running prior to the LOP will be started by the load sequencer
What is the purpose of the Containment Reactor Cavity Cooling Fans and how many fans are there?
Directs air from the lower containment volume to the reactor cavity for cooling to prevent cement deterioration
Consists of four fans
Where do the Containment Reactor Cavity Cooling Fans take suction from and where are they located?
80’ of containment
How many Containment Reactor Cavity Cooling Fans are normally running? What is the capacity of each fan?
Two fans, one from each pair (Ex A and C, or B and D)
50%
What system provides power to the Containment Reactor Cavity Cooling Fans?
SIAS load shed MCC
NH (M19 and M20)
Where is the only location that I could verify the remote position of the Containment Reactor Cavity Cooling Fan damper?
Can only be verified at the MCC supplying power to the damper
What is the auto feature associated with the Containment Reactor Cavity Cooling Fans?
Provided between ‘A’ and ‘B’ and the ‘C’ and ‘D’ fans
Ex. If ‘A’ fan is in AUTO and a low D/P is sensed across the ‘B’ fan, ‘A’ fan will auto start after 60 seconds
What is the purpose of the Containment Pressurizer Space Exhaust Fans? Where do the fans take suction and exhaust from?
Two fans that ventilate the pressurizer space within the pressurizer missile shield
draws air in from the bottom of the space and discharges at the top
How many Containment Pressurizer Space Exhaust fans are normally running?
One, while the other is in AUTO
What are the power supplies for the Containment Pressurizer Space Exhaust fans?
NH (M71, M72)
Fans will stop due to SIAS load shed
What is the auto feature associated with the Containment Pressurizer Space Exhaust Fans?
If ‘A’ fan is in AUTO and a low D/P is sensed across the ‘B’ fan, the ‘A’ fan will auto start after 60 seconds
Same would occur if ‘B’ was in AUTO and ‘A’ was running
What is the purpose of the Containment Tendon Gallery Supply and Exhaust Fans and where are they located?
Supply and exhaust fans that operate to ventilate the tendon gallery area to ensure a habitable environment prior to personnel access
Located on 100’ level outside containment building
Where do the Containment Tendon Gallery Supply fans get their suction from?
Outside air
What are the power supplies for the Containment Tendon Gallery Supply and Exhaust Fans?
NH
How many exhaust fans are normally operating in the MSSS? How are they controlled?
Each only takes suction on one side of the MSSS (north and south) so both are normally operating
Controlled locally and have no auto features
How many AFUs are used in the MSSS Ventilation Supply? What is inside the AFUs?
two, One for each fan
dry filter media with a high D/P alarm and an abandoned oil impingement cleaner
What is the auto feature associated with the MSSS Ventilation Supply?
One supply fan is normally operating with the other fan in AUTO
When operating fan trips, and low D/P is sensed across the fan, standby fan will auto start after 60 seconds
Where are the MSSS Ventilation Supply Fans controlled?
Locally with three-position switch (STOP-AUTO-START)
While doing rounds, you notice that the MSSS Ventilation Supply fan motor is operating, but the blades are not spinning. What happened?
Fans are belt driven; the belt has broken or come loose
Explain the operation of the RU-1
Located in the Aux building, it draws a suction sample from the 95’ level of containment for monitoring
After monitoring is complete, the sample is returned to containment
Describe the RU-1 containment penetration isolation valves. What system powers them? When will they fail closed?
Two installed on each penetration, one inside containment and the other outside
Each valve is class powered and will fail close upon a loss of power (PK), will close on CIAS
Suction line – UV-47 (B train) and UV-46 (A train)
Return line – UV-44 (B train) and UV-45 (A train)
Concerning the Containment Normal ACUs, how are the fans paired together?
A and B
C and D
Where do the Containment Pre-Access Filtration AFUs discharge to?
the upper portion of containment
What is the capacity of each Containment CEDM Normal ACU fan?
50%
What happens when the Containment CEDM Normal ACU control switch is turned to the start position?
ACU fans start, intake damper and NC system cooling water supply valve both open
How are the CEDM normal ACU intake dampers physically operated?
motor operated
What is the tech spec associated with the Containment HVAC system?
containment must remain at 117*F or lower
How does the HC system interface with the PPS?
pressure transmitters inside containment generate actuations based on containment pressure
