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