General Flashcards
What is the purpose of the Drywall Cooling System?
Provide cooling to the Drywell including:
1) Reactor Vessel Skirt Flange.
2) Refueling Bellows Support Skirt.
3) Annulus Space between the Vessel and the Biological Shield Wall.
How many Drywell Air Handling Units are there, and where are they located?
There are 3 Drywell Air Handling Units.
Lower AHU - Drywell 590 foot level.
Middle and Upper AHU - Drywell 637 foot level.
How many Drywell Cooling Fans are there?
There are a total of six Drywell Cooling Fans. There are two fans per Air Handling Unit with one normally running and the other in standby.
What are the sections of the Drywell Cooling AHUs?
The Drywell Air Handling Unit first stage is a Roughing Filter, followed by two air coolers in series.
Does the Roughing Filter stay installed during normal power operation?
NO, the Roughing Filter is removed to prevent it from ending up in the Suppression Pool during a LOCA.
How many cooling coils are in service at a time?
Only one cooling coil is allowed to be in service at a time due to an interlock.
What system provides the cooling water for the Drywell Air Handling Units?
Nuclear Closed Cooling(P43).
What determines which cooling coil is in service to each Drywell Air Handling Unit?
An air operated three-way valve, controlled by a switch on 1H13-P800, determines which cooling coil is in service.
What system provides air to the three-way AOV that decides which cooling coil is in service?
Instrument Air(P52).
How does cooling flow fail for the Drywell Air Handling Units?
Cooling water flow will fail to the B cooling coil service.
How do the Drywell Air Handling Units interact with the Leak Detection System?
The Upper and Middle Drywell Air Handling Units drain flows are monitored by Leak Detection to determine if there is a steam leak in the Drywell.
What are the power supplies to the Drywell Cooling Fans?
F1B08, F1C08, and F1D08.
What is the normal lineup for the Drywell Cooling Fans?
One fan running per AHU on each level with the other fan in standby.
What will cause an automatic start of the standby Drywell Cooling Fan?
The standby Drywell Cooling Fan will automatically start on low flow(D/P) with the standby fan’s switch in STBY.
Following a start of the standby Drywell Cooling Fan on low flow what will be the result of the running fan’s low flow condition clearing?
The standby Drywell Cooling Fan will shutdown following a reset of the the low flow condition.
What will happen to the normally running fan if a low flow condition locks in?
The fan will continue to run until it’s shutdown by the operator. There is no low flow trip.
Where is the vibration monitoring located for the Drywell Cooling Fans?
There is an alarm in the Control Room, but the actual vibration meters are located at IB-620.
How does the Nuclear Closed Cooling Supply Valve Control Switch determine which cooling coil is in service?
The switch, if placed in the A coil position, energizes a solenoid allowing Instrument Air to align a 3-way valve. This will direct flow to the A cooling coil. By placing the switch in B coil position, the solenoid is de-energized, allowing flow to be directed to the B cooling coil.
What is the difference between the cooling water flow through the Lower Drywell AHU cooling coils, and the cooling coils of the other two AHUs?
The flow through the cooling coils of the Upper and Middle AHUs is full flow. The Lower AHU cooling flow is throttled.
How is cooling water flow controlled through the Lower Drywell AHU?
The cooling water flow to the Lower Drywell AHU is through one coil, but a motor operated throttle valve is used in conjunction to help control temperature. The MOV acts as a bypass valve to allow flow to the bypass the cooling coil to control temperature.
What is the power supply for the Lower Drywell AHU NCC Throttle Valve?
K-1-N, non-safety and non-diesel-backed.
How will the Lower Drywell AHU NCC Throttle Valve fail on a loss of power?
The NCC Throttle Valve will fail “AS-IS”.
