SG Blowdown Flashcards
(45 cards)
What is SG Blowdown used for ?
-Used to maintain chemistry at power
-Used to maintain chemistry in SG while in wet lay-up providing: Mixing,Sampling, & chemical addition to SG
What’re the three blowdown lines tap off from on the SG ?
-Reactor Coolant Hot Leg Region
-Reactor Coolant Cold Leg Region
-Downcomer region
What will close the Blowdown Containment Isolation Valves ?
-MSIS
-AFAS
-SIAS
What source is used to operate the Blowdown Isolation Valves ?
-Air operated to open valve
- Spring loaded to close the valve
What’re the tech specs associated with the Blowdown Containment Isolation Valves & the Blowdown Sample Line Containment Isolation Valves?
Isolation valves must be checked on periodic basis to make sure they’re still operable
What’re the Blowdown Flow Control Valves used for ?
Control flow to either the flash tank or the main condenser
What’re the sizes of each blowdown line ?
Normal Rate: 2” Line
Abnormal Rate :4” Line
High Rate: 6” Line
How is a flow control valves normally aligned & operated ?
-AO must manually align the inlet & outlet valves for the Flow Control Valve
-Once FCV inlet & outlet valves are opened, control room control the FCV
Why are the inlet & outlet valves for the Normal & abnormal FCV aligned during irregular chemical activity ?
This allows control room to quickly switch between FCV as necessary
What’re the allowed SG Blowdown Lineups ?
-Both SG at normal rate to Blowdown Flash Tank or Main Condenser
-Both abnormal rate to Main Condenser
-One SG abnormal rate to Blowdown Flash Tank
-One SG High Rate to Main Condenser
What do the Blowdown FCV fail closed on ?
Fail close on:
-Loss of power to solenoid
-Loss of air supply to valves
When establishing blowdown lineup what needs to be locally controlled on the Blowdown Flash Tank ?
AO just manually control pressure to prevent lifting relief valve
What happens to the blowdown when it enters the Blowdown Flash Tank ?
It flashes to steam cooling down water & reducing pressure of blowdown
What temperature is blowdown at when it enters the Blowdown Flash Tank ?
550F saturation temperature
What does the Blowdown Flash Tank(BFT) pressure control valve do ?
It maintains BFT pressure at 200psig
Why is it important for the BFT to flash blowdown to steam ?
Cools the water down enough to be sent through Demineralizers to be cleaned
Where does the pressure relieve to from the BFT?
There is a set of Pressure Control Valves that send steam to either:
-HTR Drain Tank Equalizing line(Normal)
-Main Condenser (Alternate) path is used if normal path can’t maintain pressure
Who is supposed to control the Pressure Control valves for the BFT ?
-AO is supposed to manually control valve to maintain 200psig
-Changing blowdown alignments will need an AO to manually maintain pressure
What must happen to BFT Pressure Control Valves when plant power is changed by >5%?
AO must isolate HTR Drain Tank Equalizing Line Valves
Why do the HTR Drain Tank Equalizing Lines need to be isolated when plant power changes >5% ?
Helps reduce secondary chemical hideout by having all blowdown that goes to BFT end up in MainCondenser
What is the normal flow paths for the BFT Level Control Valves ?
1.)Blowdown HEX
2.)Blowdown Filters
3.) Blowdown demineralizers
4.) Main Condenser
What is the Alternate flow path from the BFT Level Control Valves ?
3 LPFWH shell side
How are the BFT Level Control Valves operated ? What do they fail closed on ?
-Automatically throttled to maintain level in BFT
- Fail closed on loss of power to solenoid
-Fail close on loss of air supply to valve
What is the Blowdown Heat Exchanger used for ?
Cool blowdown from the BFT prior to entering Blowdown Demins
