Steam Generator Blowdown Flashcards
What is the purpose of S/G blowdown?
Compensate for the impurity concentration effect on the S/Gs by continuous blowdown and processing of a portion of the fluid from each steam generator.
Also maintains S/Gs in wet layup by allowing for adequate mixing, sampling, and chem add.
Draw blowdown.
Include all major parts
How many blowdown connections are there and where are the from?
3
Hot leg, cold leg, and downcomer
What will cause the two blowdown containment isolation valves to shut?
AFAS, MSIS, and SIAS
Where can the blowdown lines be immediately directed to?
Main condenser or blowdown flash tank
Which blowdown connection is normally used?
Downcomer
Where does the vapor that that accumulates in the BFT discharge to?
Through the vent line to the heater drain tank equalizing line or to the main condenser.
How is the liquid in the BFT processed for reuse?
It goes through the blowdown HX, a filter, demins, and then discharges to the condenser hotwell.
What cools the blowdown HX?
Condensate from the discharge of the CD pumps.
How is BFT pressure maintained?
By a pressure control valve that discharges to heater drain tank or the main condenser.
Where do the blowdown demin low TDS sump and high TDS sump get pumped to?
Low TDS can go to circ water canal if no rad. If activity present then pumps to the LRS sump. Could also go to CWNT
High TDS sump pumps to the CWNT.
How do the blowdown flow control valves fail on a loss of IA?
Closed.
What can selecting the incorrect blowdown rate valves impact?
Reactor power calcs that could cause the plant to exceed power operating limits.
How is blowdown controlled?
From the control room.
3 position switch to select BFT, Cond, or off and a rate selector switch for normal, abnormal, or high rates.
What flow is the BFT sized for?
Continuous abnormal rate from 1 s/g and normal rate from a second s/g.
