SG Blowdown Flashcards
What ESFAS signals will cause the two automatic containment isolation valves on the blowdown lines to isolate the blowdown system?
AFAS, MSIS, SIAS
What is the purpose of the SG blowdown system?
Compensate for impurity concentration
Also maintains the SG in wet layup by providing the capability to adequately mix, sample and add chemicals to the SG
What are the possible possible flow paths for SG bd?
BFT, Cond, downcomer bd connection (primary)
Manually selected.
What system provides cooling for the bdhx?
Condensate CD
Where is the BFT liquid outlet routed?
3 LP FW heater
Where is the condensate cooling water discharged to after it has gone through the BDHX?
Discharge of the ED pumps just prior to the suction of the main FW pumps.
Where are the blowdown flow control valves physically located?
100’ turbine building west side
How are the bd flow control valves operated and what is their fail position?
Air operated. Fail closed.
How are the flow control valves operated?
Manually controlled inlet and outlet valves must be operated by an AO.
Where is SG blowdown controlled from and how?
From control room
Via isolation and stop valve control switches.
How many BFTs are there for both SGs?
One BFT for both SGs.
Where does the BFT discharge to?
Bdhx or the #3 LP FW heater.
How are the blowdown pressure regulating valves operated and how do they fail?
Air operated
Fail open
What is the purpose of the blowdown pressure regulating valves?
Maintain BFT pressure which can be adjusted by AO at the local pressure controller.
Describe the blowdown demineralizer package.
2 mixed bed, regen resin type units operated in series.
Where are the blowdown demineralizers located?
North yard of the turbine building
What happens to the bd demins if a high sodium level is detected?
The vessels will be removed from service IF the switch is in AUTO STOP mode.
What happens to the bd demins if a high dP is detected while in AUTO STOP mode?
The vessel will be removed from service for regen
Where is the bdhx located?
If the yard area on the plant south side of the bd demins
Where do the wet layup recirc pumps normally take suction from and discharge to?
Normally a pump from SG 1
B pump from SG 2
Can be aligned to take and discharge to either SG.
Where are the wet layup recirc pump switches located?
Ctmt next to the pumps on the 70’
Where are the 480 Vac MCC breakers that supply power to the wet layup recirc pumps located?
Aux building 120’
On loss of IA how does the bd to flash tank control valve fail?
Closed
On loss of IA how do the bd to cond control valves fail?
Closed stopping blowdown
How does the flash tank condensate level control valve to FW heater fail?
Closed
How do the blowdown flash tank pressure control valve to HDT and BFT pressure control valves to cond fail?
Open
Where does wet layup recirc water enter the tube bundle area of the SG?
Through the recirc lines
What is the disadvantage of downcomer blowdown?
Advantage- highest levels of impurities 3-10*
Disadvantage- has no cleaning effect on the tube sheet sludge pile.
