AS- Auxiliary Steam Flashcards
Why would we send Aux Steam to the MSRs?
To establish a steam blanket while the Main Turbine is offline to prevent tube corrosion
Under normal conditions, when would I use AS to provide Gland Sealing steam to the Main Turbine and MFWPs?
During a unit startup
The AS system can provide overspeed testing for what components?
Main Feedwater Pumps and ‘A’ AFP
Normally, Main Steam provides steam to the AS system through pressure reducing valves. During a shutdown or startup, where else may it be supplied from?
Auxiliary Steam of another operating unit
What is the typical Main Steam pressure and what does it get reduced to for use in the AS system?
1000-1150 psig
Reduced to 250 psig
At what pressure will the AS reliefs lift?
275 psig
AS pressure is further reduced to 50 psig for use by what components?
Gas stripper, BAC, and LRS evaporator
At what pressure is AS reduced to be sent to the MSRs for steam blanketing?
52.3 psig
What does RU-7 monitor?
AS Condensate Receiver tank
What does NH power in the AS system? What happens if we lost NH?
Condensate Receiver Transfer Pumps
AS in Aux Building will have to be secured until power is restored
Gas stripper, LRS evaporator, and BAC will no longer be available to process water for disposal or recycle
What does NC do for the AS system? What if we lose NC?
Cools AS systems’ vent condenser
If lost, AS to Aux Building will have to be secured until NC is restored
How is AS affected by a loss of Radiation Monitoring System (SQ)?
Condensate will have to be sampled before it can be sent back to the main condenser
If AS system condensate drains are contaminated, where are they sent to?
Liquid Radwaste System
Why do we establish a steam blanket in the MSRs during a shutdown?
To keep the tubes from being exposed to moisture and oxygen, minimizing corrosion
What is the Condensate Receiver volume? Design operating pressure?
335 gallons
50 psig
What is the purpose of the AS Vent Condenser?
Condenses steam which would otherwise vent to atmosphere and returns it to the receiver
What, for cooling water, flows through the tubes of the AS Vent Condenser?
Nuclear Cooling Water
What is the capacity of the AS Condensate Transfer Pumps?
115 gpm
What is the purpose of the AS Condensate Transfer Pump minimum flow lines?
Returns approximately 5 gpm to the receiver to prevent pump from overheating
What is the maximum operating temperature for the mechanical seals in the AS Condensate Transfer pumps? How does that affect the receiver?
250F
This limits the maximum operating pressure of the receiver to about 15 psig
Where is the Condensate Receiver Package located?
51’ 6” of Aux Building
What will happen if RU-7 detects high radioactivity in the condensate? What must be done when the condition clears?
ASN-RV-11A will close and -11B will open, directing the condensate from the main condenser/condensate cross-tie to the in-service low TDS holdup tank
If condition clears, ASN-RV-11A must be manually reset by lifting the latch lever upward until it engages with the latch
How do ASN_RV-11A and -11B fail upon a loss of instrument air?
RV-11A fails closed, RV-11B fails open
What is the automatic feature associated with, AS supply valves to BAC, LRS evap, seal injection HX and gas stripper, AS-PV-331 and -332? What activates it?
They will trip shut on a ruptured AS line in the Aux Building, CST pipe tunnel, or HUT tunnel
Activated by any of the 20 pressure switches scattered throughout the building, as indicated by 1.0 +/- 0.1 psig
Valves will have to be manually reset by lifting latch lever
During all modes of operation, the AS system can provide low pressure steam to what equipment?
gas stripper
LR evaporator
BAC
If a unit is receiving aux. steam from another unit, where does the condensate go?
sent to the condensate receiver package and then returned to the main condenser of the unit supplying aux steam
What are the components of the AS condensate receiver package?
receiver tank, vent condenser and two AS condensate transfer pumps
Where does the AS vent condenser send non condensable gases?
aux. building hvac
Where does the AS condensate from the turbine building drain to?
main condenser
How does the AS system interface with the ED (feedwater heater extraction steam and drain) system?
AS sends aux steam condensate drains to the ED blowdown stack
describe the manual and auto controls of the AS condensate transfer pump.
manual: local three position switch- start, stop and auto
Auto: controlled through alternator and level switches (hi-hi, lo-lo, high and low)
All AS steam is eventually condensed, with one exception. What happens to the steam after it leaves the A aux. feedwater pump turbine?
exhausted to atmosphere
Normally, all units have their AS systems cross-tied, With one unit having ASN-V015 open and the other two have ASN-V014 open. What is the purpose of this?
allows a rapid restoration of turbine GS steam via the cross tie in the event of a MSIS
Define water hammer. What causes it?
Pressure change in a closed system resulting from a change in liquid velocity. Change in liquid momentum exerts an impulse (F*t) on the liquid, and the associated energy change dissipates as a pressure shock wave. This shock wave travels at the speed of sound in the liquid.
rapid throttling of valves, introducing liquid to a voided line, steam/water interfaces where condensing steam may suddenly remove a resistance to flow of either liquid or seam
