Condensate (CD) Flashcards
What is the purpose of the Main condenser?
- Condenses and collects turbine exhaust steam and various equipment drains
- Collects and stores condensate in the hotwell, acting as a reservoir for use in the S/G
How does water flow through the condenser? Start from CW pumps
- CW pumps pump from CW canal
- There are two loops that can be cross connected, one loop goes through 1A then 1B then 1C tubes and out and back to the three towers, other loop goes through tubes 2A, 2B, 2C and same discharge. CW is in the tubes of the condenser
- CST is in the hotwell halves which the CD pumps take suction on to feed the SGs
What are the normal positions of the ‘B’ CD suction valves?
One of the suction valves has to be full open with its respective recirc valve to the correct hotwell half open
What will trip the B condensate pump?
- Low flow
- No suction valve open
- Lo lo hotwell level in either of the halves
What’s the significance of the ‘C’ reheater tray?
Condensate falls directly from the inner bottom to the hotwell. In ‘A’ and ‘B’, condensate falls on the reheater trays which then the exhaust steam from the FWPTs pass through which reheats the condensate as it falls into the hotwell. The steam that remains uncondensed then condenses on the C tube bundles
Hotwell auto makeup valve, where are they located? When would use manual or auto?
- Hotwell makeup valves CDN-LT-81/82 are located on the 140’ north of the respective halves (1A or 2A)
- We manually makeup from the CST via gravity feed when we are coming out of an outage as well as loss of IA, the auto fail closed and on CST lo lo level (30’)
What is the normal lineup for Condensate Demins?
- Demins can be full flow, full or partially bypasses and normal lineup is
- On full flow, the bypass valve CDN-V195 is full shut
- If we are bypassing the demins, CDN_v195 is full open but the inlet and outlet of the demins is still full open
Why would we have demins in service?
- Demins would go into full flow if there was a condenser tube leak
- Demins remove total dissolved solids in the CD flow to minimize contaminants into SGs
What are the auto actions of CDN-V195?
CDN-V195 will open or close automatically to maintain <55 psid demin DP and auto open if the inlet or outlet are not full open
How to manually operate CDN-V195?
- Read the placard next to the valve
- You have to have the switch on the valve to ‘manual’
- Isolate hydraulic air to the operator
- Crank it clockwise for close or counter for open and ensure before going back to auto on the switch that there is hydraulic air so it can do its thing on its own
What is the drawoff valve?
Drawoff valve is downstream of demins
In pump discharge header, it removes excess condensate from hotwells. Opens based on higher level in 1C or 2C
What are the auto actions of the drawoff valve and when would you bypass it?
Auto close if MFP suction pressure too low, or high cation conductivity in the hotwell
Bypass switch is a cabinet (ZTN-C01) when you enter turbine building from catwalk on 140’ - bypass to drain to CST the bypass will only bypass the high conductivity feature, not the low FWP suction
How much flow goes through the BDHX?
The flow is determined by the temperature of the BDHX to ensure efficiency
CD downstream of the pumps is aligned to go through the BDHX to cool it and its usually around 350 gpm to keep the temperature ~135F in the BDHX
What is the BFT rated for? Temperature limits of operation?
- The BFT is rated for one normal and one abnormal rate from the SGs
- BFT going through the BDHX must be <135 F to ensure resin integrity
Classify the CD Pumps
- NB powered, 50% capacity vertical 6 stage centrifugal pump with capacity of 9100 gpm
- Seal water: condensate service header
- TC cools LO coolers
- Mini flow recirc: 4500 gpm
Describe CD flow through the LPFWH
CD flows through #1-#4 LPFWH increasing in temperature increasing efficiency of the plant and generator output
What is some OE on CD System?
CDN-V195 failed closed and started Three Mile Island by losing of feed so then they couldn’t feed the SG
What is the purpose of the dogbone seal?
- Connects the condenser shell to the LP Turbine
- Prevents air leakage into the condenser while allowing movement between the turbine casings and condenser sections
What is the purpose of the water sealed Condenser Equalization Duct and where is it located?
- Located above A and B shell false bottoms
- Allows pressure between the sections to equalize if an abnormal
pressure/temperature differential develops - The water seal will “blow out”, thus equalizing pressure, if the
temperature in any section exceeds that in the adjoining section by
30F
How is each section of the condenser protected from overpressure?
Rupture discs set at 5 psig on its associated LP turbine hood
Why do the tube lengths vary in the three condensers?
To compensate in part for the progressively higher CW temperatures since it flows through them in series
What is the purpose of the Condenser Waterboxes?
Provide the supply and return headers to the condenser tubes
How can Reheater Tray level affect ‘A’ AFP operability after a LOOP?
After an MSIS, level can back up and potentially back up the steam line drains and cause the pump to be inoperable
Why are the hotwells equipped with spargers?
- Could be used to admit AS directly into the condensate located in the hotwells
- Can be done during startup to heat the water for cleanup purposes
- This operation is not normally performed
Where are the Longitudinal divider plates installed? Purpose of the plates?
- These plates ensure condensate formed around a given set of tube
bundles will flow to the associated hotwell half - This feature allows continued operation if a tube leak occurs in one CW flowpath
- The corresponding hotwell half can be isolated and pumped out to the Circ Water System by one of the condensate pumps to minimize further secondary system chemical contamination
What is the purpose of the Condensate detention time?
Aids condensate reheating and sampling
Why is there a salinity detection bay provided near each waterbox?
To detect CW leakage between the tubes and tube sheet
How much condensate storage volume is provided by the hotwell?
100,000 gallons
What is the condensate storage volume based on?
4 minutes of operation at “valves wide open”
What CST level would cause the Hotwell Makeup valves to auto shut?
30’
How do the Hotwell Automatic Makeup valves respond to a loss of IA?
Fail Close
Where are the Hotwell Automatic Makeup valves located?
140’ Turbine Building
Where are the manual make up valves located?
100’ Turbine Building
The draw-off automatic control valve will open based on the higher to two levels of what condenser hotwells?
1C or 2C
What are the interlocks associated with this valve?
It will automatically close when either SG feedwater pump suction pressure is low or any condenser hotwell cation conductivity is high
If the valve closes due to high conductivity, how can I operate it?
By placing the key-locked bypass switch to the bypass position
Where does the seal water for the CD pumps come from?
Condensate Service Header
What is the purpose of the CD pump minimum flow lines?
Keeps the CD pumps from overheating
Set to 4500 gpm
What happens to the mini-flow valves when its associated pump stops or is tripped?
Valve goes closed (Solenoid is energized)
How could the position of ‘B’ CD pump’s two suction valves affect the pump?
At least one of the two suction valves from 1C or 2C must be full open or the ‘B’ pump will trip
What is the normal operating level of the hotwell? At what level in a hotwell half will the associated CD pump trip?
41”
30”
What are the power supplies for all three CD pumps?
‘A’ & ‘B’ – NBN-S01
‘C’ – NBN-S02
Which CD pumps have connections to the ‘Overboard Valves’?
‘A’ & ‘C’
What is the purpose of the ‘Overboard’ lines? What must be done prior to using the ‘Overboard’ lines?
- Allow for a ‘feed and bleed’ of the condensate and feed systems to
remove system impurities, specifically rust, following dry layup
conditions during refueling outages - Prior to using the Overboard lines, condensate must be verified to be non-radioactive through chemistry sample
To what pressure is the Condensate reduced to when going into the Condensate Service Header?
90 psig
If no CD pumps are available, what can be used to supply the Service Header?
DW
What are the major loads provided by the Condensate Service Header?
- CD pump seals
- Condenser Expansion Joints
- Vacuum Pump Makeup
- Hydrazine & Ammonia Dilution
- Cooling jacket around the Heater drain pump mech seal
What is the interlock associated with the Demin bypass valve?
- When both inlet and outlet valves are open a modulate permissive for the bypass valve is generated
- The bypass will modulate to maintain set pressure if both the inlet and outlet valves are open and demin D/P is less than ~55 psid, otherwise the bypass will be full open
At what temperature is the condensate when it enters and exits the LPFW heaters?
130F entering
330F exiting
How do the LPFW heaters respond to a high level? High- High level?
HL - High level control valves will attempt to diver excess water into the condenser
HHL - Condensate flow will be automatically isolated to that heater string by two redundant, motor operated valves
What is the capacity of the CD pumps at 100% power?
Each pumping ~ 8000 gpm
What happens upon a loss of condensate that results in both feed pumps tripping offline?
- Reactor will trip on low S/G water levels followed by a MT and Main Generator Trip
- Aux Feed system will start and restore S/g water levels
What happens upon a loss of condensate that results in only one feed pump trip?
Reactor power cutback will initiate which will reduce turbine and reactor power to between 25 and 75% power
What will happen if there is a loss of condenser vacuum?
- Will prevent the SBCS valves from dumping to the condenser
- The main turbine will trip followed by a trip of both Main Feedwater Pumps
- Reactor will trip on low S/g water level and Aux Feedwater system will start and restore S/G level
How is CD affected by a loss of IA or electrical power?
- CD pump mini-flow valves will fail open, which prevents running the pump with the discharge valve closed and no mini-flow that could lead to a loss of suction on the Feedwater Pumps
- Hotwell make-up and drawoff valves fail closed, so hotwell level control will need to be performed manually
