Main Condenser, Condensate and Feedwater Flashcards Preview

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Flashcards in Main Condenser, Condensate and Feedwater Deck (56):
1

What is the purpose of the main condenser, condensate and feedwater system?

Recover and preheat condensate for reuse as steam generator feedwater

2

Is the main condenser, condensate and feedwater system safety related.

Not safety related.

Safety Related Function

  • CHP or SG Low Pressure
    • Close Feedwater Regulating Valves and Bypass Valves

3

What is the flow path of the Main Condenser, Condensate and Feedwater System?

  1. Steam exhausts from LP turbines into the Main Condenser where it makes a single pass around the tube bank area to be condensed and de-aerated.
  2. Condensate Pumps take suction on hotwell and discharge to a common line that splits in two passes in parallel through the air ejector condenser and the gland seal condenser.
  3. Piping taps off to CV-0730, Condensate Recirc Valve, and recircs to Main Condenser when system flow is low.
  4. The flow recombines into a common line and then splits and is routed through Drain Coolers E-7A and E-7B and through LP feedwater heaters E-1A-4A and E-1B-4B.
  5. Flow from the LP heaters passes through HP Feedwater Heaters E-5A and E-5B and is crosstied at the suction header of the Main Feed Pumps (MFPs) where it combines with P-10 A/B, Heater Drain Pumps discharge.
  6. MFPs discharge through the Feedwater Regulating Valves and/or Feedwater Regulating Valves Bypass Valves and through HP Feedwater Heaters E-6A and E-6B to the SGs. 'A' pump feeds 'B' SG and vice versa.
  7. MFP Recirc Valves are just upstream of the Feedwater Regulating Valves and direct recirculation flow to Main Condenser when system flow is low.
  8. Hotwell makeup gravity feeds from T-2, CST, via 3” Makeup Valve CV-0732, 6” Makeup Valve CV-0729, or 12” Makeup Bypass Valve CV-0733 (normally Isolated).
  9. Hotwell rejects from the inlet of the air ejector and gland seal condensers to T-2 through Reject Valve CV-0731.

4

  1. From memory, draw and label a one line diagram of the Main Condenser, Condensate and Feedwater system showing system interfaces and the following major components:

- Hotwell

- Condensate Pumps (P-2s)

- Gland Seal Condenser

- Air Ejectors

- Feedwater Heaters (E-1s - E-5s)

- Drain Cooler (E-7s)

- Main Condensate recirc line to the Hotwell

- CV-0730 (Recirc CV)

- Heater Drain Pumps (P-10s)

- Feedwater Heaters (E-6s)

- Main Feed Pumps

- Main Feed Reg Valves

- Main Feed Reg Bypass Valves

- Steam Generators

in accordance with P&ID M-207. (056 K1, 059 K1)  

DRAW

5

What could be the cause of lowering vacuum in the main condenser?

  • Reduction in circulating water flow
  • Increase in circulating water temperature
  • Air inleakage in excess of the SJAEs
    • Air inleakage may also raise secondary system oxygen levels above limits.

Could lead to a Main Turbine trip.

6

What is the result of condenser tube leakage? What happens if a waterbox is removed from service?

Tube Leakage

  • Increase in secondary side oxygen levels.

Waterbox removal

  • Derate to <55%

7

What are the indications and at what level is the hotwell normally maintained?

Hotwell level indication

  • LI-0729 on C-01

Normal Level

  •  ~ 66% to 71% to ensure Condensate Pump NPSH

8

What is the normal hotwell fill?

Normal make-up

  • Automatic via 3" Makeup Valve CV-0732. 
  • Modulates open at 66%.

9

What are other methods beyond the normal for filling the hotwell?

Six-Inch Makeup

  • CV-0729 (manual) from the control room, via Yokagawa controller thumbwheel
    • Blue pen is signal to CV-0729. 
    • Red pen not used.

12-Inch Makeup

  • CV-0733 automatically opens on low level @ 58%.
  • Designed to compensate for Atmospheric Steam Dump operation.
  • Normally isolated as an Appendix R requirement.

10

How is hotwell reject handled?

Hotwell Reject

  • 4” Condensate Reject Valve CV-0731
  • Modulates open automatically at 76%.
  • Rejects flow in excess of makeup capability of the combined 3” and 6” makeup valves.

11

What is a concern with the hotwell reject valve?

Valve operates only by the level controller and cannot be closed by the operator.

  • Open failure
    • Condensate Pump damage
    • and/or T-2 damage due to overfilling.

12

What is the power supply, discharge pressure and flow of the condensate pumps?

Discharge Flow and Pressure

  • 9250 gpm each
  • Minimum is approximately 1400 gpm each
  • Approx 500 psig

P-2A - Alpha Bus

P-2B - Bravo Bus

13

What and why is the power limit for operation with one P-2, Condensate Pump?

  • Plant power level is limited to < 30%
  • Prevents challenging the MFP low suction pressure trip.

14

What are the Condensate Pump starting limits?

2 starts allowed in succession with the motor initially at room ambient temperature, OR 1 start with the motor at a temperature not exceeding normal operating temperature.

WHEN P-2 motor has been running continuously for > 30 minutes OR idle for > 60 minutes, THEN it is considered to be not exceeding normal operating temperature

15

What are the Condensate Pump controls, indications and normal parameters?

Controls

  • Four position switch for each pump on C-01.
    • Trip
    • Close
    • Normal After Trip
    • Normal After Close

Light Indication

  • Green Light for OFF
  • Red Light for RUN

Indications

  • Motor amps:   Normally 325 to 375 amps
  • Motor winding temperatures:  200° to 220°F
  • Motor thrust bearing temperature:  100° to 125°F

16

What is Condensate Recirc Control Valve CV-0730?

Condensate Recirc Control Valve CV-0730

  • Dowstream of Gland Seal Exhauster and SJAE
  • 12" valve modulates on a flow signal from FC-0730
  • Maintains minimum flow for Condensate Pumps
    • Minimum flow of 6800 gpm
      • 1600 gpm through the gland seal condenser
      • 5200 gpm through the air ejector condenser

17

What are the indications for CV-0730, Condensate Recirc Control Valve?

Red and green position indicating lights on C-01

  • Dark Stroke

Fails closed on loss of air.

Downpower

  • Should start opening at approximately 25% power

Power Escalation

  • Should be full closed at 35 to 40% power

 

18

What happens if CV-0730 fails to open?

As long as a feedwater pump is still operating there is no concern for CV-0730 failing to open as the feedwater pump recirculation valve will be open maintaining an adequate flow path for the condensate pumps.

19

Discuss the FW heaters in terms of design and pressure?

E-7A/B

  • Drain Coolers - Full of Water on both shell and tube side

E-1A/B through E-4A/B

  • Low Pressure Heaters
  • Shell is Extraction steam/Condesate
  • Tube is Feedwater

E-5A/B - E-6A/B

  • High Pressure Heaters
  • Shell is Extraction steam/Condesate
  • Tube is Feedwater

20

How are feedwater heaters bypassed?

  • E-7A (B), E-1A (B), and E-2A (B) must be isolated and bypassed together.
  • E-3A (B) and E-4A (B) must be isolated and bypassed together.
  • Although E-5A (B), and E-6A (B) can be isolated individually, administratively they must be isolated and bypassed together.

21

What are the main feed pump discharge, pressure, flow, etc.?

  • 13,600 gpm
  • Total discharge of 831 psi when operating at 5000 rpm
  • Turbine drivers rated at 7000 HP at 5000 rpm
  • HP Steam Supplied at < 30% power
  • LP Steam at power >30% power

22

What are the main feed pump permissives?

Suction valve for associated pump open.  Open limit switch POS-0787 (POS-0788) made up.

Main Condenser vacuum PS-0583 (PS-0586) ≥ 15” Hg

23

What are the automatic trips of a main feed pump?

Automatic Trips

  • Thrust bearing axial movement - Solenoid trip
  • Low bearing oil pressure (9 psig)
  • Low governor oil pressure (25 psig).
  • Overspeed (5500 ± 50 rpm).
  • Low feedwater pump suction pressure (250 psig with a 3 second time delay). -Solenoid trip

24

What is the relationship with the main feed pump and Heater Drain Pumps Discharge Throttle Valve CV-0608?

Feedwater pump suction pressure at 270 psig fully opens Heater Drain Pumps Discharge Throttle Valve CV-0608 to ensure adequate MFP NPSH.

25

During Startup of a main feed pump, when does the control room have control?

At 3250 rpm when the pump is on the governor. NPO starts pump.

26

What is the consequence of starting a feed pump with the hand controller set at maximum?

Speed will rise to 5250 rpm before governor will assume control.  This could result in excess feed to the S/Gs (adds positive reactivity) if S/G pressures are not prohibitively high.

27

How is a main feed pump shutdown or manually tripped?

Normally in control room via pushbutton on C-01 (solenoid trip)

If feed pump does not trip from the Control Room, it can be tripped locally by:

  • Pushbutton on local control panel
  • Manual trip plunger (trip palm button)

28

How do MFP Discharge Recirc Valves CV-0710 and CV-0711 function?

Modulate based upon feed pump suction flow

  • 3000 gpm (valve full open)
  • 6500 gpm (valve full closed).

Red and Green indicating lights (Light Stroke)

Interlocked with T&T valves.

  • With both T&T valves closed, the recirc valves are closed.
  • If any T&T valve is open; recircs modulate based upon pump suction flow.

During a power escalation:

  • 1st pump on:  Recirc valve closes at 30-35% power
  • 2nd pump on:  Recirc valve closes at ~ 45-55% power

29

What is the motive force, power supplies and loss of power mode for CV-0710 and CV-0711, MFP Recirc Vaves?

CV-0710

  • Y-10

CV-0711

  • Y-20

Motive Force

  • Instrument Air
  • Fail Closed on Loss of Air

The T&T closed interlock is removed if D11-1 is lost.  Valves will then operate based on flow

30

What is the consequence of allowing a MFP to warm up for an excessive period of time?

Depending on the position of the T&T valve, the recirc CV may not be open.  The recirc. CV will not open until the position switch on the T&T valve shaft opens.  With the T&T valve in some mid position, this switch may still be energized causing the recirc CV to remain closed.  There is no recirculation flow until the recirc CV is open, thus you are operating the pump deadheaded.

31

How do Feed Regulator Valves CV-0701 and CV-0703 function?

Controlled via Steam Generator Water Level Control System (SGWL)

Automatically Close on:

  • CHP
  • SG pressure at 500 psia.  Value for affected S/G only
  • SG high level override at 84.7%.  Value for affected S/G only

Manually closed following a RX trip or plant S/D via controller.

The SG low pressure closure can be bypassed using the MSIV Bypass pushbuttons (HS/LPE-50A and HS/LPE-50B) located on C-01.  Requires 3 out of 4 SG safety channels to be within 512 and 548 psia.

 

32

How do Feed Reg Bypass Valves CV-0734 and CV-0735 function?

Modulate open closed via LIC-0734/-0735. Auto or Manual

Valves automatically close if:

  • CHP
  • SG pressure at 500 psia.  Value for affected S/G only

SG Low Pressure automatic closure can be defeated by the SG main feed bypass valve CV-0735 (0734) low SG pressure auto close

33

Why should operators close the feed reg and bypass valves on a normal plant cooldown?

Prevent Condensate Pump feeding the S/G when S/G pressure is lowered to Condensate Pump discharge pressure.

34

What are and how do Main Feed Reg Block Valve CV-0742 and CV-0744 function?

Key operated switches on C-01:  CLOSE/OPEN

Red and Green position indicating lights on C-01.

DP across the Main Feed Reg Block Valves may impact ability to open block valves.

  • Open MFRV bypasses to equalize DP

35

Review the following controls/indications on C-01 in the simulator.

Panel C-01

  • Main Condensate Pump amps
  • Hotwell level LI-0729
  • 6” Condenser makeup valve CV-0729 controller HIC-0729
    • Yokogawa manual thumbwheel with demand indicator
  • Turbine Backpressure PI-0763
  • Condensate Pump control switches and indicating lights
  • Condensate recirc valve CV‑0730 indicating lights
  • Main Feedwater Pump common suction pressure indicator PIA-0786
  • Main Feedwater Pump discharge pressure indicator PI-0701 (0703)
  • Steam Generator level controller LIC-0701 (0703)
  • Steam Generator steam/feed flow indicator FI-0701 (0703)
  • Main FW Reg Valves CV-0701 (0703) position indicator POI-0701 (0703)
  • Main Feed water Regulating Bypass controller LIC-0735 (0734)
  • Main Feedwater  Regulating Bypass Valve CV-0735 (0734) position indicator POI-0735 (0734)
  • Main Feedwater Regulating Bypass Valve CV-0735 (0734) low SG pressure auto close Enable/Defeat switch
  • Main Feedwater  Regulating Bypass Valve CV-0735 (0734) low SG pressure auto close Defeat light
  • Main Feed Pump Turbine K-7A (K-7B ) trip pushbuttons
  • Main Feed Pump Turbine K-7A (K-7B ) trip circuit trip power available light
  • Main Feed Pump Combined Speed Controller HIC-0525
  • A (B) Main Feedwater Pump Individual Speed Controllers HIC-0526 (0529)
  • A (B) Steam Generator Feed Block Valve CV-0742 (CV-0744) control switch and indicating lights
    • OPEN/CLOSE key switches
  • A (B) Main Feed Pump Recirc. Valve CV-0711 (0710) indicating lights
  • A (B) Main Feed Pump low and high pressure T&T valve indicating lights
  •  

36

Review the following controls/indications on C-11/C-12 in the simulator.

Panel C-11

  • Cond. Vacuum/Turbine Back Pressure Recorder, REC-C11-03
  • Condensate pump motor temperatures
    • Winding - TIA-0711 (0715)
    • Thrust Bearing - TIA-0713 (0717)
  • A/B MFP LP steam flow recorder, REC-C11-03
  • A/B MFP HP steam flow indicator FI-0529 (0526)
  • A/B feed water temperature recorder,REC-C11-03
  • A/B MFP vibration recorders, REC-C11-02 (03)
  • MFP and turbine temperature indicators
  • Feedwater Heater Normal and High level indicating light

C-12

A/B SG feed/steam flow recorders, FLIR-0701 (0703)

37

What is the system interelationship between the main condensor and turbine?

  • Main Condenser condenses LP Turbine exhaust and collects the subcooled liquid in the Hotwell.
  • Loss of the Main Condenser will result in a Main Turbine trip on low vacuum

38

What is the system interelationship between the feewater heaters and extraction steam?

Preheats feedwater in the Feedwater Heaters to improve plant efficiency

39

What is the system interrelationship between heater drains and the main condenser, condensate and feewater system?

  • Collects drains from the MSRs and HP Heaters and pumps to the suction of the MFPs to improve plant efficiency.
  • When required, condensate is supplied to the suction of the Heater Drain Pumps to provide sub-cooling water to prevent flashing to steam

40

What is the system interrelationship between main steam and the main condenser, condensate and feewater system?

Supplies steam for operation of the MFP Turbines during startup and low load conditions

41

What is the system interrelationship between steam generators and the main condenser, condensate and feewater system?

  • Feedwater maintains SG water level to remove heat from the PCS and generate steam for the Main Turbine.
  • Loss of feedwater to the SGs results in loss of the normal heat sink for the PCS and reactor core and will result in a reactor trip.  Excessive feedwater flow will result in overcooling the PCS causing power excursions and a reactor trip

42

What is the system interrelationship between reheat steam and the main condenser, condensate and feewater system?

Supplies steam for operation of the MFP Turbines when plant load conditions provide adequate reheat steam pressure

43

What is the system interrelationship between auxiliary feedwater and the main condenser, condensate and feewater system?

  • Condensate Storage Tank T-2 provides the normal water supply to the Auxiliary Feedwater Pumps.
  • Loss of T-2 will require use of SW and Fire Protection Water supplies to the Auxiliary Feedwater Pumps

44

What is the system interrelationship between circulating water and the main condenser, condensate and feewater system?

Supplies cooling water to the Main Condenser tubes to cool and condense LP Turbine and MFP Turbine exhaust and other drains and traps

45

What is the system interrelationship between the condenser air removal system and the main condenser, condensate and feewater system?

  • Condensate provides the cooling medium to the Air Ejector Condensers for condensing the steam used by the Air Ejectors.
  • Air Ejector System removes non-condensables from the Main Condenser to establish and maintain vacuum.
  • Loss of air ejector condenser cooling will result in over heating and improper operation of the air ejector

46

What is the system interrelationship between gland sealing and the main condenser, condensate and feewater system?

  • Condensate provides cooling for Gland Seal Condenser to condense steam from the Main Turbine gland seals.
  • Loss of gland seal condenser cooling will result in improper operation of the Main Turbine gland seals

47

What is the system interrelationship between exhause hood spray and the main condenser, condensate and feewater system?

Supplied by the condensate pumps via piping off the condensate header to lower exhaust hood temperature

Can also provide a flow path for hydrazine injection. (Currently the bypasses are left open to facilitate chemical injection.)

48

What is the system interrelationship between service water and the main condenser, condensate and feewater system?

Provides cooling to the Condensate Pump and MFP gland seal condenser and oil coolers

49

What is the system interrelationship between chemical injection and the main condenser, condensate and feewater system?

Corrosion in the secondary system is controlled by:

  • Minimizing dissolved oxygen.
  • Maintaining basic pH (8.8‑9.2)
  • Minimizing solids such as chlorides and fluorides

Hydrazine is added to scavenge oxygen from the condensate and raise pH.

Morpholine is added to the feedwater to raise the pH.

Boron is added to prevent SG tube denting.

50

What is the system interrelationship between Demin water and the main condenser, condensate and feewater system?

Supplies makeup water to Condensate Tank T-2 and Primary Makeup Storage Tank T-81

51

What is the system interrelationship between SIAS and the main condenser, condensate and feewater system?

CV-1359 closes - isolates noncritical service water. Condensate pumps lose cooling

52

What is the system interrelationship between 4160 busses and the main condenser, condensate and feewater system?

Bus 1A supplies P-2A

Bus 1B supplies P-2B

53

What is the system interrelationship between 120v Preferred AC and the main condenser, condensate and feewater system?

Y-10 supplies power to P-1A Recirc Control Valve CV-0711 and Y-20 supplies power to P-1B Recirc Control Valve CV-0710.

The Main Feedwater Pump P-1A(B) Recirc Valve(s) fail open on a loss of power to it’s respective Preferred AC Bus.

54

What is the system interrelationship between 125V DC and the main condenser, condensate and feewater system?

D-11-1 supplies power to the T&T Valve position indication switches.

D11-2 supplies trip power to K7A, MFP

D-21-2 supplies trip power to K7B, MFP

55

What is the system interrelationship between Y-01 and the main condenser, condensate and feewater system?

Supplies power to the MFP Controllers and Condensate Pump indications on C-11.  Controllers fail to minimum on loss of Y-01.

56