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Block 4 > Circulating Water > Flashcards

Circulating Water Flashcards

1
Q

Describe the Circulating Water System Big Picture Flowpath.

A

Ocean => Two 12 foot ID concrete pipes => Intake Canal => Coarse Screen (Trash Rack) => Traveling Screen => CW pump => CW pump discharge valve => Debris Filter System => Condenser to the Condenser Outlet Valve => Two Sealwells (A1 & B1 waterbox go into same Seal Well) => Discharge Canal => 12 foot ID pipe that splits into two 7 foot ID pipes to the ocean

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2
Q

When do the Screen Wash pump(s) automatically start?

A

In Auto: Both pumps start when there is a 6” level deviation between upstream stationary screens and downstream travelling screens.

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3
Q

Describe the travelling screen auto start.

A

A pressure switch starts all screens in slow speed when it detects water from the pumps.

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4
Q

What causes a travelling screen to switch to fast speed?

A

The affected screen will switch to fast mode when level deviation is 10”.

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5
Q

Describe the Condenser Waterboxes.

A

A1 & B1 (A2 & B2) Waterboxes discharge to the same Seal Well
Each waterbox has a pump supplied from A and B bus
(i.e. if you lose 1A2 or 1B2 4160v bus, you will still have flow through A and B Waterboxes)
Each have a SJAE suction piping penetration which extends into the center of the tube bundle

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6
Q

Describe Condenser Water Box Priming.

A
  • Keeps the Waterboxes full
  • 1 Primary Ejector (Manual steam supply) placed in service during startup
  • 4 Auxiliary Priming Ejectors
  • 4 Vacuum Tanks – maintained 21-23” Hg
  • Steam Supply: 200 psig from Main Steam
  • Exhausts to atmosphere - Potential release path in event of SG tube leak / rupture
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7
Q

Describe the Waterbox Vacuum Breakers.

A
  • If BOTH parallel pumps TRIP, BOTH Discharge Valves CLOSE and waterbox vacuum breakers OPEN for 5 minutes, then reclose.
  • IF starting first CW pump in a common discharge tunnel, THEN ALLOW 5 minutes to elapse following insertion of CWP breaker trip fuses prior to starting CWP which allows vacuum breakers on associated waterbox sufficient time to close.
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8
Q

Describe the Condenser Integral Tubesheet Pressurization System.

A
  • Condenser Waterbox Tube Sheets are essentially a double wall, with a space between that is supplied with fresh water so that if a leak in either side develops it can be identified by quantifying the makeup to the head tank and NO salt water leaks into the condenser
  • On inlet and outlet of each condenser
  • Supplied by either Demin Water or Condensate Water
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9
Q

Describe the Debris Filter System (DFS).

A
  • Improves condenser performance by limiting macro fouling of the tube sheets and preventing tubes from becoming blocked by debris
  • Differential Pressure Measuring System (DPMS), Flushing can occur 3 different ways:
    Automatically - timer (every 3 hours), Manually, Every time the DFS backwashes
  • DFS bearings cartridge are lubricated by a propylene glycol system
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10
Q

Describe the Condenser Tube Cleaning System (CTCS).

A
  • Limits micro fouling of condenser tubes by passing sponge balls through them, thereby maintaining the heat transfer capability of the tubes
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11
Q

Describe the Circulating Water Pumps.

A

122,650 GPM each
* Propeller Type Pump - (Amps Increase if waterbox fouling occurs)
* Air Cooled Motor, Lubricated by ICW (or domestic water system)
* Disch Press ~ 17 psig
* Power - A1 / B1 CW pumps - A2 4160 Bus, A2 / B2 CW pumps - B2 4160 Bus
* RTGB Handswitch controls both the CW pump and the discharge valve
* Pump and discharge valve also controlled locally from individual handswitches

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12
Q

What are the power supplies to the Circulating Water Pumps?

A

A1 / B1 CW pumps - A2 4160V Bus
A2 / B2 CW pumps - B2 4160V Bus

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13
Q

Describe the Circulating Water Pump Start Interlocks.

A

BIG PICTURE OVERVIEW: Pumps are interlocked based on which are connected to the same discharge tunnel - (A1 & B1) and (A2 & B2)

1st Pump Start:
* Control Switch or PB taken to start
* Discharge valve strokes to 30% open, then Pump starts and
* Discharge valve remains at 30% for 15 minutes, then fully opens

2nd Pump Start:
* Control Switch or PB taken to start
* Discharge valve strokes to 30% open
* Discharge valve remains at 30% for 5 minutes, then fully opens

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14
Q

Describe the Circulating Water Pump Detailed Starting Logic.

A

(A1 & B1 start logic described – Assume you are starting the A1 CW pump)

The ‘A1’ Circ Water Pump will start if:
* The ‘A1’ Circ Water Control Switch taken to “START” or the Local ‘START” pushbutton pressed
AND
* The ‘A1’ CW Pump Discharge Valve has been closed for at least 2 min
* The ‘A1’ CW Pump Lube Water Pressure / Flow > 8 gpm
* The ‘A1’ CW Pump condenser outlet valve is 100% open
* The ‘A1’ CW Pump discharge valve reaches 30% open
* The ‘A1’ CW Pump breaker is racked in
* The ‘A1’ CW Pump Waterbox Vacuum breakers are closed

                          AND
  • The ‘B1’ Circ Water Pump Discharge Valve is closed (logic sees this as pump is off)
    OR
  • The ‘B1’ Circ Water Pump is running with its discharge valve open for at least 1 minute
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15
Q

Describe the Circulating Water Pump Discharge Valves.

A
  • Local control switches for each valve
  • Powered from the A3 / B3 480V MCC
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16
Q

What are the CW Pump Discharge Valve Opening Interlocks?

A

Fully closed for a minimum of 2 minutes
Associated Waterbox vacuum breaker valves are fully closed
Parallel pump discharge valve fully closed or fully open for 60 seconds if running

17
Q

Describe Important CW Pump Starting Info.

A

If All Pump Start Interlocks are made up:
* Discharge valve opens 30% and then the CW pump starts
* On pump start, personnel are stationed to open valve breaker if the valve travels past its 30% mark
* After 5 minutes, the Pump discharge valve then slowly fully opens (parallel pump running) or after 15 minutes (parallel pump not running)
* Wait at least 1 minute after First Pump’s discharge valve gets to full open before attempting to start a second CW pump OR the First pump will trip
* If running pump trips w/in 5 minutes of starting the second pump, the second pump trips
* Allow 60 minutes between starting pumps (prevents slumping)
The general startup logic for the circulating water pump(s) was designed to:
a) Gradually introduce water to prevent water hammer and to minimize starting loads on the pump motor.
b) Prevent backflow into the parallel pump should it be inoperable.

18
Q

Describe the Circulating Water Pump Start Permissive Light.

A

CW Pump Amber Permissive Starting Light – (comes on when these permissives are met)
* Breaker racked in
* Condenser Outlet valve is full open
* Lube Water Flow > 8 gpm
* Normally out when the CW pump is running since the breaker is closed

19
Q

Describe the Circulating Water CW Pump Stop Logic.

A

(The discharge valves automatically close on all pump stops/trips)

Manual:
* Control Switch or Local P/B to “STOP”

Automatic:
* 2nd pump trips within 5 minutes after starting it
* Overcurrent
* 4.16 KV Bus U/V

20
Q

Describe Circulating Water System “Pull-To-Drain”.

A

Pull-To-Drain:
* Closes discharge valve & Condenser Outlet Valve
* Opens Inlet & Outlet Waterbox Vacuum Breakers
* Re-Opens CW pump discharge valve to drain the Waterbox
* Prior to returning control switch from Pull to Drain to Normal, CWP breaker fuses must be removed or the CWP discharge valve breaker must be OPEN. Prevents TRIPPING running CWP in opposite train.

21
Q

What is required when starting CW Pumps with 1 Ocean Intake Pipe Out Of Service?

A

Space starting of CW pumps at least 90 minutes apart.

22
Q

Discuss CW Pump Shutdown.

A

First Pump
* Place switch in STOP
* Pump stops and discharge valve closes
* Waterbox vacuum breakers remain closed
* Wait at least 1 minute after discharge valve is closed
* Condenser Hotwell level may be unreliable if the Main condenser is under a vacuum and less than 4 Circ water pumps are in service. Closely monitor hotwell level and isolate make-up sprays as necessary or adjust vacuum drag (per NOP) to maintain hotwell level < 3’ 8” by local sightglass indication. If hotwell > 3’ 8” by local sightglass indication and negatively impacting condenser backpressure, AOP directs to reduce turbine load until level restored below 3’ 8”.

Second Pump
* Place switch in STOP
* Pump stops, Discharge valve stays open
* Waterbox vacuum breakers open, and re-close 5 minutes later
* Steam Supply to Aux Priming Ejectors close
* Discharge valve closes

23
Q

Discuss CW Pump Shutdown To Clean Waterboxes.

A
  • Use “Slow Drain Method”
  • Slow Drain Method is performed locally
  • Use Local PB to close discharge valve to 30%
  • Use Local PB to stop CW pump
  • Discharge valve will close the rest of the way when the CW pump is shut down
  • Manually crack the discharge valve off its seat to drain the waterbox
  • Space shutdown of pumps at least 60 minutes apart to prevent slumping
24
Q

Describe the actions for CW Pump Trip.

A
  • Close discharge valve immediately, Wait 2 minutes, before attempting restart of pump
  • If CW pump cannot be restarted then close the SJAE Suction Valve from that Condenser section to prevent saturation of SJAE and the loss of Condenser vacuum
25
Q

Describe CW Pump Lubewater.

A

Normal supply is ICW.
Backed up by Service Water (Domestic Water)

[Isolated by a SIAS signal on Unit 2. Supply would be from Service Water (Domestic Water)]

26
Q

Describe Condenser Vacuum Trips (Manual).

A

> 8.5” Hg Abs w/Load > 55 %___Max Permissible Condenser Vacuum
2” Hg abs DP__________________Start reducing load
2.5” Hg Abs DP________________Manual trip - Max Permissible D/P between Condensers
In Restricted Region____________Manual Trip before 300 second time limit reached

27
Q

Describe Condenser Thermal Limits (Per NPDES).

A

Normal Limits
Alarm at 109 F, then reflashes at 111F.
At 111F, establish DS-30 to monitor temperature to ensure 115F not exceeded.
Max Discharge to Ocean temperature: 115 F
Max Condenser DT: 30 F
Max Discharge Canal Level: 14.5 ft
The discharge canal temperature may exceed 115°F or the ΔT between intake and discharge temperature may exceed 30°F if the below conditions exist and discharge is maintained below 117°F and ΔT less than 32°F. Chemistry must be notified in either case. (Section 6.2 Commitment 1)

The 115F and 30F limits can be exceeded for:
* Circ Water or Condenser maintenance
* Condenser Waterbox fouling

Maximum Limits (when in Maintenance, or fouling equal to 1 CW pump)
* Discharge to Ocean Max temperature: 117 F
* Max Condenser DT: 32 F

None of these limits apply during:
* National Power Emergency
* Regional Emergency
* Reactor Emergency
* When the public health or safety is endangered due to a lack of electrical supply

Block 4 (7 decks)

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