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Secondary Systems > Circ Water > Flashcards

Circ Water Flashcards

1
Q

What is the purpose of the CW system?

A

Receive heat rejected by the turbine thermal cycle
Receive heat from the PW system
Use the cooling towers to dissipate the heat.

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2
Q

How does the CD system interact with the CW system?

A

The CW system provides a place to discharge condensate during overboarding.
It also removes heat from the condensate in the main condenser.

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3
Q

How many supply lines are there on the CW pump discharges?

A

two. A & B supply one and C&D pumps supply the second.

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4
Q

What is the normal position of CWN-V11?

A

The supply line cross connect is usually open when operating 3 or 4 pumps. It can be open if using 1 or two pumps if supplying through both loops is desired.

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5
Q

How do we fill the CW system after draining?

A

using the PW pumps discharging into the supply lines.

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6
Q

How are the “C” shell outlet water box vent lines different from the others?

A

There are relief valves on the vent lines, so installation of isolation valves was not permitted. The lines are stainless steel to reduce the likelihood of an unisolable leak.

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7
Q

Which cooling tower has both a PW return and a CW return in one header?

A

2 cooling tower

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8
Q

Describe the flow through the cooling towers.

A

CW lines deliver the water to the top of the cooling tower. => dispersed around the top via a distribution flume => flows into the distribution basin => flows through holes in the distribution ring over the tower fill media => into the collection basin => back to CW pump suctions

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9
Q

How many cooling tower fans are there and where do they take a suction from and discharge to?

A

16 fans that take a suction on the lower portions of the cooling tower across the tower fill media and discharge out the top of the cooling tower.

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10
Q

Why is there a constant feed and bleed on the CW system?

A

to minimize the build up of chemicals and impurities to keep them within the allowable limits. The major concern is silica that can plate out on the Ti tubes in the condensers.

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11
Q

Where does makeup water for the CW system come from?

A

it is provided by the storage reservoir via the TB system.

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12
Q

What supplies cooling water to the CW pump motor lube oil cooler?

A

TC

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13
Q

What chemicals are added to the CW system?

A

hypo
foam control agent
sulfuric acid
scale dispersant

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14
Q

What other items discharge to the CW intake canal?

A

low TDS sump pumps from the polishing demins
OW yard area sumps
Turbine building roof runoff
Spray pond backwash sump pump

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15
Q

How many trains of TB are there?

A

two, “A” (original old system blowdown currently unused, but makeup is used) and “B” (newer section that is used)

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16
Q

How is the presence of a clogged trash screen detected?

A

level difference across the screen.

17
Q

Where does the water used for trash screen clean up come from?

A

PW pumps

18
Q

What is the design makeup rate for the CW system (daily)?

A

19,600 gpm. 18,300 evaporated and 1300 gpm blowdown

19
Q

What is the power supply for the CW pumps?

A

NAN-S01 (A&B) & NAN-S02 (C&D)

20
Q

What interlocks must be met in order to start a CW pump?

A

pump discharge valve fully closed & either the same flow train condenser outlet valve open or the CONDENSER OUTLET VALVE INTERLOCK OVERRIDE push button depressed.

21
Q

When will the CW pump breaker open after the switch is placed in STOP-CLOSE?

A

When the discharge valve is s breaker will open

22
Q

What % is the pump discharge valve open when there is only 1 CW pump running in a train?

A

44%

23
Q

What permissive is in place for the condenser outlet valves to be allowed to open?

A

There is a water box full permissive that must be satisfied in order to open the valves.

24
Q

What automatically closes the CW supply cross tie valve?

A

if both pumps in a loop are shutdown when the valve is in AUTO, then the valve will close.

25
Q

How do the CW vent valves for the main condenser work?

A

They have a float chamber. When there is no water present, the float is down and air can come in to prevent drawing a vacuum. When water is present it seats the float and keeps the water in.

26
Q

How are the cooling tower fans controlled?

A

from the control room via the PMUX system to the fan breakers

27
Q

How long is the high vibration trip over ridden on startup of the fans?

A

30 seconds. If the fan trips there will be a blue light on the load center.

28
Q

Why are some of the cooling tower fans secured during the winter months?

A

to prevent over cooling the condensate in the condenser and reducing efficiency
Also to prevent drawing too low of a vacuum which could lead to increased tube erosion due to higher steam velocities

29
Q

What happens on a complete loss of CW?

A

shut down of the plant.

decay heat removed via the SBCVs that dump to atmosphere

Secondary Systems (36 decks)

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