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Secondary > Normal Chilled Water > Flashcards

Normal Chilled Water Flashcards

1
Q

What is the purpose of the WC normal chill water system?

A

Provide chilled water at 45F to the cooling coils of the normal HVAC in containment, Aux and Radwaste buildings

Chilled water is also sent to:
non-nuclear sampling
polishing demin sample coolers
blowdown demin sample coolers
main generator collector housing cooler.

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2
Q

What is the interlock associated with the containment ACUs?

A

Closes an isolation valve and stopping chilled water flow when the fan is not running

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3
Q

What system provides cooling to each chiller package?

A

NC (low flow of NC will trip a chiller)

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4
Q

What is the power supply to ‘A’ normal chiller?

A

PB (4160)(4.16kv)

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5
Q

What system is used as a makeup source of water for WC?

A

DW

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6
Q

What powers the WC recirc pumps?

A

NH

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7
Q

What system powers the ‘B’, ‘C’, & ‘EO2’ chilers?

A

NB (4160) (4.16kv)

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8
Q

what system can I use if NC is unavailable for cooling?

A

EW

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9
Q

What are the 3 circ pumps associated with the large chillers rated for?

A

1200gpm @ 100ft

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10
Q

What is the small chiller circ pump rated for?

A

320gpm @100ft

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11
Q

Why does the compressor start after a time delay?

A

To allow oil pressure, chilled water and cooling water flow to establish

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12
Q

Where are the WC circ pumps located?

A

Roof of the aux building

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13
Q

What is the normal level in the WC expansion tank?

A

36 inches

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14
Q

What pressure is the nitrogen maintained in the WC expansion tank?

A

15psig

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15
Q

What are the high and low pressure setpoints for the WC expansion tank?
When will the expansion tank relief lift?
When will the vacuum breaker relieve?
When would the makeup valve open and close for the expansion tank?

A

High 45psig
Low 5psig

lift 60psig

Relieve 2 in Hg

Opens at 24 inches and closes at 48 inches

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16
Q

Where is the WC chem add tank located?

A

Next to ‘A’ Chiller on the aux building roof

17
Q

What are the precautions associated with adding chemicals to WC?

A

Water drained from system needs proper disposal

Do not add more than 1 chemical at a time

Wear proper PPE (apron, face shield and gloves)

Temp eye wash station required

18
Q

What is the basic refrigeration cycle?

A

Compressor(low press high temp) to
Condenser (hi press hi temp) (NC) to
Flash economizer (hi press low temp) to
Cooler (low press low temp)(WC)

Draw the T diagram temp up goes up and pressure low to high left to right.

19
Q

Why do chillers ‘B’ and ‘C’ have increased capacity greater than 1000 tons?

A

Due to increased amperage

20
Q

How are the compressor and motor cooled and lubed?

A

refrigerant cooled and oil lubed

21
Q

How long does the oil pump run before the compressor starts?

A

28 seconds

22
Q

Where is the vapor from the flash economizer directed?

A

to the 2nd stage of the impeller inlet

23
Q

What is purpose of the float valve in the flash economizer?

A

Ensures liquid level is maintained in the economizer to prevent equalizing pressure between the cooler and condenser

24
Q

What are the 3 efficiency designs of the normal chillers?
Which of the 3 increase refrigeration effect?

A

Integral thermal economizer
Flash economizer
Two stage compressor

Integral thermal economizer increases refrig effect

25
Q

What is surging?

A

When refrigerant pressure in the condenser momentarily becomes higher than the pressure of the compressor discharge and allows back flow thru the compressor

‘Back flow from the condenser thru the compressor’

26
Q

When does surging occur?
How do we prevent it?

A

During low load conditions

prevented by hot gas bypass - routes hot gas from the compressor discharge to the evaporator

27
Q

What happens when you take the chiller switch to start?

A

Circ pump starts

NC water valve opens

23 seconds later the lube oil pump starts

28 seconds later the lube oil starts

compressor starts

28
Q

What happens when the switch is taken to STOP or if the compressor trips?

A

Compressor motor and circ pump motor stop and the NC valve closes

41 seconds later the lube oil pump will stop

15 min timer starts preventing the restart of the chiller package

29
Q

What is the high level and low level alarm setpoint for the WC expansion tank?

A

High 72 inches
Low 12 inches

30
Q

What are the 3 most limiting concerns upon loss of WC?

A

Main gen collector housing temp exceeding 50C, requiring shutdown

Containment temp not being maintained within tech spec

CEDMCS cabinet room temps reaching limit of 104F which could lead to rod slippage

31
Q

What is the temp limit of the control room?

A

80F

32
Q

IA dropping to 27psig would have what effect on WC?

A

auto make up valves will fail closed and WC tank makeup will need to be done manually

33
Q

How is WC affected by a loss of NC?

A

Running chillers will trip on loss of condenser cooling flow.

Control room may shift priority loads to EW

Secondary (26 decks)

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