Annulus Ventilation(VE) Flashcards

1
Q

What is the purpose of the Annulus Ventilation System?

A
  1. Produce and maintain negative pressure in the annulus during a LOCA
  2. Reduce radioactivity in the air
  3. Provide long term fission product removal
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2
Q

What is the system designator for the Annulus Ventilation System?

A

VE

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3
Q

What is the design/purpose of the Annulus Ventilation Fans?

A
  1. Two fans per unit, one in each train

2. Each fan is 100% capacity rated for 9000cfm

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4
Q

What are the power supplies to the Annulus Ventilation Fans?

A

A - EMXI

B - EMXB

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5
Q

What will cause the Annulus Ventilation Fans to automatically start?

A

The fans are automatically started by the D/G sequencer following a Safety Injection

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6
Q

What is the Annulus Ventilation Fan flowpath?

A

The fans suck from the top of the Annulus and return the air to the bottom to ensure proper mixing of air

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7
Q

What is the basic design of the Annulus Ventilation System?

A
  1. The Annulus Ventilation System will produce approximately a 1.5”H2O vacuum within 60 seconds following a Safety Injection.
  2. Discharges air from the Annulus to maintain a negative pressure
  3. Maintaining a negative pressure allows leakage from containment to enter the annulus for collection and filtration prior to release to the unit vent.
  4. Filtration reduces possible offsite dose rate
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8
Q

What is the design/purpose of the Filter Trains in the Annulus Ventilation System?

A

The Filter Train consists of:

  1. Prefilter
  2. Demister
  3. Heater
  4. HEPA filters
  5. Carbon filter
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9
Q

What is the purpose of the Prefilter?

A

Removes large particles from the flowpath

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10
Q

What is the purpose of the Demister?

A

Removes at least 99% of the incoming moisture

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11
Q

What is the purpose of the Heater?

A

The Heater reduces the relative humidity to increase the efficiency of the filters

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12
Q

What is the purpose of the HEPA filters?

A
  1. Inlet to Carbon Bed - Removes small particles

2. Outlet from Carbon Bed - Removes Carbon Filter material before it’s released to the system

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13
Q

What is the purpose of the Carbon Bed?

A

Removes radioactive iodine

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14
Q

When does the heater in the filter plenum energize?

A

The electric heater will energize when the fan starts with proper filter unit differential pressure

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15
Q

What is the power supply to the electric heater in the filter train?

A

A - EMXI

B - EMXB

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16
Q

How is pressure maintained in the Annulus by the Annulus Ventilation System?

A

The exhaust and recirculation dampers will modulate to control annulus pressure at approximately 1.5”H2O vacuum

17
Q

What is the affect on the Recirculation and Exhaust Dampers on a loss of power?

A
  1. The recirculation damper will fail closed

2. The exhaust damper will fail open

18
Q

What is the purpose of the Miniflow Dampers?

A

The Miniflow Dampers allow for cooling a hot carbon filter bed using the other train’s fan.

19
Q

How will the Miniflow Dampers operated with their control switch in AUTO?

A
  1. They will close when the associated fan starts

2. They will open when the associated fan is stopped

20
Q

How will the Miniflow Dampers fail on a loss of power?

A

The Miniflow Dampers are motor operated and will fail AS-IS

21
Q

What is the design/purpose of the Manual Isolation Dampers?

A

The Manual Isolation Dampers are located downstream of each train’s exhaust damper. They prevent backflow from the Unit Vent(backdraft dampers).

22
Q

What is the generic procedure for extinguishing a fire in the carbon filter?

A
  1. Ensure the associated fan is OFF
  2. Manually close the sprinkler drain valve
  3. Manually open the sprinkler deluge valve
23
Q

How is an Annulus Ventilation Fan stopped following an automatic start?

A
  1. Ensure ECCS signal is reset
  2. Ensure D/G sequencer is reset
  3. Depress the OFF pushbutton
24
Q

What is the Annulus Ventilation interrelationship with the Fire Protection System?

A

The Fire Protection System provides water for extinguishing fires in the carbon filter

25
Q

What is the Annulus Ventilation interrelationship with the Demineralized Water System(YM)?

A
  1. The YM System provide automatic makeup to the Annulus floor drain loop seals
  2. The filter plenum has a loop seal on the pre-filter/demister drains which receives automatic makeup from YM