Control Room Ventilation

Question 1

Describe the Mode 1 L/U for control room vent.

Include % recirc and m/u

Answer 1

normal L/U

• suction from outside (27% m/u)
• suction from CR (73% recirc)
• one supply fan (S-36 or S-35)
• one exhaust fan (E-35)

Question 2

Describe the Mode 2 L/U for control room vent.

Include % recirc and m/u

include any drawbacks

Answer 2

fire mode

• suction from outside (100% m/u)
• one supply fan (S-35 or 36)
• one exhaust fan (E-35)

air conditioning not rated for 100% flow => temp will rise in CR

Question 3

Describe the Mode 3 L/U for control room vent.

Include % recirc and m/u

include any deficiencies

Answer 3

toxic gas

• suction from CR
• disch to CR (100% recirc)
• one booster fan
• through roughing/hepa/charcoal filter
• one supply fan (S-36 or S-35)

since recircing air O₂ is slowly depleted=> limited time

Question 4

Describe the Mode 4 L/U for control room vent.

Include % recirc and m/u

Answer 4

Pressurization

• suction from CRPS (control room press system)
• suction from CR
• one CRPS fan (OS-98 or 99)
• through filters (roughing, hepa, charcoal)
• one booster fan (S-39 or 40)
• one supply fan (S-35 or 36)
• disch to CR
• positive press in CR

Question 5

Describe actuation logic for CR ventilation into Mode 4

Describe sequence for starting fans for CR ventilation if LOCA is on U-1

Answer 5

1. Phase A
2. Hi Rad on RE-25 or 26

LOCA on U-1 (Phase A or RE-25/26)

• CRV goes into Mode 4
• U-2 CRPS “selected” train fans start
• if “selected” train fails non selected train will start
• if U-2 rad mon (RE-51 or 52) indicate Hi rad, U-1 CRPS fans will start

Question 6

What areas/ compartments make up the Control Room Envelope (CRE)?

Why is it important to maintain the CRE boundary?

Answer 6

• U-1 and 2 control room
• computer room
• ssps room
• briefing room
• shift manager office
• restroom and kitchen area
• U-1 and 2 mech equip room on 154’ (above CR)
• CRVS press duct from T.B. to CR roof

if boundary not maintained, design basis of limiting control room personel to 5 Rem whole body during durration of DBA is not ensured.

Question 7

(CRVS) What will block Mode 1 and 2 operation?

Durring CRVS mode changes are the Modes always matched between control rooms (U-1 and U-2)?

Answer 7

• If Mode 3 or 4 is initiated anywhere (either bus, on either unit)
• No, All modes are matched with the exception of Mode 4. When one unit is in Mode 4 the opposite unit is taken to Mode 3. (Damper L/U is same but piping cant handle two Pressurization fans)

Question 8

What must not be done if both Units CRV are selected for Bus H?

Answer 8

Dont select one unit from normal P.S. and other unit from alternate P.S. (they will both be powered from same bus)

Then

You must declare one Unit CRV inoperable