Containment HVAC

Question 1

STATE the functions of the Containment Air Handling (CAH) system

Answer 1

• The primary function of the containment air handling (CAH) system is to remove the heat generated by equipment within the containment structure.
The CAH secondary functions are:
• Recirculate containment structure air following a loss-of-coolant accident (LOCA) ,
• Filter containment structure air prior to personnel entry.

Question 2

Briefly DESCRIBE the flowpath from suction to discharge for the following subsystems of the CAH system: containment structure cooling

Answer 2

Filter->Cooling Coils->Fan->Backdraft Damper -> Distribution

Question 3

Briefly DESCRIBE the flowpath from suction to discharge for the following subsystems of the CAH system control rod drive mechanism cooling

Answer 3

Shroud Inlets-> Nozzles-> CRDM’s -> Fan’s -> Backdraft Dampers

Question 4

Briefly DESCRIBE the flowpath from suction to discharge for the following subsystems of the CAH system recirculating filter unit (recirc mode)

Answer 4

Containment Dome -> Damper -> Fan -> Below 25ft Containment Floor

Question 5

Briefly DESCRIBE the flowpath from suction to discharge for the following subsystems of the CAH system recirculating filter unit (filter mode)

Answer 5

Containment 25 ft. to the Filter -> Damper -> Fan -> Below 25 ft. Containment Floor

Question 6

STATE the functions of the Combustible Gas Control (CGC) System

Answer 6

– Monitor the concentration of H2 gas within the Containment structure.
– Reduce the concentration of H2 gas in the Containment atmosphere to prevent fires / explosions. (Containment Integrity => fission barrier)

Question 7

STATE the functions of the Containment Air Purge (CAP) system

Answer 7

• Provides Containment ventilation during refueling operations for personnel comfort
– Note: air is conditioned (heated or cooled via PAH system)
• Provides filtration of Containment exhaust air during refueling operations to ensure potential radioactive releases are within Federal Guidelines
• Provides ventilation for the radiological control access (RCA) walkways (tunnel).
• Provides filtration of RCA exhaust air to ensure any potential radioactive release is within Federal Guidelines

Question 8

Briefly DESCRIBE the flowpaths of the CAP system from the fresh air suction to the discharge to the plant vent in the following mode: RCA Walkway

Answer 8

– CAP-MM-726 (CAP-FN-179) RCA air supply heating and ventilation unit supplies 4000 cfm of outside air to the RCA
– CAP-FN-10 discharges air to the Plant vent
– Damper 1013 opened to provide »11,000 CFM back to fan suction via filter for flow balancing

Question 9

Briefly DESCRIBE the flowpaths of the CAP system from the fresh air suction to the discharge to the plant vent in the following mode: Pre-Entry Purge

Answer 9

– The Pre-entry Supply Fan (CAP-FN-9) draws 11,000 cfm of air from the PAB supply fan bay
– CAP-FN-9 discharges into a supply header through CAP-V-1&2 (flange removed)
– The supplied air is distributed within the Containment via CAP ductwork
– CAP exhaust air is drawn across the refueling cavity by CAP exhaust fan (CAP-FN-10).
– The exhaust air exits Containment through CAP-V-3 and V-4 (flange removed)
– The exhaust air then passes through a HEPA filter unit (CAP-F-310)
– Air then routed to HEPA/Charcoal filter unit (CAP-F-40) “CAP air cleaning unit” for removal of radioactive gaseous Iodine and radioactive particulate matter
– CAP-FN-10 (Pre-entry Purge exhaust fan) discharges to Plant vent.

Question 10

Briefly DESCRIBE the flowpaths of the CAP system from the fresh air suction to the discharge to the plant vent in the following mode: Refueling

Answer 10

– The Refueling Purge Supply Fan (CAP-FN-34) draws 31,000 cfm of air from the PAB supply fan bay (same flow path as Pre-Entry)
– Refueling Purge Exhaust Fan (CAP-FN-35) draws 31,000 cfm of air across the refueling cavity (same flow path as Pre-Entry)
– Air routed through F-310
– CAP-FN-35 discharges to Plant Vent

Question 11

STATE the functions of the Containment On-line Purge (COP) system

Answer 11

• Purge the containment atmosphere periodically during normal plant operation and to
– Reduce containment pressure
– Reduce containment airborne radiation levels

Question 12

Briefly DESCRIBE the flowpath of the COP system from the fresh air suction to the discharge to the plant vent.

Answer 12

• The COP Supply Fan (COP-FN-73) draws 1,000 cfm of air from the PAB supply fan bay
• COP-FN-73 discharges air to Containment via COP-V-1 and V-2
• The “COP” air is mixed by the running CAH Structure Cooling Fans
• PAH filter exhaust fan PAH-FN-8-A or B draws COP exhaust air from Containment via COP-V-3 and V-4
• Exhaust air discharged to Plant Vent