RB and AB Ventilation

Question 1

What’s the purpose of the backdraft dampers?

Answer 1

Prevent reverse flow through idle RB cooling fan.

Question 2

What is the purpose of the bypass damper?

Answer 2

Used to bypass the chill water coil during ESAS and is cooled via SW.

Question 3

What is the difference in the ‘E’ RB Cooling fan?

Answer 3

Does not have SW cooling coil. Has a 2 stage fan and was added to aid in RB heat load.

Can not be in service when Purge fan is running.

Question 4

How do the RB cooling fan SW MOVs operate? What is the normal position of the solenoid bypass valve and its purpose?

Answer 4

When HS is taken to open, inlet valve travels 25 - 40% open and outlet will start to travel open. When closed, outlet valve begins to close and when 80 - 90% closed, inlet valve will close.

The solenoid bypass valve is normally open to keep system filled and avoid hydraulic lock in the header caused by warming and expansion of cold water when coolers are isolated.

Question 5

What actuates the RB coolers and what is the time delay for start?

Answer 5

VSF-1A-D receive a start signal from ES 5 or 6. VSF-1A/B are powered from B-5 and C/D from B-6.

Cooling fans will start after 50 seconds due to EDG load sequence.

Chill water closes, SW opens and cooler bypass dampers unlatch to pass air flow across SW coils.

Question 6

What is the TS required RB pressure?

Answer 6

-1 to 3 psig modes 1 - 4 and restore within 1 hour per TS 3.6.4.

Per limits and precautions if average of all 4 RB pressure indicators is > 2.64 psig or < -0.64 psig modes 1 - 4.

Question 7

What TS is associated with RB cooling system?

Answer 7

TS 3.6.5 requires both RB cooling trains operable (only one train required modes 3/4) in modes 1/2. If one is inoperable then restore in 7 days.

Both RB cooling trains provide 100% cooling capacity. 1 train of RB cooling and 1 train RB spray provides 100% capacity.

Question 8

What is the start sequence for the RB purge dampers based on RB pressure?

Answer 8

If RB pressure positive - open outlet dampers first, then inlets

If RB pressure negative - open inlets first, the outlets

Question 9

What ES signal will close purge dampers?

Answer 9

ES 3 or 4 will close purge isolations.

Question 10

What interlock is present between RB purge exhaust and supply fan?

Answer 10

VEF-15 is interlocked with supply fan to start upon VSF-2 start. If VEF-15 fails to start then VSF-2 will trip after 10 seconds.

Question 11

What is required prior to placing RB purge in service?

Answer 11

Gaseous release permit

Question 12

When will Hydrogen Recombiners be placed in service? What are their power supplies?

Answer 12

When hydrogen sampler reading of 3% concentration. They operate at 1150 - 1400 deg F to combine hydrogen with O2 to form water.

Powered from B-53 and B-61

Question 13

What are source of H2 generation in RB?

Answer 13

• Radiolytic decomposition of water
• Metal-to-water reaction (Zirc-water rx)
• Reactor coolant water
• Corrosion of aluminum
• Zinc base paint

Question 14

What are TS requirements for RB leak detector?

Answer 14

TS 3.4.15 for RCS leakage detection instrumentation One RB sump monitor and One RB atmosphere monitor (gaseous or particulate) are required in modes 1 - 4.

Question 15

What ES channels will isolate the RB leak detector?

Answer 15

ES 3 or 4.

Question 16

What temperature will cause AB fans to trip?

Answer 16

Fan will trip off if temp leaving heating coils drops to < 35 deg F.

Question 17

What elevations do VSF-7A/B supply in aux building?

Answer 17

VSF-7A - 354’ and above

VSF-7B - 317 and 335’

Power from B15

Question 18

What interlock is associated with AB Ventilation for start?

Answer 18

Cannot start VSF-7s unless VEF-8 is running.

Tendon galery fans also start when VSF-7B is started.

Question 19

What occurs with ABHV if exhaust isolation dampers are closed?

Answer 19

If Exhaust fan dampers close during operation, the exhaust fan and supply fan will trip. One exhaust fan must be running for supply fan to run.

Exhaust fan also trips when 3” vacuum is sensed at suction.

VEF-8 dampers will close on ES 5/6. Fan trips are generated off damper limit switch for ES actuation, not vacuum trip function.

Question 20

Which rooms are equipped with HELB dampers and what are their purpose?

Answer 20

HELB dampers are installed in LSEPR, LNEPR, UNPPR.

Purpose is to mitigate the spread of high pressure/temperature and water/steam vapors from piping penetration rooms into electrical pent rooms

Question 21

What areas does SFP ventilation supply?

Answer 21

• SF handling elevation
• BAMT Room
• X-8/hallway area
• RB Purge equipment room

Question 22

What causes automatic actuation of Pent Vent fans? What is the low flow alarm?

Answer 22

ES 5/6.

On ES channel 5, VEF-38A will start. If fails to sustain flow > 1700 cfm in 20 sec it will stop. If ES 6 is also actuated, VEF-38B will start after 5 sec delay.

Normal flow ~ 1800 CFM. Low flow alarm is < 1700 CFM.

If VEF-38B running and ES 5 occurs, A fan will start and B will stop

Question 23

When is VSF-4 not allowed to run?

Answer 23

During train bay operation when SFP deck hatches are removed.

Question 24

What TS requirements are applicable for Pent Vent Fans?

Answer 24

TS 3.7.11 requires 2 PRVS trains operable in modes 1 - 4.

Question 25

What autostarts the EDG room fans? How many are required for operability?

Answer 25

VEF-24A/C start in auto at 90 deg F.

VEF-24B/D startin in auto at 105 deg F.

If outside temperature < 85 deg F, only 1 required. Otherwise both are required.

Question 26

What will autostart ES switchgear chiller and what is its design temperature?

Answer 26

Autostart occurs at 95 deg F and designed to maintain 104 deg F in accident condition.