General

Question 1

What is the purpose of the Annulus Exhaust Gas Treatment System?

Answer 1

Maintain Annulus pressure at a slight negative pressure to ensure any Containment Vessel or Shield Building leakage is into the Annulus.

Filter any airborne radioactive Iodine and particulates form the air which leaks out of the Containment Vessel.

Monitor exhaust gases prior to release to the atmosphere.

Question 2

What is the normal differential pressure maintained in the Annulus?

Answer 2

0.75 - 1.0 Inches of Water vacuum.

Question 3

What components makeup the Annulus Exhaust Gas Treatment system Exhaust Plenum?

Answer 3

Demister –> Roughing Filter –> Electric Heating Coil –> HEPA Filter –> Charcoal –> HEPA Filter.

Question 4

What is the purpose of the Demister in the AEGTS Exhaust Plenum?

Answer 4

Remove water droplets and large particles entering the plenum.

Question 5

What is the purpose of the Roughing Filter in the AEGTS Exhaust Plenum?

Answer 5

Removes large particles from the process stream.

Question 6

What is the purpose of the Electric Heating Coil in the AEGTS Exhaust Plenum?

Answer 6

Reduces humidity thereby increasing the efficiency of charcoal adsorption.

Question 7

What is the purpose of the HEPA Filter in the AEGTS Exhaust Plenum?

Answer 7

Removes fine particles from the process stream to increase the efficiency of charcoal adsorption.

Question 8

What is the purpose of the Charcoal in the AEGTS Exhaust Plenum?

Answer 8

Removes radio-iodine in the process stream.

Question 9

What is the purpose of the second HEPA Filter in the AEGTS Exhaust Plenum?

Answer 9

Removes charcoal fines.

Question 10

What is the rated flow for each Annulus Exhaust Gas Treatment Fan?

Answer 10

2000 scfm

Question 11

What is the power supply for the Annulus Exhaust Gas Treatment Fans?

Answer 11

A: EF-1-B
B: EF-1-D

Question 12

What are the start permissives for the Annulus Exhaust Gas Treatment Fans?

Answer 12

There is ONLY one: Deluge Switch NOT ARMED.

Question 13

What will cause the Annulus Exhaust Gas Treatment Fans to automatically start?

Answer 13

1) RHR LOCA(16.5 inches RPV level and/or 1.68 psig Drywell pressure)
2) Low flow on the running fan.

Question 14

What is the value for the Low Flow automatic start of the Annulus Exhaust Gas Treatment Fans?

Answer 14

Less than 1500 scfm, the alarm comes in when flow is less than 1650 scfm.

Question 15

Can the Low Flow automatic start be overridden?

Answer 15

NO, the standby fan that auto started can be stopped with the control switch, but as soon as its released the fan will restart if the low flow condition still exists.

Question 16

Can the RHR LOCA automatic start signal be overridden?

Answer 16

YES, and the amber LOCA override light will be illuminated.

Question 17

What effect will a Loss of Offsite Power have on a running Annulus Exhaust Gas Treatment Fan?

Answer 17

The fan will shutdown momentarily, but will restart when power is restored with the Diesel.

Question 18

What is the fail position of the Annulus Exhaust Gas Treatment Dampers, and why?

Answer 18

The AEGTS dampers will fail to their standby positions:

Recirculation Damper - CLOSED
Exhaust Damper - OPEN

The dampers fail, or lineup to this position in standby, to draw a maximum vacuum.

Question 19

Do the dampers in the standby train modulate based on changing vacuum?

Answer 19

NO, the dampers only modulate when the damper logic 42 contact is closed by energizing the fan.

Question 20

How does the differential pressure controller control the position of both dampers? What will 0% and 100% output equal as far as damper position?

Answer 20

The “Split Range Damper Control” controls the position of each damper based on differential pressure. At 0% output the exhaust damper is full open and the recirculation damper is full closed. The recirculation damper begins to open as output increases towards 50% where it reaches full open. At 50% output the exhaust damper which is still full open begins to close. At 100% controller output the exhaust damper reaches full closed, and the recirculation damper remains at full open.

0% = Full Exhaust
100% = Full Recirculation

Question 21

What are the conditions that must be met to manually start the Annulus Exhaust Gas Treatment Electric Heating Coil?

Answer 21

1) No Hi-Hi heater temperature trip(this must be reset at the plenum).
2) No Hi Heater temperature trip.
3) No high fan discharge temperature.
4) Exhaust fan running, and a valid flow signal.
5) Heating coil thermostat circuit closed.

Question 22

What will cause the AEGTS Electric Heating Coil to automatically start?

Answer 22

RHR LOCA signal(16.5 inches RPV level and/or 1.68 psig Drywell pressure).

Question 23

Can the AEGTS Electric Heating Coil be overridden off with an RHR LOCA signal locked in?

Answer 23

NO, but you could cause an indirect trip by shutting off the fan. This will cause a loss of a start permissive.

Question 24

What will cause an automatic trip of the AEGTS Electric Heating Coil, and does this apply during RHR LOCA conditions?

Answer 24

A loss of any start permissive will cause an automatic trip of the electric heating coil. This applies under all conditions, including RHR LOCA.