Standby Gas

Question 1

What’s the purpose of the recirc fans?

What ratio is it mixed at?

Answer 1

Mix a quality of air from enclosure building with air from lower regions of the Aux building

> 3:1

Question 2

What’s the power supplies for the recirc fans?

Answer 2

15BA3

16BB3

Question 3

How do dampers respond after initiation?

Answer 3

F021/F022 are open on initiation and remain open ( Enclosure bldg to recirc fans)

At -.20” wc is reached, aux steam tunnel F005/F006 go to intermediate

90 seconds later all other dampers go to intermediate

If enclosure building >.20”wc, dampers re-open

Question 4

What will trip the heater in SBGT?

Answer 4

> 200 deg F (auto reset)

> 225 deg F (manual reset)

Question 5

What setpoints will start the standby, SBGT?

Answer 5

< 8500 scfm running enclosure building recirc fan low flow

<1250 scfm running exhaust filter train low flow

> .20” wc in enclosure building low negative pressure

Question 6

How do you place a train of STBY gas in standby?

Answer 6

IF:
> 8500 scfm running enclosure bldg recirc fan
> 1250 scfm running exhaust filter train flow
> .20” w.c. in enclosure bldg pressure

THEN:
Mode switch to STBY
amber light
reset manual initiation logic
stop SBGT train

Question 7

How do the exhaust fan vanes react off initiation? (F500A/B)

Answer 7

Initially open for 120 seconds or .75” w.c. enclosure bldg pressure.

THEN:

Modulate to maintain 3875 scfm system flow rate through the filter train

Question 8

what signals start standby gas?

Answer 8

• 41.6” Rx water level
  1. 23 psig drywell pressure

30 mr/hr fuel pool sweep

3.6 mr/hr FHA exhaust

Question 9

purpose of demister?

Answer 9

removes water

Question 10

purpose of electric heater?

Answer 10

reduces humidity to 70%

Question 11

purpose of prefilter?

Answer 11

removes large particle matter

Question 12

purpose of HEPA (1st filter)

Answer 12

Removes fine particulate matter

Question 13

purpose of charcoal filter?

Answer 13

removes gaseous IODINE

Question 14

purpose of 2nd HEPA filter?

Answer 14

Collects carbon fines exhaust from charcoal beds

Question 15

Will stop handswitch secure STBY gas with signal sealed in?

Answer 15

NO

Question 16

What is the NSSSS logic?

Answer 16

A and D

OR

B and C

Question 17

How long after VOCs have been used in the Aux, CTMT, or enclosure building can standby gas be ran in nonemergency mode?

why?

Answer 17

16 hours

protect the charcoal

Question 18

What is the purpose of STBY gas?

Answer 18

Limits the environmental release of radio isotopes which can leak from CTMT or FHA boundary under accident conditions