CP- Containment hydrogen purge

Question 1

What are the two subsystems of the CP system? Purposes?

Answer 1

Refueling Purge Subsystem – provides ventilation air for personnel comfort when the plant is shutdown during refueling operations and maintenance

Power Access Purge Subsystem – provides ventilation air to allow operator access for limited periods during power operation. Also used to control pressure in the containment by periodically venting a portion of the containment air to the plant vent

Question 2

What provides cooling in the Refuel Purge AHU and how is it controlled?

Answer 2

Normal Chilled Water

Automatically controlled to maintain inlet air temperature at a preset value

Question 3

When does the WC system provide cooling to the Power Access Purge AHU?

Answer 3

When outside temperature is too high

Question 4

How does Instrument Air interact with the CP system?

Answer 4

Provides air for the operation of dampers, valves, controllers, and air operated containment isolation valves in the CP system

Question 5

How is the system affected by a loss of IA?

Answer 5

Air operated dampers and valves fail closed, which will cause associated AHUs, AFU, supply or exhaust fans to trip

Question 6

When is the Refueling Purge Supply AHU operated and where is it located?

Answer 6

Only in Mode 5 or 6

Located on the Aux Building roof

Question 7

How does the Power Access Purge Supply AHU handle outside temperature being too low?

Answer 7

Electric heating coils are energized

Question 8

Where is the Power Access Purge Supply AHU controlled from? Where is it located?

Answer 8

Control Room

aux. building roof

Question 9

Why is there a heater installed up stream of the Power Access Purge Normal Exhaust AFU?

Answer 9

To maintain humidity low to prevent damage to the charcoal filter down stream

Question 10

Concerning the Power Access Purge Normal Exhaust AFU, what is the purpose of the charcoal filter and second HEPA filter?

Answer 10

Charcoal filter removes fission product gases (mainly iodine) by adsorption
Second HEPA filter removes any carbon dust emitted from the charcoal filters

Question 11

Which radiation monitors continuously monitor Purge discharge flow to the plant vent?

Answer 11

RU-37 and RU-38

Question 12

What happens if monitors RU-37 and RU-38 detect excessive radiation?

Answer 12

Initiate a CPIAS and stop the purge

Question 13

What will stop a containment purge besides RU-37 and Ru-38 detecting radiation?

Answer 13

CIAS

Question 14

The Power Access Purge has what two modes?

Answer 14

Venting or depressurization mode

Power Access Purge mode

Question 15

When would I use Venting mode?

Answer 15

Utilized to depressurize the containment atmosphere during normal power operation or prior to power access purge

Question 16

How is the CP system affected by a loss of Class 120 VAC?

Answer 16

Causes the CP system to shutdown and isolate from the containment

Power is lost to RU-37 (A Train) or RU-38 (B Train), which are used to generate CPIAS

Question 17

How is the CP system affected by a loss of Non-Class 125 VDC?

Answer 17

Containment Refueling Purge AHU outlet dampers fail closed which will prevent operation of the AHU

Containment Power Access Purge AHU inlet damper fails closed which prevents operation of the AHU

Question 18

Where does the containment purge system purge the containment atmosphere to? Where does the filtered and treated make-up come from?

Answer 18

plant vent stack

outside air

Question 19

What is the flow path of the Containment Purge refueling purge subsystem?

Answer 19

outside air is drawn in through a single AHU with two fans. sends air through dampers and isolation valves to containment

two exhaust fans drawn air out of containment through dampers to the plant vent

some of the exhaust air flow goes through rad monitors with two external rad monitors as well

Question 20

What does the containment purge refueling purge subsystem AHU consist of?

Answer 20

filter, heating and cooling coils two fans

Question 21

In both of the containment purge subsystems, what happens when the exhaust rad monitors sense high radiation levels? The external rad monitors?

Answer 21

alarm

system isolates

Question 22

What is the flow path of the containment purge power access purge subsystem?

Answer 22

outside air drawn in to a single AHU to containment

containment atmosphere is exhausted through isolation valves, heater and into exhaust AFU and then to the plant vent with rad monitors internal and external

Question 23

What does the containment purge power access purge AHU consist of?

Answer 23

inlet damper, moderate and high efficiency filters, coils, fan and exhaust damper

Question 24

What does the containment purge power access purge exhaust AFU consist of? Where is it controlled from? Where is it located?

Answer 24

moderate, HEPA, charcoal, and HEPA filters and a fan

control room

aux. building roof

Question 25

How many containment purge refueling purge exhaust fans are normally running while the system is in operation?

Answer 25

two, keeping containment at a slight negative pressure

Question 26

Operating together as necessary for containment atmosphere clean-up is the Power access purge subsystem and what other system?

Answer 26

HC pre-access Normal AFUs