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Systems > CAC > Flashcards

CAC Flashcards

1
Q

Which subsystems comprise CAC?

A 
Nitrogen Makeup
Pumpbakc system
DW cooling
DW Purge
APCV
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2
Q

What is the purpose of the N2 Makeup system?

A

Provides pressure control support to Primary Containment as well as nitrogen feed and bleed vapability should combustible atmosphere develop post accident.
Provides makeup, inerting and NCAD flow paths

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3
Q

What is Nitrogen COntainment Atmospheric Dilution (NCAD)?

A

Provides more reliable source of nitrogen for combustivle gas controll following an accident - provides 29cfm through each line when normal makeup flow not available

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4
Q

What are the N2 low flow and high flow paths normally used for?

A

Low flow path - makeup

High flow path - Inerting post outag

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5
Q

How is DW inerting performed?

A

Using N2 Makeup High flow portion utilizing a steam heated vaporizer (from heating steam) which is capable of rapidly vaporizing liquid N2 at a nominal flow rate of 2500cfm

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6
Q

How is N2 Makeup performed?

A

Using the low flow portion of the system - used as makeup to PC for sligh leakages to maintain DW slightly higher than 1psig

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7
Q

What is the purpose of the Pumpback system?

A

Maintain slightly greater than 1 psid between DW and Torus and supply AOVs in DW via DW Pneumatics

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8
Q

How many Pumpback compressors are there per unit?
Power Supply?
Cooling?

A

2 per unit
pwr - 28-1/29-1(38-1/39-1)
ALL COOLED BY U2 RBCCW

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9
Q

What poweres DW Pneumatic Vlv Solenoids and how does a power loss impact valves?

A

Powered by IB - vlvs close on loss of IB (MSIV’s close w/in 1 minute)

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10
Q

What causes trip of Pumpback AIr Compressor?

A

Low Oil Pressure (15-17psig)
Hi RBCCW Temp (180F)
Lo Suction Pressure (5” Hg)
Breaker Trip

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11
Q

What is normal Pumpback flow path?

A

Suction from Torus to Torus to maintain 1pside

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12
Q

What happens to pumpback compressor on Grp II Isolation?

A

Runs unloaded and eventually trips on low suction pressure

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13
Q

How does the DW/Torus DP Control system function?

A

Pumpback compressors take suction on Torus and charge Pumpback receiver to 100psig and then air flows back to DW through PCV

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14
Q

What controls Pumpback flow and operation?

A

PCV to maitnain DW press ~1psig

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15
Q

What happens in Pumpback and DW pneumatic pressure drops?

A

N2 backup valve opens to maintain pressure to valves in DW. This is necessary to maintain MSIVs open for small period of time.

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16
Q

What powers Pumpback Receiver Digital Indicator and where is it?

A

902-4 powered from IB

17
Q

What causes a change in containment pressure during normal operation?

A

Convective heating during startup or power reduction;
Malfunction of Pumpback system
Leak in DW pneumatics
Change in Ambient press(sensed relative to RB Press)

18
Q

What signals cause closure of 57,58 and 59 Pmpback valves?

A

Grp II, loss of IB, Loss of IA

19
Q

What does DW Pneumatics do?

A

Supplies pressure to operate AOVs in DW and AOVs that control DW pressure & DP

20
Q

What is pressure set for N2 backup valve to open?

A

if Pumpback and DW pneumatic drops to ~80psig, valve 4723 opens to maintain pressure using backu supply

21
Q

Which containment Dampers have fail safe accumulators?

A

1601-21, 22, 23, 24, 56, 60,63

22
Q

What is the purpose of DW Air Cooling System?

A

maintains DW atmosphere temp less than those assumbed for DBA initiatl conditions
Temp between 135F and 150F

23
Q

Where are the DW coolers and what are their power and cooling?

A 
A-E on DW Basement 
F,G on 515
A,B, F, G powered by Bus 28
C,D,E powered by Bus 29
All cooled by RBCCW
24
Q

What causes DW Cooer Trip?

A

Fans trip on ECCS Initiation (CS DWB Relay) and breaker trips
DO NOT TRIP ON UV LOAD SHED
(ECCS Trip may be defeated by lifting and taping leads)

25
Q

What are the DW Purge Fans for? Power?

A

Designed to draw PC atmosphere through set of filters and discharge to RB Vent exhaust fans to RB Stack or SBGT
Normally used to de-inert DW for entry
Powered from MCC 28-1, 29-1

26
Q

What happens to DW Purge Fans during Secondary Containment Isolation?

A

Both Unit Purge Fans trip and inlet and outlet dampers close

27
Q

What is Augmented Primary Containment Vent?

A

APCV allows venting primary containment directly to 310 Chimney using IA and ESS for opening. fails closed on eitehr.

28
Q

What is power supply for APCV?

A

ESS powers logic and valve solenoids

29
Q

What is APCV design flow?

A

Equivalent to 1% rated thermal power (78910lb/hr) at 62psig torus bottom pressure and normal Torus water level

30
Q

What are concerns fro SBGT Duct Work concerns?

A

Venting DW under high pressure (DBA) may result in failure of SBGT duct work in TB and contamination of TB areas.

Systems (97 decks)

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