ADS Flashcards
What is the purpose of ADS?
Act as a backup to HPCI and perform the function of vessel depressurization for all small breaks within the containment or small breaks outside of containment THIS IS ECCS
How long is HPCI designed to maintain Rx Water level for small coolant leaks w/out other ECCS systems?
1000 seconds
What two indications does ADS use to determine the location of the leaks?
Uses -59 Lo-Lo Water Level and +2# DW Pressure.
If -59 w/ +2#, then inside DW.
If -59 w/out +2#, then outside DW.
How many valves function as part of ADS? Which ones?
5 - all ERVs including target rock
What is the logic scheme for ADS, and what does that mean?
It is 2 out of 2 once - energized to actuate. This means that an initiation signal from either trip system will actuate
Which ERV’s have a time delay? How long? what is it for?
The B&C ERVs (low setpoint) have a 10 second time delay that prevents AUTO REOPENING on a demand signal from ADS.
Allows sufficient time for operation of vacuum breaker on relieve valve discharge.
At what pilot valve indication does the target rock indicate open/closed?
Open on >50#, Closed on <40#
What are the normal and alternate power supplies to the ERVs for each unit?
Unit 2:
Normal: 125vdc 2A-1; Alt: 125VDC 2B-1
Unit 3:
Normal: RB Dist Panel; Alt: 125VDC Bus 3B-1
What powers the ADS Divisional Logic for Unit 2 and 3?
Division 1 : logic power from 2(3)A-1 ; NO BACKUP
Division 2: logic power from 2(3)B-1; Backup from 2(3)A-1
What required signals/actuations are required to initiate ADS for a leak INSIDE The DW?
RPV Lo Lo Level -59”
DW Pressure Hi - 2# - This will initiate a 2 minute timer
2 minute time out
DW Reset Button NOT in Reset
DW PRESSURE Timer Reset Not Depressed
Lo Pressure ECCS Pp Running - Measured at Pp Discharge as 100psig
ADS NOT IN INHIBIT
This allows both the 106 and 107 relays from EITHER ADS division to be energized and supply power to relief valve solenoids to open
On a leak inside the drywell, what is the condition of the DW Hi Pressure signal once received?
It is seal in - must have DW pressure reset button pushed
What does the Timer Reset push button do?
It will reset the 2 minute time delay for the Leak inside the DW
On a leak outside the drywell, what signals/actuations are required for ADS initiation?
CS Lo-Lo Level (and redundant Lo-Lo Level) -59”
-59” 8.5 minute timer
Lo Pressure ECCS Pp Running - sensed at discharge pressure 100psig
Timer Reset not pushed (does not reset, but will inhibit if held)
ADS NOT in Inhibit
How do you reset ADS?
Depress Timer Reset and Turn Drywell Pressure Reset
NEED BOTH
What happens if ADS is initiated on leak inside DW and Timer Reset is pushed (while conditions still exist)?
ADS valves will closed and then re-open after 120 seconds
