CCW Flashcards
Purpose of CCW? Safety related functions of CCW?
-Remove heat from safety and non-safety related equipment during all situations -provide monitored, buffer system between radioactive systems and environment - automatically isolate non-vital equipment during accident conditions (ensure vital equip have flow) - maintain pressure on system to prevent flashing in CFCU’s (resequencing)
Describe normal system alignment and flowpath for CCW
- 3 pumps in parallel (2 running, 1 stby)
- 2 hx (1 in service, ASW cooled)
- 3 headers (A, B and C)
- A and B disch to surge tank, 3 headers back to pump suctions
Auto starts of CCW pumps
- xfr to DG (5 sec delay)
- SI (14 or 18 sec delay)
- lo Press vital header (69.5 #)* (A and B) * switch must be in auto and waits for oil pressure from AOP
(auto start won’t happen on pump trip due to pressure on surge tank)
CCW pump trips
- O.C.
- Load shed (xfr to DG)
Auto features on CCW AOP
Start
- any CCW pump start
- CCW pump stop (runs for 3 min)
(CCW pump will not wait for AOP on SI or xfr->DG start)
Stop
- when attached oil pump has adequate pressure
What signal opens the CCW pump recirc valves? Is this signal ever blocked? How long can pumps operate on recirc flow?
- low CCW pump amps (44 amps), equates to low flow
- blocked 10-30 sec after pump start (allow sys stabilize)
- 15 min (1100 gpm minimum flow)
What happens if RM-17A or B alarms
RCV-16 will close (isolation to CCW surge tank vent)
How does the CCW surge tank ensure there is water to at least one vital header in event of pipe rupture?
Divider in surge tank (won’t completely isolate but will slow leak considerably)
Why is the CCW surge tank pressurized?
- event large break LOCA and loss of power it is possible to have “double sequencing” - Xfr to S/u, CFCU cycle on (LOCA inside cnmt) degraded 230 causes loss of S/U, CCW inside coils flashes, when xfr to DG happens the CCW becomes vapor bound. - pressurizing CCW precludes flashing in this scenario
What are different methods of pressurizing CCW surge tank?
What pressure is maintained?
1- 115# N2
2- backup N2 bottles
3- 100# inst air
20 #
Loads on CCW header A? B? C?
A- CCW lube oil coolers(2,3), CCP lube oil and gear coolers(1), SIP lube oil cooler(2), RHR hx and lube oil coolers(1), CFCU (3,4) coils and motor coolers
B- CCW lube oil coolers(1), CCP lube oil and gear coolers(2), SIP lube oil cooler(1), RHR hx and lube oil coolers(2), CFCU (1,2,5) coils and motor coolers
C- waste gas comp. seal water cooler, sample coolers, RCP lube oil coolers and thermal Barrier hx, Seal water hx, Excess letdown hx, Letdown hx, Spent fuel pool hx, SGBD sample cooler
What is purpose for b/u accumulator on RHR hx cut in valve (CCW side), FCV-365, 364?
- keep valve closed on loss of air and loss of bus H=> maintain flow to vital loads
- loss air, valve fail open=> flow going not supposed to
- loss H, lose CCW pump=> less flow
- lose H, phase B won’t isolate hdr C=> less flow to vital
Why are the RHR HX outlet valves (FCV-364/365) remained closed? For how long?
The RHR HX outlet valves are maintained closed so that the remaining CCW pumps can provide sufficient flow to the required ESF equipment (CFCUs) to cool containment.
4.5 hours
How many CCW HXs are required to be in service if two RHR hxs in service
Both ccw hx in service required
How long can you run a ccw pump with a closed discharge valve
15 minutes
