Core Spray Flashcards
What is the purpose of the Core Spray System?
Showers fuel to prevent exceeding thermal limits as a result of LOCA
What conditions is Core Spray designed to inject?
LOCA break size conditions which core cooling by HPCI alone up to and including DBA LOCA
What capacity (%) of DBA leak is CS designed to be able to handle?
Each of the 2 subsystems are designed redundantly to handle 100% each, without support from LPCI or offsite power
What (per TS3.5.1) is required if 2 or more subsystems of low pressure ECCS is INOP?
Enter 3.0.3 Immediately for shutdown
What is the normal suction for CS?
Torus via ECCS Suction ring header
What are the CS Injection valves? Normal operation? Normal position?
Two MOV’s
25 - Inboard - Throttleable - normally closed
24 - Normally open
Where is the Core Spray restricting orifice and what is it designed to do?
Upstream of injection valves - to prevent Pump runout
How does CS inject to the RPV?
Line penetrates core shroud and routes to a ring sparger above core - 2 100% coverage spargers
What is the alternate suction source for CS? Which CS pumps can line up to it?
CST - Can line up 2B and 3A (Centerline rooms)
Why can’t all 4 CS pumps take suction off CST?
Administratively prevented due to ECCS Jockey Pumps aligned to the 2A and 3B suction lines.
Where do the CS Pump Min Flow lines discharge to?
Torus
What is the ECCS keep fill source and purpose?
ECCS Jockey Pump - prevents water hammer on start of CS Pp
What is the CS Torus Suction Valve?
29 Manual, 3A MOV
What is the required capacity for each pump? shutoff head?
Each required to be 4500gpm at 90psig. Shutoff head 390psig
How many suction lines connect ECCS header to Torus and how many are required to provide adequate flow?
4 with suction screens. Designed such that 3 are adequate.
What are the CS Suction Valves and their power source?
1402-3A (MCC 28-1 (38-4))
1402-3B (MCC 29-4 (39-1))
What are the power sources for the CS Pumps?
A Pump Bus 23-1 (33-1)
B Pump Bus 24-1 (34-1)
What provides cooling water for the CS Pumps?
It’s own discharge
How is the area temperature maintained to prevent Pump/Motor Overheating? What is the cooling source and power?
ECCS Room Coolers -
Cooled by Service Water, CCSW (when running) or DGCWP(in needed, will INOP EDG)
PPowered by MCC 28-1(38-1) / 29-4(39-1)
How do the ECCS Room Coolers auto start and how are they secured?
If Control switch in neutral, will auto start on high local area temps.
MUST MANUALLY SECURE
At what flow rate will the CS minimum flow valve open/close? what is it’s normal condition in standby?
When system flow exceeds 750gpm, min flow vlve closes, if <750 valve is fully open; therefore, it is fully open when not in operation
What is normal power for CS min flow valve?
38A/B valves powered by MCCs 28-1(38-4) / 29-4(39-1)
How is the CS min flow valve controlled?
Flow transmitter powered through AC portion of ATS system.
What is the CS Test Line Valve number, where does it discharge to? What is it’s position on a CS initiation signal?
4A/B - Discharges to Torus via LPCI Test Line - Closes on initiation signal
What is the power source for the ECCS Jockey Pump?
MCC 28-1 (39-1)
What pressure is ECCS Jockey pump designed to maintain?
50gpm to maintain 85psig
What is the alternate CS Keep Fill supply?
Condensate Transfer via pressure regulator
If CS/LPCI headers exceed 100psig, what may actuate?
ADS permissive switch
Should the CS Injection Valves leak and permit RPV pressure to enter the CS piping, what is installed to prevent overpressure?
Relieve valve that lifts at 500psig and relieves to RBEDT
What are the CS automatic initiation signals?
+2psig DW Pressure OR
- 59” RPV LEVEL and <350psig OR
- 59” RPV LEVEL for >8.5min - allow LP ECCS inject for steam line break outside DW
What is the CS Logic Scheme?
1 out of 2 twice
What is the CS system response to Initiation Signal?
Both CS Pps start and run on min flow (unless Pp PTL)
Both CS Suct. Vlvs interlocked open (unless in Man. Bypass)
Test Line Vlvs interlock closed
Inject Vlvs stay closed unless RPV Press <350psig, then interlock open
25A/B may be throttled at any time.
How does CS Operate on loss of normal AC power?
EDG starts for ECCS condition +2# or -59” level - 10 sec for brkr close, 3 sec UV relay reset
When bus restored, first LPCI pump starts, 5 sec later 2nd LPCI starts, 5 sec later CS Pump Starts.
23 second from injection signal until all LP ECCS Pps running when on EDG. All start immediately if on normal AC. No 13 sec delay if EDG had already been running.
What are the interlock requirements for the CS Injection Valves?
Above 350psig - either 24 or 25 can be opened, but not at same time
Below 350# and no initiation signal - 25 MUST be closed for 24 to open.
If <350# psig & Init. Signal - 24 will open regardless of 25 position.
What kind of signal and interation does CS provide to ADS?
At 100psig discharge, pressure permissive sent to ADS to confirm LP ECCS pump is running
How does CS interact with the Deisel generator (Not power source)
DG starts on either +2psig or -59” Level signal
Div I CS logic starts 2/3 EDG
Div II CS logic starts Unit EDG
What is the C/CB interaction with CS Logic?
Logic 111A/B relay trip “D” C/CB Pp if all 4 are running and LOCA signal
What is CS logic tie to RBCCW?
A&B RBCCW pps trip, only if ECCS initiation with loss normal power
Why does D C/CB pp trip with LOCA signal?
Prevents overloading RAT
What is CS logic tie to SBO?
SBO switch in nomral and -59” or +2#DW signal, trip signal sent to SBO main feed breaker in Bus 23/24(33/34) - same relay that starts EDGs
What is alarm setpoint for CS Pp Seal Leak?
0.5gpm - 902-3 panel
What is the CS Overload protection?
CS Pp trip on overcurrent - 86 device need to be reset to restart
What is the “CORE SPRAY HDR DP HI” ALARM an alert of and where is it shown?
902-3 panel - identifies line break between RPV wall and core shroud, Core DP will change and alarm
Only works if >80% - reads Positive and Similar
What added interfaces does CS initiation logic have for Unit 3?
Initiation signal from Div II logic sends trip signal to normal feed for Security system at Bus 34-1 - starts Security Diesel or Security UPS
What are the control power for the CS logic System?
Div 1 - 125VDC Bus 2A-1
Div II - 125VDC Bus 2B-1
How will CS Logic Function on a loss of it’s normal power supply?
The associated pump and valves will not reposition
What is the “Core Spray System Timer Not Home” Alarm?
Means that there is a complete core spray initiation signal and 125vdc and 4kV power are avaialble
What will happen to CS flow on low Torus Level?
Low CS pump flow due to Vortexing
What are the CS Pump Trips?
Instantaneous or time delayed overcurrent
Undervoltage
