SBLC Flashcards
What is the purpose of the SBLC System?
Provides a backup system to bring the Rx to shutdown condition from any time independent of CRD System. (Per UFSAR, control pH at or above 7 during LOCA)
Why is SBLC NOT a backup for RPC Scram?
Due to the time necessary to initiate and inject full contencts
What are teh design bases for SBLC system?
- Used to maintain Torus pH at or above 7 following LOCA with significatn fission product release to ensure iodine will be retained in Torus w/ Rx at 100% power wtih equilibrium Xenon and rods in normal pattern
- Equivalent concentration of Boron of 600ppm at 68F in core (918ppm in less than 100 minutes to bring Rx from full power to 1% dk or more sub-critical)
- Designed to provide for additional margin of 25% boron to compensate for possible losses and imperfect mixing
What must the boron concentration be maintained at to achieve design concentration in core following injecton?
14% by weight at 40gpm to achieve 918ppm boron in less than 100minutes (3605 gallons of mixture)
During Hot Shutdown and Cold Shutdown Conditions, how much SBLC injection is required to bring to stable condition?
Hot: Injected to tank level of 39%
Cold: Injected to tank level of 14%
What is the saturation temperature of the Boron solution and what temperature is required to maintain it in liquid form?
saturation temperature of 62F - causes crystalization if lower
Kept above 83F (TS) and tank set at 95F
What positive reactivity effects must SBLC overcome?
Elimination of Steam Voids Moderator Temp drop to 125F Deduced doppler effect Decreased rod worth as boron competes with rods Xenon Decay
What MCR indications are there for SBLC?
5 lights - Flow, Squib, Pump 1, Pump 2
Discharge Pressure
Tank Level
1-vlv (Normally LO)
What are the 3 primary test flow paths?
Clean Demin from test tank pumped back to test tank
Clean Dmn from test tank Pp and inject to Rx
Mn Tnk pumped to Test Tank
What is capacity of Boron Storage Tank?
5250 gallons
What is the purpose of the SERVICE AIR sparger?
Provides thorough mixing of solutions
What provides power to SBLC Tank Heater?
Normal Setpoint?
Trip?
Powered by MCC 29-1 (38-1)
Normally set at 95F
Trips at level <15% (19.5”)
What is the purpose of the SBLC Tank Bubbler and what supplies it?
Bubbler used for level indication - supplied using Instrument Air
What is the total flow and pressure for the SBLC Pumps?
Total Flow of 80gpm (40gpm per Pp) at 1330psig
Design flow is 40gpm PER pump at 1500psig
What are the power supplies for the SBLC Pumps?
2A - MCC 28-1/ 2B - MCC 29-1
What provides power to the Squib Vlvs and Pump Heaters and heat trace?
The same MCC that supplies the associated Pp (28-1, 29-1)
What is different about the local SBLC control switch compared to MCR switch?
DOES NOT FIRE SQUIB
What does the -5 Panel SBLC Squib light do?
Shows valve continuity - if lit then it shows that the squib has not fired
What are the automatic starts and stops for SBLC Pumps?
THERE ARE NONE
What is the nominal setpoint of the SBLC Relief valves and where do they discharge to?
1455# to 1545# (remember 1500) - discharge to main tank
What is the purpose of the SBLC Accumulators?
Dampen pulsations from PDPs
Charged with 450psig N2
What is the location of and purpose of the SBLC spool pieces?
Located upstream of Squib Valves - allow for replacement of squib valves
What is the purpose of the Squib Valve?
Designed to pass 40gpm when actuated and allow ZERO leakage when in standby.
What is the power source of teh SBLC Squib Vlaves?
MCC 28-1/29-1 assocaited wtih pumps
How many firing circuits are assocaited with each Squib Valve?
2, protected by fuses, to create redundancy
What is the make-up for the Test Tank and Main SBLC tank?
Clean Demin
How is SBLC injected to Core?
Using the “Pipe Within a Pipe”:
Inner Pipe below Core plate with perforations at upper end for Boron injection.
Swept into core by natural circulations or Jet Pumps if RR running
What is the outer pipe-in a pipe pipe used for?
Core plate DP, CS System line break detection, RPV Pressure Input to CRD system
Where does SBLC drain to?
55 gallon drums so doesn crystalize in drains
How is SBLC Actuated?
Manually ONLY:
Local - ONLY STARTS PUMPS, does not fire squib or isolate RWCU
MCR - Place key in switch - turning switch to 1, 2, 1&2 or 2&1
Depending on selection -
associated swuib fires
associated pump starts
squib light turns off and pump light turns on
RWCU isolates AS SOON AS switch not in OFF (1,1a,2,3,7 vlvs close)
When is SBL allowed to be shutdown?
Any of these met:
All rods in (atleast 04) to ensure shutdown margin
Rx shutdown under all conditions w/out Boron
SBLC tank injected to level of 8%
What happens to SBLC on loss of I/B?
Loss of all light indications and meter on 5 panel.
***** EXCEPT SQUIB VLV - Comes off MCC
What is the effect of partial losses on the system?
Pump Power?
Squib failure?
Relief Valve Lift?
As long as one pump and one injection vavle are available, system can meet design requirements
As long as power is to both pumps, flow will be 80 gpm through one squib valve
With lift of Rlf Vlv - Pp discharge pressure will be less than Rx pressure and Pp discharge pressure oscillation
What can be done with a complete loss of SBLC system?
ALternate DEOP for injection using Condensate Demin Unit
What happens to SBLC on loss of MCC power?
Loss of indication for respective squib valves and receive continuity alarm
Associated Pp cannot start
SBLC respond to loss of IA?
Loss of air to bubbler - causing level indication lost
Loss of level indication will cause heater to trip
What provides power to SBLC MCR metering and indicating lights?
IB to MCR except squib valves - these are provided by MCC associated
