Exam 11 prep Flashcards
What is the purpose of PPS?
- Assure SAFDL AND pressurizer safety limits are not exceeded during an Anticipated Operational Occurrence
- Redundant and independent to ensure
- No single fault will cause an actuation
- No single fault will cause a loss of safety function
- 4 separate (train) sensing channels
- 6 logic matrices that contain relays to trip RTSGs
How does a loss of one PN bus affect PPS?
- Loss of a single PN power supply: 2 RTSGs open (A & C OR B & D)
How does a loss of 2 or more PN buses affect PPS?
-
Loss of any 2 or more PN power supplies: Rx Trip
- Also due to instruments losing power you will get a FULL ESFAS actuation. (Every signal except LOP)
What happens in PPS if a single parameter exceeds its trip setpoint?
What actions are required and how long do you have?
-
Single parameter exceeding trip setpoint: No trip only alarms
- If the instrument is determined to be bad causing this trip then we will bypass it. (New logic is now 2 out of 3 instead of 2 out of 4)
- 1 hour time limit to get this channel bypassed
What will happen in PPS if one parameter is bypassed in A train and its trip setpoint is exceeded in B train?
What actions are required and how long do you have to do it?
- One parameter in bypass the same parameter has a trip on another channel: NO TRIP (Only 1 out of 3, needed 2 out of 3)
- If this is also due to a failed instrument then within 1 hour 1 channel is placed in bypass and the other is tripped (this is done by I & C)
What should be done to the signals associated with PPS A if PNA is lost?
-
ALL signals on that associated cabinet should be bypassed.
- Since these are pushbuttons that stay depressed even though power is gone the bypasses will still work
Which leg of ESFAS logic is responsible for valve group actuations? Pump group actuactions?
- 1-3 leg (Valve group relays)
- 2-4 leg (Pump group relays)
How does loss of a single PN bus affect the ESFAS portion of PPS?
- Half leg trip on both A and B trains (same leg)
- The bottom of the electrical circuit for initiation relays is basically “cross-connected” so you need contacts to open on both legs to cause a full actuation. (A SINGLE CONTACT GOING OPEN WILL NOT MOVE ANYTHING)
- There is a fuse in the current return for each leg
- IF this fuse were to blow then the associated relays of that leg will also de-energize causing an actuation of its associated components (half leg trips)
What type of manual initiation is available from B05?
What configuration will ensure complete esfas actuation?
-
Manual initiation of each channel is available for each train from B05
- However there is a catch: FOR A FULL ACTUATION YOU MUST TAKE MORE THAN ONE CHANNEL TO INITIATE TO HAVE AN ACTUATION. (Also the 2 MUST NOT be same train A&C/B&D)
At the Aux relay cabinet, how are initiation signals manually initiated?
How are channels reset at the Aux relay cabinet?
-
Trip/Resetting @ Aux Relay Cabinet
- To Reset ONLY 1 BUTTON PRESS IS NEEDED (for 1 Train)
- To Initiate 2 BUTTONS ARE REQUIRED (for 1 train)
State the instruments, setpoints, and actions associated with:
VOPT
Safety NI’s
- Fixed setpoint at 110% pwr
- Variable at 9.7% above SS pwr
- rate of change at 10.6%/min
Reactor trip
State the instruments, setpoints, and actions associated with:
HI LOG power
Log signal from middle safety NI.
- >0.01%(1E-2%) pwr, (bypassed on startup at 1E-4%; will auto remove this bypass on going below 1E-4%)
Reactor Trip
State the instruments, setpoints, and actions associated with:
Hi LPD
Originates in CPCs
- > 21kw/ft
Reactor trip
State the instruments, setpoints, and actions associated with:
LO DNBR
Originates in CPCs
- < 1.34 dnbr’s
Reactor trip
State the instruments, setpoints, and actions associated with:
Hi Ppzr
PT-101A-D NR Ppzr
- > 2383 psia
Reactor Trip
State the instruments, setpoints, and actions associated with:
LO Ppzr
PT-102A-D, WR Ppzr
- < 1837 psia
Reactor trip
SIAS
CIAS
State the instruments, setpoints, and actions associated with:
LO Psg
SG 1: PT-1013A-D
SG 2: PT-1023A-D
<960 psia (variable)
Reactor trip
MSIS
State the instruments, setpoints, and actions associated with:
D/P across SG-1 and SG-2
SG 1: PT-1013A-D
SG 2: PT-1023A-D
- >185psid between S/Gs
AFAS lockout
State the instruments, setpoints, and actions associated with:
LO Lsg
SG-1: LT-1113A-D WR
SG-2: LT-1123A-D WR
<44.2% Reactor trip
<25.8% AFAS
<20.3% DAFAS
State the instruments, setpoints, and actions associated with:
HI Lsg
SG-1: LT-1114A-D NR
SG-2: LT-1124A-D NR
> 91%
Reactor trip
MSIS
State the instruments, setpoints, and actions associated with:
HI Pcont.
PT-351A-D
> 3psig NR
Reactor Trip
SIAS
CIAS
MSIS
State the instruments, setpoints, and actions associated with:
HI HI Pcont.
PT-352A-D
> 8.5psig(8.06psig per ARP)
CSAS
State the instruments, setpoints, and actions associated with:
LO Flow-RCS
Loop 1: PD-115A-D
Loop 2: PD-125A-D
Variable
Reactor trip
State the instruments, setpoints, and actions associated with:
LO Lrwt
LT-203A-D
<9.4%
RAS
What protects the plant against a RCP shaft shear event?
- “4” ∆P SG provided to protect against a RCP shaft shear
What does TS 3.3.1 require to be operable and in what modes?
- “4” ∆P SG also provided to protect against a RCP shaft shear
-
Tech spec
-
T.S. 3.3.1 requires these channels to be operable in Modes 1 & 2
- EXCEPT LOG POWER IS ONLY REQUIRED IN MODE 2 ONLY
- T.S. 3.3.2 SG ½ Pressure and Log Power High are only parameters required in MODE 3.
-
T.S. 3.3.1 requires these channels to be operable in Modes 1 & 2
What does HI Ppzr protect against?
-
High Pressurizer pressure (NR)
- Protects against
- Loss of Condenser Vacuum (AOO)
- CEA Withdrawal From Low Power Conditions(AOO)
- Chemical and Volume Control System Malfunction (AOO)
- Main Feedwater System Pipe Break (Accident).
- Protects against
What does LO Ppzr protect against?
-
Low Pressurizer Pressure (WR)
- Initiates SIAS/CIAS to protect against
- SIAS (all inside containment)
- LOCAs
- MSLB
- CEA ejection
- CIAS
- LOCAs (Inside or outside containment)
- MSLB (Inside or outside containment)
- FWLB (Inside containment)
- SIAS (all inside containment)
- Initiates SIAS/CIAS to protect against
What does LO Psg protect against?
-
Steam Generator Low Pressure
- Initiates MSIS/Reactor Trip/∆P Lockout
- Mitigates consequences inside or outside of containment for:
- MSLBs
- FWLBs
What does LO Lsg protect against?
-
Steam Generator Level Low (WR)
- Rx trip (44.3%)
- Protects against exceeding RCS design pressure during loss of heat sink event
- AFAS (25.8%)
- Maintains heat sink during a S/G Tube rupture event
- As well as a MSLB or FWLB (Inside or outside containment)
- Rx trip (44.3%)
What does HI Lsg protect against?
-
Steam Generator Level High (NR)
- High trip is specific to preventing MOISTURE CARRYOVER to the TURBINE
- Rx trip
- MSIS
What does the LO Lrwt protect against?
-
Low RWT Level (9.4%)
- Enough water left to not damage pumps during fill phase yet enough water to fill containment to allow recirculation to work.
How are the setpoints for LO Ppzr lowered during normal cooldown?
-
Setpoint Reset PUSHBUTTON
- Lowers the Low PZR pressure setpoint by 400# from CURRENT pressure. 10 second delay for each push of the button.
- This can be done all the way down to 400# pressure at which point the Low PZR pressure can be BYPASSED (amber light for permissive)
- Can be bypassed at the following:
- Bistable Control Panel (BCP)
- Remote Operators Module ROM (B05)
- RSP
- Lowers the Low PZR pressure setpoint by 400# from CURRENT pressure. 10 second delay for each push of the button.
How is Ppzr trip affected by pressurizing the RCS?
ON THE WAY UP
Bypass automatically removed @ 500# and will lag 400# until 1837# is reached.
How is HI log bypass placed or removed?
- HI log bypass
- Done between 10-4% & 10-2%. If not completed prior to exceeding 10-2% the unit will trip
- Can be bypassed at:
- BCP
- ROM
- Places itself automatically back in service @ <10-4%.
How is Psg setpoint lowered?
- SG Press
-
Lo Steam Generator Pressure Pushbutton
- Lowers S/G pressure setpoint to 200# less than the current S/G Pressure. 10 seconds must elapse as well before hitting it again.
-
Lo Steam Generator Pressure Pushbutton
How is DNBR/LPD trips bypassed?
-
DNBR/LPD (OP Bypass)
- Automatically Removed at 10-4% going up
- May be bypassed < 10-5%
- Done by using the enable key to “allow” operators to insert the OP Bypass into the ROM on B05
What would happen if an attempt to bypass the same parameter across multiple PPS channels was performed?
-
Bypassing Parameters on PPS Cabinets
- There is a priority. YOU ARE NOT ABLE TO PLACE THE SAME PARAMETER IN BYPASS ON MULTIPLE CHANNELS
- It will automatically ensure 2 channels aren’t bypassed on the same parameter by removing one of the parameters from bypass
- Priority: A→B→C→D. So if “B” is already in bypass for a parameter and “A” bypass button is pushed “B” will come out of bypassed. The same relationship exists for “B” to “C” (“C” would “lose”)
- The same priority is available for being able to place a channel in test
What indication exists on the BCP that a pre-trip has been met and what will this cause?
- NORMALLY ON GREEN LIGHT, will go out when a valid DNBR/LPD pre-trip from the CPC is causing a CWP
What happens to feed if AFAS 1-2 are manually initiated from B05 concurrent with a SG d/p lockout on one SG?
-
S/G D/P Lockout wins if initiation handswitch position is returned to its normal position.
- If the manual initiation switches on B05 are left in the initiate position Aux FW will fill the generator until the operator does something
- All 4 switches must be taken to initiate for a FULL actuation of AFAS
Describe DAFAS initiation requirements and what it will perform?
What will occur with regard to feed if a MSIS is received during a DAFAS actuation?
-
Initiation Requirements
- 2409 psia
- NO AFAS
- NO MSIS
- 2 out of 4 SG < 20.3% WR
-
YOU ONLY GET ONE FILL TO 40.8% WR and the DAFAS WILL NOT FEED ANYMORE
- If you get a MSIS in the middle of a DAFAS actuation it will stop feeding. Pumps will remain running.
- 8 keys to bypass DAFAS in the Aux Relay Cabinets - fun fact.
With regard to RAS, should it be manually initiated based on RWT level trending towards its setpoint?
Why or why not?
- RAS should NEVER be manually initiated on trend this allows enough water inventory into containment
What happens to the LPSI pumps and miniflows on a a RAS initiation?
What operator actions are required and in what amount of time?
- Operator action required w/in 5 min to close the RWT suction valves
- LPSI shutsdown, mini-flows close
Where can an MSIS be initiated from?
-
MSIS
- CAN BE INITIATED FROM RSP or B05 or Aux Relay Cabinet