.AR PLCS PPCS (Welch's Highlighted Notes)

Question 1

Pzr Level Transmitters (LT-110X and 110Y):

• Selectable input to PLCS.
• LT power: ?
• LT Output to PLCS power: ?
• LT-110X and Y:
  
  • ?

Answer 1

Pzr Level Transmitters (LT-110X and 110Y):

• Selectable input to PLCS.
• LT power: PNA-D25 (110X) and PNB-D26 (110Y).
• LT Output to PLCS power: NNN-D12 (110X) and NNN-D11 (110Y)
• LT-110X and Y:
  
  • RSP and PAM LIs (LCO 3.3.10 / 3.3.11)
  • Hi / Lo level alarms (60% / 25%)
  • Hi / Lo level deviation from setpoint alarms (+8.5% / -3.5%)
  • LT-110X - PAM recorder

Question 2

Program Level Generator:

• Based on RRS…?
• < 568°F Tave:? constant at 33%
• > 586°F Tave: ?
• 568 - 586°F: level setpoint is ramped linearly…?
  
  • ?

Answer 2

Program Level Generator:

• Based on RRS Tavg (Loop 1, 2, or average)
• < 568°F Tave: L_PZR constant at 33%
• > 586°F Tave: L_PZR constant at 52.6%
• 568 - 586°F: level setpoint is ramped linearly from 33% to 52.6% (15% to 100% power).
  
  • Low end of band keeps heaters covered / available
  • High end of band maintains a PZR bubble for proper pressure control
  • Insurge will not reach safety nozzles
  • Outsurge will not drain PZR on a Reactor trip from 100%
  • Containment loading is determined by volume of RCS and size of PZR. Ensures design limits are not exceeded during LOCA

Question 3

Master Level Controller (LIC-110, aka Level Setpoint Control)

• Red pointer: ?
• Black on white pointer: ?
• Black pointer: ?
• Outputs (0-100%): ?…
• Controller in automatic mode (remote or local setpoint): ?…
• Shifting LIC between Remote Auto and Local Auto is ….?
  
  • ​Place LIC in manual…why?…

Answer 3

Master Level Controller (LIC-110, aka Level Setpoint Control):

• Red pointer: actual level from selected channel (LT-110X or LT-100Y)
• Black on white pointer: remote setpoint from RRS (based on Tavg)
• Black pointer: local setpoint from thumbwheel.
• Outputs (0-100%):
  
  • Sends status to RRS to prevent testing unless PLCS is NOT in Remote/Automatic (PLCS in LOCAL or MANUAL).
  • Inputs to Level Error Deviation Program. (If in LOCAL)
  • Compares actual level (selected) to the level setpoint.
  • LIC output controls letdown LCVs (LV-110P/Q).
• Controller in automatic mode (remote or local setpoint):
  
  • Output is modified by a “lag” unit before being applied to the letdown control valves.
  • Lag prevents rapid valve motion. Prevent unwanted pressure transients in the letdown line.
  • Low flow limit (~30 gpm). Adequate charging pre-heat to prevent RCS charging nozzle thermal shock.
  • Upper flow limit (~135 gpm). Ensures letdown does not exceed maximum design flow rates.
  • Lag and flow limits bypassed in manual control (0-150 gpm)
• Shifting LIC between Remote Auto and Local Auto is break before make.
  
  • Place LIC in Manual prior to changing modes (prevent change in controller output)

Question 4

Letdown Control Valves…?

Answer 4

Letdown Control Valves:

• LV-110P/110Q SELECTOR (Select one or both)
• Normally only one is selected. (One is normally isolated locally)
  
  • Use BOTH up to 1000 psia during startup and when < 1050 psia during shutdown.
  • Prevents exceeding letdown relief valves capacity (< 1200 psia).
• Fail closed (loss of air / power NNN-D11).

Question 5

Charging Pump Controls

• 1-2-3, 1-2-3, 2-3-1 and 3-1-2
  
  • “Always Running” - “Normally Running” - “Standby” Charging Pump.
• Controls operation of the charging pumps in conjunction with charging pump HSs.
• HS in AUTO after stop (green flagged) allows PLCS to control, manual pump start (red flag) blocks PLCS level deviation signals
• Pumps controlled from level deviation program (bistables).
• “Always Running” – PLCS has no control
• “Normally Running”
  
  • +15% ↑ stops normally running pump (level is too high)
  • +14% ↓ starts normally running pump (level returning to program)
• “Standby”
  
  • -23% ↓ starts standby pump (level is too low)
  • -14% ↑ stops standby pump (level returning to program)

Answer 5

Charging Pump Controls:

• 1-2-3, 1-2-3, 2-3-1 and 3-1-2
  
  • “Always Running” - “Normally Running” - “Standby” Charging Pump.
• Controls operation of the charging pumps in conjunction with charging pump HSs.
• HS in AUTO after stop (green flagged) allows PLCS to control, manual pump start (red flag) blocks PLCS level deviation signals
• Pumps controlled from level deviation program (bistables).
• “Always Running” – PLCS has no control
• “Normally Running”
  
  • +15% ↑ stops normally running pump (level is too high)
  • +14% ↓ starts normally running pump (level returning to program)
• “Standby”
  
  • -23% ↓ starts standby pump (level is too low)
  • -14% ↑ stops standby pump (level returning to program)

Question 6

Pressures:

1837 to 2750…?

Answer 6

Pressures:

2750 psia – RCS Safety Limit

2500 psia – RCS design pressure

2475 psia – PZR safeties open

2409 psia – SPS HP trip (ATWS)

2383 psia – HP reactor trip (PPS)

2300 psia – Spray full open

2295 psia – DNB (LCO)

2285 psia – HP alarm / heaters trip

2275 psia – Spray starts to open

2250 psia – NOP

2225 psia – P1/P2 full ON

2200 psia – BU Htrs ON

2160 psia – LP alarm

2130 psia – DNB (LCO)

1837 psia – Rx trip / SIAS / CIAS (PPS)

Question 7

Power Supply Summary:

NNN-D11:

• ?

NNN-D12:

• ?

NKN-D42:

• ?

Answer 7

Power Supply Summary:

NNN-D11:

• Level controls (LIC and Letdown LCVs)
• ‘Y’ PT and LT

NNN-D12:

• Pressure controls (MPC and Spray Valve Controller)
• ‘X’ PT and LT

NKN-D42:

• Powers all bistables (level deviations, pressure B/Ss, 25% cutout)
• Charging pump PLCS controls

Question 8

Pressure Transmitters (PT-100X, PT-100Y):

• ?
• Power Supplies:
  
  • ?
• ?

Answer 8

Pressure Transmitters (PT-100X, PT-100Y):

• Two non-class PTs (narrow range: 1500-2500 psia). Inputs to:
  
  • PPCS
  • SBCS to bias the modulation and permissive setpoints and inputs to Quick Open and LLR signal.
  • PMS (COLSS)
• Power Supplies:
  
  • NNN-D11 supplies PT-100Y
  • NNN-D12 supplies PT-100X
• Pressure Control Channel selector switch (selects one PT for input to PPCS)
• Deviation alarm at 50 psid between the PTs
• Low Pressure Alarm ≤ 2160 psia (Reset at 2200 psia) (either PT)

Question 9

High Pressure Heater Cutout / Alarm (Bistables):

• ?

Backup Heater Control Bistables:

• ?

Answer 9

High Pressure Heater Cutout / Alarm (Bistables)

• ≥ 2285 psia (Reset at 2275 psia):
• De-energizes all PZR heaters (selected PT only)
• High Pressure Alarm (either PT)

Backup Heater Control Bistables:

• ≤ 2200 psia (Resets at 2225 psia)
• ON-OFF control for backup heaters (Selected PT only)

Question 10

PLCS Input to PPCS:

• +3% level deviation? (resets at +?%):
  
  • ?
• ≤ 25% Low Level Heater Cutout? (resets at ?%)
  
  • ?

Answer 10

PLCS Input to PPCS:

• +3% level deviation (resets at +2.5%):
  
  • Energizes all backup heaters (if < 2285 psia, level > 25%, and HS is not in OFF or PTL)
  • Heaters energized in anticipation of a large insurge of cooler water to maintain saturated conditions in the PZR
  • Reduces the duration of degraded pressure control due to unsaturated conditions.
• ≤ 25% Low Level Heater Cutout (resets at 27%)
  
  • Trips all heater breakers
  • Circuit powered from NKN-D42.
    
    • Loss of power would prevent remote heater operation. Could operate locally. (LCO 3.0.3 until control regained)
  • PZR LT(s) selected by the PZR HTR Control Level Trip Selector Switch. Normally BOTH are selected.

Question 11

Pressurizer Heaters:

Bank

Power

Control Power

Capacity

P1:?

P2:?

B1: ?

B2: ?

B3 / B4: ?

B5 / B6: ?

Answer 11

Pressurizer Heaters:

Bank

Power

Control Power

Capacity

P1:

NGN-L11

NKN-D41

150 kW

P2:

NGN-L12

NKN-D42

150 kW

B1:

PGA-L33

PKA-D21

150 kW

B2:

PGB-L32

PKB-D22

150 kW

B3 / B4:

NGN-L11

NKN-D41

300 kW

B5 / B6:

NGN-L12

NKN-D42

300 kW

Question 12

Pressurizer Heaters:

?

Backup Heater Controls:

• ?

Answer 12

Pressurizer Heaters:

36 individual heaters (50 KW each / 1800 KW total) – 8 banks

Backup Heater Controls

• Each backup heater bank has a 3-position switch (OFF, AUTO-ON, PTL)
  
  • Maintained in AUTO
• B1 / B2 have an OFF-NORMAL-ON switch on RSP.
• B2 has a LOCAL - REMOTE isolation switch (App R)
  
  • LOCAL control at RSP: interlocks and auto features are bypassed.

Question 13

Backup Heater Setpoint Override:

• ?

Answer 13

Backup Heater Setpoint Override:

• Allows BU heaters to be energized when > 2225 psia (as long as 2200 psia was reached).
• Take HS to OFF then to ON.
  
  • White OVERRIDE light illuminates.
  • After a 10 second time delay, the override can be canceled by taking the HS to OFF.
  • 10 seconds must then elapse before the override can be re-initiated.

Question 14

Backup Heater SIAS Override (B1/B2 ONLY)

• ?

Answer 14

Backup Heater SIAS Override (B1/B2 ONLY):

• B1 / B2 trip on SIAS.
• SIAS Override allows these heater banks to be reenergized with a SIAS present.
• Initiated by placing HS in OFF, then ON.
  
  • Separate white OVERRIDE light illuminates.
  • Heater banks can be cycled as desired.
  • Override remains in effect until SIAS signal is reset.

Question 15

Pressurizer Pressure Controller (PIC-100)

• ?
• Red needle – ?
• Black and white needle - ?
• Thumbwheel allows adjustment ?
• Reverse acting?: Raise output to __?\_ pressure
• Power supply: ?

Answer 15

Pressurizer Pressure Controller (PIC-100):

• Controls proportional heaters and spray valves.
• 1500-2500 psia
• Red needle – selected PZR press indication
• Black and white needle - controller setpoint (thumbwheel)
• Thumbwheel allows adjustment of controller setpoint.
• Controlling action only occurs from 0-50%. (Meter range is 0-100%)
  
  • 16.5% - zero error
  • Pressure error > +50 psi results in controller output increasing from 50% to 100% with no further action.
  • Output normally 16.5% (Heaters makeup for ambient heat loss / spray bypass flow)
• Reverse acting: Raise output to lower pressure
• AUTO control can be used to maintain 1500 - 2285 psia.

Power supply: NNN-D12

Question 16

MPC (0-50% output is the control range):

• ?

Answer 16

MPC (0-50% output is the control range):

• Raise output to lower pressure
• 50% - spray full open
• 33.5% - spray starts / HTRs off / 25 psia above setpoint
• 16.5% - zero error / HTRs 50% on (normal output)
• 0% - HTRs full on / 25 psia below setpoint

Question 17

Spray Valve Controller (0-100%):

• ?

Answer 17

Spray Valve Controller (0-100%):

• Controlled by output of PZR pressure controller in AUTO.
• Can be operated manually.
• Spray valves selected by the Spray Valve Selector Switch (100E, Both, 100F) – normally BOTH selected
• Power supply: NNN-D12

Question 18

PZR Spray Valves (RC-PV-100E / 100F):

• ​?

Answer 18

PZR Spray Valves (RC-PV-100E / 100F):

• Fail closed AOVs (powered from NNN-D12)
• Combined spray flow capacity 375 gpm.
• Design leakage across lower disc (just a slot): ~ .3 gpm
• Manual bypass valves.
  
  • Throttled to provide bypass spray flow
  • 1.5 gpm
  • Minimizes thermal shock to the spray nozzle
  • Ensures boron mixing between RCS and PZR

Question 19

Proportional Heater Power Control Units (PPCUs):

• ?

Proportional Heater Controls (HS-100-1, -2):

• ?

Answer 19

Proportional Heater Power Control Units (PPCUs):

• Silicon Controlled Rectifier (SCR) control (0 to 480 VAC), balanced 3 phase voltage to one bank of heaters.
• Controlled by output of PZR pressure controller

Proportional Heater Controls (HS-100-1, -2):

• Each bank has an OFF-NORMAL-ON hand switch (spring return to normal)
• ON – heater breaker closes
• Heater bank power is then controlled by the PPCU from MPC output.

Question 20

PZR Level Transmitter (LT) Failures (Level Controller in “REMOTE/AUTO”):

Selected PZR LT fails low:

• ?

Non-selected PZR LT fails low:

• >

Selected PZR LT fails high:

• ?

Non-selected PZR LT fails high: Alarms only.

Answer 20

PZR Level Transmitter (LT) Failures (Level Controller in “REMOTE/AUTO”):

Selected PZR LT fails low:

• Letdown flow ↓ to minimum
• “Standby” charging pump starts.
• Heaters trip if selected to “Both” or failed level channel.
• Actual L_PZR ↑ until the unaffected LT is selected.
• Select unaffected LT for heater cutout and level control.

Non-selected PZR LT fails low:

• Heaters will trip on low level (if selected on the heater cutout selector or it’s in BOTH).
• Select unaffected LT on the heater cutout selector switch.

Selected PZR LT fails high:

• Letdown flow ↑ to maximum
• “Normally running” charging pump stops.
• Possible isolation of letdown due to the auto closure of UV-515 (hi-hi RHX outlet temp due to one charging pump running with max letdown flow). (restart pump to prevent loss of letdown)
• Backup heaters energize if < 2285 psia due to high level deviation.
• Actual L_PZR ↓ until the unaffected LT is selected.
• Select unaffected LT.

Non-selected PZR LT fails high: Alarms only.

Question 21

Temperature Transmitter (TT) Failures** **(Level Controller in “REMOTE/AUTO”):

Tcold/Thot fails high (100%):

• ?

Tcold/Thot fails high (15%):

• ?

Tcold/Thot fails low (100%):

• ?

Tcold/Thot fails low (15%):

• ?

Answer 21

Temperature Transmitter (TT) Failures** **(Level Controller in “REMOTE/AUTO”):

Tcold/Thot fails high (100%):

• High Tave signal sent to PLCS resulting in maximum level setpoint. (no effect, select unaffected Tave)

Tcold/Thot fails high (15%):

• High Tave signal sent to PLCS resulting in maximum level setpoint.
• Letdown flow to minimum.
• Take local control of PLCS and shift Tave to unaffected parameter.

Tcold/Thot fails low (100%):

• Low Tave results in minimum level setpoint.
  
  • T_cold failing low (RRS in Average) will result in level setpoint of ~38%
• Letdown flow to maximum.
• Normally running charging pump stops (+15% deviation) (not for Tcold failure, only ~14% deviation)
• Possible isolation of letdown (auto closure of CHB-515 on Hi-Hi RHX outlet temp – max letdown / low charging flow)
• Energizes backup heaters if < 2285 psia (+3% deviation)
• Take local control of PLCS and shift Tave to unaffected parameter.

Tcold/Thot fails low (15%):

• Low Tave signal sent to PLCS resulting in minimum level setpoint. (no effect, select unaffected Tave)

Question 22

PZR Pressure Transmitter (PT) Failures:

Selected PT fails low:

• ?

Non-selected PT fails high:

• ?

Selected PT fails high:

• ?

Non-selected PT fails low:

• ?

Answer 22

PZR Pressure Transmitter (PT) Failures:

Selected PT fails low:

• MPC goes to Minimum output.
  
  • Proportional heaters to full output.
  • Spray valves close.
• All Backup heaters turn on (< 2200 psia).
• Actual P_PZR rises until reactor trip OR operator action
• Select the unaffected PT

Non-selected PT fails high:

• PZR trouble and Pressure Hi-Lo annunciators.
• Turbine Bypass Demand annunciator.
• SBCS affected:
  
  • PT-100X - Modulation signal biased downward / controller demand generated.
  • PT-100Y - Permissive signal biased downward / permissive light lit.
• PZR Pressure control is not affected (alarms only)

Selected PT fails high:

• PZR trouble and Pressure Hi-Lo annunciators.
• Turbine Bypass Demand annunciator (due to SBCS impact)
• SBCS affected:
  
  • PT-100X - Modulation signal biased downward / controller demand generated.
  • PT-100Y - Permissive signal biased downward / permissive light lit
• MPC maximum output.
  
  • Proportional heaters to minimum output.
  • Pressurizer spray valve controller goes to maximum output. Spray valves go full open.
• All heaters turn off (> 2285 psia)
• Actual P_PZR lowers until reactor trip OR action is taken
• Select the unaffected PT

Non-selected PT fails low:

• PZR trouble and Pressure Hi-Lo annunciators only

Question 23

Loss of NNN-D11 (120Vac):

• ?

Answer 23

Loss of NNN-D11 (120Vac):

• PT-100Y fails LOW (MPC responds, if selected)
• LT-110Y fails LOW
  
  • Heaters deenergize if selected to Channel “Y” or “both” (25% level cutout).
• Normally running and standby Charging Pumps will stop (Manual control available)
• Select Channel “X” to restore pressure control.
• Both Letdown Control Valves fail closed. (Letdown isolates)
• PZR Level Master Controller loses power / fails to zero output.
• Select Channel ‘X’ to restore PZR heater control.

Question 24

Loss of NNN-D12 (120Vac):

• ?

Answer 24

Loss of NNN-D12 (120Vac):

• MPC fails to zero output.
• Spray valves fail closed (no power to spray controller)
• LT-110X fails LOW
  
  • Heaters deenergize if selected to Channel “X” or “both” (25% level cutout)
  • LIC output 0% if selected
• Select channel “Y” to restore heater control.
• Both Backpressure Control Valves fail closed (loss of power to controller).
• TIC-223 fails LOW - closing TCV-223 (letdown HX TCV).
• Loss of power to TS-224-2: CHB-UV-523 (RHX Outlet Isol Valve) closes.
• Select Channel “Y” to restore PZR level control (Letdown is isolated, only restores control of charging pumps).

Question 25

Loss of NKN-M45 (125 Vdc):

• Same as loss of NKN-D41 and NKN-D42 combined (see below).

Loss of NKN-D41 (125Vdc):

• ?

Loss of NKN-D42 (125Vdc):

• ?

Answer 25

Loss of NKN-M45 (125 Vdc):

• Same as loss of NKN-D41 and NKN-D42 combined (see below).

Loss of NKN-D41 (125Vdc):

• P1 / B3 / B4 Heater Banks lose control power

Loss of NKN-D42 (125Vdc):

• PZR Level control bistables lose power
  
  • PZR level cutout to all heaters (local operation only)
  • LCO 3.0.3 entry is required for class back-up heaters
  • LCO 3.0.3 can be exited once local control established (RSP or at the breakers)
  • All Charging Pumps trip (Manual control is available)
  • PLCS auto circuit lost power
• P2 / B5 / B6 Heater Banks lose control power
• PZR Spray VPI is lost.
• Letdown isolates (loss of power to 63X relay causes 523 to close)
• Loss of VPI (Letdown Control and Backpressure Control Valves)

Question 26

Loss of PKA-M41 (PKA-D21):

• ?

Loss of PKB-M42 (PKB-D22):

• ?

Loss of PNA-D25 (PNB-D26):

• ?

Answer 26

Loss of PKA-M41 (PKA-D21):

• Spray valves failed closed. (Instrument Air CIV fails closed)
• One Aux Spray Valve fails closed (RCA-205)
• B1 loses control power
• Letdown isolates (Loss of power to CHA-UV-516)

Loss of PKB-M42 (PKB-D22):

• B2 (backup heater B2) loses control power
• One Aux Spray Valve fails closed (RCB-203)
• Letdown isolates (Loss of power to CHB-UV-515 and 523)

Loss of PNA-D25 (PNB-D26):

• PZR LT-110X (LT-110Y) loses power / fails low.
• PZR heater breakers open if selected to affected channel or both (25% cutout)
• Letdown to minimum if selected to affected channel
• Standby charging pump starts if selected to affected channel (-23% bistable)
• Select unaffected channel to restore level and heater control

Question 27

LCO 3.4.9 - PZR Operable with

Answer 27

LCO 3.4.9 - PZR Operable with

Question 28

TLCO 3.4.100 - Aux Spray Including its basis…

Answer 28

TLCO 3.4.100 - Aux Spray Including its basis…

Question 29

TLCO 3.4.102 - PZR HURs/CDRs:

• Max HUR of 200 *F / hour
• Max CDR of 200 *F / hour

Answer 29

TLCO 3.4.102 - PZR HURs/CDRs:

• Max HUR of 200 *F / hour
• Max CDR of 200 *F / hour