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Advanced Systems > RPS > Flashcards

RPS Flashcards

1
Q

LCO 3.3.1 “RPS Instrumentation” requirement

A

4 RPS trip units, associated instrument channels, and associated ZPM Bypass removal channels for each trip function shall be operable

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2
Q

LCO 3.3.1 “RPS Instrumentation” applicability

A
  • High SUR - Modes 1-2. Trip may be bypasse when wide range power is < 1E-4%, or when thermal power > 13% RTP
  • Loss of Load - Mode 1 when thermal power is >= 17% RTP
  • All others are Modes 1-2, and Modes 3-5 with more than 1 full length control rod capable of being withdrawn and PCS boron concentration less than refueling boron concentration
  • TM/LP, Low PCS Flow, Low S/G A Pressure, and Low S/G B Pressure trips may be bypassed when wide range power < 1E-4% RTP, and automatically removed when wide range power is >= 1E-4% RTP
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3
Q

LCO 3.3.1 “RPS Instrumentation” required action if 1 or more ZPM Bypass Removal channels inoperable

A

IMMEDIATELY remove the affected ZPM Bypasses, or declare the affected trip units inoperable

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4
Q

LCO 3.3.1 “RPS Instrumentation” required action if 1 or more functions with 2 RPS trip units or associated instrument channels inoperable

A

WITHIN 1 HOUR place 1 unit in trip

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5
Q

LCO 3.3.2 “RPS Logic and Trip Initiation” requirement

A

6 channels of RPS Matrix Logic, 4 channels of RPS Trip Initiation Logic, and 2 channels of RPS Manual Trip shall be operable

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6
Q

LCO 3.3.2 “RPS Logic and Trip Initiation” applicability

A

Modes 1-2
Modes 3-5 with more than 1 full length control rod capable of being withdrawn and PCS boron concentration less than refueling boron concentration

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7
Q

LCO 3.3.2 “RPS Logic and Trip Initiation” required action if 1 channel of Trip Initiation Logic inoperable

A

WITHIN 1 HOUR de-energize the affected clutch power supplies

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8
Q

LCO 3.3.2 “RPS Logic and Trip Initiation” required action if 2 channels of Trip Initiation Logic affecting the same trip leg inoperable

A

IMMEDIATELY de-energize the affected clutch power supplies

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9
Q

What is the logic required for RPS trips and pre-trips (alarms)?

A
  • Trips - 2/4

- Pre-trips - 1/4

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10
Q

What is the purpose of the Variable High Power Trip (VHPT)?

A
  • Protects against positive reactivity excursions during power operations, and while shutdown.
  • Input comes from TMM Variable High Power output
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11
Q

What are the VHP pre-trip/trip setpoints?

A
  • Min - 28.5%/30%
  • Max - 105%/106.5%
  • Variable - 13.5%/15% above power level when reset button is pushed
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12
Q

What is the purpose of the High Power Rate Trip?

A

Protects against an uncontrolled rod withdrawal or boron dilution while the reactor is critical, but at low power levels
-Input comes from wide range NIs (Channel A/C from NI-3, channel B/D from NI-4)

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13
Q

When is the High Power Rate Trip bypassed?

A

Below 1E-4% and above 15% power

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14
Q

What are the High Power Rate pre-trip/trip setpoints?

A

1.5 DPM/2.6 DPM

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15
Q

What is the purpose of the Low PCS Flow Trip?

A

Protects against fuel damage on a loss of coolant flow (DNB).

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16
Q

What are the Low PCS Flow pre-trip/trip setpoints?

A

97%/96%

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17
Q

What is the purpose of the S/G Low Level (A/B) Trips?

A

Protects against the loss of heat removal capability from the PCS

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18
Q

What are the S/G Low Level (A/B) pre-trip/trip setpoints?

A

31%/28%

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19
Q

What is the purpose of the S/G Low Pressure (A/B) Trips?

A

Protects against excessively high steam flow caused by a steam line break

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20
Q

What are the S/G Low Pressure (A/B) pre-trip/trip setpoints?

A

570 psia/512 psia

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21
Q

What is the purpose of the PZR High Pressure Trip?

A

Prevents operation when the reactor is generating more power than the secondary system is accepting

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22
Q

What are the PZR High Pressure pre-trip/trip setpoints?

A

2185 psia/2235 psia

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23
Q

What is the purpose of the TM/LP Trip?

A

Prevents the violation of minimum DNBR

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24
Q

What are the TM/LP pre-trip/trip setpoints?

A

Variable from TMMs or 1810 psia (whichever is higher)/variable from TMMs or 1760 psia (whichever is higher)

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25
Q

What is the purpose of the Loss of Load Trip?

A

Limits the PCS stored energy and pressure caused by the suspension of normal steam removal (prevents lifting PZR/main steam safety valves)

26
Q

What is the Loss of Load Trip setpoint?

A

Auto Stop Oil Pressure < 45 psig

27
Q

When is the Loss of Load Trip bypassed?

A

Below 15% power

28
Q

What is the purpose of the Containment High Pressure Trip?

A

Provides an earlier action that would be available with only the TM/LP trip or S/G Pressure Trip. Added to the RPS to provide diversity of reactor trip for a LOCA

29
Q

What is the Containment High Pressure RPS Trip setpoint?

30
Q

What are the power supplies for the RPS channels?

A

Y-10/20/30/40 for Channel A/B/C/D respectively

31
Q

How do the manual trip push buttons work to trip the reactor?

A
  • C-02 de-energizes all 4 M coils, which de-energizes the power supplies to the CRDM clutches.
  • C-06 de-energizes an undervoltage relay, which opens the RPS breakers.
32
Q

What is the normal voltage on the M coil volt meters?

A

20 VAC. Any other indicated voltage means there is a problem.

33
Q

What is the purpose/function of M coil arc suppression?

A

When an M coil de-energizes, a voltage is induced into the M coil from its field collapsing, which could cause damage. Arc suppression is used to prevent this damage.

34
Q

What is the purpose/function of the K relays?

A

1 relay from each CRD clutch power supply. When a reactor trip occurs, CRD clutch power supplies de-energize, which de-energizes the K relays. When the K relays de-energize, the following occurs:

  • CRDM Rundown
  • Trip Reset
  • Reset Lockout
  • Turbine Trip
35
Q

What is the CRDM Rundown function associated with de-energizing the K relays?

A

Sends a ROD IN signal to all CRDs, except the part-length rods, so any rod with a stuck clutch will be driven into the core.

36
Q

What is the Trip Reset function associated with de-energizing the K relays?

A

Prevents RPS from resetting when trip condition clears, because when the K relay de-energizes, a contact associated with the K relay opens. Prevents ratcheting damage that could occur if the clutches were re-energized before the rods fully dropped.

37
Q

What is the Reset Lockout function associated with de-energizing the K relays?

A

Prevents manually resetting RPS for 30 seconds to prevent ratcheting damage that could occur if the clutches were re-energized before the rods fully dropped.

38
Q

How does a turbine trip occur when the K relays are de-energized?

A

20/AST relay (solenoid trip on balance beam)

39
Q

What are the 3 types of RPS Trip Bypasses?

A
  • Trip Channel Bypass
  • Automatic Bypass
  • Zero Power Mode Bypass
40
Q

What is the RPS Trip Channel Bypass used for?

A
  • When a trip channel must be removed
  • To prevent a reactor trip during maintenance
  • When trip unit instrument is inoperable
41
Q

How do we bypass an RPS Trip Channel?

A

Each trip unit (11 per channel, 4 channels, so 44 total) has a bypass key switch. There is only 1 key for each trip (11 keys total), and when the key is turned to bypass, it can’t be removed, so only 1 channel of each trip can be bypassed at a time.
To bypass, insert key, and turn 90 degrees clockwise. Verify yellow light illuminates, and log it.

42
Q

What happens when an RPS Trip Channel is bypassed?

A
  • Yellow light illuminates to indicate that the trip has been bypassed.
  • Trip logic goes to 2/3 instead of 2/4
43
Q

What RPS trips are automatically bypassed, and when are they bypassed?

A
  • Loss of Load - bypassed < 15% power
  • High Rate of Change (High SUR) - Bypassed below 1E-4% power by 1 of 2 source range/wide range NIs (NI 1/3 bypass A/C channels and NI 2/4 bypass B/D channels), and bypassed > 15% power by power range NI in that channel.
44
Q

What is the Zero Power Mode Bypass used for?

A

Used when the reactor is shut down to allow control rods to be moved for testing or to reserve shutdown margin for operating conditions.

45
Q

What trips are bypassed by the ZPM Bypass?

A
  • PCS Low Flow
  • S/G Low Pressure
  • TM/LP
46
Q

How do we place RPS into ZPM Bypass?

A
  • All 4 channels must be in bypass
  • Ensure Wide Range NIs operable
  • Ensure power < 1E-4
  • Verify boron concentration > cold shutdown concentration
  • Insert key and turn clockwise
  • Push each of the 4 test switches and ensure no lights lit
47
Q

What are the yellow lights associated with the ZPM Bypass?

A
  • 1 for each of the 4 trips that are bypassed (Low PCS Flow, S/G A Lo Pressure, S/G B Lo Pressure, and TM/LP)
  • 4 (1 for each trip that is bypassed) “ZPM Auto Disable” lights
  • Lights for the individual trips will only light when you push the test button, and that trip is not bypassed
  • “ZPM Auto Disable” will only light when you push the test button and power > 1E-4
48
Q

How do you place an RPS Trip Unit in “trip”?

A
  • Loosen 2 screws, and pull out at least 2 inches

- RPS now sees this trip as tripped, so logic is now 1/3 instead of 2/4

49
Q

How long can an RPS Trip Unit be bypassed?

A

Can be bypassed for 7 days, then it must be placed in “trip”

50
Q

What is the purpose of ATWS?

A

Provides a diverse means of tripping the reactor and main turbing, and actuating aux feed when a failure of the RPS system is sensed

51
Q

What causes ATWS actuation?

A

PZR pressure > 2375 psia (2/4 logic)

52
Q

What are the ATWS power supplies?

A
  • Pressure switches - Y-10/20/30/40
  • ATWS Matrix Relays - L-58/59 (from MCC-24/21, which come from LCC-12/11)
  • 2/4 logic matrix - Y-230, which is fed from D-204 (CFMS battery charger/inverter)
53
Q

What action is required if a PZR pressure sensor fails high?

A
  • ATWS shall be bypassed

- Operation with ATWS bypassed shall be minimized, and not to exceed 7 days

54
Q

What conditions require a manual reactor trip?

A
  • Safety of the core in jeopardy
  • RPS setpoint exceeded and no reactor trip
  • To protect equipment, personnel, and/or the public
  • Unusual circumstances
55
Q

Who authorizes resetting the RPS, and how is it done?

A
  • SM authorizes
  • Ensure no reactor trip signal is present
  • ATWS aligned
  • RPS breakers reset and closed
  • Push reset push button
56
Q

How do you verify RPS is reset?

A
  • Reactor trip alarm clear
  • 24 matrix relay lights energized
  • 4 arc suppression volt meters reading 20 VAC
  • Red “Trip” light not lit
  • “AC/DC on” lights lit
  • “AC Trouble” and “Ground” lights lit
57
Q

When shall the ATWS switch be in NORMAL?

A

Whenever the reactor is critical, unless required for testing.

58
Q

How should replacement of any RPS Trip Unit Red Matrix lamps be performed?

A

Per a planned work activity due to the potential for a shorted bulb to trip both auctioneered matrix ladder power supplies and cause a plant trip.

59
Q

What are the clutch DC power supplies?

60
Q

When is the RPS placed in service?

A

While in Mode 3 with all 4 PCPs running, prior to entry into Mode 2

Advanced Systems (36 decks)

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