RPCB: Reactor Power Cutback Flashcards Preview

LOIT Systems 2018 > RPCB: Reactor Power Cutback > Flashcards

Flashcards in RPCB: Reactor Power Cutback Deck (36):
1

If the TEST/RESET button is depressed (backlit) and a RPCB occurs, what will happen?

Nothing. TEST/RESET inhibits all RPCB functionality.

2

What is a Large Load Reject?

A signal sent to RPCB sent from SBCS. SBCS compares steam flow and TLI to PZR Pressure (specifically if TLI goes down with Ppzr going up). Need both channels to sense a load change to get a LLR.

3

What happens if a selected subgroup is on the Hold Bus on a RPCB?

That subgroup will not fall into the core. CPCs will then trip the reactor for CEAs being out of sequence because it expected those CEAs to drop.

4

What happens to the CEAs after the RPCB signal clears?

Rods are then able to be controlled by the RRS and/or manual operator control.

5

What would happen if a Large Load Reject were initiated on a LOFP RPCB?

The Quick Open Block for SBCS would not work.

6

When would a Turbine Setback signal clear?

When the Load Limit Potentiometer is dialed below 60% (Load Limit light comes on)

7

What does the AUTO ACTUATE OOS button do in the RPCB System?

Defeats automatic only RPCB operation.

8

When a Cutback is generated for a lost Main Feed Pump, what signal is sent to SBCS? Why?

Quick Open Block

QO is for a Main Turbine Trip. A MFP is lost, not the turbine. We'd couple a significant reduction in feed with a large increase in steam demand.

9

How do you perform a manual RPCB?

Push the DROP SUBGRP button concurrently with the LOFP button or the LLR button on B05.

10

What two events will result in a RPCB?

- Loss of a Main Feed Pump
- Large Load Reject (LLR)

11

What happens if RRS Tave fails low on a Main Feed Pump trip?

CEAs drop due to RPCB and you'd get a continuous Main Turbine Runback

12

What needs to work correctly to keep from tripping the Reactor on a Turbine Trip?

RPCB
SBCS
Fast Bus Transfer

13

How long is a RPCB signal present?

10 Seconds

14

How do you reset a RPCB?

Press the AUTO ACTUATE OOS and TEST/RESET buttons. Then dial the Load Limit Potentiometer counter clockwise until the Load Limit light illuminates.

15

What signals are sent to the EHC System on a RPCB?

Setback
Runback
Increase Inhibit

16

What is the purpose in the ARM signal sent to CEDMCS on a Cutback?

Prevents CEA re-latch before hitting the bottom of the core.

17

Which signal sent to CEDMCS actually opens the circuit to the CEA coils?

DROP

18

To de-select the CEAs for RPCB and leave RPCB in service, what buttons need to be pressed?

AUTO ACTUATE OOS and TEST/RESET both, twice.

19

What specific parameter on a Main Feed Pump will initiate a RPCB when you lose it?

Main Feed Pump oil pressure <75 psig from both of 2 pressure switches (2/2 logic)

20

What happens on a Turbine Setback?

MT Control Valves go to 60% at 480%/minute

21

When is a Main Turbine Runback signal get generated?

When both ARM and DROP signals are present concurrent with:
- TLI > 60% OR
- sum of PT-1024 and Tave are low.

22

What happens to the RPCB System if NNN-D11 is lost?

RPCB is totally disabled (no CEAs or turbine actions)

23

To initiate a RPCB on a loss of a Main Feed Pump, what additional parameter must be met?

Reactor Power > 74%

24

What happens to the RPCB System if NNN-D12 is lost?

Turbine Runback is disabled.
- On a cutback, the Main Turbine will only setback to 60% which will result in a Reactor Trip due to Secondary Power > Primary Power

25

Where does the signal for a Main Turbine Runback get generated?

From SBCS

26

What (if anything) happens to Turbine Runback capability when SBCS is placed in TEST or disconnected?

Main Turbine Runback is blocked

27

What happens if PT-1024 fails low on a Main Feed Pump trip?

CEAs drop due to RPCB and you'd get a continuous Main Turbine Runback

28

What is a RPCB Flag?

Its a signal generated by the CPCs that says its ok if a flagged CEA drops into the core because its associated with a RPCB.

29

What is Turbine Increase Inhibit and when does it occur?

- Prevents the INCREASE LOAD button from raising Main Turbine Load until the RPCB is manually reset.
- Occurs on any RPCB

30

How fast a Main Turbine Setback?

Moves the Main Turbine at 480%/min to 60%

31

If the Main Turbine is in Standby, what features of the RPCB system pertaining to the Main Turbine don't work?

Setback
Runback
Increase Inhibit

32

When does a Turbine Setback occur?

When both ARM and DROP (1 and 2) signals exist.

33

What two signals are sent to CEDMCS to drop rods for a Cutback? How long?

ARM and DROP

10 seconds

34

What criteria must be met to get a RPCB for a Loss of a Main Feed Pump?

Two switches on one Main Feed Pump must read < 75psig control oil pressure

35

How fast is a Main Turbine Runback?

Lowers load reference 130%/min due to Load Set Motor limitations.

36

What does the TEST/RESET button do in the RPCB System?

It removes ALL auto and manual RPCB capability from service. Also deselects any selected CEAs.