Reactor Regulating System (RRS)

Question 1

What is the power supply for the Reactor Regulating System?

Answer 1

NNN-D12 supplies power to RRS
NNN-D11 powers input sensors

Question 2

What is the design basis for RRS?

Answer 2

The system is designed,** in conjunction with** SBCS and RPCS, to control, without significant transient overshoots, reactor power and turbine steam bypass to counter or make adjustment for the following:
* Load rejection of any magnitude.
* Up to 10% step change in NSSS load.
* Up to 5% per minute ramp change in NSSS load.

Question 3

How is Tref calculated? Over what ranges?

Answer 3

Main Turbine (MT) – Turbine Load Index (TLI)
* 1st stage pressure (TFSP) converted to Tref (linear correlation to turbine load)
o MTN-PT-11A and 11B
o 0 - 125% turbine load
* Tref is linear (564 - 587°F)
o TLI output to Tref is capped at 564°F (no load) to 587°F (100% power)

Question 4

How is the CEA Motion Demand Compensate Temp Error calculated? What values drive the different withdrawl/insertion rates?

Answer 4

Total Error
* Generated by summing Power Error and Temperature Error.

Temperature Error
* Tavg compared to Tref to develop a temperature error (Et).
o Temperature Error (Et) = TAVG - TREF.

• Low Rate (3”/min):
  o +3°F: CEA insertion demand
  o** -3°F**: CEA withdrawal demand
  o Resets at ±2.84°F.
• Large error ± 4.53°F: high rate signal is generated.
  o CEAs insert at high rate (30”/min)
  o CEAs will NOT Auto withdraw at the high rate.

Question 5

What causes an Automatic Withdrawl Prohibit (AWP) in RRS?

Answer 5

AWP (Automatic Withdrawal Prohibit):
* Prevent CEA auto withdrawal.
* TAVG - TREF is > 6°F (insertion should be demanded)
* Either Tc is > 575°F (RCS temp too high)

*Actual SBCS demand also causes AWP. *

Question 6

What will generate an Automatic Motion Inhibit (AMI) in RRS?

Answer 6

AMI (Automatic Motion Inhibit):
* Prevent automatic CEA movement (In or Out).
* RRS input deviations while selected to “AVERAGE”.
o Tavg ± 5 °F.
o Reactor Power ± 5%.
o TLI ± 5% load.

SBCS also causes AMI (reset by RRS withdrawal demand)

Question 7

Which Excore detectors provide input to the Reactor Regulating System (RRS)?

Answer 7

**Control Channels **(powered NNN-D11/D12)

Each Reactor power input is continuously compared to the other channel and an AMI is generated at a 5% difference between channel inputs if the Reactor Power input is selected to average.

Question 8

What is Power Error in regards to the Reactor Regulating System (RRS)?

Answer 8

Power Error
* Power Error = PRX - TLI.
* Dynamically compensated by a rate of change network.
o Output is proportional to power error rate of change.
* When power is stable this signal will NOT contribute to the Total Error signal.

Question 9

What is the permissive to place RRS in “Test” ?

Answer 9

Test” Push-button
* Places RRS in test and allows test signals to be input into RRS.
* RRS test permissives:
o PLCS NOT in Remote/Auto.
o CEDMCS NOT in *Auto *Sequential.
* If CEDMCS placed in AS or PLCS placed in Remote/Auto, RRS will be automatically removed from test.

Question 10

What is the proper sequence when using the Meter Input Selector?

Answer 10

Meter Input Selector (20 push-buttons)
* 18 push-buttons used to select input for digital voltmeter.
* “Test Probe” push-button: used to read voltage on any one of the RRS program front terminals.
* When pressing any test push-button, the “Test Probe” position is first selected to ensure the output voltage is ZERO prior to selecting another channel.
o** Verify voltmeter reads zero** to ensure no signal is present due to a stuck push-button.
o **Prevent cross connecting signals **due to problems with the switch.

Question 11

know ALL failures:
power supplies, Th/Tc, TLI, Control Channels

Answer 11

Loss of NNN-D11/12
Th/Tc Hi/Low
TLI Hi/Low
Control Channels Hi/Lo

Selected to average, failed channel, or good channel

Question 12

What will cause an AMI (RRS&SBCS)?

Answer 12

AMI (Automatic Motion Inhibit):
* Prevent automatic CEA movement (In or Out).
* RRS input deviations while selected to “AVERAGE”.
o Tavg ± 5 °F.
o Reactor Power ± 5%.
o TLI ± 5% load.

SBCS also causes AMI (reset by RRS withdrawal demand)less than 15% power AND power is below the lesser of (TLI+SBCS availability OR AMI Threshold setpoint ~50%)

Question 13

What causes an AWP (RRS&SBCS)?

Answer 13

AWP (Automatic Withdrawal Prohibit):
* Prevent CEA auto withdrawal.
* TAVG - TREF is > 6°F (insertion should be demanded)
* Either Tc is > 575°F (RCS temp too high)

*Actual SBCS demand also causes AWP. *
Permissive and Modulate OR
Quick Open X1 and X2 OR
Quick Open Y1 and Y2 and
SBCS in service (not in Emergency Off or disconnected)