Reactor Regulating System

Question 1

What is the function of the Reactor Regulating System?

Answer 1

Compute a Tave signal – used for PPLCS (PZR level setpoint calculation) & SBCS
Compute a Tref signal - (representative of turbine power) used for control purposes when moving the unit
Provide input to auto CEA movement (Disabled)

Question 2

Describe the Design Basis of the Reactor Regulating System.

Answer 2

Automatically (automatic function removed) adjust Rx power and RCS temperature during the following:
* 10% step increase in steam flow between 15% & 90% power
* 10% step decrease in steam flow between 100% and 25% power
* 5% per minute ramp change in steam flow between 15% and 100% power

Question 3

Describe the inputs and outputs to the Reactor Regulating System.

Answer 3

Inputs
1. Cold Leg Temperature
2. Hot Leg Temperature
3. Turbine Inlet Pressure
4. Control Channel Nuclear Power

Outputs
1. Tavg
2. Tref
3. High Tavg-Tref alarm
4. High Tavg-Tref AWP
5. Low Tavg-Tref Alarm
6. Selected RRS Inoper Alarm
7. CEA auto motion low power prohibit alarm
8. CEA Status (Withdraw and Insert)
9. CEA Speed (HIgh or Low)
10. Pressurizer Level Setpoint

Question 4

What are the inputs to the Reactor Regulating System?

Answer 4

• Cold Leg Temp
• Hot leg Temp
• Turbine First Stage pressure
• Nuclear instruments Channels 9 & 10 -> Blue Pen
• Usually ‘A’ Loop instruments go to RRS-1, ‘B’ to RRS-2, (switches in test drawer can change inputs)

Question 5

Discuss Cold Leg Temperature Inputs to Reactor Regulating System.

Answer 5

Cold Leg Temperature
* {TE- 1111Y– A2, 1121Y – B2, 1115 – A1, 1125 – B1} [TE - 1111Y- A2, 1121Y - B2]
* 465 - 615°F
* Only 1 Tc RTD is used per channel of RRS (Example – 1111Y feeds RRS-1 & 1121Y feeds RRS-2)
* Tc Selector Switch – {HS-1111}. Unit 1 only. Selects which Tc signals feed RRS.

Question 6

Discuss Hot Leg Temperature Inputs to Reactor Regulating System.

Answer 6

Hot leg Temperature;
* TE -1111X, 1121X
* 515 – 665°F

Question 7

Discuss HP Turbine First Stage Pressure Inputs to Reactor Regulating System.

Answer 7

HP Turbine First Stage Pressure:
* PT-22-37A (RRS-1) & PT-22-37-B (RRS-2)
* PT-22-36 feeds RTGB and Ovation
* This is a linear signal that is fixed at hot zero power (532°F) and is variable at the 100% power value
* After each core reload and prior to startup, a new 100% Tref value is determined based on reload calculations. If required, I&C will adjust the program circuitry.

Question 8

Discuss Nuclear Power Inputs to Reactor Regulating System.

Answer 8

Nuclear Power (Control Channels)

• > 15%  - Would allow auto CEA movement
• <11%↓ - would prohibit auto CEA movement & cause “CEA Auto Motion Low Power Prohibit” alarm
• All auto CEA functions disabled however alarms still functional and can be used for event diagnosis

Question 9

Discuss Tave Outputs to Reactor Regulating System.

Answer 9

Tave:
* Provides input to PZR level setpoint (Lsp) calculator
* Provides input to Steam Bypass Control System (SBCS)
* Provides input to Tave / Tref comparator circuitry
* Recorder on RTGB 104 [204]

Question 10

Discuss the affect of Loss of Reactor Regulating System.

Answer 10

• Lose Tave input therefore Lpzr controlled manually (LIC)
• SBCS quick opening feature affected

Question 11

Discuss the affect of Loss of Power to Selected Channel of Reactor Regulating System.

Answer 11

• PZR level setpoint goes to 0%
• Letdown goes to maximum

Question 12

Discuss the affect of RRS-1 selected and 1111X (Th) fail high at 100%.

Answer 12

• Annunciator’s - Tave/Tref High & AWP
• Loop A Tave recorder to 582F (average of 615F and 548.5F)
• Lpzr doesn’t change
• Insert High Rate light on RRS-1

Question 13

Discuss the affect of RRS-1 selected and 1111X (Th) fail low at 100%.

Answer 13

• Annunciator’s- Tave/Tref Low
• Loop A Tave recorder to 532F (average of 515F and 548.5F)
• Lpzr setpoint goes to 33% (due to 532F Tave)–All htrs ON, Max Letdown, Level alarms
• Withdraw High Rate light on RRS-1

Question 14

Discuss the affect of RRS-1 selected and 1111Y (Tc) fail high at 100%.

Answer 14

• Annunciator’s - Tave/Tref High & AWP
• Loop A Tave recorder to 607F (average of 615F and 598F)
• Lpzr doesn’t change
• Insert High Rate light on RRS-1

Question 15

Discuss the affect of RRS-1 selected and 1111Y (Tc) fail low at 100%.

Answer 15

• Annunciator’s-Tave/Tref Low
• Loop A Tave recorder to 557F (average of 515F and 598F)
• Lpzr setpoint goes to 33% (due to 557F Tave)–All htrs ON, Max Letdown, Level alarms
• Withdraw High Rate light on RRS-1

Question 16

Discuss the affect of RRS-1 selected and 1121X (Th) or 1121Y (Tc) fail low at 100%.

Answer 16

• Loop B Tave recorder indicates low

Question 17

Discuss the affect of RRS-1 selected and Pturb fails low.

Answer 17

• Annunciator’s - Tave/Tref High & AWP signal
• Loop A Tref fails to 532F
• Insert High Rate light on RRS-1
• Tref indication on RTGB doesn’t change

Question 18

Discuss the affect of RRS-1 selected and NI fails low.

Answer 18

• Annunciator’s- CEA Auto Motion Low Power Prohibit
• Withdraw High Rate light on RRS-1

Question 19

What are the three functions provided by the RRS RPUC?

Answer 19

TAVG calculator
Pzr level setpoint (LSP) calculator
Tref calculator