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Recirc Flow Control
ILT '09
24
Other
Not Applicable
12/20/2007

Additional Other Flashcards

 


 

Cards

Term
Explain the purpose and function of Recirc Flow Control.
Definition

To control reactor power over a limited range by varying the core flow rate.

Term
Predict the impact/consequences on recirc flow control for PLC failure
Definition
Loss of power and other failures result in actuator remaining in position.
Term
Function of Drive motor
Definition

Constant speed (1190 rpm) motor provides motive force for turning the Recirc Pump Generator through the Fluid Coupler.

Term
Function of Variable Speed Generator
Definition
Provides electrical power at variable frequency and voltage to operate the Recirc pumps.
Term
Function of Fluid Drive
Definition
Provides method for varying Generator rotor speed.
Term
Function of Speed Control System
Definition
Converts electrical input into mechanical movement of Limitorque actuator to position the scoop tube.
Term
Function of Tachometer
Definition
Attached to Generator shaft to provide generator speed signal.
Term
Function of Voltage Regulator
Definition
Controls exciter output to produce 70V/Hz main generator voltage.
Term
List the prerequisites to close the drive motor breaker
Definition
  1. Generator field breaker open;
  2. Lube oil pressure greater than or equal to 20 psig;
  3. No generator lockouts;
  4. No drive motor breaker trips actuated;
  5. Recirc pump suction valve open;
  6. Recirc discharge valve closed;
  7. Drive motor breaker is racked in;
  8. Control switch is taken to START.
Term
Tech Spec 3.4.1 LCO/Applicability and Basis
Definition

Section 3.4: RCS

Tech Spec 3.4.1: Recirculation Loops Operating

 

LCO 3.4.1: Two recirc loops with matched flows shall be in operation within the Normal Region of the power to flow map specified in the COLR;

 

OR

 

One recirc loop shall be in operation within the Normal Region of the power to flow map specified in the COLR and with the following limits applied when the associated LCO is applicable:

  • LCO 3.2.1 ""APLHGR"", single loop operation limits specified in the COLR
  • LCO 3.2.2, ""MCPR"", single loop operation limits specified in the COLR and
  • LCO 3.3.1.1 ""RPS"" Function 2.a (APRM Flow Referenced Neutron Flux - High High),

Allowable Value of Table 3.3.1.1-1 is reset for single loop operation.

 

NOTE: Operation within the Stability Buffer Region of the power to flow map specified in the COLR is allowed provided the power distribution controls specified in the COLR are in effect.

 

APPLICABILITY: Modes 1 and 2.

 

BASIS: During a LOCA caused by a recirc loop pipe break, the intact loop is assumed to provide coolant flow during the first few seconds of the accident. The broken loop flow ceases almost immediately. The pump in the intact loop coasts down relatively slowly.

Term
Tech Spec 3.4.2 LCO/Applicability and Basis
Definition

Section 3.4: RCS

 Tech Spec 3.4.2: Jet Pumps

 

LCO 3.4.2: All jet pumps shall be OPERABLE;

 

APPLICABILITY: Modes 1 and 2.

 

BASIS: An inoperable jet pump increases the blowdown area during a LOCA and compromises the ability for core re-flood.

Term
What is the frequency range on the Recirc MG sets? What is the rpm range on the generator?
Definition

Frequency: 11.5 - 57.5 Hz

 

230 - 1150 rpm

Term
How is Recirc MG set speed indication signal affected by a PLC failure?
Definition

It is NOT affected because it is not processed by the PLC.

Term
"During pump startup, with the field breaker open, in what position does the Flow Control system place the scoop tube?"
Definition
The mid position.
Term
"After the field circuit breaker is closed, what position does the flow control system place the scoop tube at?"
Definition
The equivalent of 30% speed.
Term
State the timing sequence for a Recirc Pump start (in seconds from start switch --> START)
Definition

t=0: hand switch to START, Generator speed peaks between 80 and 100% speed (because field breaker is OPEN);

 

t=6 sec: Field circuit breaker closes (excitation provided from Y-20); Generator speed lowers to about 40% and then lowers to minimum speed.

 

t=10 sec: switch excitation from Y-20 to self;

 

t=15 Generator Lock-out relay analyzes for incomplete start sequence (is field breaker shut? is field flashed? is differential pressure >7.5 psid?);

 

t=66 sec: Discharge valve must be greater than 20-25% open."

Term
What are the pre-requisites for Recirc Pump start?
Definition
  1. Generator field breaker open;
  2. Lube oil pressure greater than or equal to 20 psig;
  3. No generator lockouts;
  4. No drive motor breaker trips actuated;
  5. Recirc pump suction valve open;
  6. Recirc discharge valve closed;
  7. Drive motor breaker is racked in;
  8. Control switch is taken to START.
Term
What is the rate of change of speed limited to for changing Recirc pump speed?
Definition
The Programmable Logic Controller limits rates of change to 2.5% per second when lowering speed, and 2.0% per second when raising speed.
Term
List the conditions which cause an automatic scoop tube lock.
Definition

PER THE ARP (4-C-05):

  • Drive Motor Breaker Under-Volts (also a Drive motor bkr trip)
  • Low Lube Oil Pressure (27psig for 6 sec... also a Drive motor bkr trip)
  • High Lube Oil Temperature (210 degrees F... also a Drive motor bkr trip)
  • Speed Control signal failure
  • Loss of power to actuator (Y-20... or momentary loss of power to Y-20 during transfer from Normal (MCC-143) to Alternate (MCC-133))
  • Actuator HI or LO Electrical limit switches

According to the B-manual:

  • If Recirc Flow Control senses a change in MG set actuator position which was not called for by the Control Room operator;
  • speed rate-of-change exceeded;
  • adjustable speed drive trouble;
  • communication fault;
  • PLC trouble.
Term
State the Recirc Pump Motor Volts/Hz alarm set point.
Definition
73.5 Volts/Hz for more than one minute
Term
State the Recirc Pump automatic runback events and the approximate speed runback to.
Definition

An automatic runback of both Recirc Pumps will result in a decrease of speed at the allowed max rate down to approximately 50% speed in the event of a Feed pump trip or a Condensate Pump trip.

 

NOTE: Runback will not occur in Single Loop Ops

Term
When is Recirc Pump Automatic runback available? When does it become unavailable? What is the basis for these values?
Definition

The runback becomes available when STEAM FLOW reaches 55.4% on the way up. The runback becomes unavailable at 50.7% STEAM FLOW on the way down.

 

These values were chosen to accommodate single condensate pump capability, which is less than single feed pump capability.

Term
How can the operator terminate a Recirc pump runback?
Definition
Take the pump speed control switch momentarily to RAISE.
Term
List the Recirc Control System equipment powered by Y-20. What is powered by panel L-11?
Definition

Actuator Position Indicators, Programmable Logic Controllers, Speed Transmitters, Relay Output Module, Generator Voltage Transmitter.

 

L-11 powers the adjustable speed drive.

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