What is IOPS powered by?
- CRIDS I, II, III ***
What does IOPS do?
- Backup to DCS overspeed trip via 3 passive magnetic pickup probes (2/3)
- 110% Overspeed Trip ** (Hardwire trip)
- Its energize to trip (2/3) ***
What is the DCS power supply?
- BOP Battery (250 VDC) thru inverter **
- BLC/CLC backup to inverters **
What is the DCS purpose?
- Supply hydraulic fluid for stop/control valve operation during normal and emergency conditions. ***
What does hood spray protect?
- Prevents LPT blade overheating ***
What parameters will a 10% manual runback give you?
- 114.9 MW (121.7)** < actual load
- Lower Target Load by 100 MW/min
- Forced to MW In
When is a loss of a MFP runback enabled?
- > 60%
What are the parameters that a loss of a MFP runback give you?
Main Turbine > 60% Load
- Goes to 625 (725) MW
- U1 goes @ 600 MW/min
- U2 goes @ 1000MW/min when > 90% Pwr and 140MW/ min at < 90%
- Forced to MW In
What parameters will a 20% manual runback give you?
- 229.8 MW (243.4) < actual load
- Lower Target Load by 100 MW/min
- Forced to MW In
What parameters will a OPΔT and OTΔT (Rx) Runback give you?
- Target Load to 30 MW *** @ 124 (144) MW/min
- Speed x10 for the first sec to equal the 124/144 MW/min) (1 sec, then waits 9.5 sec until 1st stage # is < 40%)
- Forced to MW In
When is power load unbalance armed?
- Armed when 1st Stage Press > 40% (from DCS) ***
When is power load unbalance actuated?
- Actuated if difference between turbine and generator current is > 40% AND rate of change in current is > 13k amps /sec.
What does a power load unbalance signal do when it acutates?
- Load Ref to 30 MW @ 1389 Mw/min. (MW-Out)
- Fast close solenoids for control and intercept valves actuate
- Forced to MW Out
What does the Droop Speed override signal do?
- Protects Turbine from overspeed condition with output breaker closed
- Biases Load Ref signal which closes down on control valves and Intermediate Valves
When is the Droop Speed override signal active?
- > 1805 rpm
What is the primary tripping device of the Main Turbine?
- Trip Block Assembly
How do the trip block assemblies work?
- De-energize to trip on 2/3 solenoids which drain back to EHC tank***
- One Trip block trip will close all 20 valves
What are the trip block assemblies powered by?
- CRID I, II, III
What is the one turbine trip input from TSI?
- Thrust Bearing Wear ***
Will a failure of all 3 PLC speed sensors on the Turbine give you a turbine trip while on the grid?
- No, it will not ***
What does an ATWS runback do?
- Target Load to 1 MW at 1389 MW/min.
- Forced to MW In
- Signal clears when MT impulse pressure is < 40%
What is the purpose of Power Load Unbalance?
- Provides overspeed protection in the event of a large load rejection
- Used only on ATWS when the MT also fails to trip with manual AMSAC or Solenoid Trip
When you are starting up the Turbine when do the Reheat Valves open?
- The Reheat Valves open when the Turbine is “Reset”
What do the combined stop and intercept valves do for the turbine?
- protect against overspeed of the turbine from residual steam from the MSRs on a turbine trip ***
