Power Operations Flashcards
When does the CR need to notify Chemistry during a Power Change? Why?
> 15% of RTP/Hour (9ZZ05)
NOTE: 9ZZ05 requires informing Chemistry during ANY power increase or decrease
TS 3.4.17, SR 3.4.17.2 - Verify I-131 (Minimize offsite dose, SGTR accident)
What are the Required operator actions in response to Main Turbine Vibration?
Normal MT vibration is 5 Mils
Trip the Turbine IF:
1-Filtered vibration >10 mils, abrupt trend to 12 mils
2-Filtered >10 mils, slow to 12 mils after 15 mins
During downpower:
>2 mils - Stop downpower, reduce rate
When should the Reactor be tripped during a Normal Plant power reduction with Planned Reactor shutdown?
1 - Sudden step increase in turbine vibrations of 2 mils
2 - Vibration has increased to 10 mils
Monoblock rotors are susceptible to vibration based on what factors?
1 - Low Turbine Loading
2 - High Rates of Condenser vacuum change
3 - Main Condenser backpressure levels approaching 2”HgA
4 - Differential temperature across condenser section
During Turbine startup, which shell is used for backpressure? What is maintained?
“C” shell
> 2” HgA and equal to or less than 4” HgA (as close to 4” as possible)
Max for “C” = <5” HgA
MT can’t be operated for >1 hour when load is less than or equal to ___ with vacuum > than ____ HgA but less than or equal to ___
410 MW ; 4” ; 5”
Turbine shall not be operated at less than ___ load with back pressure > ___
40% ; 5”
40OP-9MT02 also states that operation of MT in this condition may result in damage to MT
How can we raise backpressure (less vacuum)?
Remove cooling tower fans and/or pumps from service
Anytime a CW Pump operates, why do we have a sufficient number of Cooling Tower Fans in operation?
Ensures environmental license isn’t violated. Prevent spillage past concrete liner.
Why is MT load reduced when FW Heaters are removed from service?
To prevent undue loading or overstressing of any turbine part.
Why do we maintain correct DP across FW Econ Valves? And How?
Feed SGs during normal transients, Avoid excess DP causes valve oscillations, DP as low as possible to improve MW’s, at 100% maintain DP > 100#
BIAS the MFP speed controllers
Per Appendix L of 40OP-9ZZ05, what is Monitored during CEA insertion or withdraw?
Reactor Power,
RCS Tavg,
CEA Group and subgroup deviations,
ASI
Depressurizing the section of line between the FWPT discharge check valve and discharge valve prevents ___
Pressure Locking and potential Damage to discharge valves
Why do we use the Generator capability curves (Appendix I, 40OP-9ZZ05)?
To maintain load, VARs and cooling within allowances to prevent generator overheat
What are some of the factors that increase vibration susceptibility in Monoblock rotors?
LO Temps Low Turbine Loading High Rates of Power change High rates of condenser vacuum change Main condenser backpressure near 2" HgA MSR Ops Steam Drain Ops Other thermal transients (steam to condenser)
Operating all MSRs in same mode ensures Max Symmetrical Delta T on each LP turbine is maintained LESS than ___
50F
PSCEA deviation will alarm a CWP when deviation is more than ___ inches
4.95”
Max Generator cold gas temp at 75# is limited to ___
Generator terminal voltage limits are ___ to ___
48C
22.8 kV to 25.2 kV
How long can we operate the Main Turbine if Exhaust Hood is between 200F and 225F?
15 minutes
When power is < 70%, what is taken out of service? 60%? 50%?
70% - RPCB OOS “Auto Actuate OOS”
60% - Shutdown a MFWP
50% - Place SGN-HS-1189 in “Venturi” position
When using Aux Spray during downpower, thermal shock occurs.
What must be determined for each cycle of main spray with < 4 RCP’s? And for Every cycle of Aux Spray?
Spray valve water differential temperature
Power ascension max rate is ___ above 20%
This limit is changed to ___ above 40%
- 5% per hour
- 5% per hour initial after reload
NOTE: Monitor via JSCALOR (NKBDELT can be used)
What is “Rapid Unloading”? And is it a Acceptable method?
1 to 3 minutes, by closing control valves quickly and tripping immediately thereafter
YES
How do we maintain Operating ASI?
Boration and Dilution CEA Movement (typically Groups 4 and 5) or PSCEA moves
During power ascension with power >20%, ___ of full power ESI or as directed by Reactor Engineering
> 50%, ___ of full power ESI
+/- 0.05
+/- 0.01 (same with steady state)
During power ascension or reduction, if ASI can’t be maintained ___ of full power ESI as directed by Reactor Engineering, and power is <70% (55% with COLSS OOS), then Group 4 CEA’s ___
+/- 0.05
May be inserted beyond the normal overlap limit
What is NOT normally considered as an available method for ASI dampening?
CEA Withdrawal and Boration
At EOC, Xenon oscillations are ___ and ASI oscillations become ___
More Extreme
Divergent
When the bottom of the core has a HIGHER neutron flux than the top half of the core?
Negative Axial Offset exists
Axial Offset Anomaly - Caused likely by crud buildup on fuel assemblies in upper portion of reactor core
If Power is shifted to the BOTTOM of the core, what happens?
Reduction in SDM and Increase in Local Peaking Factors
The capability curve is limited by what?
Field Winding Temps
Armature Temps
Armature Core Temps
If turbine vibration rapidly increases above setpoints, trip turbine and break vacuum at what setpoints?
<800 RPM - 8 mils
800-1400 RPM - 14 mils
1400-1800 RPM - 12 mils
NOTE: Breaking vacuum >1200 RPM may damage last stage buckets (LP)
If downpowering due to loss of transmission lines, what is the time required for the evolution?
3 hours
