EOP 1 Flashcards
What are the EOP-1 entry conditions?
EK-0972, “REACTOR TRIP”
Control Rod bottom lights on
Rapid reduction of Reactor power
Red trip lights lit on Clutch Power Supplies 1 through 4
RPS trip logic lights on
RPS trip setpoint(s) exceeded
Licensed operator evaluation indicates conditions warrant a Reactor trip
What is the purpose of the standard post trip actions?
Verifies that the safety functions are being met
AND
Serves as a diagnostic tool
What is the basis for the chosen acceptance criteria?
The operator is given specific, unambiguous acceptance criteria that can be evaluated without interpolation directly from the control room instruments.
SPTAs are organized around critical safety functions in order to ensure that the plant is placed in a stable, safe condition or that the plant is configured to further respond to a continuing casualty.
When is the response not obtained (RNO) column entered? Completed?
If needed, the RNO actions should be implemented but not necessarily completed prior to completing the remaining SPTA.
The emphasis should weigh equally between assessing the status of each safety function and implementing right-hand column actions for already assessed safety functions.
Why is reactor shutdown step 1? Why the chosen criteria?
Reactor power lowering indicates heat input into the primary coolant system is lowering. Criteria for verification is based on conditions which would prevail during first 10 minutes of a trip.
Why “Is a maximum of one full lenght control rod NOT fully inserted?” The first criteria?
It is related to a core design criterion.
The core is designed to be shutdown will all but one full-length control rod not fully inserted.
If any doubt exists as to the status of the control rod, it should be treated as not fully inserted.
Is start-up rate instrumentation highly accurate immediately following a reactor trip?
It is expected that a negative start-up rate will exist following a Reactor trip.
However, it is recognized that several minutes after a Reactor trip, when Reactor power has significantly decreased, SUR instrumentation may not be entirely reliable due to fluctuations in the indication due to a low signal and circuit noise.
What is the function of Step 2 “Is the main turbine tripped?”
An untripped turbine would result in an uncontrolled cooldown of the PCS resulting in an uncontrolled reactivity addition.
Why are the main generator output breakers verified open or openned after verifying steam is secured to the main turbine?
Disconnecting the generator from the grid before securing steam could result in overspeeding the turbine.
Why are steps associated with securing the main turbine and generator before steps with reducing main feedwater flow?
Ensures a continued feedwater supply by Main Feedwater System until the turbine is tripped.
The reactor is critical at less that 15% power when it trips. What do you do with generator output breakers?
The generator should not be connected to the grid at this point and MOD may be open with output breakers closed. Openning output breakers could destabilize the grid/plant offsite power.
Why are main feed pumps ramped to minimum post trip?
The feeds pumps will automatically ramp down, however, the process is slow and results in overfeeding of the generators. Ultimate result (about 2 minutes) is a SIAS.
It is important to verify Main Turbine is tripped prior to reducing feedwater flow to prevent lowering S/G levels excessively.
After the pump has ramped to minimum speed, the NCO should close the feed regulating valves. This will allow for a maximum amount of feed to the steam generators and at the same time prevent excessive feeding.
Why is the second main feed pump ramp down delayed until Tave lowers towards 525F (535F preferred)?
525F is the minimum expected post trip Tave.
Why do we close Main Feed and Main Feed Bypass valves?
Manually closing both Main Feed Regulating Valves and Bypass Feed Regulating Valves and/or reducing pump speed will limit overfeeding of the Steam Generators.
This will allow time for an Auxiliary Operator to trip the pump locally in the event a Feed Pump cannot be tripped from the Control Room.
When does an NPO trip a main feed pump.
Directed to do so anytime it cannot be done from the control room.
MVAE is a higher priority than feed water regulation. Why is ramping down the feed pumps and closing feed reg/bypass valves before electrical?
It is sequenced after Main Turbine-Generator steps and prior to the remaining MVAE steps in order to mitigate overfeeding of the S/Gs following a Reactor trip which can cause a SIAS actuation.
When only one NCO is in the control room, what is the order of EOP-1?
Reactor Trip
Turbine Trip
Generator Disconnected
MFP Ramp Down
MF Reg and Bypass Valves Closed
What is the purpose of the safety function status check for MVAE?
To ensure power to vital loads has
1) Been maintained by the Safeguards Bus
2) Fast Transferred from Station Power to Offsite Power
3) Transferred from SG Bus to EDG Output
Electrical power is esential to subsequent safety functions.
Why is Echo bus verified to have power?
Pressurizer spray heaters trip off at 36% level. They will not reenergize from delta bus.
Echo bus trips on SIAS, verification of power available allows for pressurizer pressure control via heaters.
Why are Alpha and Bravo buses required?
Buses 1A and 1B are required for continued forced circulation and the continued availability of the Main Condenser as a heat sink for S/G steam. Forced primary circulation enhances PCS recovery in all events except those that include an uncontrolled primary system break (uncontrolled LOCA) or a total loss of Feedwater to the S/G heat sink.
Is Y-01 vital and why is it checked?
Not considered vital, but loss of it will hinder operator ability to mitigate the event.
