Main Turbine

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heidin
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156335
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Main Turbine
Updated:
2012-05-29 16:39:41
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Main Turbine Generator ILC
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  1. During normal full power operation of Unit Two FW Heater 5A Level High-Low alarm
    (UA·046·B) is received. The operator notes that Drain Cooler Approach (DCA) for FW
    Heater 5A (process computer point C157) is 5°F, lowering.

    Which of the following describes if the level in FW Heater 5A is high or low, and the potential impact on the Heater of the off-normal level?

    FW Heater 5A level is:

    A. low. This can result in flashing at the subcooling zone inlet leading to erosion failure of the tubing.
    B. high. This can result in flashing at the subcooling zone inlet leading to erosion failure of the tubing.
    C. low. This can cause blockage of the internal vents, buildup of corrosive gases and internal corrosion.
    D. high. This can cause blockage of the internal vents, buildup of corrosive gases and internal corrosion.
    D. high. This can cause blockage of the internal vents, buildup of corrosive gases and internal corrosion.


    Normal DCA is 10°F. Abnormally low DCA indicates heater level is high. High level can block the operating vents for the heater and result in build up of gases inside the heater that can lead to corrosion. Flashing in the subcooling zone is a problemassociated with low heater level.
  2. Following a Unit Two (2) Reactor scram, plant conditions are:

    Steam Flow 3.5 X 10 lbm/hr
    RPV Level 155 inches and rising steadily
    APRMs Downscale
    Control Rods 10 rods failed to insert
    Level set 170 inches
    RFPs 2 in operation

    The operator should immediately:

    A. trip the Main Turbine
    B. trip one Reactor Feed Pump
    C. place the Mode Switch to Shutdown
    D. enter Alternate Control Rod Insertion
    A. trip the Main Turbine
  3. Unit Two is at 100% power with the following conditions:

    UA-13 5-4, Main Xfmr Trouble in alarm
    UA-13 2-2, Main Xfmr Winding Temp High in alarm

    An AO at the "A" Phase Transformer reports:
    - Winding Temp Monitor at 121°C
    - Top Oil Temp Monitor at 98°C

    All available "A" Phase cooling fans are operating.
    The operator is required to reduce winding temperature below 120°C within:

    A. eight hours or immediately remove the transformer from service.
    B. thirty minutes or immediately remove the transformer from service.
    C. eight hours or reduce load to maintain winding temperature below 110°C.
    D. thirty minutes or reduce load to maintain winding temperature below 110°C.
    C. eight hours or reduce load to maintain winding temperature below 110°C.


    If winding temp reaches 130°C, or top oil temp reaches 110°C, all load must beremoved from the transformer within 30 minutes. If either winding temp exceeds 120°C or top oil temp exceeds 100°C, the operator is required to log the start time to ensure the eight hour constraint is not exceeded. If winding temp exceeds 120°C for eight hours, reduce load to maintain temp below 110° C.
  4. Unit One is operating at 100% power with the normal electrical distribution lineup, with the exception of part time load shedding being enabled. Circ Water Intake Pumps (CWIP) 1A, 1B, and 1C are running. CWIP 1A is aligned for LOCA load shed, and CWIP 1B is aligned for Unit Trip load shed. A turbine trip results in a reactor scram and a generator lockout. BOP Bus 1C fails to transfer from the UAT to the SAT and is de-energized. BOP Bus 1D transfers as designed. What is the status of CWIPs?

    A. No CWIPs are running.
    B. CWIP 1A only is running.
    C. CWIP 1B only is running.
    D. CWIP 1C only is running.
    A. No CWIPs are running.


    The generator lockout results in a Unit Trip load shed for bus 1D loads since the SAT breaker closes. Since CWIP 1B is fed from Bus 1D. it will trip on UTLS. CWIP 1A and 1C are both powered from Bus 1C and will trip on undervoltage. This leaves no CWIPs running (CWIP 1D is available, and 1B will be available once the generator lockout is reset).
  5. The Main Generator has been synchronized to the grid with a load of 110 Mwe for three hours for post-maintenance testing.

    If all systems respond as expected, how will reactor power change following a trip of the turbine?

    A. Power rises due to loss of extraction steam.
    B. Power lowers due to loss of extraction steam.
    C. Power rises due to the increase in Xenon-135 production.
    D. Power lowers due to the decrease in Xenon-135 production.
    A. Power rises due to loss of extraction steam.
  6. Unit 1 is operating at 94% power. The Extraction Steam Non-Return Valve (NRV) to #5A Feedwater Heater will close if the:

    A. Main Turbine trips due to hight vibration
    B. #5 FW Heater level becomes abnormally low
    C. NRV Air Supply Solenoid becones de-energized
    D. RTGB Test Pushbutton for the NRV is depressed
    B. #5 FW Heater level becomes abnormally low
  7. Which one of the following identifies the reason that the Turbine Bypass Valves will open following a main turbine trip from full power?

    A. Prevent overspeeding of the main turbine during the coastdown.
    B. Prevent over pressurization of the MSR cross-over piping.
    C. Prevent over pressurization of the reactor vessel.
    D. Prevent rupture of the LP Turbine rupture discs.
    C. Prevent over pressurization of the reactor vessel.



    • Bypass valves open to prevent overpressurization of the reactor when the turbine control valves close on
    • a turbine trip signal.

    • CHOICE "A” The intermediate stop valves close on a turbine trip to prevent overspeeding the main turbine. Extraction steam will be lost following a turbine trip and bypass steam is directed to the main condenser.
    • CHOICE "B" over pressurization is a function of the cross over relief valves.
    • CHOICE "C" correct answerCHOICE "D" No problem with the condenser (vacuum) which would cause pressurization of the LP turbine.
  8. Generator MVARs are indicating 0 MVARs.

    Which one of the following identifies the actions required to restore MVARs to the limits specified in OP-27, Generator and Excitation System Operating Procedure?

    Coordinate with the Load Dispatcher to either:

    A. Raise the auto voltage regulator or place a capacitor bank in service
    B. Lower the auto voltage regulator or place a capacitor bank in service
    C. Raise the auto voltage regulator or remove a capacitor bank from service
    D. Lower the auto voltage regulator or remove a capacitor bank from service
    C. Raise the auto voltage regulator or remove a capacitor bank from service
  9. A grid disturbance occurs with the following Unit Two plant parameters:

    Generator Load 980 MWe
    Generator Reactive Load 160 MVARs, out
    Generator Gas Pressure 50 psig

    Which one of the following identifies all of the available options that will place the Unit within the Estimated Capability Curve?

    A. Raise Gas Pressure or lower MWe.
    B. Raise Gas Pressure or raise MVARs.
    C. Raise Gas Pressure only.
    D. Lower MWe only.
    A. Raise Gas Pressure or lower MWe.


    Based on the conditions, the student should plot the current location on the graph. Plot MWe along the bottom and MVARs up the side. Where these two points intersect, based on 50 psig gas pressure line is outside of the safe area. (Must be inside the curve to be safe) Lowering MWe or raising gas pressure are the only options. Lowering or raising MVARs would still be outside the curve.
  10. Unit Two is at 100% power. The 2A-1 and 2B·2 Isophase Bus Duct Cooling Fans are operating; the 2A-2 and 2B-1 fans are in standby.

    The following occurs:

    The fan belts break on the 2A·1 Isophase Bus Duct Cooling Fan
    Isophase Bus Return Air Flow-Low, (UA-13 3-5) has alarmed
    Isophase Bus Duct Cooling Fans swap as designed
    Isophase Bus Duct Cooling Fan 2B-1 then trips on thermal overload
    Isophase Bus Fan Trip (UA-13 1-5) alarms

    What operator action is required?

    A. Insert a manual scram and then trip the main generator.
    B. Reduce generator load as required to maintain bus duct temperatures below 105°C.
    C. reduce generator stator amps to less than or equal to 12,000 amps within 15 minutes.
    D. Ensure Isophase Bus Duct Cooling Fan 2A-2 is running and manually start Bus Duct Cooling Fan 2B-2.
    B. Reduce generator load as required to maintain bus duct temperatures below 105°C.


    This sequence leaves only one bus duct cooling fan available for operation since fans 2A-2 and 2B-2 cannot be operated simultaneously by system design. The low air flow will trip both 2A-1 and 2B-2, and start 2A-2 and 2B·1. The subsequent thermal trip leaves only 2A·2 running. Per the APPs, the operator must monitor bus duct temp and reduce load if necessary to maintain less than design. Reducing to <12,000 amps in 15 minutes is required if no fan is running (from full power, this would require a scram to meet this requirement).
  11. Unit Two is operating at rated power. The 2A·1 and 28·2 Isophase Bus Duct Cooling Fans are operating, and the 2A-2 and 2B·1 fans are in standby.
    A loss of TBCCW flow is sensed to the cooling coil #1 due to a failed flow switch.
    Isophase Bus Cooling Wtr Flow-Low (UA-13 2-6) alarms.
    How will the Isophase Bus Cooling system respond?

    A. Fan 2A·1 only trips, fan 2A-2 only auto starts.
    B. Fan 2A·1 only trips, fan 2B-1 only auto starts.
    C. Fans 2A-1 and 2B·2 trip, fans 2A·2 and 2B·1 auto start.
    D. Fans 2A·1 and 2B-2 remain running, fans 2A·2 and 2B·1 auto start.
    B. Fan 2A·1 only trips, fan 2B-1 only auto starts.


    On a loss of TBCCW to a single coil. the fan running on that coil trips after a 30 second TO. and its standby fan starts. This leaves both fans in operation on the coil that has TCC flow sensed. Both fans trip and both fans auto start on loss of TCC to both coils or on low air flow. Interlocks prevent running 2A·1 and 2B·1 or 2A-2 and 2B-2 at thesame time.
  12. While operating Unit 1 at full power, annunciator (UA-13, 2-5) ISOPHASE BUS FAN VIB/LOSS CONT. POWER, alarms.

    Which one of the following local observations is accurate for determining the cause of the alarm?


    A. If all the fans have tripped, there has been a loss of all contol power.
    B. If the standby fans are operating, a high vibration condition has occurred.
    C. If there is no indication for which fans are operating, a loss of all control power has occurred.
    D. If one or both of the fan vibration coil high vibration lights on lit on the local panel, the cause is a high vibration.
    D. If one or both of the fan vibration coil high vibration lights on lit on the local panel, the cause is a high vibration.


    The loss of control power will de-energize the alarm indicating lights only. It will not trip the fans. High vibration does not cause a fan trip; therefore, the standby fans should not have started. If a high vibration light is energized, then a high vibration NOT a loss of control power has occurred.
  13. Unit Two (2) is at 100% power. A clearance error causes instrument air to be isolated to the valves associated with the extracton steam system. The CO looks at the RTGB to determine valve position. What is the expected position of the moisture removal valves (MRVs) and the extraction steam non-return valves (NRVs)?

    The MRVs are _____(1)______ and the extraction steam NRVs are ______(2)______ .

    A. open; closed
    B. open; open
    C. closed; closed
    D. closed; open
    B. open; open
  14. How do the main turbine control intercept valves (CIVs) respond to an overspeed condition?


    A. All four valves begin to throttle close at 105% turbine speed and should be full closed by 107%.
    B. CIV 1 & 2 begin to throttle closed at 105% turbine speed and CIV 3 & 4 will close when CIV 1 & 2 reach 50% closed. CIV 1 & 2 are full closed at 107% turbine speed.
    C. CIV 1 & 3 begin to throttle closed at 105% turbine speed and CIV 2 & 4 will close when CIV 1 & 3 reach 50% closed. CIV 1 & 3 are full closed at 107% turbine speed.
    D. All four valves go to their No-Load setting, at 105% turbine speed CIV valves 1 & 3 close, at 107% valves 2 & 4 close.
    B. CIV 1 & 2 begin to throttle closed at 105% turbine speed and CIV 3 & 4 will close when CIV 1 & 2 reach 50% closed. CIV 1 & 2 are full closed at 107% turbine speed.


    • When turbine speed exceeds 105%, the intercept valve regulation potentiometer is tuned such that the negative signal being developed by the overspeed condition diminishes the SI output. Consequently, the Intercept Valve portion of the Combined Intermediate Valves begin to close. The Intercept Valves will throttle closed from 105% (+90 rpm) to 107% (+126 rpm). At 107%, synchronous speed, the Intercept Valves will be fully shut with the control valves receiving a large negative signal demand to shut.
    • Intercept Valves #1 and #2 are referred to as the master valves. The #3 and #4 Intercept Valves are slaved to the #1 and #2 Intercept Valves by position switches. For example, opening #1 (2) IV 90% allows #3 (4) IV to open. Closing the #1 (2) IV 50% causes the #3 (4) IV to close.SD-26
  15. Unit One (1) is at 62% power during a plant startup.

    The plant conditions are as follows:

    Generator Load 468 MWe
    Turbine Control Valves Throttled (1 & 2 open)
    Bypass Valves Close
    Turbine Load Set Set at 80%
    Load Limit Set at 80%
    Max Combined Flow Set at 72%

    The Reactor Operator is increasing power to 80%.

    Which one of the following will occur as power is increased?

    A. Control Valves CLOSE to increase Generator Load and Reactor Pressure increases until the Bypass Valves open.
    B. Control Valves CLOSE as Reactor Pressure increases. At about 72% power, Reactor pressures increases rapidly to the scram setpoint.
    C. Control Valves OPEN as power is increased. At about 72% power, the Bypass Valves start to OPEN to control Reactor Pressure.
    D. Control Valves OPEN as power increases. At about 72% power, Reactor Pressure increases rapidly to the scram setpoint.
    D. Control Valves OPEN as power increases. At about 72% power, Reactor Pressure increases rapidly to the scram setpoint.

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