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LOIT 2020 GOP phase > Power Operations 20-100% > Flashcards

Power Operations 20-100% Flashcards

1
Q

Why should you slowly place MSRs in service?

A

avoids excessive temp transients which minimizes Turbine vibrations.

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2
Q

What operator actions with MSRs helps maintain LP Turbine dTemperature < 50F?

A
  • Operate MSRs in the same Mode to maintain LP Turbine ∆T’s < 50°F.
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3
Q

State several items that can affect the intensity of MT vibrations during operation.

A
  • Lubricating oil temperature
  • Low turbine loading
  • High rates of power change
  • High rates of condenser vacuum change or approaching 2” HgA
  • ∆T across the condenser section
  • MSR operation
  • Steam drain operation
  • Thermal transients (Equipment malfunctions that direct steam or drains to the condenser)
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4
Q

What steady state method of turbine control maintains plant stability?

What else does this minimize with respect to the TCVs.

A
  • Steady state: turbine control on the load limiter. Maintains plant stability and minimize pressure surges on control valves.
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5
Q

What is the normal MT vibration threshold?

What is the MT trip criteria for high vibrations?

When should a reactor trip be performed with regard to high vibrations in the MT?

A
  • 5 mils (normal Turbine vibration)
    • Auto turbine trip at 12 mils unfiltered
  • Turbine trip criteria:
    • Filtered journal vibration > 10 mils and rapidly ↑ towards 12 mils at rated speed
    • Filtered vibration > 10 mils with a slow ↑ towards 12 mils after a 15 minute time span at rated speed
  • Reactor trip criteria (if during normal power reduction with a planned reactor trip):
    • Sudden step ↑ of 2 mils
    • Vibration ≥ 10 mils
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6
Q

What is the temperature limit for the following:

MT oil drain temp.

MT bearing metal temp.

LP turbine steam inlet temp change limit.

A
  • ≤ 170°F: Limit for Turbine oil drains during continuous operation at the hottest bearing.
  • ≤ 225°F: Normal turbine bearing metal temperature.
  • < 125°F/hour: Normal LP turbine steam inlet temperature change limit. Short term changes limited to 250°F/hour.
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7
Q

What operations should be avoided to minimize MT damage with regards to vibrations?

A
  • < 40% load with C shell ≥ 5 inches HgA (vibrations)
  • < 40% load (410 MW) and C shell > 4” to < 5” HgA for 1 hour max (vibrations)
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8
Q

How can breaking vacuum above 1200rpm affect the turbine?

When is it allowed?

A
  • Breaking vacuum > 1200 rpm (excessive loading on Last Stage Buckets)
  • In emergencies only.
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9
Q

What is detrimental about maintaining vacuum without GS in service?

A
  • Maintaining vacuum after gland seal steam lost can cause thermal shock to rotor by intake of cold air.
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10
Q

What can happen if excessive use of exhaust hood Sprays at low speeds and low loads is allowed?

A

erosion of last stage buckets

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11
Q

What minimum speed and load should be avoided with regards to the MT?

A
  • Operating < 800 rpm (> 5 min). (Cause packing rub, high vibes not indicated, or bowed rotor)
  • Minimize operation < 5% load (moisture erosion on last stage buckets)
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12
Q

What are teh exhaust hood temperature limits and what coudl happen if they are violated?

A
  • ≤ 125°F: rapid load changes allowed
  • 125 - 175°F: may operate continuously but change load slowly (0.5%/min) (avoids unnecessary thermal stress)
  • 200-225°F: 15 minute max operations (turbine trips at 225°F)
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13
Q

State the following:

rate of turbine load reductions

normal power reductions

TG operation prior to start

continuous TG operations.

A
  • ≤ 10%/min load reductions minimizes turbine thermal stresses.
  • Limiting normal power reductions to 20%/hour (4 hour normal shutdown) will minimize turbine vibration.
  • < 48 hours TG operation prior to turbine start may cause shaft bowing
  • Avoid long periods of TG operations. Generator field grounds may occur from copper dust build-up. (galling of windings)
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14
Q

With regard to Condenser backpressure:

  1. State the C shell max backpressure
  2. C shell operations that minimizes MT vibrations
  3. Reactor trip setpoints
A
  1. C shell max backpressure is < 5.0” HgA.
  2. C shell > 2” HgA and ≤ 4” HgA minimizes Turbine vibration.
  3. Trip reactor if load < 410 MW and > 4” HgA for > 1 hour
    • Trip reactor if load < 410 MW and > 5” HgA
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15
Q

Why should the condenser vacuum be maintained as close as possible to table values?

> 40% pwr

A
  • > 40% power: maintain average pressure as close to table values as possible (↑ turb efficiency / ↑ MWe)
  • Maintain A shell pressure above the table values (↓ erosion of condenser internals from excess steam velocities)
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16
Q

What actions are taken to prevent exceeding 5” HgA?

A
  • Reduce turbine load to prevent exceeding 5” HgA
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17
Q

State the ASI limits associated with LCO 3.2.5.

A
  • LCO 3.2.5 ASI limits:
    • COLSS Operable
      • -0.18 ≤ ASΙ ≤ 0.17 (> 50%)
      • -0.28 < ASI < 0.17 (> 20% and < 50%)
    • COLSS out of service (CPC)
      • ± 0.10 ASI (>20%)
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18
Q

When should ASI dampening be performed?

A
  • ASI dampening performed if ASI will exceed ESI by ± 0.1.
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19
Q

At what ASI threshold is a reactor trip performed?

A
  • Trip the reactor if exceeded or trending to ± 0.5 (CPC Hot Pin ASI Aux Trip).
    • ASI input to CPC aux trip depends on power
    • ≥ 51% (sum of the 3 NIs): uses actual power distribution (during power ascension)
    • ≤ 45% (sum of the 3 NIs): uses a canned value (during power reduction)
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20
Q

Which of the following should be used during a downpower?

Colss asi or CPC asi?

A
  • CPC and COLSS can calculate a large ASI difference due to design differences and calculation processes. CPCs generate an auxiliary trip prior to COLSS indicating a problem with ASI.
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21
Q

When is PZR boron equalization performed?

A
  • ≥ 50 ppm RCS Boron conc. change: perform PZR boron equalization
    • Maintain until ≤ 10 ppm difference (RCS vs PZR)
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22
Q

Who is notified if Rx power is < 85% for more than 10 days?

A
  • Power < 85% for > 10 days: notify nuclear fuel groups for evaluation.
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23
Q

Who is notified if a power change is required or ASI dampening is performed and why?

When is the sample required?

A
  • Chemistry notified of any power change or ASI dampening (sample for iodine spikes)
  • LCO requires sample within 2-6 hours of a ≥ 15% / hour power change
24
Q

What is required from section 6.1 prior to raising power > 20%?

A
  • 20% mode change checklist complete (ZZ11)
  • Maintain Power Ascension Rate Limits (App. A)
  • Unit Ops Manager permission required if SBCS, PLCS, PPCS, or FWCS are NOT in Auto.
  • Monitor AZTILT (LOC limit and CPC value < actual tilt)
  • Place MSRs in-service
25
Q

When are both HDPs placed in service?

A
  • 20-25% plant power: place both HDTPs in-service
26
Q

When are extr steam drains and turbine drains closed?

A
  • 250 MWe: close extraction steam drains and turbine drains
27
Q

What happens at 30, 50 and 90% on power ascension?

A
  • 30%, 50%, 90%: chemistry hold points
28
Q

When is the 3rd CDP started?

A

40%

29
Q

When is the second MFP started?

A

40-60% reactor power

30
Q

When is RPCB placed in service and when are subgroups selected?

A
  • 70% reactor power: place RPCB in-service with NO subgroups selected
  • 74% reactor power: select RPCB subgroups
31
Q

When is SBCS placed in remote auto?

A

75%

32
Q

Define Axial Offset Anomoly and what adverse effects it will cause core operations.

A
  • Axial Offset Anomaly (CIPS): CRUD builds up on the high power fuel pins. Lithium boron absorbed in the CRUD (plates out). Causes power shifts to bottom of core.
    • – AOA: more flux in bottom of core (opposite of ASI)
    • ↓ SDM and ↑ power peaking
33
Q

State the following Generator limits for normal operations:

  1. Vterm
  2. Buck
  3. Boost
  4. ECC max voltage
  5. max H2 cold gas temp
  6. H2 min/max press
  7. limits associated with the capability curve.
A
  1. 22.8 – 25.2 kV (Generator Terminal Voltage band 24 kV ± 5%)
  2. - 310 MVARs (max Buck Limit to minimize low voltage conditions on the buses)
  3. + 560 MVAR (max Boost Limit)
  4. 535.5 kV: ECC max voltage limit
  5. ≤ 48°C (118.4°F): Max inlet H2 cold gas temp. Ensure adequate generator cooling.
  6. 30 psig: Min H2 pressure. Ensure adequate density of the gas for cooling the generator. (Max load 940 MW (~ 67%))
  7. 75 psig: Max H2 pressure.
  8. Capability curve: AB (field heating), BC (armature heating), CD (armature core end heating)
34
Q

How can RG 4 be used to control ASI?

A
  • Use RG 4 to control ASI if heavily top peaked
    • ASI cannot be maintain with ± 0.05 of ESI and < 70% (< 55% if COLSS OOS)
    • RG4 can be inserted beyond normal overlap
    • Maintain RG 5 > 75”
    • Maintain RG 4 ≥ 10” above RG 5 (if RG4 < RG5, an out of sequence CPC trip will occur)
    • Track time that RG 4 is between ARO and transient RIL
35
Q

What is the desired band for RTP and by what indication?

What is licensed power based on?

How should the crew adjust hourly power if 100% is exceeded?

A
  • Desired control band for RTP is between 99.8% and 100% using hourly average calorimetric power (JSCALORH).
  • License limit is the 12 hour average
  • If hourly exceeds 100%, reduce to < 100% in the next hour. Monitor 10 minute average.
36
Q

What minimizes MFW imbalances?

A

maintaining MFP biasing ≤ 100 rpm difference minimizes MFW imbalances

37
Q

What is MFP bias adjustment based on?

Why is 100 psid at 100% maintained?

A
  • Lower MFP speed (- bias) until MFP discharge pressure is 100 psig > SG pressure or – 500 rpm
  • Maintain ~ 100 psid at 100% (sufficient FF to SGs, low enough to minimize ECCV oscillations, low enough to improve MWe output / efficiency)
38
Q

What limit to rated power exists if using NKBDELTC for > 12 hrs?

A
  • If controlling power with NKBDELTC for > 12 hours, reduce power to 96.6%
39
Q

When is CEDMCS placed in AS?

A
  • Placed in AS when > 40%
40
Q

How is EOL coastdown performed, big picture?

A
  • EOL Coast down (↓ turbine load as Tavg drops OR Tcold coastdown)
    • CEDMCS Not in AS if performing Tcold coastdown
41
Q

How should Tave-Tref be maintained when >90% power?

What does this accomplish?

A
  • Maintain Tavg/Tref ± 3°F
    • When > 90%, maintain Tavg as close to Tref as possible.
    • Minimize potential for VOPT pre-trip alarms when Tavg is high or MSIS pre-trip alarm when Tavg is low.
42
Q

What must be met to stop HDPs after taking the turbine off-line?

A

HDT level are stable and pumps are operating on mini-flow

43
Q

Whose permission does it take to go above 20% if SBCS, PLCS< PPCS, FWCS are not in AUTO?

A
  • Unit Ops Manager permission required if SBCS, PLCS, PPCS, or FWCS are NOT in Auto.
44
Q

When is the UFM placed in service on power ascension?

A
  • 93%: UFM placed in-service
45
Q

Why must power ascension rates be strictly adhered to and when do they apply?

A
  • Prevents fuel damage / voiding fuel warrenties. Applies > 20%.
    • Initial start-up limits below 20% are covered by 72PA-9ZZ07, “Reload Power Ascension Test.”
46
Q

Whose permission is requried for the following:

  • Maneuvering plan predicts ASI will exceed LCO limit during power reduction.
  • SBCS, PLCS, PPCS, or FWCS are NOT in Auto.
A
  • Unit Ops Manager permission required if plan predicts ASI will exceed LCO limit during power reduction.
  • Unit Ops Manager permission required if SBCS, PLCS, PPCS, or FWCS are NOT in Auto.
47
Q

At what hotwell level should HDPs be stopped?

A
  • 46-48” Hotwell level prior to stopping HDTPs
48
Q

How are NAN-S01 and S02 powered if reactor power is to be reduced < 20%?

A

From offsite power via the SU XFMRs

Ensure not more than 1 Unit is powered from 1 SU XFMR.

Ensure other unit’s DG’s are not in parallel with off-site power.

49
Q

What actions are taken at < 70% on shutdown?

A
  • < 70%: remove RPCB from service (40OP-9SF04 - Auto Actuate OOS and Test/Reset PBs)
  • < 70%: place HDT LICs in Local-Auto (7’ setpoint)
50
Q

When <60% power, which MFP is removed from service first and why?

A
  • < 60%: stop 1st MFP (preferably A MFP due to water intrusion issues)
51
Q

What should be removed from service if the MT is being shutdown?

A
  • Remove MSRs from service if generator is being shutdown
52
Q

With regards to the SGBDs, what must be ensured at ~ 25%?

A
  • < 25%: ensure SGBD is NOT aligned to the SGBD demins
53
Q

How is the plant stabilized if 20-30% power is to be maintained with the MT tripped?

A
  • Place one SBCV in Manual permissive (1001)
  • Place SBCS in Local-Auto. Adjust SBCS master controller to open 1001
  • ↓ turbine load to 50 MWe
  • Place more SBCVs in manual as needed for load reduction
  • Trip the turbine when ≤ 50 MWe
  • Shutdown the generator (open disconnects)
  • Reclose the generator PCBs within 2 hours
54
Q

Why should only 2 charging pumps be running prior to tripping the reactor?

A

prevent lifting the letdown relief CHN-PSV-345.

55
Q

Briefly describe the process to stop Condensate pumps per 40OP-9ZZ14.

A
  • Throttle open SGBD HX condensate outlet valves to maximize flow (suction pressure) to MFPs (500 gpm max per path)
  • Throttle open Cond Demin bypass (PDV-195) to maximize MFP suction pressure
  • Close the Condensate pump discharge valve and stop the pump
56
Q

Briefly describe the process of stopping the first MFP per 40OP-9FT01/02.

A
  • Reduce speed on the MFP (use Bias or manual speed control) until discharge pressure is below the other MFP
  • Close the MFP discharge MOV
  • Trip the MFP
  • Place on turning gear, re-open discharge MOV, adjust lube oil and seal pressures

LOIT 2020 GOP phase (8 decks)

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