NOPs Flashcards
What rate of power reduction requires a RCS sample for iodine?
Any power change greater than or equal to 15% per hour
What is the setpoint and coincidence of P-8? What is the reset setpoint and coincidence?
Active when 3/4 power Range channels are less than or equal to 29%. (Permits auto block of “at power” trips).
Reset when 2/4 PR channels are greater than 29%
When is the interlock C-5 active?
Blocks auto rod withdrawal when turbine impulse pressure (MPC-253) is less than 15% equivalent power pressure
If Improper bank overlap occurred during the Rx shutdown, what actions would you take?
Notify MTI and SS of the problem but continue w the Rx shutdown until all roads are fully inserted and Rx trip breakers are open.
When one feed pumps speed is lowered what causes the other feed pump to speed up?
The FP speed controller compares feed hdr and steam hdr pressure difference to a programmed d/p value.
How many PR channels must be less than 10% in order to clear P-10 status light. What should be done if it doesn’t clear?
3/4 channels less than 10% clears the P-10 status light.
Corrective measure steps of the procedure should be performed.
Why are the steam dumps placed to steam pressure mode?
To align control system so that Tavg is maintained via steam pressure of the bypass hdr. This allows dumps to assume temp control as the turbine is unloaded and prior to being tripped.
Why should the high flux at shutdown alarm setpoint be changed?
Bc the neutron source strength is greater than it was when the reactor startup was performed
Why do we energize Pressurizer heaters 12 hrs before a planned power reduction?
Minimize the impact on RCS Hydrogen
Why are all available PRZ hers energized during a power change?
To minimize the PRZ and RCS loop boron concentration difference.
What can prolonged use of maximized pressurizer spray result in?
Hydrogen being stripped out of solution, requiring additions to VCT.
How many source range channels shall be in operation and recording continuously on NI Recorder SG-12 while the reactor is shutdown with fuel in the reactor?
Minimum of 2
Prolonged Turbine operation at less than 10% load must be avoided due to…..
Moisture erosion of last stage blades and exhaust hood heating
When the reactor is critical RCS temperature is maintained greater than or equal to 541*F. IF it falls below this temp, how long do you have to get it back and how do we do so?
30 minutes by reduction in steam demand.
What is the limit for rod movement above the POAH?
3 steps at a time until the associated reactivity effects are complete
What does it mean if P-10 remains lit with an inopeable power range channel?
- PR high flux low setpoint trip is not enabled
- IR high flux trip is not enabled
- SR detector voltage will not be restored below P-6 setpoint
Whose permission is needed if we plan on using SG PORVs as a planned method of RCS temp control?
Ops Director
Whose permission is needed for extended low-power operation?
Plant Manager
How can we alleviate potential issues with RCS Hydrogen?
Maintain VCT pressure at the high end of the band
How many NIs are required to perform Rx Startup?
Per TS: 2 SR, 2 IR, and at least 3 PR
How are the control rod urgent and non-urgent alarms reset?
At startup, the step counter reset can be used to reset the alarms.
After rod withdrawal begins, the alarm power reset at the cabinet must be used
Why are we required to perform ICRR plot during a reactor startup?
It’s a backup to the ECP. The prediction helps ensure that the critical rod position is above the Lo-Lo Insertion Limit, thus ensuring adequate SDM during startup
What indication will you observe when the reactor goes critical?
Power rising with a sustained positive start up rate with no rod motion
Why is the high flux at shut down alarm defeated before the reactor start up?
The alarm is there to alert the operator that an unplanned reactivity addition is occurring and should be investigated. A reactor start up is planned, and therefore the alarm is of no value and could be distracting if not blocked prior to start up
When do you expect the high flux at shutdown blocked annunciator to clear?
The alarm should clear as P-6 which is one out of two (1/2) intermediate range NIs at 10 E10 Amps
What is the basis for T average greater than 541°F prior to criticality
It ensures the following:
-MTC within analyzed range
-protective instrumentation and normal operating range
-pressurizer is capable of being operable with a steam bubble
-reactor pressure vessel is above minimum nil ductility temperature
How long will you wait after stopping rod motion before login data for the 1/M pot
Until the counter rate stabilizes
What is proper bank overlap and rod alignment?
Successive rod banks start moving when the preceding bank reaches 128 steps. All rods within a bank within 12 to 18 steps of the demand bank position
What is the zero power rod insertion limit?
128 steps on bank C or 0 steps on bank D
What rod height is associated with the ECP, the -1000 PCM position, and the +500 PCM position?
Refer to the ECP for correct answers. These values should also be written on the ICRR plot
What actions will you take if it appears the reactor will become critical below the rod insertion limit for zero power (LCO 3.1.6)?
Open reactor trip breakers, commence emergency boration, perform SDM calc, and determine the problem
As the start up has progressed, it has taken longer for the start up rate to fall to zero after rod motion has stopped. Why?
Sub critical multiplication process and the approach to KEff of one takes longer with more neutrons.
How do you recognize the point of adding heat?
Nuclear indication will show negative reactivity due to Doppler. RCS indications also rises in T average and pressurizer level. Steam generator pressure will rise and steam dumps will open
When during heat up and power escalation must an RCS leak rate be completed
Within 12 hours of establishing steady state operation in modes one through four. Therefore, the surveillance requirement should have been completed prior to entry into mode one.
As power level rises, what happens to the pressurizer reference level? Why?
Pressurizer reference level rises as T average rises. It is programmed to follow T average to minimize the mass change in the RCS with power. This reduces the amount of liquid rad waste.
When can rod control be placed in auto?
After power is above 15% and the C-5 interlock light is out
What is AFD?
AFD is the difference in normalized flux signals between the top and bottom halves of a two section excore neutron detector.
How is AFD calculated manually?
AFD can be manually calculated by recording each detector current, dividing each reading by that detectors 100% current reading, and subtracting the lower value from the upper value for each channel
What function does P8 perform?
When the P8 light is not lit, it will change coincidence of reactor trip due to low RCS flow from 2 loops to 1 loop and enables reactor trip from a turbine trip.
What is QPTR?
QPTR is the ratio of the highest normalized upper Excore detector output to the average of the upper Excor detector outputs. (or lower detectors)
Why does an extreme high-level on any of the high-pressure heaters close the affected heaters bleed steam inlet valve?
To prevent water backing up into the high pressure turbine
Why does extreme low level in a #4 heater in unit 2 trip the heater drain pump taking suction from that heater?
To prevent losing suction pressure for the pump
With QRV303 in auto, when will the valve divert flow from the VCT to the HUT?
QLC 451 will open QRV303 at 87% VCT level.
QLC 452 will start to modulate QRV303 open at 78% VCT level with valve full open at 87%
What is the concern of exceeding 120 gallon per minute through a deborating or mixed bed demineralizer based on?
Channeling of the resin making the demineralizer less efficient
What is delta flux (AFD) and why is it maintained within a narrow target band during normal operation
Delta flux is the normalized difference between neutron flux in the top half of the core and neutron flux in the bottom half of the core. Delta flux is maintained in a narrow band during normal power operations to ensure a nearly uniform axial flux distribution. This will minimize the potential for a large power peak in the bottom or top of the court during operation
Why do we limit power to 50% if delta flux has been out of the band for greater than 1 hour and what is significant about 1 hour?
Power is limited to 50% to ensure that even if there is a large peak at the top or bottom of the core in a transient, it will not cause excessive heat and potential fuel damage. 1 hour is set to minimize the potential for a xenon oscillation been created, which would accentuate the power peak
What is the difference between conditioned and unconditioned fuel?
Unconditioned fuel is fuel that does not meet the conditioned definition.
Fuel is defined to be conditioned for power escalation to a power level if it has operated at that power level for greater than 72 hours in the last 30 days. For initial cycle start up, the requirement is 72 hours cumulative out of the last seven day operating.
What are the signals necessary to actuate the AMSAC system and what actions are initiated by the actuation of the system
Actuation occurs when 3 of 4 feedwater flows are less than 25% with 2 of 2 turbine impulse pressures greater than 40% within the previous 6 minutes. Actuation causes a turbine trip, start of all aux feedwater Pumps, and initiates a feed water conservation
What is an ATWS and why is it a concern for a safe plant operation
Anticipated transient without scram is an occurrence of a condition 2 event that should have resulted in a reactor trip, but because of a common mode failure, an automatic trip did not occur. Additionally the turbine did not trip nor did AFW pumps start.
It is a concern because we have a situation where excessive heat is produced greater than decay without the ability to remove it in the steam generators. It could lead to an Overheating of the fuel and potential damage
What is the setpoint And coincidence of P 10, and what actions can be taken when P 10 is satisfied?
P 10 is satisfied with 2 out of 4 PR NIs are at 10% going up. When satisfied, it seals out the source range high-voltage, resets P7, and allows the operator to manually block the intermediate range rod stop, intermediate range high-level trip, and Power Range low level trip
What inputs do the FRV controllers use in AUTO control while in the startup mode?
The FRV controller normally uses a flow error (mismatch by feed and steam flows) and a level error (actual level vs a fixed program level).
During startup, the steam flow input is substituted by Delta T from that loop. This was done in an attempt to provide more stable control during startup situations with low steam flow values.
Why do we adjust synchroscope for rotation slowly in the FAST direction and incoming voltage slightly higher than running voltage?
Having the generator at a higher frequency and at a slightly higher voltage ensures that when the output breakers are closed, the generator will pick up load instead of a reverse power condition.
What are the at power trips that are blocked when P-7 is met?
Pressurizer Low Pressure Pressurizer High Level RCS Loss of flow RCP UV RCP UF RCP Bkr Open
How much penalty time is accumulated when delta flux is outside the target band?
With power greater than 50%, for every minute outside the target band, 1 minute penalty time is accumulated. If power is between 15 and 50%, 1 minute penalty time is generated for every 2 minutes outside the band.
In Tavg Mode, what signals will arm and actuate steam dumps?
C7A and C7B and C8
What function does Low Tavg at 554 degrees Fahrenheit serve?
Low T average coincident with P4, reactor trip, generates a feedwater isolation signal to prevent an excessive cool down during a trip due to over feeding steam generators
What must we do if reactor power level will be maintained between 15 and 70% power for a period in excess of 24 hours or nuclear instruments will be adjusted down with reactor power less than 70%?
Power range high range high flux reactor trips at points must be lowered from 107% to 79% power
Bubble formation may be indicated by
a lowering pressurizer level with CVCS charging and letdown flow being controlled to maintain Pressurizer pressure between 50 and 60 psig.
Prz bubble causes RCS/Prz liquid level to
expand/compress air bubble in the SG tubes.
Which Mid-loop indicating levels are in service with RCS level at 2 feet below the reactor vessel flange?
NLI-122, NLI-1000, NLI-132, NLI-142, NGG-100, and NLI-112.
When performing the first RCP runs, what will be the expected RCS pressure response and why? How does this relate to the T.S. requirement to NOT start a RCP with cold leg temperatures < 1520F unless 1.) The Pressurizer is <62% or 2.) The secondary water temperature of each steam generator is <500F above each RCS cold leg temperature?
RCS pressure will rise due to cold (stagnant) water in the SGs being forced into the core, subsequently heating up and expanding or heat input from warmer water in the secondary (if the SGs are hotter than the RCS). Therefore the RCS will be protected from overpressurization.
When in Mode 5, Technical Specifications allow two SGs with sufficient water level as a substitution for an Operable RHR loop. What is the basis for this substitution?
This Tech Spec. assumes the loops are filled and ensures single failure criteria is maintained with one RHR loop out of service. The SGs with sufficient levels provide an alternate method for decay heat removal in the event the operating RHR loop fails.
How do we determine what boron concentration is needed to meet Shutdown Margin requirements following refueling (Mode 6 to 5) if a new TDB figure has not been issued?
Contact Reactor Engineering.
Why are we concerned with recording the lowest of all loop temperatures? What two loops have the potential to lower the most during RCS fill and vent operations?
The lowest loop temperature ensures compliance with LTOP requirements. Loop 1 and 4 receive charging and have the greatest potential to lower as the RCS is filled especially when RHR is aligned to loop 2 and 3.
What limitations are imposed procedurally on the use of QTI-60?
If QTI-60 indicates <130°F then you must use 32°F when calculating spray line ∆T.
Why is backflow from the VCT undesirable?
Particles from the Seal Water Return Filter may enter the seal surface and potentially cause damage.
What elevation is water flow expected to flow through the bulls-eye.
Elevation 631’3” or 1-2% Pressurizer level.
Why is steam bubble formation expected to occur at 280 for 35 psig if Wide Range RCS pressure is 50 – 60 psig?
RCS pressure instruments are located at elevation 614’. Total static head with a full Pressurizer is approximately 27 psig. The actual pressure in the Pressurizer is therefore only about 35 psig.
What is the basis for the temperature limits for bumping #23 and #24 RCPs?
The lower temperature limit ensures PZR spray line ∆T is less than 320°F limit (TRM). The upper limit ensures the RCS remains in mode 5.
Why is it important to designate a single PORV for venting?
Using the PORV raises the probability of seat leakage. Therefore designating one PORV reduces potential maintenance and maintains other PORVs Operable.
What does the procedure mean by cycling the PORV until a minimal change in PRT pressure is detected?
As steam and gas are admitted into the PRT, the pressure will initially rise. However, the steam will condense and the gases will not. Once the gas has been removed from the PRZ, PRT pressure change will be minimal.
Why is seal water return and VCT temperature limited to 130°F?
Temperature limit is based upon RCP seal injection temperature limits.
Which temperature indication is used in the current seal water return lineup, QTI-60 or QTI-451?
QTI-451 when RCP seal return aligned to VCT.
How does throttling closed on the normal spray valves control RCS depressurization?
With the normal spray valves open, charging flow will take the path of least resistance and bypass or short circuiting the spray line/Pressurizer backflowing into the loops 3 and 4. Throttling these valves closed forces charging flow into the Pressurizer.
What do we consider running a RCP for LTOP purposes?
Note 4 of Table 1 defines running as being longer than 2 minutes. Therefore, full speed bumps and 2 minutes runs do not apply to LTOP.
Why are all 4 RCPs are required to be in operation with Tave > 541°F
to ensure protective instrumentation associated with the loops are operable
Spray differential temperature limits are only applicable when Auxiliary Spray is in-service. What is the temp?
TRO 8.4.2 – 320°F
Cool down of the RCS is limited to _____. If you exceed the cool down rate, you must______.
100oF/hr
be less than 100oF/hr within 30 minutes
What are the concerns associated with cool down rates of the RCS?
Faster cool down rates lead to a delta T forming across the vessel wall. The inside wall is attempting to contract which causes tensile stress while the outside wall is contracting slower (relative to inside wall) causing compressive stress.
Why are we concerned with the surge line temperature? (What can cause large changes in the surge line temperature?)
The pressurizer will typically be hotter than the RCS due to the heat being added by the pressurizer heaters to maintain saturation operating condition. Changes in net charging can cause insurges or outsurges. These can cause rapid temperature changes in the surge line and lower half of the pressurizer.
Why is it necessary to use NLI-151 and the correction figure to determine PRZ level?
The NLI-151 Cold Cal indicator compares the weight of the water in the pressurizer vs. the weight in the reference column. The indicator is calibrated using a reference temperature of 150ºF. If the water temperature of the PRZ is hotter than 150ºF it is less dense. Therefore, the indicated level will read lower than the actual level in the pressurizer.
What is the coincidence and function of P-12?
P-12 - 2/4 Tave<541ºF, Function: Permits the block of steam line SI and auto blocks operation of all steam dumps. Allows manual bypass for Group 1 dump valves.
What is the U-2 setpoint, coincidence, and function of the steam line break SI?
500 psig on 1/1 on 2/4 SG steam pressures - protects against (+) reactivity addition
What is the coincidence and function of P-11?
P-11 - 2/3 PRZ Pressure channels < 1910 psig, Function: Permits the block of PRZ Pressure SI.
What concerns are there with stopping the RCS cool down in regards to the PRZ? (Subcooling? - Insurge?)
If the RCS cool down is stopped but the de-pressurization is continued, subcooling could be lost.
Since charging is > than letdown to accommodate the density change, the PRZ will start to fill from the RCS - Insurge - causing a temperature transient on the surge line and lower PRZ
Why do we have a LTOP system? What is it protecting against?
over pressurizing the RCS at low temperatures.
This could lead to possible failures due to rapid pressure rise on a relatively cold system. One PORV or RHR Suction Safety can provide sufficient mass relief capability for a transient caused by the inadvertent start of a single CCP.
What is the RCS temperature associated definition of MODE 5?
When the average of all the T-hot and T-cold instruments is less than 200ºF
What are interlocks and requirements to start a RCP?
Interlocks to start RCP: Lift Pump running, Lift Pump discharge pressure ≥ 510 psig.
Ensure RCP seal differential pressure > 215 psid.
Systems required to establish Condenser Vacuum:
o Condensate System – cool SJAE condensers
o TACW system – cool Gland Steam Condensers
o Aux Steam for steam seals
o Circulating Water System
o Miscellaneous Drain Tank – SJAE drains
o The Main Turbine (MFPs if establishing MFP Condenser vacuum) is on turning gear
o #2 Feed water Heaters
Why will the hot calibrated channels read higher than actual level if the temperature in the Pressurizer is below normal?
The Pressurizer hot calibrated channels are calibrated at a temperature of 653º F. If the temperature in the Pressurizer is less than 653º F, the density of the water is higher and exerts more pressure on the variable leg of the D/P cell. This results in the D/P between the variable and reference legs lowering and is seen as a higher level in the Pressurizer.
Admin half loop is
614.6 foot elevation
How would a low gas pressure in the PRT relative to the RV head change the relationship between indicated level and actual level?
A high relative pressure in the PRT/tailpipe line will artificially depress indicated level relative to actual level in the system.
Why is containment closure a concern?
Concerned about loss of RHR and eventual RCS boiling with resultant release. Loss of RHR procedure has time to boil graphs. Time to boil after loss of cooling is a briefing item at reduced inventory.
Why is hot leg vent path required? (≥ 0.5 ft2)
Provides steam space vent which provides cooling (break flow) and allows more ECCS flow to be delivered to cool core since pressure is maintained lower (in particular, gravity feed of RWST is impacted by a repressurized RCS).
Why is maximum RHR flow rate at reduced inventory 4000 gpm?
To prevent air entrainment/vortexing and loss of RHR pump.
What is the Alternate cooldown flowpath?
Injection path (from W RHR HX) going to cold legs 2 & 3 when RCS temperatures above 200ºF and thermal sleeves required.
Why only one RHR pump running at a time at half loop?
To prevent air entrainment.
What is done to prevent RHR suction valve closure? What mode must the plant be in to do this?
Remove power from valves.
MODE 5 – The ability to close the suction valves to respond to a MODE 4 LOCA requires that they be energized in MODE 4.
Why would you direct RHR return flow to hot leg 2?
Hot legs 2 and 3 are paired and (some) flow is directed to hot leg 3 during pressurizer out surges to keep the hot leg subcooled with mixing from cooler RHR flow when hot water moves out of the PRZ
How is RHR flow throttled to maintain it less than 4000 gpm?
Hx outlet valve and bypass valve are worked fully open (incrementally) and injection line containment isolation valve is throttled closed so that flow is 4000 gpm with AOVs wide open.
