Excore NI's Flashcards
What is the purpose of the Excores NI system?
provides reactor power signals to protection and control circuits
All of the detectors are located outside of the reactor vessel and measure neutron flux that leaks from the core
What trips are provided by RPS regarding excore?
Which trip is associated with the Safety channel linear power signals?
what trip is associated with the Safety Channel log power signals?
VOPT, Hi Log Power
VOPT
Hi-Log Power
What does Log Power provide a permissive to RPS for?
bypassing the Hi-Log Power trip when starting up the plant
What happens if the Excore NI signals fail high?
VOPT or Hi-Log Power trips may occur
When do Log Power channels provide a permissive to the Core Protection Calculators?
low power levels
What happens if a control channel signal is lost to Reactor Regulating system?
AMI (auto-motion inhibit)
What happens if a control channel signal is lost to Steam Bypass Control system?
the SBCS may generate a low power (< 15%) AMI (auto-motion inhibit).
What are the startup channel proportional counter chambers filled with?
Where are the startup channels powered from?
BF3
NNN_D11/D12
What are the control channel uncompensated ionization chambers filled with?
Where are the control channels powered from?
Boron LINED
NNN-D11/D12
What is the signal flow path for a Control Channel?
detector > amplifier > summer (develops an average power signal) > CAL SUM amplifier (creates a calibrated control channel power signal) > signals sent to recorder and indicator, PMS, DFWCS, and RRS
When using the calibration pot at the control channel drawer, what points do you calibrate it to?
JSCALOR (normal)
NKBDELT (if needed)
Where do the safety channel detectors get power from?
PNA/B/C/D
How many detectors per startup channel?
Control Channel?
Safety Channel?
1
2
3
Where does Log power receive its signal from?
Down to what measurement will these log power indicators read?
What is the purpose of the Log power portion of this system?
the middle detector on the safety channels
2 x 10^-8%
to prevent inadvertent low power criticality
What trip signals will the Excore safety channels provide to PPS?
VOPT
HIGH LPD (21 kW/ft)
Low DNBR (<1.34)
High Logarithmic Power
What does the LOG 1 bistable do?
Actuates at 10^-4% log power and rising and provides a permissive to permit the operator to MANUALLY bypass the high log power trip.
The bypass is AUTOMATICALLY removed at 10^-4% and lowering.
What does the LOG 2 bistable do?
Actuates at 10^-4% power and lowering (conservatively set to 10^-5% power after fuel loading) and provides a permissive to MANUALLY bypass the DNBR and LPD trips (CPC trips).
The bypass is AUTOMATICALLY removed at 10^-4% and rising.
What is the purpose of the rate circuit that is included in the lo circuit?
measures the rate at which log power level is changing in decades per minute (DPM)
For the safety channels, the three detectors provide power to the summer block. What happens if one detector is lost?
What else happens when you lose the middle channel specifically?
the linear power signal will go to 66-67% at 100% power
log power will go to 0% at 100% power
Where are the “A” and “B” safety channel preamplifiers located?
what are they used for?
outside containment
post-accident monitoring
Why do the startup and safety channels have preamplifiers?
used as wide range detectors, therefore they need to indicate power in the source range
Explain how the Boron Dilution Alarm System (BDAS) works?
setpoint follows actual going down
going up in power, setpoint doesnt follow, so you will have to reset it frequently
regarding the Boron Dilution Alarm System (BDAS), what happens when you push the reset push button?
the alarm setpoint resets to ~ 1/3 decade above the current input flux signal
When are the safety channels normally inservice?
Startup channels?
Control Channels?
normally. like all the time
when reactor is shutdown and during startup up to 10k CPS
above 10k CPS
What is needed to swap from the startup channels to the control channels during a reactor startup?
overlap observed on the safety channel log power indications
How are the Hi-Log trips bypassed?
manually
which Rx power point (JSCALOR or NKBDELT) is used for calibration below 20% power?
above 20% power?
NKBDELT
JSCALOR
At what Log power are Startup channels energized during a plant shutdown?
2x10^-6%
During refueling ops, how many startup channels are required to be operable?
what needs to be done if 1 channel is lost?
2 channels
core alterations must halt
