Neutron flux monitoring system
The system is a part of a control and protection system (SUZ) of NPP power units.
Functions:
- monitoring, continuously registering, and archiving current values of reactor relative physical power, velocity (period) of its change, and reactivity;
- generating discrete signals on exceeding emergency and preliminary protection setpoints, setpoints of control and regulation by relative physical power and period for SUZ and power unit’s ICS subsystems;
- presenting analog and discrete signals in the optical and acoustic form to operators of main, backup control rooms and a fuel reload machine, to operating personnel;
- automatically correcting neutron power measurements taking into account thermal physic and other parameters characterizing state of a reactor facility;
- monitoring fixation of in-core devices by results of neutron detector signal fluctuation analysis;
- monitoring subcriticality of a reactor facility.
The system includes two sets of APZ-SKP for SUZ and MCR, one set for BCR.
Each set includes three independent channels of neutron flux monitoring. Each neutron flux monitoring channel consists of:
- detection devices containing:
- detection units based on ionization chambers (for startup and operating ranges), on boron or helium corona radiation-resistant highly sensitive neutron counters (for an SKP fuel reload monitoring system);
- amplification and digital conversion units;
- an accumulation and processing device;
- a device for input of power setpoints;
- recording and display units for a main control room and a fuel reload machine panel to display and archive current parameters, as well as to transfer information to unit’s adjacent systems – common for three neutron flux monitoring channels.
Advantages:
Automation of calibration of neutron flux density monitoring channels
during operation using a reactor kinetics simulator developed by SRPA “Impulse”;
High accuracy
due to use of highly sensitive boron and helium neutron sensors;
Integration of a fuel reload monitoring system into the system;
Absence of influence of residual readings
of detection devices after power operation due to use of fluctuation mode of an ionization chamber;
Possibility of immediate calibration of power readings in MCR
with automatic recalculation of calibration coefficients.


