The AKNP-IF neutron flux monitoring system is a part of a control and protection system (SUZ) of NPP units.

Functions of AKNP-IF:

  • 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 unit’s I&C 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.

Composition of AKNP-IF:

  • two sets of AKNP-IF APZ-SKP for SUZ and a main control room;
  • one set of AKNP-IF BCR for a backup control room.

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;
  • registration 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.


Detection unit
for start-up
and working rangesв

Detection unit for SKP

System advantages:

  • automation of calibration of neutron flux density monitoring channels during operation of AKNP-IF using a metrologically certified reactor kinetics simulator developed by SRPA “Impulse” (signals are simulated in a whole range of neutron flux monitoring without necessity of access to sensors in a restricted zone);
  • high accuracy due to use of highly sensitive boron and helium neutron sensors;
  • integration of a fuel reload monitoring system into AKNP;
  • absence of influence of residual readings of detection devices after power operation due to use of fluctuation mode of an ionization chamber;
  • possibility of operational calibration of power readings in MCR with automatic recalculation of calibration coefficients;
  • high fail-safety of the system due to use of redundant hardware and diverse software.

Safety class – 2.
Safety category – А.

Implementation facilities:

  • Zaporizhzhya NPP, units 1-6
  • Khmelnitsky NPP, units 1, 2
  • Rivne NPP, units 1-4
  • South-Ukraine NPP, units 1-3
  • Armenian NPP, unit 2

SRPA “Impulse” is a leading Ukrainian designer, manufacturer, and supplier of highly-reliable instrumentation and control systems for nuclear power engineering and railways.
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