Effect of the control element group position on integral neutron flux through the WWER-440 reactor vessel lateral surface

Effects of control element group position and boron concentration is a coolant on indications of power meter which is used in the armennian-1 reactor is evaluated. The power meter monitor is placed under the reactor vessel near its geometrical axis. Radiation field in the monitor location area is formed primarily by neutrons, which have passed through the reactor vessel lateral surface into the space between the vessel and the concrete shield and which have undergone several scatterings. Calculations and experiments have shown, that the change in control element group position from the complete submersion up to the complete withdrawal (under stable reactor power) reduces integral neutron flux through the reactor core lateral surface by 10-15%. The change of boron acid concentration in a coolant in the range of 2.5-6.8 g/kg does not influence significantly the integral neutron flux and power meter indications