METHOD FOR DETERMINING REACTIVITY COEFFICIENTS FROM FUEL TEMPERATURE AND COOLANT DENSITY FOR THE REGION OF LOW POWER LEVELS FOR HIGH-POWER NUCLEAR REACTORS SUCH AS PRESSURIZED WATER POWER REACTORS Russian patent published in 2022 - IPC G21C7/00 

FIELD: nuclear power plants.

SUBSTANCE: invention relates to a method for determining the reactivity coefficients from fuel temperature and coolant density at nuclear power plants with large-capacity VVER-type nuclear reactors. For the region of low power levels, before the initiation of the transient process in the reactor, the temperature of the coolant in the primary circuit and the power of the reactor are stabilized at a level at which the temperatures of the fuel and coolant in the core do not differ. Then, a transient process is initiated by introducing a positive reactivity by moving the group of control elements upwards, and after the reactivity decreases to zero, due to the action of temperature feedbacks, a negative reactivity is introduced into the core by moving the group of control elements downward. In the course of these processes, the values ​​of the currents of the ionization chambers are recorded according to the readings of the neutron flux control equipment, the temperatures of the coolant in the threads of the primary circuit before entering the reactor and after leaving it, and the position of the regulatory bodies; additionally, the flow rate of the coolant through the reactor and the pressure in the coolant of the primary circuit are recorded. Based on the data obtained, the desired reactivity coefficients are determined.

EFFECT: determination of reactivity coefficients by fuel temperature and coolant density for the region of low power levels for a high-power nuclear reactor of the VVER type.

6 cl, 13 dwg, 3 tbl