Сriterion Method for Determining the Conditions for Occurrence of Thermoacoustic Instability in the Reactor Core

Abstract

The subject of research is the thermoacoustic instability (TAI) of the coolant of a nuclear reactor core. The occurrence of TAI in the reactor core leads to high-frequency and high-amplitude cyclic loads on internal reactor structures and can be one of the reasons for the loss of tightness of fuel elements. A criterion method has been developed for determining the boundaries of the coolant TAI area in the nuclear reactor core under operating, transient and emergency modes. Based on the developed method, the occurrence of TAI area in the coolant was determined, with the criteria of TAI being formulated. A dimensionless determining criterion of the TAI area was justified depending on the rate of heat release, flow rate and enthalpy of the coolant at the entry to the reactor core. Applying the format of dimensionless parameters, the area of TAI of a water-cooled reactor core has been determined, with the relative power of the reactor being more than 0.25 and the relative flow rate of the coolant being less than 0.75.