Diagnostics of sodium boiling stages and process of development within a fuel subassembly by neutron flux noises

The problem of description of the diagnostic parameters of different stages and the process of sodium boiling development in a fuel assembly according to neutron flux noises is discussed. The main data obtained as a result of the experiments realized at the BN-600 reactor are analyzed. The conditions for fulfilment of the experiments concerning the boiling are described. The boiling process is conditionally divided into three stages depending on the diagnostic parameters in neutron noises and the degree of thermal loads in a boiling zone. The neutron noise characteristics typical for each stage are considered. The parameters which measuring provides an opportunity to control the boiling development process course are suggested basing on the physical ideas being in agreement with the experiments