SOD System is designed for continuous diagnostics of the first safety barrier status of the core (active zone) of fuel claddings in the course of operation of shipborne nuclear power systems.
Field of application – systems for control and security of nuclear reactors of surface ships and submarines.
The system provides:
- continuous control of hermetic sealing of fuel elements and detection of depressurization;
- generation and processing of a signal proportional to a flux of delayed neutrons;
- display of parameters specifying the current status of neutron flux monitoring channels;
- generation of warning alarm signals.
The system includes two channels to record delayed neutrons (isotopes) in the primary coolant. KNK-15-1 uranium-lined fission-type ionization chambers of the pulse type/current type are used as detectors that must be placed on the pipeline so that they will be sensitive to neutrons of the controlled fission products at the distance from each other, taking into account the neutron sources decay in the coolant.
Emergence of microfractures on the fuel cladding leads to the emission of delayed neutrons into the coolant and, consequently, to the increase of signals from neutron detectors. Excess of difference between two signals over the predetermined limit is a signature of depressurization of the fuel cladding.