METHODS AND MEANS OF CONTROL OF NUCLEAR MATERIALS AND STATUS OF PROTECTIVE BARRIERS AT NPP IN WARTIME CONDITIONS

Abstract

The level of development and application radiations technologies is largely determined by the state of nuclear instrumentation. In a relatively short period of time, this industry went through several stages of development, and each them was marked by the appearance of various devices that register and measure the parameters of ionizing radiation nuclear materials: gas discharge counters, scintillators, semiconductor detectors, and others.
The appearance of modern semiconductor radiation sensors for the first time connected nuclear instrumentation and electronics into a single complex - a semiconductor detector. It combines a semiconductor primary converter of ionizing radiation (sensor), a secondary converter of information from the sensor (electronics) and software for processing this information, which are interconnected by the problem to be solved and parameters. However, the development of atomic energy, spread of nuclear technologies in various industries has put forward new requirements for the control and metrology of ionizing radiation, which cannot be fully satisfied by modern level of nuclear instrumentation and applied nuclear physics research. The new generation radiation sensors and measurement systems based on them created in this work open up previously unknown opportunities in solving the problems of nuclear fuel analysis, increasing the accuracy and efficiency of monitoring technological parameters and the state of protective barriers in nuclear power plants, and creating means for MASATE inspections.
In the work, the use of algebraic reconstructive passive tomography (APT) methods for the reconstruction of the image of the internal structure of heat-emitting assemblies is proposed for the first time. For this purpose, a new algorithm for passive tomography of nuclear fuel was developed using the example of VVER-1000, which uses the method of angular projections own radiation of heat-emitting assemblies (HEA). Computer tomography experiments of this object showed that radiation intensity measurements at 360 points of the detector location relative to HEA axis are optimal for two or more values of the gamma radiation energy of the reference isotope 134Cs. In this case, the proposed APT method makes it possible to identify defective tvels cells with a leakage level of more than 30% on restored tomograms, as well as the absence of tvels cells in HEA.