Radiation Changes in the Nanostructure of Graphite-Like Boron Nitride and Monitoring of the Temperature of In-Channel Reactor Irradiation

摘要

Abstract— Graphite-like materials, due to the strong anisotropy of the crystal structure, are microscopically different-modular; i.e., they have significantly different elastic resistance to tension and compression at the subatomic level. As a result of microscopically different modularity, the crystallite microdeformations unavoidable in ceramic materials cause large shifts and nonuniform broadening of X-ray lines. Reactor irradiation changes both the magnitude of microdeformations and the microscopically different modularity of graphite-like nanostructured materials. The microscopically different modularity of boron nitride ceramics is analyzed by X-ray line decomposition (00l) using Lorentz functions. In pyrolitic materials (very microscopically different-modular materials), it is necessary to use approximation by the Poisson distribution of X?ray lines rearranged in dimensionless coordinates (00l). A method for determining the temperature during high-dose (up to 3 × 1023 n/cm2) high-temperature (up to 1800 K) reactor irradiation of material science containers using pyrolytic boron nitride monitors is described. The method uses the relationship between the magnitude of induced microscopically different modularity of the material and the irradiation temperature.