Implementation of a laboratory for measuring thermophysical properties of nuclear fuels and materials through flash laser method at CDTN

In this work, a project for a thermal conductivity measuring system using the flash laser method is presented. This project lead to the implementation of a laboratory at CDTN, equipped with a system for measuring thermophysical properties of general-purpose materials, with emphasis on nuclear fuels. In this method, a light pulse of short duration and high intensity, provided by a power laser beam, is applied to one side of a small dislike sample. This produces an account of the resulting temperature on the opposite side, as measured by a temperature sensor. The thermal diffusivity is determined from the thickness of the sample, and the time for the temperature on the opposite side of sample, to rise to a specified fraction of its maximum value. The specific heat is calculated from the maximum temperature as indicated by the temperature sensor, whereas the thermal conductivity is determined by the product of the thermal diffusivity, the specific heat and the density of the sample. This method has been used to evaluate materials whose thermal diffusivities vary in the range from 1.1x10-6 m2.s-1, under temperatures ranging from 80 K to 3000 K, providing information within seconds this method has been used to measure the thermal diffusivity of metals, alloys, ceramics, material used in nuclear reactor fuels, semiconductors, composites, liquid metals, carbon fibers, materials strengthened by fibers, individual layers or layered composites, thermal contact conductance in interfaces, and dispersed composites, as well as other regular measurements. It has been shown that by using suitable mathematical models, it is possible to keep measuring errors below 0.5. (author)