Dependence of the thermophysical properties of alloys of the Fe - Cr - Al - Si system on the composition and temperature

Abstract

Pressurized water reactors (PWR, VVER, EPR, CAP) are currently the backbone of the world's nuclear power industry. The fuel in this type of power plants is uranium dioxide pellets enclosed in a sealed zirconium shell. Loss Of Coolant Accident (LOCA) emergencies can cause partial or complete destruction of zirconium claddings and accumulation of hydrogen in the reactor pressure vessel and reactor building. This is due to the so-called steam-zirconium reaction: an exothermic process of zirconium oxidation in an atmosphere of saturated water vapor at temperatures above 900 °C. The products of this reaction are hydrogen and brittle zirconium oxide, which collapses under the action of its own weight and the weight of the fuel column. Fuel for pressurized water nuclear power reactors that is resistant to a loss of coolant accident is the subject of research around the world. One of the ways of implementation is the use of alloys of the Fe – Cr – Al system as a fuel element cladding material, since they have high corrosion resistance in water. The work is devoted to the determination of the coefficient of linear thermal expansion (CLTE), specific heat capacity, thermal conductivity and the influence of composition on them for Fe – Cr – Al – Si alloys in the temperature range of 200–1000 °C. New data on the dependence of the thermophysical characteristics of alloys of the Fe – Cr – Al – Si system on temperature and chromium concentration have been obtained. It is shown that the CLTE, specific heat capacity and thermal conductivity weakly depend on the chromium content in the studied concentration range, the main contribution of alloying elements is made by the position of the Curie.