Protective Coating of Irradiation Device for Fast-Neutron Reactor

Abstract

The objective of this paper is to select a coating on the surface of zirconium hydride (ZH) in order to reduce hydrogen losses under the operating conditions of an irradiation device of FN-reactors. Tests were carried out on the samples of the moderator units made of zirconium hydride. Oxide, phosphide-oxide and oxide-enamel coatings were considered as a protective layer. Hydrogen yield out of the ZH was studied using a calorimeter and a mass spectrometer by thermal heating of the samples according to the test program (heating rate of 10 °C/min, maximum temperature of 1000 °C, isothermal exposure of 40 min, cooling with a furnace). The hydrogen content in the samples was determined by high temperature vacuum extraction. It is shown the oxide coating is the most technologically advanced and effective. A thermogravimetric analysis of the ZH sample with the protective oxide coating was carried out, and the temperature-time dependence of a stoichiometric coefficient (H / Zr) was determined. The amount of the hydrogen released was determined in a temperature range of 20–1100 °C. The temperature increase in up to 1100 °C leads to almost total loss of hydrogen (98–99 %). In this case, the sample retained its integrity, and the coating exfoliated and fragmented.