Use of Vacuum in Processing of Uranium

摘要

Natural uranium in the form of metal and alloys with suitable heat treatment are being used as fuel in research and some power reactors. The fuel is required to satisfy the purity specifications from the criteria of neutron economy, corrosion resistance and fabricability. Uranium and its alloy fall under the category of reactive materials. They readily react with atmospheric air to form oxides. If molten uranium is exposed to atmosphere, it reacts violently with atmospheric gasses and moisture, leading to explosion in extreme cases. Hence, protective inert atmosphere or high vacuum is required in the processing of these materials, especially during the melting and casting operation. Vacuum is preferred for melting and re-melting of metals and alloys to remove the gaseous and high volatile impurities, to improve the mechanical properties of the material. Also, under vacuum sound castings are produced for further processing by mechanical working or use in casting forms. The addition of reactive alloying elements in uranium is efficiently carried out under vacuum. The paper highlights vacuum systems deployed and applications of vacuum in various operations involved in the processing of uranium and its alloys.