Natural Uranium : Yellow Cake & Zircaloy production

 

NURAL URANIUM :

The raw material for the production of PHWR fuel is Magnesium Di-uranate(MDU) popularly known as ‘yellow cake’.   The MDU concentrate is obtained from the uranium mine and mill at Jaduguda, Jarkhand, operated by Uranium Corporation of India Ltd.    The impure MDU is subjected to nitric acid dissolution followed by solvent extraction and precipitation with ammonia to get Ammonium Di-uranate (ADU).   By further steps of controlled calcinations and reduction , sinterable uranium dioxide powder is formed which is then compacted in the form of cylindrical pellets and sintered at high temperature to get high density uranium dioxide pellets.

For BWR fuel, the enriched uranium hexafluoride is subjected to pyrohydrolysis and converted to ammonium di-uranate which is treated in the same as natural ADU to obtain high density uranium dioxide pellets. 

Zircaloy production :

The source mineral for the production of zirconium metal is zircon (zirconium silicate) available in the beach sand deposits of Kerala, Tamilnadu and Orissa and is supplied by Indian Rare Earths Ltd.  Zircon sand is processed through caustic fusion, dissolution, solvent extraction (to remove Hafnium) , precipitation and calcinations steps to get zirconium oxide.   Further, the pure Zirconium oxide is subjected to high temperature chlorination, reactive metal reduction and vacuum arc melting to get homogeneous zirconium sponge.   The sponge is then briquetted with alloying ingredients and multiple vacuum arc melted to get homogeneous zircaloy ingots which are then converted into seamless tubes, sheets and bars by extrusion, pilgering and finishing operations.