Process for making a ceramic composition for immobilization of actinides

A process for immobilizing plutonium and uranium oxides in a ceramic form comprising pyrochlore, brannerite and rutile, which comprises the steps of:

• milling said oxides using a high-speed attritor mill into powder form to achieve nominal powder particle size of than 20 microns;
• calcining ceramic precursors at a temperature of about 750 deg C., in an air atmosphere for about one hour, said ceramic precursors comprising TiO2 (anatase), Ca(OH)2 and neutron absorber materials HfO2 and Gd2O3;
• blending said calcined ceramic precursors with said milled oxides powder using a high-speed attritor mill to a degree such that uniform blending on a scale of less than 20 microns is achieved;
• granulating said blend with addition of binder and lubricant materials,
• pouring said blend into a die and cold pressing said blend at 2000 psi,
• heating said cold pressed blend to binder burnout temperature of 100 to 300 deg C. and holding at said temperature for one-half to two hours in an air atmosphere;
• sintering said heated blend to 1350 deg C. and holding at said temperature for 4 hours in an air atmosphere;
• and cooling said ceramic to room temperature.

A process for immobilizing actinides in a ceramic form comprising pyroclore, brannerite and rutile, which comprises the steps of:

• oxidizing said actinides;
• milling said actinide oxides into powder form to achieve nominal powder particle size less than 20 microns;
• blending ceramic precursors with said powder, said ceramic precursors comprising neutron absorbers and oxides or hydroxides of titanium and calcium, wherein said blending is accomplished via wet ball milling or an attritor mill;
• pouring said blend into a die;
• cold pressing said blend at a pressure in the range of 1,000-20,000 psi;
• and sintering said pressed blend at a temperature range of 1200-1500 deg C. for 1-8 hours in an atmosphere selected from the group consisting of air, reducing atmosphere and inert atmosphere to form a ceramic material.