Centrifugal Separation - hdbk1113cn10128

DOE-HDBK-1113-98

Radiological Safety Traning for Uranium Facilities

Module 102 - The Nuclear Fuel Cycle

Centrifugal Separation

Centrifugal separation is based on heavier compounds migrating to the outside

when spun at a high rate of speed.

238

The uranium le ft over from the e nrichment pro cess is mostly

U, with a reduced amount

of 235U (usually 0.2% by weight). This byproduct is called "depleted uranium" and has

additional uses such as radiation shielding, armor plating, and ammunition.

During World War II, uranium work was secret and code names were used for the

different forms of uranium. Natural uranium was named "Tuballoy," a name that grew

out of a cover story that the Allies were investigating alloys for high-quality tubing.

Highly enriched uranium was then named "Oralloy" for "Oak Ridge Alloy," sometimes

abbreviated to "Oy." Depleted uranium was once called depletalloy, but more commonly

was called "D-38" since it consists mostly of 238U. These historical names are sometimes

still used within the DOE complex.

Fabrication

The last step in the nuclear fuel cycle is changing the enriched uranium into an

appropriate form for fabrication. The fabrication process differs depending on the

application. For fabrication of fuel elements, the process generally includes the

following steps.

Uranium dioxide (UO2) is produced by reacting UF6 with water and then with a

hydroxide salt.

The resulting precipitate is dried to form "orange oxide," which is reduced with

hydrogen to form UO2 powder.

The UO2 powder is compacted into cylindrical pellets that are loaded into thin-

walled tubes made of either stainless steel or an alloy of zirconium called

"zircalloy."