Westinghouse Electric Corporation

The United States of America As Represented by the United States

James M Pope

Don E Harrison

Edward Jean Lahoda

Kenneth C Radford

Susan Wood

Disclosed is a process for making a cinder aggregate from neutralized PUREX waste. The PUREX waste is concentrated to about 30 to about 40 percent solids and a colloid of such de-alcoholated alkoxides of silicon, boron, and aluminum are added to the PUREX waste as are necessary to produce a mixture containing about 0.0001 to about 1 percent aluminum hydroxide, about 5 to about 15 percent silica, and about 1 to about 3 percent boric oxide. The resulting mixture is heated to about 400 to about 700.degree. C. which produces a cinder. The cinder will be transported to a vitrification center where it can be disintegrated in ammonium hydroxide and the nuclear waste can be permanently encapsulated in glass.

Cinder aggregate from PUREX waste

Disclosed is a method of containing nuclear waste. A composition is first prepared of about 25 to about 80%, calculated as SiO.sub.2, of a partially hydrolyzed silicon compound, up to about 30%, calculated as metal oxide, of a partially hydrolyzed aluminum or calcium compound, about 5 to about 20%, calculated as metal oxide, of a partially hydrolyzed boron or calcium compound, about 3 to about 25%, calculated as metal oxide, of a partially hydrolyzed sodium, potassium or lithium compound, an alcohol in a weight ratio to hydrolyzed alkoxide of about 1.5 to about 3% and sufficient water to remove at least 99% of the alcohol as an azeotrope. The azeotrope is boiled off and up to about 40%, based on solids in the product, of the nuclear waste, is mixed into the composition. The mixture is evaporated to about 25 to about 45% solids and is melted and cooled.

Alcohol-free alkoxide process for containing nuclear waste

A method is disclosed for producing a dimensionally stable UO.sub.2 fuel pellet of large grain mole %, and relatively large pore size. A dopant containing an element selected from the group consisting of aluminum, calcium, magnesium, titanium, zirconium, vanadium, niobium, and mixtures thereof is added to a highly sinterable UO.sub.2 powder, which is a UO.sub.2 powder that is sinterable to at least 97% theoretical density at 1600.degree. C. in one hour, and the UO.sub.2 powder can then be formed into fuel pellets. Alternatively, the dopant can be added at a step in the process of producing ammonium diuranate. The ammonium diuranate is collected with about 0.05 to about 1.7 mole%, based on UO.sub.2, of a compound containing said element. That mixture is then calcined to produce UO.sub.2 and the UO.sub.2 is formed into a fuel pellet. The addition of the dopant can also be made at the hydrolysis stage in the manufacture of UO.sub.2 by a dry conversion process.

Method of making stable UO.sub.2 fuel pellets

Disclosed is a method of immobilizing nuclear waste in glass. A composition is prepared of 60 to 100% of a hydrolyzed glass-forming silicon compound and up to about 40% of a glass-forming aluminum compound. About 1 to about 50% liquid nuclear waste and up to about 10% solid nuclear waste is mixed into the composition. The composition is heated at about 200.degree. to about 500.degree. C. to drive off water and organics, with the resulting vitreous product totally containing the nuclear waste. Finally, this product can be sintered at about 800.degree. to about 900.degree. C. to reduce porosity, or warm pressed into block form.

Containing nuclear waste via chemical polymerization

Disclosed is a method of immobilizing nuclear waste in glass. A composition is prepared of about 30 to about 85% of a hydrolyzed glass-forming silicon compound, about 5 to about 30% of a glass-forming sodium compound, up to about 30% of a glass-forming aluminum compound, and about 5 to about 30% of a glass-forming boron, calcium, or magnesium compound. Up to an equal amount of nuclear waste is mixed into the composition and the mixture is heated at up to 500.degree. C. until dry. The mixture is then melted at 800.degree. to 1300.degree. C., and can be poured into ingots and cooled. The mixture can also be melted in situ with a laser.

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Monroeville, PA, United States of America

James M Pope