Vitrification

DOE-HDBK-1132-99

and D&D projects. For example, considerations related to electrical power,

radiation shielding, structural integrity, and work process controls, are

discussed in the preceding section on D&D projects.

VITRIFICATION .

2.14

2.14.1

Introduction . The process of vitrification is the melting and fusing of

materials to produce a glass. It is one of the preferred treatment options for

many types of hazardous and radiological waste. The general design

considerations in developing a vitrification plant are discussed below.

2.14.2

General Vitrification Processes and Steps to Consider . Waste composition

may make material more or less amenable to the use of vitrification as a

treatment technique. It affects pretreatment required and influences the

transport of material within a vitrification plant. Characteristics to consider

include the following:

Physical Characteristics . Physical characteristics of the waste material,

including whether the material is in solution, a slurry, or a solid, influences

transport within the plant and the material' ability to form a homogenous

mixture with glass formers. Imposed constraints on transport, mixing, melting

the material, and the need for pre-treatment are all considerations subject to

physical characteristics of the waste.

Chemical Characteristics . Certain chemicals (notably sulfur) are

incompatible with vitrification and if present influences the amount of final

waste produced. Other chemicals may be volatile and very difficult to retain in

the glass product. Factors like pH may complicate the process of mixing a

final feed material, due to rheological considerations or corrosion.

Radiological Characteristics . The radiological characteristics dictates

shielding requirements, remote operations, off-gas processing, and possibly, a

requirement for criticality controls.

2.14.3

Waste Extraction from Tanks . Waste extraction from tanks is the first step

in the actual vitrification process. (Some in situ vitrification techniques

eliminate this and many other steps discussed below, but this technology is

I-144