Nature of Special Tritium Compounds

DOE-HDBK-1184-2004

2 - NATURE OF SPECIAL TRITIUM COMPOUNDS

2.1 General

Hydrogen atoms (including those that exist in the form of tritium) tend to diffuse through

materials with which they come into contact, and may be released at a later time

(commonly referred to as "outgassing"). While this property of hydrogen atoms may

complicate measures implemented to contain tritium, it has been well characterized, and

appropriate materials can be specified to minimize unintended adverse effects. This

property can also be used to practical advantage, as hydrogen atoms can be diffused

through other materials and stored within the matrix for subsequent storage, transportation,

release, and use. The diffusion and outgassing processes may be accelerated through

application of heat.

2.2 STC Host Materials

STCs can be created by intentional combination of tritium with the desired materials or by

inadvertent contamination of a material that has been subjected to the presence of tritium

for a period of time. DOE facilities have used a wide variety of metals (e.g., Ti, Zr, U, and

Hf) in tritium research, purification, and storage, creating an equally wide variety of

materials referred to as "metal tritides." Metal oxides (e.g., rust), siliceous materials

(environmental dust), and carbonaceous materials (e.g., polymers or environmental dust)

can also become tritium contaminated and exhibit particulate properties. Tritium may also

react with organic materials, resulting in the formation of organically-bound tritium (OBT).

The main types of OBT encountered in the DOE com plex are solvents, oils, and solid

particulates (e.g., plastics, nylon, and organic dust forms). OBT can be particulate or non-

particulate in nature.

2.3 STC categorization

In this handbook, STCs will be categorized according to (1) the ease with which the tritium

(either unbound or bound to an STC) can be taken into the blood stream and (2) the

physical form of the STC (e.g. particle, vapor, large solid, and liquid). Table 2-1 illustrates

this classification scheme.

Table 2-1: Categorization of Special Tritium Compounds

Ease of Uptake

Insoluble

Soluble

Large

Liquid/

Physical Form

Particle

Solid

vapor

Vapor

Form

Tritiated

Hf-T

Tritiated Ti

Tritated

U-T

Pump Oil,

Ti-T

source for

Methane,

Pd-T

Examples of

Eu-T

neutron

Tritiated

STCs

Zr-T

generator,

Solvents

Dust

Tritiated

(acetone,

Rust

nylon

octane)

Pump oil

Droplets,

Tritiated

Flyash