Module 101 - Properties of Uranium

DOE-HDBK-1113-98

Radiological Safety Training for Uranium Facilities

Module 101 - Properties of Uranium

I. MODULE 101 - Properties of Uranium

A. Objective

EO1

Describe the physical, radioactive, toxicological, and chemical properties and biological

effect s of uran ium.

B. Physical Properties

Uranium can be encountered as a solid, liquid, or gas, depending on its chemical form and

surrounding conditions. Each of these physical forms has particular hazards. Sometimes, changing

the form of uranium can lead to radioactive decay products accumulating or becoming concentrated

in a particular location, such as on the surface of a liquid. The result can be an apparent increase in

the radioac tivity.

1. Solid

The solid forms of uranium are generally the most stable configurations. The shiny, silvery

metal form is rarely seen except in a workshop when it is being machined. After machining, the

surface oxidizes, typically within hours, to a hard, black surface.

After some time, depending on temperature, humidity, and alloy, the surface may change color

and begin to flake. Orange or yellow co lored su rfaces are usua lly more fl aky and sol uble. In

these forms, co ntamination c an be more easil y spread, inhal ed, and absorb ed into the bod y.

2. Liquid

Uranium melts at 1133C, so molten uranium is unusual, except in a foundry. It has often been

observed that the radioactivity appears to increase when uranium is melted. This is because

radioactive decay products, such as radium and thorium, float to the surface. The density of

radium is 5 g/cm3, compared with 19 g/cm3 for uranium; therefore, radium floats in molten

uranium.