Types of radioactive material

Radioactive materials are classified by three categories: open radioactive sources, sealed or closed radioactive sources, and mobile apparatus.

Open radioactive sources

These are radioactive materials that you can readily divide or dilute. They include radioactive gases, liquids and some solids, eg radioactive laboratory chemicals and radiopharmaceuticals. Using these materials can potentially contaminate other materials.

Sealed or closed radioactive sources

The structure of these sources prevents the spreading of radioactive material during normal use. Closed sources include foil or electro-deposited materials. High-activity sealed sources (HASS) are included in this category.

Mobile radioactive apparatus

These include apparatus, equipment, appliances or other things that are radioactive and:

• are designed to be transported from place to place, eg portable soil moisture gauges, or 
• are portable and used for releasing radioactive material into the environment or introducing it into organisms.

You must register mobile radioactive apparatus with the environmental regulator in each part of the UK that you use it.

Radon

Radon is a naturally occurring radioactive gas that can seep out of the ground and build up in your workplace. All employers in the UK must review the potential radon hazard in their premises. See the Health and Safety Executive (HSE) website for more information.

In this guideline: