Waste Technology Section

Management of Disused Sealed Radioactive Sources


What is a Sealed Source?

A sealed radioactive source is a small device containing encapsulated radioactive material, which usually has the appearance of a small, harmless piece of metal. In more technical terms, it is radioactive material that is (a) permanently sealed in a capsule or (b) closely bonded and in a solid form. The capsule or material of a sealed source is strong enough to maintain leak tightness under the conditions of use for which the source was designed, and also under foreseeable mishaps. Such sources usually have high radioactivity concentrated in a small volume (high specific activity) that, if lost, not properly controlled or fall into the wrong hands can present a risk to public health and the environment, possibly resulting in significant social and economic disruptions.

 

Why use a sealed source?

The first use of a sealed source dates back to 1901. Until the 1940s sources were made only using naturally occurring isotopes (radium and polonium). Today sealed sources are made of numerous radioisotopes. Such sources are used in various human activities (e.g. medicine, agriculture, industry, transportation, construction, geology, mining, research, etc.). In most of these areas use of these sources either cannot be replaced by other methods or provides results that are unmatched by other methods.

Functions

- Level Measurement;

- Measurement of Minimum and
maximum levels;

- Density measurement;

- Process control (material
flow/supply)

 

In normal and extreme process conditions, e.g.:

- High pressure;

- High temperatures;

- Toxicity;

- Abrasion;

- Viscosity.

 

 

Where and how many
sealed sources exist?

Sealed sources are in use worldwide. It is estimated that several million individual sources exist in various countries. By far the largest numbers are located in the developed countries. Most sources are shipped to countries through direct sale, many however, have been provided by donations, international cooperation programmes and medical practitioners joint activities. International engineering firms have brought, in the course of their work, a considerable number of sealed sources to developing countries.