Industry and research have been using ionising radiation sources for a long time in a variety of applications.

Material testing

One of the non destructive testing techniques uses radioactive sources: gammagraphy, which assesses the lack of homogeneity in metal, in particular in weld beads. This technique uses sources of highly active iridium 192 and cobalt 60 (usually around 3 TBq).

Monitoring of industrial processes

The most commonly used radioactive elements are krypton 85, caesium 137, americium 241, cobalt 60 and promethium 147. Source activities range from a few kBq to several GBq.
Sources are used to:

• measure dust accumulation in the atmosphere;
• measure paper grammage;
• measure the level of liquid;
• measure soil density and moisture. When sources are sealed and used appropriately, they generally represent little risk to the environment, the general public and the workers.

Research

The main radioactive elements used in research are mostly in the form of unsealed sources: phosphorus 32 or 33, carbon 14, sulphur 35, chromium 51, iodine 125 and tritium. They are used as tracers and/or for metrology purposes. The main risks are personnel contamination and radionuclide dispersion, notably in waste.

Waste management and radioactive discharge

The handling of unsealed sources generates radioactive waste, in solid or liquid form.

Short-lived radioactive elements (less than one hundred days half-life) can be collected and stored for a duration of approximately ten times the half-life of the radioactive element, sufficient to allow the radioactivity to practically disappear. Subsequently, this waste can be disposed of after inspection in traditional waste disposal channels and liquid wastewater is discharged after verifying that its activity is lower than regulatory thresholds.

Radioactive elements with a half-life higher than 100 days are collected and treated by the National Agency for the Management of Radioactive Waste (ANDRA).

Disposal of sealed sources is ensured by the source supplier or by ANDRA.

Measurement units and limit exposure values:

To quantify radioactive emissions, scientists have established three units designating different phenomena:

• the Becquerel (without a unit) measures the number of atom disintegrations per second;
• the Gray (Joule/Kg) measures the energy transferred and absorbed by the exposed organism;
• the Sievert (Joule/Kg) assesses the effects of the radiation received on the organism.

Annual exposure limits

Maximum permissible levels for the marketing of food products (in Bq/kg)