Radioecology and health impact of the carbon-14 contamination on the Ganagobie site (Provence, France)

In 2001, at the Prefecture's request an investigation was carried out by OPRI at Isotopchim (Ganagobie), an industrial firm specialized in organic radioactive molecule synthesis (mainly carbon-14), in order to evaluate the dosimetric and consequently the health impact related to the site's contamination and its geographical spreading. The study of the carbon-14 air spreading brought to the fore high radioactivity levels in different areas of the plant especially in the laboratory where the surface contamination reached a level higher than 20 000 Bq/cm2. The study also demonstrated the association of strongly radioactive materials with highly inflammable chemicals stored in critical conditions. As a result of OPRI's recommendations, a security perimeter was set up around the plant in order to avoid any uncontrolled spreading of the radioactivity. The cartographic study showed the decrease of the specific marking proportionally to the distance with regard to the point of release and to the atmospheric spreading linked to local climatic conditions. A significant radioactive marking was measured in the soils (66 000 Bq/kg C) and in the plants (25 000 Bq/kg C) within a 50 meters radius around the facility. In spite of the extreme scenario, the values showed after the dose calculations were much inferior to the authorized limit set out by Directive Euratom 96/29 (1 mSv/year). The site features a rather rare example of manifest carbon-14 contamination. Therefore, it can lead to a further in situ study of the repartition, elimination or concentration of the carbon-14 in the soil and in the biological indicators. (authors)