IRSN, Institut de radioprotection et de sûreté nucléaire

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Research programmes

The CAROL programme

CAmargue RhOne Languedoc (CAROL) : studying stocks and flows of radionuclides in the environment



The purpose of the CAROL program is to study the distribution of artificial radionuclides in a wide geographical area, identify the respective contribution of various sources of contamination (fallout from nuclear weapons tests, the Chernobyl accident, release from nuclear facilities, etc.), and determine how contamination is likely to evolve over the coming decades.

Studies have focused on three areas:
  • a plain ecosystem including the Rhone drainage basin downstream of the Marcoule nuclear facility as far as the Mediterranean,
  • a mountain ecosystem including the Mercantour national park in the southern Alps,
  • Corsica for estimating radionuclide deposits and transfers in the food chain in May 1986, and studying to what extent they remain in the soil today.


The study of the Rhone River basin has made it possible to assess the stocks of radionuclides in various storage and transit compartments and calculate transfer flows between compartments. In this way, transuranic elements were characterized over the entire area right down into the prodelta.
In the Mercantour national park, soil concentration processes are studied on the scale of a workshop area to understand the mechanisms involved and allow forecasts to be made for similar areas of the French Alps.

This program has brought answers to many questions. As part of a study to explain the presence of cesium-137 in the soil, a quantification was made of the relationship between deposits due to the Chernobyl accident and rainfall during the first week of May 1986 when contaminated air masses passed over France. The first result of this study was a map showing 137Cs deposits in the east of France, later followed by a similar map covering the whole country. By placing this map over another one showing fallout from atmospheric nuclear testing based on measurements taken by OPRI as of 1961, we can now answer the question about the level and origin of existing 137Cs activity in French soil, a subject previously given considerable media coverage.



Article and final report

an article in the IRSN scientific and technical report about this project
The final report of this project has been published on October 2004, and has been the subject of a press release


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