Study of a District Built upon Soil Contaminated with Radium-226. Methodology for Radiological Inspection and Assessment of Doses Relating to Present and Potential Exposure of Residents.
R. AMÉON, M.C. ROBÉ, A. RANNOU, I. CLAIRAND and J-F. BOTTOLLIER-DEPOIS
European conference on radon risk calculation and risk communication
Besançon France / 23-24 septembre 2002.
Following its discovery in 1898 by Pierre and Marie Curie, radium was used in the industrial and medical fields for more than sixty years. Several radium extraction plants were built in France to isolate radium chemically from large quantities of uranium ore (or pitchblende). This activity ceased towards the middle of the 20th century, and some sites were transformed into housing developments.
One example of this is a district built upon a site known for its former industrial activity. IRSN participated in a program of systematic radiological inspection of this site launched by the public authorities.
The purpose of this program was to estimate any increase in exposure to ionizing radiation suffered by residents of the district, in comparison with exposure due to natural radioactivity. Different exposure pathways were considered: inhalation of radon-222 and its short-lived daughter products, external exposure to gamma rays emitted by radium and the different radionuclides produced when it decays and, lastly, radium and long-lived radionuclides incorporated via the food chain (e.g. products grown in kitchen gardens) and the respiratory tract.
The residents' yearly effective dose was assessed by calculating the dose for each of the above-mentioned exposure pathways, based on the following data:
§ results from different measurements taken during the inspection campaign, in accordance with a strict protocol complying with different AFNOR standards applying to measurement methods for radon and its short-lived daughter products,
§ the definition of standard resident profiles integrating residence time at various locations in the district; personalized protocols were also used in some cases,
§ dosimetric models.
This paper presents the methodologies defined for the following tasks:
- performing systematic radiological inspection of the district,
- assessing doses relating to the present and potential conditions of residents of this district, presenting the data used, the hypotheses adopted, and the dosimetric results obtained, and lastly, discussing the uncertainties and limits of this type of study.