In 2016, as part of the EURADOS network, IRSN proposed and organized an intercomparison on the lifetime dose assessment received by nuclear workers exposed to uranium. The results were summarized in a report, which has recently been published.
Coordinated by the IRSN, the intercomparison aimed to evaluate the uncertainties related to the lifetime dose assessment received by workers exposed to a risk of uranium contamination. Indeed, the IRSN conducts epidemiological studies looking at the long-term effect of uranium intake on health, and to do that, accurately estimates the internal dose received by people exposed, to identify a possible link between uranium and the pathologies studied. Nuclear workers are a very interesting cohort for this type of study since they are monitored regularly by biological tests (mostly urine) and their conditions of exposure can be reconstructed from their workstation data. However, the data is old and little-accurate. Many of the biological tests have values under the technical limit of detection used, and the exposure conditions (i.e. Exposure times) are not always fully known. To assess the internal dose on the basis of this information, dosimetry experts can put forward numerous different hypotheses for reconstituting exposure scenarios. This is why the uncertainty to assess the radionuclides dose received during a lifetime is considered to be significant. This finding by the IRSN sparked organization of this intercomparison within the EURADOS network.
To quantify this uncertainty, the 16 participants in the intercomparison assessed the “lifetime” doses of 3 workers from the French nuclear industry exposed to uranium. This work was used to compare the dose assessment protocols and the various hypotheses used by the participants, to identify the sources of the uncertainty and to discuss evaluation of the uncertainty concerning the dose.
The dispersion of the dose assessments is important, higher than that usually acknowledged for uncertainty of internal doses. This analysis was used to compare the dose assessment protocols and to identify the sources of uncertainty. The next step will be to identify those with the most impact on evaluation of the dose received by the workers during their lifetime. The main perspective of this intercomparison is to prepare a joint protocol to evaluate the internal lifetime dose received by nuclear workers, which will be used in future epidemiological studies.
EURADOS (European Radiation Dosimetry Group) is an organization which supports scientific and technical research into ionising radiation dosimetry in Europe and internationally. The main objectives of this permanent network of experts, and reference laboratories in radiation protection, radiobiology, diagnostics and radiation therapy, are to harmonise existing working practices and implement training in ionising radiation dosimetry.
Read the report (PDF)