Initial individual dose assessment following a nuclear accident

Cecile Challeton de Vathaire (1) , Emmanuel Quentric (2) , Damien Didier (3) , Eric Blanchardon (4) , Estelle Davesne (1) , Alain Rannou (5) , Michelle Agarande (6) , Valérie Renaud-Salis (3) , Didier Franck (7)

1 IRSN/PSE-SANTE/SDOS/LEDI - Laboratoire d'évaluation de la dose interne
2 IRSN/PSE-SANTE/SESUC/BMCA - Bureau de Modélisation des transferts dans l'environnement pour l'études des Conséquences des accidents
3 IRSN/PSE-SANTE/SESUC - Service des situations d'urgence et d'organisation de crise
4 IRSN/PSE-ENV/SEREN/BERAP - Bureau d'expertise en radioprotection de la population
5 IRSN/PSE-SANTE - Pôle Santé Environnement - Direction Santé
6 IRSN/PSE-ENV/SAME - Service d'analyses et de métrologie de l'environnement
7 IRSN/PSE-SANTE/SDOS - Service de dosimétrie

In the early phase of a nuclear reactor accident, in-vivo monitoring of impacted population would be highly useful to detect potential radionuclides inhaled during the passage of the cloud and to estimate the dose from these radionuclides. However, it would be important to take into account other exposure components: (1) inhalation of unmeasured radionuclides and (2) external irradiation from the plume. Methods and results Here is presented a methodology to calculate coefficients used to convert in-vivo measurement results directly into doses, not only from the measured radionuclides but from all sources of exposure, by combining accidental model-based projected doses with the results of the in-vivo measurements of a tracer radionuclide. As an illustration, the methodology is applied to two scenarios of accidents affecting a nuclear power plant (Pressurized Water Reactor type): a loss-of-coolant accident (LOCA) leading to core meltdown and a steam generator tube rupture (SGTR) accident. Calculated coefficients are directly applicable to perform a first dosimetric assessment of the exposure for a person with 131I measured in the thyroid in the aftermath of an accident related to one of the two scenarios considered (i.e. with similar activity releases and dispersion conditions). Conclusions Early interpretation of in-vivo measurement, as presented, gives crucial indication on the real level of exposure of the population around the nuclear site. It allows to communicate with the measured persons on the basis of individual measurement results. A more sophisticated dose assessment, taking into account the local isotopic composition of the cloud, the time-pattern of the exposure, subsequent measurements if any and possibly the post-accidental exposure, will have to be performed in a second time in order to evaluate individual health risk for long term medical survey and to provide a quantification of the exposure for epidemiological studies.

Domaines: Sciences de l'ingénieur [physics]

Cecile Challeton de Vathaire, Emmanuel Quentric, Damien Didier, Eric Blanchardon, Estelle Davesne, et al.. Initial individual dose assessment following a nuclear accident. International Conference on Individual Monitoring of Ionising Radiation (IM2022), Apr 2022, Cracovie, Poland. ⟨irsn-04023906⟩