Modelling transfers of carbon 14 emitted by pressurised water reactors under normal operating conditions, in continental ecosystems.

S. Roussel-Debet, J. Garnier-Laplace, C. Mourlon and P. Calmon Actes du congrès ECORAD, 3-7 sept 2001, Aix en Provence, France Radioprotection - Colloques, volume 37, C1-141 / C1-146.

A model of transfers of 14C in the terrestrial and freshwater environment, emitted by atmospheric and liquid discharges from Pressurised Water Reactors under normal operating conditions, is proposed. Despite the complexity of the ecosystems involved, a simple assessment of the transfer pathways in the environment may be envisaged on the basis of the following assumptions: (a) 14C behaves like 12C with an isotopic ratio between the two isotopes that is unvarying during all considered transfers, and, (b) the 14C concentrations in the environment are constant over time, which is only valid for chronic discharges. This model takes into account the chemical form, mineral or organic, of the released 14C, and the input of 14C through the irrigation water in the case of terrestrial agricultural products. An example of human dose calculation is achieved on the basis of a standard diet, assumed to be entirely self-consumed and contaminated by a chronic discharge. In this case, the annual dose equivalent by ingestion is respectively 40 µSv year-1 for a volumic air activity of 1Bq m-3, and near 0,1 µSv year-1 for a volumic water activity of 1 Bq m-3.