首页|Intercomparison of model predictions of ~(14)C concentrations in agricultural plants following acute exposures to airborne ~(14)C
Intercomparison of model predictions of ~(14)C concentrations in agricultural plants following acute exposures to airborne ~(14)C
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NETL
NSTL
Elsevier
Carbon-14 (14C) is one of the main radionuclides released during normal operation by nuclear power plants, nuclear defense facilities and nuclear fuel reprocessing plants. It is mainly released in the form of carbon dioxide gas denoted 14CO2, which has the specificity of being incorporated into food webs via photosynthesis by primary producing organisms. In order to better assess the environmental and human impacts of 14CO2 under normal operating conditions - or after potential accidental releases - from nuclear facilities, it is necessary to improve our understanding and our predictions of the behaviour of this radionuclide along the human food chain. To achieve this goal, the International Atomic Energy Agency (IAEA) Environmental Modelling for Radiation Safety (EMRAS) model evaluation programme included the Tritium and 14C Working Group (TCWG) which dealt with the intercomparison exercises between several models of environmental transfer in the case of routine and accidental releases of these radionuclides into the environment, and their performance testing. The TOCATTA-chi model developed at IRSN is a dynamic compartment model with high temporal resolution, which simulates the transfer of 14C (and tritium) in grassland ecosystems exposed to gaseous 14CO2 (and HTO) from nuclear facilities under normal or accidental operating conditions. Following this work, IRSN proposed a related project to extend the application of the TOCATTA-chi model to 14C estimates in leafy vegetables, fruits and roots. This article deals with the application of the TOCATTA-chi model to a specific real-case scenario identified within the framework of the TCWG. The scenario provides experimental data and predicted results from models developed at the international level. Model-model and model-data intercomparison exercises were thus carried out to validate the evaluations of the TOCATTA-chi model. In addition, this paper discusses the parameterization of the TOCATTA-chi model for this scenario and the development of modules for 14C concentrations in potato tubers, based on the assumption that photosynthetic transfer occurs directly from leaves to tubers and depends mainly on the growth stage of the tubers. It is observed that the predictions of the TOCATTA-chi model for the concentrations of 14C in leaves and tubers are slightly better than the other models due to the modelling approaches adopted by TOCATTA-chi for the calculation of key ecophysiological processes that govern plant functioning. Overall, the TOCATTA-chi model reduces the Root Mean Square Error (RMSE) by a factor of less than 8 compared to other models. In addition, most of the predicted results of the TOCATTA-chi model better match the measurements and are within the measurement uncertainty limit, while a few are overestimated. This could be due to the high uncertainty associated with the experimentally measured 14C activities, which reflects the field variability in plant growth rate.
Helmholtz Zent Dresden Rossendorf HZDR, Reactor Safety Div, Bautzner Landstr 400, D-01328 Dresden, Germany|Inst Radioprotect & Surete Nucl IRSN, Lab Rech Transferts Radionucleides Ecosyst Terr, CEN Cadarache, PSE ENV SRTE LR2T, F-13115 St Paul Les Durance, France
Inst Radioprotect & Surete Nucl IRSN, Lab Rech Transferts Radionucleides Ecosyst Terr, CEN Cadarache, PSE ENV SRTE LR2T, F-13115 St Paul Les Durance, France
NETL
NSTL
Elsevier
