The objective of the study is to define the countermeasures to be applied in order to improve the radiological quality of agricultural products after a major nuclear accident at a NPP (PWR type).
A study has been done to define the countermeasures to be applied in order to improve the radiological quality of agricultural products after a major nuclear accident at a nuclear power plant (NPP) (pressurised water reactor (PWR) type).
For the 3 nuclear site studied in Belgium the sensitive soils and crops for caesium and strontium have been identified. For caesium, as for strontium, permanen pastures appear to be the critical pathway in the soil plant foodchain because of both their abundance in the country and their high transfer factor values. In the case of caesium, special attention has to be given to potatoes cultivated on sandy and loamy soils. An experiment on permanent pasture was designed to estimate the transfer factors from soil to grass and from grass to milk for radiocaesium and strontium. The transfer of the radiouclides released as aerosols was compared with that of ionic solutions of well known chemical form to assess the bioavailability of these 2 different source terms.
Except for the contamination stage, the results obtained confirm the higher mobility of strontium than caesium even in aerosol form. The statistical comparison of the behaviour of caesium and strontium under both source terms shows a permanent superior availability for grass of these 2 radionuclides under ionic forms. The calculated transfer factors to milk show that the radiocaesium in both forms is equally available for secretion into milk. Similar transfer factors to blood were estimated indicating that both forms are absorbed to the same extent through the gastrointestinal barrier.
Strontium as aerosol particles appears to be 30% less available than ionic strontium. A similar respective behaviour in milk, urine and faeces of both radionuclides, regardless of their origin, during the decontamination period suggests that the fraction absorbed joins pools specific for these nuclides independently of the initial physicochemical forms that were investigated.
In order to reach this goal, one should consider two main phases:
identification of sensitive soils and agricultural products in the near and intermediate fields and experiments on the behaviour of the radionuclides (Cs, Sr released from the simulated PWR source-term) in the soil to plant to animal food chain transfer;
experimental research to define the parameters and the methods to reduce the transfer along the soil to plant to animal food chain, and to investigate the possible use of industrial process to reduce the level of radioactivity in the end products of plant and animal production.
The project is of a cooperative nature among all Belgian laboratories interested in this field, in particular:
the Faculty of Agricultural Sciences (Gembloux) (Various research units);
the Belgian Nuclear Establishment (CEN-SCK Biology Department);
the University of Liege (Lab. of Radioecology).
There is also a close cooperation with the SERE/CEN Cadarache and coordination with other countries through the IUR Working Groups.