The choice of soil monoliths, the definition of their associated relevant climatic conditions, the characterisation of their physico-chemistry, and the definition of the crop growth features they could support in the RESSAC facility have first been achieved. Simulations of aerosol-based radioactive contamination have next been carried out in order to investigate various aspects of radioelements interaction with vegetation and soils.
The IPSN has produced a software (DACFOOD) allowing a cost-effectiveness analysis of strategies that can be undertaken in case of foodstuff contamination (a strategy being defined as a set of elementary countermeasures). A scenario has been developed, in order to test the robustness of the system, to verify the consistency of the analysis, and to provide the other contractors with a case study. This scenario has emphasized the need for further work concerning economical data. This software is written in C and can be used independently of acceptance considerations.
A large part of the work conducted by Leeds University was devoted to the comparison of multicriteria analysis methods. During the course of the project, several kinds of difficulties have been encountered: in particular, the application of outranking methods to the evaluation of countermeasures leads to combinatorial problems, so that the comparison with multi-attribute utility methods cannot be done. The large number of strategies has lead to the development by the Leeds University of a coarse expert system to filter unfeasible strategies. This part of the contract had been closely turned to the RODOS programme, in which the expert system has been implemented. Leeds University had also produced a report dealing with the global evaluation of the uncertainties, taken into account each module of the code.
In a real case, the number of strategies increases dramatically with the number of groups of population, the number of foodstuffs and of elementary countermeasures. To limit the number of combinations a multiobjective interactive procedure for supporting the selection of countermeasures has been studied by the Paris-Dauphine University, to define an optimized solution according to <> (total amount of concerned foodstuffs, processing capacities,...) and <> (maximal acceptable cost, minimal reduction dose required,...). These constraints can be modified by the user during the decision process. This procedure has been tested on a scenario provided by the IPSN.
Difficulties encountered have demonstrated the need for further works in different fields. For this reason, it has not been possible to carry out the final objective of the contract (the elaboration of a software dealing both with dosimetric and economic aspects and with public acceptance).
THE RESSAC PROGRAMME (REHABILITATION OF SOILS AND SURFACES AFTER AN ACCIDENT) IS AIMED AT PROVIDING DATA TO BE USED FOR THE MANAGEMENT OF THE EMERGENCY RESPONSE TO A NUCLEAR ACCIDENT, AND TO TRY EFFECTIVE AGRICULTURAL COUNTERMEASURE TECHNIQUES RENDERING THE DECONTAMINATED ZONE HABITABLE. BY THE END OF 1992, A SPECIAL FACILITY WILL BE PUT IN SERVICE FOR THE SIMULATION OF FALL-OUT RADIONUCLIDE DEPOSITION ON LYSIMETRES WITH A SPECIAL DEVICE (THE POLYR FURNACE) ABLE TO SIMULATE THE CORE MELTING AND THE SUBSEQUENT HOT-PARTICLE EMISSION. THE LYSIMETERS ARE AIMED AT SIMULATING NATURAL CONDITIONS OF (I) SCALE FACTOR, MINIMIZING EDGE EFFECTS, (II) SOIL PROFILE MOISTURE, WHICH GOVERNS RADIONUCLIDE BIO-AVAILABILITY, (III) CLIMATIC CONDITIONS, AIR/SOIL TEMPERATURE, AIR MOISTURE WITH AN EFFECT ON SOIL BIOCHEMISTRY AND PLANT PHYSIOLOGY. IN COMPLEMENT TO FRENCH SOIL TYPES, THE MAIN TYPICAL SOILS FROM THE EUROPEAN COMMUNITY WILL BE REPRESENTED (E, B, D, UK AND F). COUNTERMEASURES INVOLVING RADIOACTIVE TRACERS STUDIING THE EFFECT OF DIFFERENT AGRICULTURAL PRACTICES ON THE PLANT TRANSFER WILL BE MADE IN THE LYSIMETERS. SOME COUNTERMEASURE TECHNIQUES SUCH AS SOIL SCRAPING TOGETHER WITH THE DECONTAMINATING VEGETAL NETWORK (D.V.N.), USE OF POLYSACCHARIDES, TRIALS OF CHEMICAL DEFOLIANTS ETC... NECESSITATE IN-SITU EXPERIMENTS. THE D.V.N. PRINCIPLE IS TO GROW GRASSE WITHOUT SOIL TILLAGE BY SPRAYING A MIXTURE OF PEAT, POLYSACCHARIDES, FERTILIZERS AND GRASS SEEDS OVER THE CONTAMINATED SOIL. AFTER 6 MONTHS OF GROWTH THE TURF CAN BE HARVESTED WITH A TURF-HARVESTERM CAPABLE OF REMOVING THE FIRST TOP SOIL CM WHICH CONTAINS THE MOST PART OF THE CONTAMINATION. THE USE OF POLYSACCHARIDES TO COVER THE SOIL AFTER FALLOUT RADIONUCLIDE DEPOSITION HAS THE DOUBLE ADVANTAGE OF PREVENTING THE HORIZONTAL/VERTICAL MIGRATION AND RE-SUSPENSION, AND TO ALLOW THE REMOVAL OF THE FIRST TOP SOIL MMS BY MEANS OF MECHANICAL BRUSHING. PREVIOUS INVESTIGATIONS ON THE NON-LETHAL DEFOLIATION HAVE SHOWN THAT SOME NON-ZOOTOXIC CHEMICAL DEFOLIANTS CAN BE SUSED ON FOREST TREES TO BURN THE LEAVES WITHIN 3 TO 20 DAYS, DEPENDING OF THE TREE SPECIES. A JOINT PROPOSAL TOGETHER WITH, ATHENS UNIVERSITY OF AGRICULTURE, AND CATHOLIC UNIVERSITY OF PIACENZA IS AIMED TO STUDY THE POSSIBLE USE OF NON-LETHAL DEFOLIATION TO MINIMIZE THE FOLIAR UPTAKE OF READIONUCLIDES BY THE VINE.
Funding SchemeCSC - Cost-sharing contracts
OX11 0RA Didcot