Disposal of the radioactive effluents at the 'Commissariat a l'Energie Atomique'. Treatment leading to evacuation into a river

1) The problems dealing with the treatment of the radioactive effluents at the 'Commissariat a l'Energie Atomique' have been studied in order to allow evacuation into a river - after treatment - with respect for the standards regarding radiation protection. 2) At Saclay where there is no possibility of evacuating the effluents, the liquids are directed towards Fontenay-aux-Roses by means of tank wagons. They are removed temporarily into the sewers and will be evacuated later on into the Seine. 3) ln Le Bouchet, the effluents coming from the Factory where urano-thorianite ore is treated will undergo a two stages treatment. The elimination of radium in the first phase facilitates decontamination in the second phase. 4) In Marcoule: a study of synthetic effluents of the Marcoule type is being carried on in order to perfect a selective elimination method of Sr90 and Cs137 by coprecipitation. 5) In the general case of the final evacuation into a river, the following problems have been studied: - pre-dilution of treated waters between the storing tanks and the river; - admission in the river; dilution in the river (preliminary study by means of a tracer); - evolution of the activity in the water of the river (adsorption by inert or living elements), contamination of the banks; - locating of the site; - isotopic dilution. 6) Circumstantial study of that last problem. 7) The quantity of a given product in water conditions the isotopic dilution of its radioactive isotopes. When the analysis shows the lack of an element, stable isotopes should be added in order to compensate it. 8) That method led to difficult analysis (specially as far as Sr90 is concerned), for the percentage of stable isotopes necessary to an important isotopic dilution is very low. 9) The standard regarding the quantity of Sr90 in drinking water is 8.10-8 c/m3 or 4.10-10 g/m3. So a percentage of 40 μg/litre of Sr is enough which is difficult to find out in loaded water, 10) Important elements other than Sr90 are also studied. (author)