Skip to main content

Improvement in the performance of the conventional Treatment of Liquid Effluents by Co-Precipitation

Objective

The capacity of treatment of the COGEMA irradiated fuel reprocessing plant at The Hague is to be progressively increased from 400 to 1600 tonnes a year. The regulations authorize the release of the following radioactive effluents into the sea: 1665.10{3} GBq for all radioelements (except tritium) including 222.10{3} GBq for Sr-90 and Cs-137; 1700 GBq for a emitters. The efficiency of radioactive liquid effluent chemical treatment should therefore be improved. At present, the Liquid Effluent Treatment Plant (so called STE3) implements a process involving a chemical co-precipitation for low activity (beta activ. < 185 GBq/m{3}) and medium (beta activ. 1.11 10{4} GBq/m{3}) activity radioactive effluents and a neutralization, followed by filtering for any effluents suspected of the slightest radioactivity (a activ. < 3.7 MBq/m{3}, beta activ. < 370 MBq/m{3}). In association with the treatment plant operators of STE3, who are to supply actual radioactive effluents, we propose to implement complementary treatments in a hot laboratory, using for example mineral exchangers, organic extractants and chemical precipitation, the application of which, in the STE3 plant at The Hague, should entail only minor modifications to the existing process.
The aim is to improve the efficiency of radioactive liquid effluent chemical treatment. At present, the liquid effluent treatment plant (STE3) implements a process involving a chemical coprecipitation for low activity and medium activity radioactive effluents and neutralization and filtration for any effluents suspected of the slightest radioactivity. In association with the treatment plant (STE3) operators who are to supply actual radioactive effluents, we propose to implement complementary treatments in a hot laboratory, using, for example, mineral exchangers, organic extractants and chemical precipitation, the application of which, in the STE3 plant at The Hague, should entail only minor modifications to the existing process.

An assessment was made of the radioactivity releases from the STE3 plant at The Hague, from its conception until the year 1990. Low and medium activity radioactive effluents from the STE3 reprocessing plant were received and characterized. In particular, the ionic forms of ruthenium and antimony were determined by electrophoresis, in relation to the medium acidity.

Insolubilization and filtration tests were performed on the available V effluents, while, using synthetic effluents labelled with strontium-90, the interest of carboxylic and complexing resins was confirmed.
Work programme:

The work programme consists of:

- the characterisation of the chemical forms of the radioelements to be removed,
- the insolubilization of these radioelements by means of mineral exchangers in powder form (oxides, sulfates, phosphates,...) of supported organic extractants (active carbon, silica) and of precipitation treatments,
- the study of the separation of the insolubilized activity by means of the most appropriate processes: tangential filtering, centrifugation or columns used singly or in series
- the carrying out of tests on a radioactive pilot mock-up (1/60 scale)

Coordinator

Commissariat à l'Energie Atomique (CEA)
Address
Centre D'études De Cadarache Sere-ders
13108 Saint-paul-lez-durance
France