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TREATMENT OF REPROCESSING CONCENTRATE BY EXTRACTION CHROMATOGRAPHY AND INORGANIC ION EXCHANGE

Objective

IN THE F.R.G. LOW AND INTERMEDIATE LEVEL LIQUID WASTES ARISING DURING REPROCESSING OPERATIONS ARE CURRENTLY MIXED AND EVAPORATED. THE RESULTING WASTE, CALLED "REPROCESSING CONCENTRATE", IS THEN CONDITIONED INTO CEMENT OF GAMMA EMITTERS (E.G. CS-134/137, RU-106,SB-125) IMPORTANT SHIELDING OF THE WASTE PRODUCT CONTAINERS HAS TO BE PROVIDED THEREBY INCREASING BY FAR THE WEIGHT AND VOLUME OF WASTE TO BE TRANSPORTED AND DISPOSED OF. NOTICEABLE ECONOMICAL SAVINGS ARE EXPECTED TO BE ACHIEVED IF REPROCESSING CONCENTRATE CAN BE SPLIT INTO A HIGHLY ACTIVE FRACTION WHICH COULD BE ADDED TO HIGH LEVEL WASTE FOR VITRIFICATION AND A LOW ACTIVE FRACTION CAPABLE TO BE MANAGED WITHOUT CEMENT SHIELDING. TO THIS END, PREVIOUS STUDIES HAVE SHOWN THAT DECONTAMINATION FACTORS HIGHER THAN 280, 12 AND 6 SHOULD BE REACHED FOR CAESIUM, ANTIMONY AND RUTHENIUM, RESPECTIVELY.
BECAUSE DECONTAMINATION OF REPROCESSING CONCENTRATE REVEALED DIFFICULT OR INEFFECTIVE BY MEANS OF CHEMICAL PRECIPITATION ESPECIALLY FOR ANTIMONY AND RUTHENIUM, THIS RESEARCH ACTIVITY FORESEES THE IMPLEMENTATION OF INORGANIC ION EXCHANGE AND EXTRACTION CHROMATOGRAPHY AS TREATMENT PROCESSES.
THEREFORE THE MAIN OBJECTIVE OF THIS CONTRACT IS TO ASSESS THE PERFORMANCES OF THESE ALTERNATIVE TREATMENT PROCESSES FOR DECONTAMINATION OF REPROCESSING CONCENTRATE. THE CONTRACT DEALS WITH THE DEMONSTRATION AND FEASIBILITY FOR DECONTAMINATING MEDIUM LEVEL REPROCESSING CONCENTRATE THROUGH SUCCESSIVE TREATMENT INVOLVING EXPERIMENTS IN 1,20 AND 100L SCALE WITH SIMULATED IN AN 1 AND 20 L SCALE GENUINE ILW SOLUTIONS.
One of the main goals of this work was to check the influence of a scaling up from laboratory scale to pilot plant operations. The comparison of the secondary wastes, estimated from the 1 l experiments with the larger 11 l active experiments, has shown that these wastes will be 1000 kg as calculated on the basis of exact results for the breakthrough points of antimony-125 and ruthenium-106. Furthermore the hydraulic behaviour of the apparatus was tested for 1, 20 and 100 litres of simulated intermediate level waste solution (ILWS).

The technical feasibility of partitioning concentrated nitric acid intermediate level waste solutions from the Purex process into a small volume of high level waste and a large volume of low level waste using the sorption methods has been demonstrated for 1 litre and 11 litre batches. Caesium-134 and caesium-137 were selectively separated with a decontamination factor greater than 1E5 in a newly developed suspended bed column filled with the microporous inorganic exchanger, ammonium molybdophosphate.
2.2. COMPLEMENTARY LAB-SCALE EXPERIMENTS
2.3. EQUIPMENT INSTALLATION FOR SCALE-UP EXPERIMENTS
2.4. INACTIVE TESTING WITH 20 AND 100L ILW SIMULANTS
2.5. ACTIVE TESTING IN A 20L SCALE IN GLASS COLUMNS
2.6. HOT-CELL DECONTAMINATION AND REMOVAL OF THE EQUIPMENT
2.7. DATA EVALUATION (DESIGN AND FLOW SHEET)

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Forschungszentrum Karlsruhe Technik und Umwelt GmbH
Address

76021 Karlsruhe
Germany