ELECTROCHEMICAL ION EXCHANGE SORPTION FOR MEDIUM ACTIVE LIQUID WASTE TREATEMENT

Ziel

THE SPECIFIC AIM OF THIS CONTRACT IS TO DEVELOP ELECTROCHEMICAL ION-EXCHANGE/SORPTION PROCESSES (EIX) FROM A BENCH TOP TO A DEMONSTRATION PRE-PILOT SCALE, AND VERIFY THEIR CAPABILITIES IN THE TREATMENT OF SYNTHETIC AND GENUINE LIQUID WASTE STREAMS AT FLOW RATES OF 0.1-1 M3/H FOR THE REMOVAL OF BOTH "BETA GAMMA" AND "ALPHA" ACTIVITY.

THE PROGRAMME IS DIRECTED AT OPTIMISING EQUIPMENT DESIGN AND PROCESS CONTROL, AND OBTAINING SUFFICIENT PERFORMANCE DATA ON THE RELATIONSHIPS BETWEEN FLOW RATE, ELECTRICAL CURRENT, STREAM DECONTAMINATION AND OVERALL VOLUME REDUCTION FACTORS SO THAT REALISTIC FLOW SHEETS MAY BE DRAWN UP. THESE COULD SUBSEQUENTLY BE A BASIS FOR EVALUATING THE POTENTIAL OF A CLARIFICATION NEEDED BEFORE TREATMENT WILL ALSO BE CONSIDERED - EXAMINING THE POSSIBILITY OF DESORBING ANY COLLOIDAL FOULING DURING THE SUBSEQUENT ELUTION HALF CYCLE. IN ADDITION, THE EFFECT ON EIX PERFORMANCE OF THE PRESENCE OF POTENTIALLY INTERFERRING IONS THAT ADVERSELY AFFECT NORMAL ION-EXCHANGE AND FLOC PROCESS (E.G. COMPLEXING AGENTS) WILL ALSO BE EVALUATED.

ANOTHER IMPORTANT TECHNICAL GOAL OF THE PROGRAMME IS TO COMPARE THE PERFORMANCE OF THESE ELECTROCHEMICAL PROCESSES WITH EXISTING TREATMENT ROUTES - SUCH AS ION-EXCHANGE, FLOCULATION AND EVAPORATION - AND EFFECTIVENESS.
Electrochemical ion exchange (EIX) has been firmly established as an effective process for the treatment of a wide range of liquid radioactive wastes including pressurised water reactor (PWR) low level liquid waste (LLW) and primary coolant drain wastes, fuel storage pond water (Magnox, PWR and MTR), research centre waste (LLW and medium level waste (MLW)) and fuel fabrication wastes. Inactive simulant trials have been substantiated by test with genuine waste for 4 of these. Both organic (for low specific activty streams) and inorganic systems (for higher activity wastes) have been demonstrated. A low cost current feeder electrode has also been developed, with a projected lifetime of more than 6 years.

While cation EIX can be used for the treatment of low salt content streams, combination with anion EIX to control the pH can extend its range of application to more than 30 meq/litre. At the same time, it is also able to remove activity complexed in an anionic form. Anionic electrochemical ion exchange (AEIX) has also demonstrated its ability to remove radionuclides with insoluble hydroxides (eg cobalt, uranium and plutonium) from both high and low salt content streams.

EIX has been successfully scaled up from the bench top scale of 0.16 litre/hour to 1 m{3}/hour, firstly by increasing electrode size by a factor of 11, and then by operating 5 units in parallel. An improvement in performance by a factor 3 was observed over a simple increase in area due to the minimization of edge effects in the larger units. Despite the handmade nature of the electrodes, their performance was within 3%. This has demonstrated the practicality of the multimodular approach to scale up.

In a comparison with floc, ion exchange (IX) and evaporation, EIX was able to give equal, if not better, direction finding (DF) performance with a system simply controlled through an automatic power supply. However, the most significant advantage of EIX is its compactness with plant sizes of less t han one tenth of its competitors. This has important cost implications in minimizing the size, and hence cost, of the controlled area. EIX, along with IX, and floc processes, has a significantly lower energy requirement than evaporation, thus minimizing running costs, and is able to achieve volume reduction factors comparable to those expected from flocculation (greater than 1000).
THE DESIGN , CONSTRUCTION AND COMMISSIONING OF A 0.1 M3/H EIX MODULE AND ITS ANCILLARY PUMPS, TANKS AND CONTROL GEAR FOR THE TREATMENT OF "BETA GAMMA" WASTE SOLUTIONS.

EVALUATION OF 0.1 M3/H MODULE PERFORMANCE ON THE TREATMENT OF GENUINE "BETA GAMMA" WASTE STREAMS. SMALL SCALE SUPPORTING WORK ON INTERFERRING IONS.

DESING, CONSTRUCT AND COMMISSION A 1 M3/H EIX UNIT, INCORPORATING AND MODIFICATIONS ARISING FROM THE PREVIOUS TASKS. EVALUATE PERFORMANCE CHARACTERISTICS OF THE 1 M3/H UNIT FOR THE TREATMENT OF GENUINE WASTE STREAMS FOR FLOW SHEETING PURPOSES.

DEVELOP HIGH CAPACITY ELECTROSORPTIVE ELECTRODES FOR THE TREATMENT OF ALPHA BEARING WASTES. EXAMINE THE EFFECT OF INTERFERRING IONS. DESIGN, CONSTRUCT AND COMMISSION A 10 E/H MODULE BASED ON THESE RESULTS.

EVALUATE THE PERFORMANCE OF THE 10 E/H MODULE ON GENUINE WASTE STREAMS.

ON THE BASIS OF THE RESULTS, DESIGN, CONSTRUCT AND COMMISSION A 0.1 M3/H PLANT FOR THE TREATMENT OF WASTES. EVALUATE THE PERFORMANCE OF THE 0.1 M3/H REMOVAL PLANT ON GENUINE WASTES.

Wissenschaftliches Gebiet

Programm/Programme

FP1-RADWASTOM 3C - Research and development programme (Euratom) on the management and storage of radioactive waste, 1985-1989

Thema/Themen

Data not available

Aufforderung zur Vorschlagseinreichung

Data not available

Finanzierungsplan

CSC - Cost-sharing contracts

Koordinator

United Kingdom Atomic Energy Authority

EU-Beitrag

Keine Daten

Adresse

353,Harwell
OX11 0RA Didcot - Oxfordshire
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