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INVESTIGATIONS ON RECYCLING OF RADIOACTIVE NON-FERROUS ALUMINIUM AND COPPER BY MELTING PROCESS

Objective

The research work aims principally at developing a method to refine contaminated aluminium and copper scrap to a product that enables unrestricted reuse in conventional industrial process.

Parameters such as heating rate, temperature, slag former, surrounding atmosphere will be varied to get optimum conditions for decontamination by melting.

The behaviour of the most relevant isotopes will be investigated and the possibility of melt decontamination on aluminium and copper will be examined. For the treatment of Al, cooperation with CIEMAT, Madrid, will be established (contract No. FI2D0023).

The organic coatings on various copper items represent a special handicap. Investigations will be made on how the radioactivity is distributed between metal and coatings, whether the separation prior to melting is necessary or not and how harmful gaseous effluents can be managed.

In preceding works, the melting technique was already assessed for steel (contracts Nos. FI1D0044 and FI1D0016).
The research work aims principally at developing a method to refine contaminated aluminium and copper scrap to a product that enables unrestricted reuse in conventional industrial processes.

In industrial scale, contaminated aluminium scrap is melted by an inductively heated furnace. Therefore, in order to meet the same melting conditions, and inductively heated furnace was installed to perform melting experiments in a laboratory scale.

A container with 160 kg of radioactive contaminated aluminium scrap was obtained from different nuclear power plants. The scrap was cut into pieces with outer dimensions smaller than 5 cm. Thus it can be used in the graphite crucibles with an inner diameter of 10 cm for the melting experiments.

Samples of a copper test melt were analysed for lowest alpha, beta and gamma activity. The results showed activities below the limit values for unrestricted reuse.

Because copper is usually covered by other materials, eg by plastics, glimmer or rubberlike materials, these casings had to be removed in order to avoid complications during melting (off gas from plastics). A solution was a general purpose chopper device, able to cut, in a first step, a large variety of cables (including strong motorwindings). In a second step a rotating chopper cuts the chopper/coating elements (and thereby separates them) into small grains.

On a preliminary experiment with a customary resistance furnace a small portion of aluminium scrap was molten together with slag former sodium chloride, potassium chloride and calcium fluoride. The contaminated scrap was procured from a nuclear power plant. The gamma spectrometric examination showed mainly cobalt-60 and silver-110 as contaminating nuclides. After melting a decontamination factor of 30 resulted for cobalt-60 and a factor of 3.5 for silver-110 only.
WORK PROGRAMME

1. Arrangement between CIEMAT, Madrid/Siemens-SG to co-operate in aluminium melting.

2. Installation of an inductively heated furnace with exhaust system. (SG)

3. Procurement of representative contaminated aluminium and copper samples. (Siemens)

4. Treatment of copper. (SG)

4.1. Investigations on metal coating separation and gamma-nuclide distribution.
4.2. Basic melting experiments with observation of radiation and contamination of workers and working area.
4.3. Supplementary melting experiments with varying melting conditions.
4.4. Determination of radionuclide distribution in slag, metal, dust and coating.

5. Laboratory-scale melting experiments with aluminium. (Siemens)

5.1. Optimization of melting conditions.
5.2. Determination of radionuclide distribution.
5.3. Investigations on recycling of the salt melts.

6. Melting of aluminium in an industrial furnace. (SG)

7. Derivation of specific data on costs, radioactive job doses, working time and secondary waste arising from the above items. (all)

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Siemens AG
Address
Berlinerstraße 295-303
63067 Offenbach Am Main
Germany

Participants (1)

SIEMPELKAMP NUKLEAR- UND UMWELTTECHNIK GMBH & CO.
Germany
Address
45,Siempelkampstra?e 45
47803 Krefeld