Tritiated materials

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• Desorption
• Autoradiography

In fusion devices operating with tritium, different tritiated materials are produced. Two main strategies can be adopted for tritiated waste management: waiting for natural decay of the radio-nuclides or applying some detritiation process. The second strategy is being investigated by the Fusion Technology Task Force. Dedicated procedures for decreasing the tritium content inside the materials removed from the torus are being developed for stainless steel, carbon-based materials (graphite and carbon fibre composite), organic liquids (pump oils, liquid scintillation cocktails) and water, together with process and housekeeping wastes. In all these projects, the right balance between the production of secondary waste and the reduction of waste classification has to be reached.

Autoradiography of the Carbon Fibre Composite (CFC) plates before and after detritiation by Radio Frequency heating

Oxidation has been used to transfer the tritium atoms from organic oil molecules to more stable and more easily treatable inorganic molecules. Thermal desorption in the range from 20 to 1100°C under a stream of helium containing 0.1% hydrogen has been used for carbon samples obtained from tritiated JET tiles.

Heating of full CFC divertor tiles via radio frequency has been performed. The amount of tritium before and after the procedure is being measured by calorimetry and full combustion. Autoradiography (a method of detecting and measuring the deposition, distribution and quantity of a radioisotope present on any material by registering its radiation on a photographic plate placed directly on the material) showed that after several heating cycles at the average temperature of only 490 °C, more than 99% of the tritium can be efficiently removed from a the surface of a tile. Full combustion measurements showed that 95% of tritium from the bulk was released.