Characterisation of flakes generated in JET after DD and DT plasma operations

Approximately 1g of the 150g collected at the JET was send to the Tritium Laboratory Karlsruhe (TLK) for physico-chemical characterisation. The flakes were extensively analysed using several experimental tools, such as calorimetry, X-ray-diffraction, thermal desorption, helium pycnometry, scanning electron microscopy, etc. The specific surface area measurements according to the Brunauer–Emmett–Teller (BET) method, showed a value of about (4.7±0.3)m2g−1 while their average tritium activity was estimated to be (1.17±0.1)TBqg−1 (i.e. 3–3.3mg of tritium per gram of flakes) and their average real density (1.69±0.02)gcm−3. Based on these results we estimate that at the end of the remote tile exchange (RTE) at JET the 3.0g of tritium which did not return to the AGHS after the DTE1 remained in the vessel mainly in form of flakes, i.e. approximately (950±80)g of flakes are still inside the machine.