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

Approximately 1 g of the 150 g 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) m2 g−1 while their average tritium activity was estimated to be (1.17 ± 0.1) TBq g−1 (i.e. 3–3.3 mg of tritium per gram of flakes) and their average real density (1.69 ± 0.02) g cm−3. Based on these results we estimate that at the end of the remote tile exchange (RTE) at JET the 3.0 g 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.