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Search for mobilised dust during operations with equipment for remote handling in JET with ITER-like wall

Accumulation of dust on the equipment for remotely handled (RH) operations was studied in JET with the ITER-like wall (JET-ILW) during the shutdown period following the third ILW campaign. The topic is connected to licensing procedures for ITER: the need to assess risks related to the external transfer of beryllium and radioactive matter with tritium and activation products. Ten adhesive carbon pads were placed in different locations on the robotic arm operated in-vessel for 672 h. Also air samplers were used during the RH operation and smear tests of the RH boom were performed to quantify specific contamination levels by beryllium and tritium. Dust morphology was determined by microscopy techniques. The areal density of dust varies at different sticker position on the boom. On some parts (e.g. ‘wrists’ of the robot) the density of particles exceeds 1000 per mm2. Their morphology is very diverse but most collected objects originate from the construction material (aluminium) of the RH equipment itself. The accumulation of Be- and W-based particles is negligible. The study confirms earlier experimental evidence that Be-rich co-deposits (and also W coatings on CFC) adhere well to plasma-facing components and they are not easily mobilised.