Assessment of the flash-lamp photon-cleaning detritiation method tested at JET

Flash-lamp photonic cleaning has been tested in situ and at the Beryllium Handling Facility (BeHF) at JET. Two adjacent number 4 divertor tiles have been exposed to numerous pulses up to the nominal energy of 500 J. Starting the photon-cleaning process with tile G4A and using energies up to 350 J did not appear to be efficient for detritiation. Consequently, the untreated tile G4B has been treated at the maximum energy of 500 J. Combustion measurements confirmed that the photon-cleaning was partly efficient as about 74% of the initial tritium concentration has been released. The average tritium concentration on the surface of the tile after treatment was 2.45 × 108 Bq/cm3 which is only four times lower than the initial activity. However, it is remarkable to notice that the bulk activity of the tiles remains constant indicating that during the detritiation treatment there is no tritium diffusing into the bulk of the tile.