Foerfarande foer behandling av avfall som innehaoller laogaktiva organiska avfallssammansaettningar fraon kaernkraftverk med hjaelp av anaerobisk jaesning

The invention concerns a procedure and a bioreactor for treating low activity wastes from nuclear power plants with the aid of anaerobic fermentation. The waste (11,28) is subjected to desired pretreatment, such as e.g. comminution (12) and suspending (13), or a special treatment (30), such as e.g. hydrolysis and/or physical dispersion, such as e.g. irradiation, heat treatment or equivalent. The pretreated waste is conducted into a bioreactor (15), where anaerobic decomposition takes place in two steps, the first step being an acid step (15a) and the second step, a methane step (15b). The gases produced in the decomposition process are conducted from the methane step (15b) to gas burning (27), and the undecomposed waste is removed from the process to concentration (20) and packed in barrels (21) or equivalent.