Characterization and Treatment Experience of TRU Sludges During Decommissioning NPP A-1 in Slovak Republic

Many special tasks have to be solved during the decommissioning of the NPP A-1 in Jaslovske Bohunice, Slovak Republic. One of them is the safe treatment of TRU sludges from the past. After the removal of fuel elements from steel casings, deposits of radioactive sludges at the bottoms of the casings were observed. High gamma radioactivity and contents of transuranic radionuclides in these sludges were the main reason for the selection and preparation of the sludge immobilization directly in the original steel casings. After TV and radiation monitoring, sampling of the sludge and laboratory verification, the in-situ immobilization of the sludge was realized. The applied SIAL matrix (mainly Si and Al compounds) has been developed and optimized to encapsulate the sludge giving high compressive strength and high index of leachability of the resulting product. Realisation of the sludge immobilization in 45 steel casings was performed.