Aim of the research is to make a general overview on the industrial wastes (by the technical and regulation point of view) in order to identify toxic and hazardous wastes (THW) subjectable to be processed with methods or techniques up to now adopted only for low and intermediate level radioactive wastes.
Refuses containing asbestos (RCA) have been identified as the wastes more suitable for the compaction and immobilization process, widely considered a good balance between technical and economical features for low activity radwaste management. An experimental campaign to verify the feasibility of the above process for RCA has been started.
RCA collected in plastic bags and delivered to NUCLECO facility in metal drums, have been previously shredded and then compacted using two different sets of pressing equipment available in the plant: vertical four columns heavy load press (1500 tons maximum); horizontally mounted double stroke press (80 tons).
First results showed that the shredding reduces the volume of RCA by a factor of 2, while the following compaction step, depending on the pressing load, provided a further reduction by a factor 3 to 5, so attaining a total volume reduction factor (VRF) ranging between 6 and 10 and a corresponding increase of the volumetric mass. Normal values of VRF are in the range of 3 to 5. On the other hand the negative result obtained is the very low consistency of compacted RCA, which makes it quite impossible to handle the pressed material for the following overpacking operations. Many tests have been carried out by increasing load pressures and varying the RCA packing before pressing.
After these process steps the compacted material has been transferred in concrete overpacks and then embedded in a mortar matrix with the same recipe as duly qualified for radwaste embedding. During the above process steps, done in nuclear containment conditions, air samples have been taken in order to evaluate the contamination due to asbestos free fibres. The results of the analysis gave very high values of contamination justifying the choice to perform all the operations inside containment rooms (tent or containment box). The final step of embedding has been carried out using such containment criterion.
The final result, in terms of volume reduction, shows a total VRF about 3, in spite of the handling difficulties.
- To select and evaluate THW groups, featured by an environmental impact involving particularly restrictive management rules similar to low activity radwastes.
- To select the radioactive wastes treatment and disposal techniques already tested and used.
- To analyze the feasibility of converting specific kinds of TWH into an inert from, with reduced volume and hazard, allowing a landfill disposal.
- To develop the basic design of a pilot plant performing a selected process for THW treatment.
- To study for the process: costs/benefits analysis, environmental impact, future experimental campaign with the pilot plant, interventions in-situ.
Funding SchemeCSC - Cost-sharing contracts