Electrolytically Assisted Surface Decontamination
Low Level Waste (LLW) is radioactive waste or material that is contaminated by radioactivity through its use. Simple examples would include paper, plastic and protective clothing and when facilities cease operating may also include building rubble, soil and steel items such as pipework and storage vessels. Estimates of the volumes of LLW that will need to be managed between 2014 and 2029 have been generated using national inventory data for the nuclear industry. These estimate around 1.1 million m3 of LLW will need to be managed over this period, a proportion of which will be waste steel.
Given that LLW steel may typically only be contaminated to a surface layer of less than 100 microns, processes that can facilitate economic re-use rather than disposal of this waste steel, will therefore become increasingly attractive to waste owners or operators of disposal facilities.
The EASD process
The application of an electric current to steel, whilst in contact with a variety of cleansing acids to remove surface oxides or other contaminants is well established in the elds of electropickling and electropolishing.
However research work carried out by C-Tech Innovation has shown very significant improvements in process times, compared with acid descaling or DC electrolytic processes. In addition considerable reduction in required acid strengths was possible using EASD. These improvements could signal a major opportunity for the more rapid re-purposing of LLW steel waste resources.
Descaling of oxidised stainless steel strip
EASD key features
- Rapid scale/surface decontamination removal
- High rate dissolution of the underlying clean metal if required, to prevent ‘sweating’ back of the contamination
Comparison of descaling times
|Austenitic 304||5 to 10 min||2 to 12 hours|
|Austenitic 316||10 to 20 min||10 to 30 hours|
|Duplex||20 to 30 min||24 to 48 hours|
Stainless steel after EASD treatment