Decontamination of big components in nuclear power plants

Electricite de France (EDF) has developed a soft chemical process for the decontamination of large components such as the primary circuit in pressurized water reactors; the process is based on the removal of oxide on the surface of the primary circuit, by the means of an alternation of a very oxidizing solution (dissolving the chromium) and a very reductive solution (dissolving the chromium-depleted residual oxide). The development of the processes (EMMA and EMMAC) is reviewed together with the studies on its potential corrosive effects on the materials. Processing of the induced wastes is also described. Application examples are discussed and results are given: decontamination of primary circuit plugs for vapour generator replacement, and decontamination of hydraulic parts in primary pumps