Electrochemical technique for the segmenting of activated steel components

Electrochemical machining (ECM) is well known in non nuclear metal working i.e. for special manufacturing tasks. In the nuclear power plant KRB unit A electrochemical decontamination has been introduced for decommissioning. Therefore it was obvious to examine ECM technique for the potential of cutting thick walls of activated steel. Three different methods (static, step by step and dynamic cathode movement) have been tested on non irradiated samples of the reactor pressure wall (22NiMoCr37 with stainless cladding). The best test results could be achieved by a stepwise moving cathode. On the test facility a 143 mm thick sample has been cut through within 750 min by an abrasion efficiency of 0,9 mm3/A*min. The dissolved material out of the 8 mm gap was converted to approximately the double amount of waste in form of dry metal salt. (author)