Abstract: A method and an apparatus for removing residues from an inner wall surface of a liquid-filled vessel includes a submergible carrier unit drivable in liquid; a coaxial, multi-pole electrode system mounted on the carrier unit; an arrangement for steering the carrier unit to a desired location at the wall surface; and a high-power pulse generator connected with the electrode system for generating a shock wave to be applied to the wall surface at the desired location, whereby the push-pull effect of the forces derived from the shock wave causes the residues to loosen and drop off the wall surface.