Manipulator for carrying out measurements, tests, inspections and repairs in an open-top reactor pressure vessel comprising a manipulator bridge movable along the auxiliary bridge a platform with a substructure disposed above the manipulator bridge a non-rotating boom supported by a bearing surface supported by the platform, the boom projecting into the pressure vessel, guide rails disposed over the entire length of the boom, a U-shaped channel disposed over the length of the boom a boom bearing including a cylindrical part on the substructure, two roller guides inside the cylindrical part, a retaining mechanism for the boom, a carriage including a sleeve tube enclosing the boom braced against the boom, rollers guiding the tube, a fixed support ring, a rotatable support ring, a supporting member supported about the carriage for equipment, drives for the supporting members a load lifting device moving the carriage along the boom including cable drums cables wound on the drums with a free end fastened to a bracket of the carriage, a horizontal guide track disposed in the manipulator bridge between the cable drums, a cable guide chain disposed on the guide track passing through the U-shaped channel and having an end fixed to the carriage power and control lines for the carriage and the supporting member disposed in the cable guide chain and a cable storage device disposed on the auxiliary bridge and coupled to the manipulator bridge including a drivable cable drum for winding and unwinding the cable chain.