Decontamination apparatus

Decontamination apparatus for decontaminating radioactive nuclear steam generators comprising:

• an attachment mechanism attached to a tube sheet of said nuclear steam generator for completely suspending said decontamination apparatus therefrom;
• a first support member attached to the under side of said attachment mechanism;
• a harmonic first drive mechanism attached to said first support member for rotating said decontamination apparatus in a horizontal plane parallel to said tube sheet;
• a harmonic second drive mechanism attached to said first drive mechanism for rotating said decontamination apparatus in a plane substantially perpendicular to the plane of said tube sheet;
• a support arm attached to said second drive mechanism;
• a nozzle support mounted on said support arm;
• at least two nozzles mounted on said nozzle support and arranged at between approximately 30.degree. to 70.degree. from the center line of said support arm;
• a chain and sprocket third drive mechanism disposed in said support arm and attached to said nozzle support for moving said nozzle support and said nozzles in a direction along said support arm, said drive mechanisms providing a means of locating said nozzles near the various surfaces of said nuclear steam generator while maintaining said nozzles approximately 6 to 10 inches from said surfaces;
• and
• water-grit supply means connected to said nozzles for supplying a water-grit mixture to said nozzles at a pressure between approximately 200 psi and 2700 psi and with said water grit-mixture having a grit concentration of approximately 3% to 7% by weight, said nozzles directing said water-grit mixture toward the surface of said nuclear steam generator and thus decontaminating said nuclear steam generator.