Abstract: A canopy seal clamp assembly (40) for stopping leaking in a canopy seal weld (42) located between a nuclear reactor vessel nozzle (30) and an elongated housing (24) includes an upper plate (44) having a central aperture (50) and an inner flange (52) spaced apart from a lower plate (60) having a central aperture (66) and an inner flange (68), a seal carrier (70) located adjacent the lower plate carriers a seal (72) for contacting an outer surface of a leaking weld (42) and connector (56) between the upper and lower plate maintain a compressive load to tightly seal the leaking weld and the compressive load tends to close and arrest further crack propagation in the weld. A method for repairing a weld is also described.