Waterproof node structure, nuclear power plant and waterproof method

The invention discloses a waterproof node structure which is used for reducing the damage of a structural stress concentration part to a water stop belt and improving the waterproof effect of a gallery. The waterproof joint structure comprises a plant bottom plate (1) and a gallery outer wall (2) located below the plant bottom plate (1), and at least one part of the plant bottom plate (1) and the gallery outer wall (2) jointly form part of the side wall of the gallery. A lug wall (3) is arranged on the side, facing the gallery outer wall (2), of the plant bottom plate (1), and the lug wall (3) is arranged close to the outer side face of the gallery outer wall (2) and extends to be right opposite to the gallery outer wall (2). A deformation joint (4) is formed by gaps among the gallery outer wall (2), the plant bottom plate (1) and the ear wall (3), and the deformation joint (4) is in an inverted L shape. And a water stop (5) is arranged at the deformation joint (4) between the gallery outer wall (2) and the e