Pipeline inner surface monitoring device

A permeation liquid is coated on a surface of pipelines to be inspected in a nuclear power plant, and then an inspection device for inspecting the inner surface of the pipeline is carried into a predetermined position of the pipelines. A developing liquid is sprayed from a spray can in the axial direction of the pipeline. Among the sprayed developing liquid, the developing liquid on the axis of the pipeline passes through the hollow portion of a reflection plate and recovered in a bag for liquid. The developing liquid at a position apart from the axis of the pipeline is partly formed into a mist and is reflected on the reflection surface of the reflection plate and formed into a mist and deposited on the surface to be inspected. The developing liquid flowing near the surface to be inspected is sucked to the outside of the pipeline by a vacuum device. The surface to be inspected is photographed by a CCD camera by way of a mirror. As a result, presence of defects on the surface to be inspected can be observed even if the pipeline has a small diameter. Defects on the inner surface of the welded portion of a pipeline can be inspected by permeation of liquid. (I.N.)