Abstract: For the inspection of a reactor vessel (1) there is used a carriage (4) provided with wheels (15) to enable the carriage to be driven around a reactor opening (2). The carriage supports a mast (36), which is provided with inspection equipment (38) which can be driven along the mast. Known apparatus of this kind block the reactor opening, thereby to prevent other work from being carried out during an inspection period, for example such work as the change of fuel elements. According to the invention, the carriage with mast and inspection equipment are so formed that a geometric projection thereof onto a plane extending perpendicularly to the geometric axis of the cylindrical reactor vessel lies within a sector of less than 180.degree., with the exception of an area outside the geometric projection of the reactor hearth onto the same plane.

Abstract: An arrangement for inspecting a reactor vessel immersed in a water-filled tank (31) comprises a mast carriage which is arranged for movement around the opening of a reactor vessel and which has fixedly connected thereto a mast which carries a track means (10) on which inspection apparatus (19) can be driven. To render it unnecessary to lift the mast carriage and mast into the reactor hall when, for example, replacing inspection apparatus, there is arranged, in accordance with the invention, on the upper end (20) of the mast a docking unit (21) which is provided with a second track means (22) connecting with the first track means (10). A carriage supporting the inspection apparatus can be driven onto the second track means.