Surveying interior of ductwork entering steam generator of nuclear reactor prior to cutting - using laser beam detector which is movable inside duct and adjacent spigot

摘要

The internal shape and dimensions of primary fluid ductwork (3,3a) where it is connected to the water box (1a) of a steam generator, inside the biological shield of a nuclear reactor, is measured using a laser beam detector (22), which is rotatably and axially movable inside the duct (3) and an adjacent spigot (3a) which joins the duct to box (1a). Detector (22) measures the distances between itself and many points spaced around and along the ductwork. The detector is supported by a support (21) which is rigidly mounted just inside the box (1a) and which also carries three sighting rods (25a) on an arm extending back into box (1a). A theodolite (30) takes sightings through a manhole opening (18) on the rods (25a) inside the box (1a). The readings obtained enable an accurate assessment of the internal shape of the ductwork and its position relative to box (1a). USE - Measuring the shape, dimensions and position of connecting ductwork to facilitate subsequent cutting thereof when the steam generator is replaced.