Manhole cover e.g. for nuclear apparatus confinement chamber incorporates lead glass transparent panel to permit visual observation

摘要

Manhole cover consists of a movable shutter with similar confinement characteristics to the wall of the chamber (2) in which the manhole is located. It incorporates at least one panel (6A) of transparent lead glass to allow visual observation of the interior of the chamber through the manhole cover. At least one of the glass panel's faces is protected by a sheet of tempered glass, and the panel itself is mounted in a frame (7A) hinged to a supporting frame fixed to the chamber. The remaining part of the cover is also hinged in one or more sections, allowing the different areas of the manhole to be opened separately as required.