Position detector for components in radio - actively contaminated locations

摘要

A packet of needles guided in several perforated plates is inserted into guide tube above a fuel element which is to be located in a nuclear reactor. Glass plate seals off the guide tube but allows a visual observation of the top of the packet of needles which is an image of the fuel element top and can be aligned relative to cross wires on the glass plate. Sealing can be improved if the needle diameter and the hole diameters in the perforated plates are staggered.