Applications of neutron back-diffusion technique for wall thickness and scale measurements at desalination or chemical plants

Abstract

A neutron back-diffusion method was used for measurements likely to be found at desalination plants, refineries or chemical plants. Thickness change due to erosion can successfully be measured. The range of thickness measured was more than 5 cm in iron and more than 10 cm in concrete, aluminum and glass. Scale deposit that accumulated on thick walls or inside pipes was also determined by this technique. These measurements can be made without the wall penetration needed for insertion of measuring instruments and without any system disturbance. Neutrons from a 241 Am-Be source are allowed to be incident on the pipe or container. They are moderated by the water or liquid inside, diffuse backward following reduction in energy where some will get absorbed by the pipe's wall or the deposit before being measured by a BF 3 slow neutron detector where counts will decrease with thickness.