Neutron Back Scatter 

NBSNeutron Back Scatter is an NDT technique for identifying the presence of moisture in insulation, which can lead to corrosion of the component under the insulation. A radioactive source emits high-energy neutrons into the insulation. A neutron is similar in mass to a hydrogen atom and so the high-energy neutrons are moderated by collision with hydrogen atoms present in any moisture within the insulation. A NBS detector, sensitive only to low-energy neutrons, is used to count the number of low-energy neutrons. The count gives an indication of the amount of hydrogen, and hence water, in the insulation: wet insulation will produce a higher count per unit of time than dry insulation.

As with all other NDT methods, the application of NBS is dependent on a number of factors. These include: the time of shot count; the insulation type and thickness; humidity levels; hydrocarbon levels; shot location; and equipment orientation. Since hydrogen is present in many materials, NBS is used to give a relative measurement which highlights a change in the neutron count. NBS is also used to identify the level of water in tanks from the outside.

For more information on the use of NBS enter Neutron Back Scatter into your search engine.

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