Detection of hidden shot balls in a gas-cooled turbine blade with an NRT gadolinium tagging method

This report provides a preliminary insight into the benefits and effectiveness of neutron radiography in identifying alien materials, namely shot balls hidden in a turbine blade that are otherwise undetected using other methods. The detection of 0.2-mm-diameter shot balls in gas-cooled turbine blades is possible for thermal neutron radiography. A tagging processing is more useful for a distinctive image of newer turbine blades. Areas of concern for the tagging process include the solution concentration and the possibility of a slight washing of the blades. The location of the shot balls within the turbine blades tagged with Gd((2%, 5%)+water) was shown. Shot balls were placed externally on a turbine blade (F100-700, F100-200) surface in order to check for a dead zone from a surface examination. The image is produced from neutron radiography after a 5 min exposure time. When the blade is tagged with 2% and 5% Gd with slight washing, the shot can also be effectively seen on the SR-45 film. Shot balls are more obvious on a neutron image SR-45 film than an image plate or a DR film.