Abstract
Ensuring the safety and high operation reliability of nuclear reactors takes 100% inspection of geometrical parameters of fuel assemblies, which include the grid spacers fabricated as cellular structure with fuel elements. The required grid spacers' geometry of assembly in the transverse and longitudinal cross sections is extremely important for maintaining the necessary heat regime. A universal method for 3D grid spacer inspection using the diffractive optical element, which generates, as the structured light, a multiple-ring pattern on the inner surface of a grid spacer cell is investigated. The experimental measurement error for cell centers position deviation is ±7 μm, and the error for overall dimensions is ±11 μm.