In order to support research in nuclear safety and security, JRC Petten carries out measurements in metallic components used in nuclear applications. The neutron diffraction facilities at the High Flux Reactor of JRC Petten facilitate residual stress measurements in metallic components for nuclear applications, for example, welded joints. Neutron diffraction is a special technique that is only available at high flux neutron sources. It allows for the non-destructive measurement of the residual stresses in the bulk of a component, unlike the related X-ray diffraction, which can only measure at the specimen surface. The two diffractometers at the horizontal beam tubes HB4 and HB5 are supporting nuclear safety relevant research in the JRC Directorate for Nuclear Safety and Security.