Fretting experiments in Pb on surface aluminized fuel cladding material at 550°C

One of the most important mechanisms for fuel leakage in pressurised water reactors is wear due to friction between the gr_id and the rod, the so-called grid-to-rod fretting. This fretting wear is caused by flow induced vibrations (FIV) which led to low amplitude sliding between the rod and the grid and inadequate grid to rid contact. GTRF (grid-to-rod fretting) is also expected in heavy liquid metal cooled systems. Studies in liquid Pb/LBE with advanced materials and convention_al materials with coatings are lacking. In previous fretting tests 15-15Ti, T91 and T91 with a FeCrAI coating treated by GESA were tested especially at 450°C, the set of data were used to create preliminary fretting maps for fretting damage prediction. Less was done at 550°C. Therefore, within the EU projeot LESTO (Lead fast reactor Safety design and Tools), KIT is conducting fretting experiments at 550°C in liquid Pb with sofved oxygen to gain tribological data on sample with surfa.ce aluminized steels by pack cementation and GESA treatment by variety of settings (load and stroke). The frequency is be 10Hz and the exposure time 100h. In this presentation results on fretting in liquid Pb will be presented and discussed.