Fabrication of FeCrAl cladding for accident tolerant fuel
General Electric (GE) is working with the US Department of Energy (DOE) to develop a high performance nuclear fuel that will have enhanced tolerance to failure under severe accident conditions. The leading FeCrAl alloy candidate for the cladding is APMT, a powder metallurgy alloy developed by Kanthal/Sandvik for high temperature applications. Zirconium alloys have been used for cladding the fuel for over six decades. That is, zirconium alloys can be fabricated as several meters long tubes with an outside diameter of about 10 mm and a wall thickness in the order of 1 mm or less. The GE team is working to demonstrate that APMT can be fabricated as long thin walled tubes for the cladding application. A first production route for 10 x 0.5 mm APMT tubes was established showing that pilgering and drawing are viable processes to fabricate the APMT cladding. The mechanical properties of APMT were evaluated before and after the cold forming. Yield strength, tensile strength and hardness increased and elongation decreased due to cold forming, which was expected. No abnormality has been noted in the microstructures. The 3D image visualization of TIG welded APMT rodlet and the images of welding areas taken at different locations show no welding defects such as distortion, porosity or lack of penetration along/adjacent to the welded areas, confirming overall good welds and no opening or defects across the entire width of the tube thickness. Tests have shown no effect of welding on the hardness or mechanical strength in the area nearing the weld.