As part of efforts toward improved safety and reliability for light-water reactors, Mitsubishi Heavy Industries, Ltd. (MHI) and Mitsubishi Nuclear Fuel Co., Ltd. (MNF) have been working on the advancement of reactor fuel. In the short and medium term, we are undertaking the development of the MNF Robust and eXcellent performance fuel assembly (M-ReX TM) with the purpose to increase the seismic resistance and reliability of the fuel, aiming to achieve stable and on schedule operation of light-water reactors. In the medium and long term, we plan to develop a Chrome (Cr)-plated Zirconium (Zr)-base alloy fuel cladding that will have higher accident tolerance than the existing Zr-base alloy, as well as a Silicon Carbide (SiC) fuel cladding that is expected to achieve an even higher level of accident tolerance. This report provides an overview of our progress relating to these new types of fuel cladding.