This lecture focuses on the accelerated development of MAX phase materials for Gen-II/III light water reactors (LWRs) and Gen-IV lead-fast reactors (LFRs). The MAX (Mn+1AXn) phases are nanolayered ternary carbides/nitrides, where M is an early transition metal, A is an A-group element, X is C or N, and n = 1, 2, 3. Conventional nuclear material development involves many cycles of production, neutron irradiation and post-irradiation examination until the property requirements of the end application are met. This approach is time-consuming and costly, discouraging industrial investments in innovative materials. The accelerated materials development approach, however, ensures that design, production, and performance assessment are interconnected, expediting the deployment of novel nuclear materials. Two applications are considered: (a) pump impellers for Gen-IV LFRs, and (b) accident-tolerant fuel (ATF) cladding materials for Gen-II/III LWRs. Tests done in static & flowing liquid LBE, PWR water & steam, ion irradiations at 350-800C to 40 dpa.