[en] Objectives of FRAMES - For quantitative and defensible analyses: On the role that nuclear energy can play in present and future electricity systems; On the optimal grid integration of advanced (e.g. Gen IV) nuclear technologies; On the optimal share of nuclear and renewables for each particular grid, demand profile, VRE potential etc.; On the optimal policy mechanisms to achieve climate targets; On the flexibility requirements for nuclear power plants in future energy systems (useful for technology developers, e.g. of Gen IV systems); On non electric application of nuclear energy (cogeneration, energy storage, multigeneration etc.), e.g. in synergy with advanced nuclear technologies. Conclusions: • The IAEA is developing FRAMES as an in house modelling capability for integrated systems assessment. • FRAMES can help quantify the value that nuclear brings to low carbon systems, especially with nuclear and renewables, • It can inform policy and other techno economic evaluations: e.g. features of Gen IV reactors that make them advantageous for the decarbonized systems of the future. • Currently, FRAMES is used to support IAEA s messages on nuclear energy s role in decarbonization strategies (for example at COP 26 • Collaborations on complex energy system modelling and methodologies with MSs could be considered in the future.