However, with the very rough and ready metric for system adequacy used in this exercise, which is the ratio of total generating capacity over peak demand, ceteris paribus the SSDI would increase in response to increased renewable production. During their life cycle, nuclear power plants source up to 90% of their inputs in terms of value domestically. Imports of uranium, just as imports of rare earths for the rotors of wind turbines, are not a major concern as they are widely diversified and frequently stem from other OECD countries.