as long as adequate framework conditions are provided in particular low financing costs and stable electricity prices nuclear energy is wellplaced to contribute to the security of energy supply and the smooth working of electricity systems with adequate capacity margins in oecd countries from this discussion can be drawn a number of broad policy conclusions as far as the temporal dimension is concerned one can distinguish periods reaching from a few seconds for technical failures a few days for policy responses to supply interruption to several years the time to implement new policies up to years the lifetime of certain energy structures the list of security of supply risks presented above quite naturally reflects this distinction between a shortrun and a longrun aspect of the security of energy supply