RE:info on light water reactors (LWR)U235 enrichment is between 3 and 5% for PWR's depending on where the fuel is located in the core. Higher enrichment fuel has been used because it has higher burn up (Megawatt days per tonne). All correct for reactors in steady state operation but for new reactors all of the initial fuel load is new fuel and between one half and one third is replaced on the first refuel outage. That is why new reactors consume considerable more fuel than older ones in their initial years of operation.
Good post thanks Dart.
M