The most important metrics are cost and speed of co2 reduction. An 80% renewable grid may achieve that more effectively than nuclear. It may be optimal to bur

The most important metrics are cost and speed of co2 reduction. An 80% renewable grid may achieve that more effectively than nuclear. It may be optimal to burn gas for a couple of weeks per year. Or to build massive pumped storage and nuclear stations. But trying to hit some purity target of 100% is irrelevant. There are lower hanging fruit for decarbonisation than the last few percent of power generation.