Essentially. The CO2 cooled AGR has much lower power density and was thought by its designers to be a much superior design to water cooling for safety and cost

Essentially. The CO2 cooled AGR has much lower power density and was thought by its designers to be a much superior design to water cooling for safety and cost reasons. It turns out, definitely not on cost grounds and the AGRs are all reaching technical end of life a few years after their original rated lives whereas light water reactors are getting life extensions basically everywhere for decades beyond that. Light water thermal reactors are the worst kind of nuclear reactor except for all the other ones which have been built.