This is the Compact 480MW 48x48 reactor from https://factorioprints.com/view/-KjUiaibx5dJBC9svbMy with added circuit network logic to only insert fuel when steam is running low making it much more fuel efficient at low utilization. I also adjusted the design a bit so you can walk to the center.
For fuel efficiency to work correctly you need to setup 4 passive provider chests close by that hold ONE uranium fuel cell each (use inserter stack override to 1 to drop fuel cells on the ground/belts and then fill chests with exactly 1 fuel cell). If you don't do this your researched construction robots might bring multiple fuel cells at once and the stack override from the requester chest into the reactor doesn't work (for whatever reason).
5 Turbines are missing. 4 of them were replaced with steam tanks and one is missing in the top right as my roboport stands there :). You can add the turbines outside the 48x48 to actually reach the full 480MW.