So, time for some fun, because nuclear power is something I know a thing or 12 about.
Chernobyl reactor No. 4 blew up because the RBMK type reactors in common usage in the USSR at the time used graphite (a neutron moderator) in their control rods. When the reactor started overheating, they SCRAM’d the reactor, causing all of the rods to fully insert, displacing large quantities of neutron-absorbing water. This causes the reactor to generate MORE heat and more neutrons, as it’s now supercritical, and sustaining itself solely off of prompt fission events (basically, in most nuclear reactors, fission is actually sustained by secondary neutrons, released after a fission event occurs, so called slow neutrons. These reactors are not usually intended to operate safely in a supercritical state, where fission is sustained off of neutrons released immediately, and those slow neutrons are just extra on top).
This is coupled with bad engineering, as the backup generators for the pumps that supplied cooling water to the reactor took over a minute (approximately 57 forevers in nuclear engineering) to come up to full speed and provide the needed power to run the coolant pump.
On top of this, there was supposed to be a safety test that day, that was pushed back, which they continued with despite the reactor having been acting oddly, due to operator error.
Contrast this with NR-1, in the USA, which is the reason why the US Army doesn’t get to have reactors, because they managed to kill 7 people by operating a reactor in accordance with DoE instruction (albeit a very bad set of instructions, which included manually disconnecting and reconnecting control rods as part of shutdown procedures). Managed to nail a guy to the ceiling with a control rod through his torso after the reactor went prompt critical and blew the fuck up.
However, all the science in the world here on reactor safety doesn’t actually matter, as you wanted to talk about land area. Let’s look at how many square miles of the earth have been devastated by other forms of large scale power generation. According to estimates, a bit over 13,000 square miles have been adversely affected by coal mining, in the USA alone. Hoover dam’s reservoir lave is over 250 square miles. Itaipu Dam in South America has a reservoir of something like 1200 square miles. Those are pretty common numbers. And yeah, there’s a bit of a difference, those lakes could be drained and people could live there, whereas living in one of the areas affected by coal mining is “inadvisable” due to groundwater contamination, which will take decades to fix itself. And most of the Chernobyl exclusion zone is not noticeably radioactive, never was. The area around Pripyat, it’s a hotspot yeah, but it’s less “will kill you if you live there” and more “you may get cancer in 30 years if you live here”.
