Had a conversation with a friend today (we’ll call him Lee), he was voicing his concerns about nuclear energy and I was putting them at ease with facts and sources. Another friend also added some input, we’ll call her Kel. Our conversation went like this:
Lee: My only concern with nuclear is the danger of a plant exploding. It’s impossible to clean up and can cause health issues for millions (looking back at the Chernobyl event). If a wind turbine fails it’s easy to clean up and replace, same with solar. So it’s kind of like you have to evaluate what’s the injury or hazard rate per square mile of foot print (if that makes any sense).
Me: Chernobyl caught on fire and didn’t have a containment dome (reactors cannot “blow up”). No western reactors on earth are without a containment dome, that was just the USSR cutting corners on cost. With such a dome, there would have been no spread of contamination.
I’ll come back to Chernobyl in a minute but look at Fukushima and Three Mile Island. Not a single death due to radiation, no widespread contamination, etc. Of the hundreds of nuclear plants on earth, only these three have had significant problems. If you look at the deaths per kilowatt hour by energy generation type, you’ll find that nuclear is by far the safest source of energy we’ve ever used.  And that’s before factoring in the 7+ million deaths per year due to air pollution from fossil fuels (which wind and solar rely on for backup). 
Now back to Chernobyl; a few dozen people were killed (not the hundreds of thousands that anti-nuclear fearmongers claim) and 300,000 were forced to evacuate. We now know that evacuation zones around nuclear plants are WAY larger than necessary (as was proven by Fukushima), and this is the result of bad policy brought on by irrational fear.  As a result of the evacuation, the Chernobyl Exclusion Zone is now essentially a wildlife preserve; wildlife is thriving due to a lack of humans.  To top it all off, there were indeed people who refused to evacuate. They’re doing just fine, and in addition to that, only reactor 4 melted down; the other three continued to operate with the last one (reactor 3) not shutting down until the year 2000. This image will give you an idea of how close the reactors are. Not exactly the uninhabitable wasteland we were told to believe…
Lee: Oh ok, I wasn’t sure what their unit of measure was for the dangers of nuclear. That’s pretty cool. I heard somewhere that Chernobyl caused hundreds of thousands of deaths and like a million cases of injury from exposure to radiation. But then maybe those facts were exaggerated or just people pointing fingers at Chernobyl since it was in proximity of these cases. That’s good to know about the containment dome. What does a containment dome look like?
Kel: Moose nailed Chernobyl, there was a lot that happened there. But all nuclear reactor “explosions” are actually steam explosions – the heat exchange/turbine system blows. This can make a mess… I see a lot of people equating it to a nuclear bomb though and that’s just plain wrong. By the way, the heat exchange system contains only water and is not radioactive.
Me: Dome in the middle.
Me: When Chernobyl first happened, it was predicted that there would be thousands of deaths.  Birth defects and similar issues were also predicted, but none have been shown to be a result of radiation. If radiation could cause such things, we would have seen it when we bombed Japan. We didn’t just bomb them and then f*** off for 45+ years, we’ve actually been studying and documenting survivors and their families for decades now.  Anyway, anti-nuclear NGOs (Non-Government Organizations, like Greenpeace) like to cite these predicted numbers as if they’re facts, to scare people away from nuclear energy.  This is also why they always equate nuclear energy with nuclear weapons; that’s like equating civilian crop-dusters with guided missiles. Not even close. All those deaths that were supposed to happen, didn’t.  What did happen was 4,000 people, many of which were children, got thyroid cancer as a result of radioactive iodine. If I remember correctly, like 9 of them died.  Thyroid cancer is easy to detect and treat. They were exposed when radioactive iodine settled on crops in the area, were eaten by cows and then ended up in the milk.
We learned a lot from Chernobyl, and we’ve seen what a worst-case scenario looks like. There is no reason to fear nuclear anymore because this type of accident literally could not even happen again. Now, here’s how the reactor caught fire, and why it cannot happen again:
Me: The RBMK is the type of reactor that Chernobyl used. These do not exist outside of the former USSR, I think there are only like 10 left in the world but I believe they all have had modifications to improve safety as a result of the Chernobyl accident.
First you need to know how a nuclear reactor works: when a Uranium atom decays, it releases a bunch of energy, plus 2-3 neutrons.  These neutrons are moving too quickly to break apart more uranium atoms; they just bounce off due to their small size. So how do we create a chain reaction? We slow the neutrons down, using a moderator of water or graphite. Neutrons that have been sufficiently slowed down CAN break apart other uranium atoms, releasing more energy and more neutrons, until a chain reaction can be sustained. Regardless of moderator, water is used to keep the reactor from getting too hot due to all the energy. All western reactors use water as both the coolant AND the moderator. This way, if there is a loss of coolant, we also lose the moderator and a chain reaction cannot continue.
The RBMK reactor type uses graphite as the moderator instead of water. At Chernobyl, they had a loss of coolant but the moderator is still there, so the chain reaction continues. This resulted in the reactor getting hotter and hotter until a fire broke out.  Gas buildup did blow the roof off the building but this was a chemical reaction, not a nuclear one. Now, with a burning reactor core, no roof and no containment dome, smoke brought radioactive particles into the atmosphere and spread it across Europe. This is where the radioactive iodine (and other isotopes) came from.
Not only does every modern reactor have a containment dome, but none use graphite as a moderator. For these reasons, another accident like this is not even physically possible.