What Azzanine said. Take the classic meltdown: Chernobyl. While a lot of the structure was destroyed, for sure, the greatest reason that place is now a condemned, radioactive shithole is because of the massive amounts of radiation that were leaked out by a combination of waste being sent (by the explosion) into the atmosphere, exposed (and irradiated) fuel rods, and large amounts of corium where the reactor core was, which (if I understand it correctly) is basically a molten sludge of various, horrifically radioactive materials. Doesn't help that the Soviet system was more interested in assigning blame and trying to sweep the disaster under the rug instead of finding a way to prevent radioactive materials from leeching into the groundwater. While a large amount of the short-term, high-radiation waste has decayed in the 30 some-odd years since the meltdown, there are still long-term isotopes that will be there for millennia to come, unless we find a way to clean and dispose of it.
ReC mimics those reactor failures quite accurately, from my experience. A sizable explosion occurs, but it doesn't do that much collateral damage. Honestly, I've had IC2 machine explosions cause more damage than a ReC meltdown. If you can deal with having to walk around exclusively in a hazmat suit and living in a wasteland where nothing can grow, then...it'll still be a pain, but markedly less so than if you were relying on farming (which RoC kinda requires that you do, since you need canola for lube) to support your infrastructure.
(Also, minor point of correction, the initial Chernobyl explosion was a steam explosion, if memory serves. The intense heat of the reactor flash vapourized the coolant, which prevented it from absorbing neutrons, which made it hotter, thus creating a positive feedback loop until the boilers exploded from the pressure. The second explosion, though, that was a hydrogen explosion. Then there was a small criticality event [on the order of 10 tonnes of TNT], but that was only in a small part of the reactor core.)