Early in the morning on 26 April 1986, a safety system test at the Chernobyl power plant in Pripyat, now part of Northern Ukraine, ended in a nuclear disaster with catastrophic consequences for both those working at the plant and those living in the surrounding area. The narrative seems to be a classic cautionary tale against the utilisation of nuclear reactors to generate power, but the reality is more nuanced. Here, we look at how nuclear reactors work generally, what led to the accident at Chernobyl 30 years ago, and the differences between Chernobyl and modern reactors.