Radioactive decay (also known as nuclear decay, radioactivity or nuclear radiation) is the process by which an unstable atomic nucleus loses energy (in terms of mass in its rest frame) by emitting radiation, such as an alpha particle, beta particle with neutrino or only a neutrino in the case of electron capture, or a gamma ray or electron in the case of internal conversion. A material containing such unstable nuclei is considered radioactive. Certain highly excited short-lived nuclear states can decay through neutron emission, or more rarely, proton emission.

In the Chernobyl disaster, the moderator was not responsible for the primary event. Instead, a massive power excursion during a mishandled test caused the catastrophic failure of the reactor vessel and a near-total loss of coolant supply. The result was that the fuel rods rapidly melted and flowed together while in an extremely-high-power state, causing a small portion of the core to reach a state of runaway prompt criticality and leading to a massive energy release,[22] resulting in the explosion of the reactor core and the destruction of the reactor building. The massive energy release during the primary event superheated the graphite moderator, and the disruption of the reactor vessel and building allowed the superheated graphite to come into contact with atmospheric oxygen. As a result, the graphite moderator caught fire, sending a plume of highly radioactive fallout into the atmosphere and over a very widespread area.[

The ‘uncanny’ might serve us better. One of the most chilling traces of the Anthropocene is the global dispersal of radioactive isotopes since mass thermonuclear weapons testing began in the middle of the 20th century, which means that everyone born after 1963 has radioactive matter in their teeth. The half-life of depleted uranium (U-238) is around 4.5 billion years, roughly the same as the age of the Earth, while that of the plutonium in Chernobyl’s nuclear reactor is 240,000 years. Such timescales resist the imagination, but exist as a haunting presence in our daily lives.