The matter of how a nuclear reactor works and the nature of radiation is a complicated one, but it doesn't take a nuclear physicist to recognize that the atrocities of Chernobyl, depicted in the HBO mini-series of the same name, was devastating to both humans and the environment. While the efforts to clean up Chernobyl started immediately after the explosion, scrubbing the presence of radioactivity in the area is a process that could end up being a centuries-long endeavor. While we know how Chernobyl is being cleaned up, the question of how long it will be until Chernobyl is entirely safe again is a question without a clear answer.
Following the explosion, the most immediate clean-up crews consisted of local firefighters who eventually suffered the consequences of entering a radioactive site without proper protection. However, the circumstances of the Chernobyl explosion were such that the clean-up efforts would have to involve a lot of people and much more severe safety precautions.
According to Wired, the job of cleaning up Chernobyl came down to 600,000 people ranging from state servicemen like firefighters, members of the military, and blue-collar professionals such as janitors and miners. These positions were referred to as liquidators. "The liquidators were sent into impossible scenarios where even machines failed," says photographer Tom Skipp who documented some of the workers who helped clean Chernobyl for his portrait series The Liquidators. "Each [liquidator] has a human story seemingly entangled in the complex history of communism and duty to the motherland."
The work that these liquidators did was as far from glamorous, as one can imagine. Some of the work involved building massive, expensive structures like the concrete and steel sarcophagus that was placed over the destroyed reactor. Much of the work, however, was done by people on-the-ground getting dangerously close to radioactive materials. Igor Kostin wrote in his book Chernobyl: Confessions of a Reporter that liquidators were "instructed to throw a shovelful of radioactive dust and then run ... General [Nikolai] Tarakanov ordered them to remove the lead sheets covering the walls of the government subcommittee bureaus in order to make them rudimentary protective clothing. These suits were not wearable more than once: they absorbed too much radioactivity," per Ranker.
The most gruesome part of the clean-up, however, was disposing of the bodies of first-responders whose bodies still carried radioactivity after that same radioactive exposure had killed them. Many first-responders were placed in lead coffins and buried in concrete. Some sources estimate the ultimate death toll of Chernobyl, including those who suffered the consequences of being exposed to radioactive material during the clean-up process, is as high as 60,000.
The clean-up is still going on today, with people testing radiation levels on nearby areas to ensure that wildlife can people can safely begin to start living around the Chernobyl area again, and the eventual application of the Chernobyl New Safe Confinement which replaces the sarcophagus places atop the reactor thirty years prior. It's possible that in 30 more years, a new containment will have to be replace the NSC, and that the mess of Chernobyl is so massive and unseeable that it can never be truly cleaned, only contained.