A haunting part the latest episode of HBO's Chernobyl, "The Happiness of All Mankind", is the fact that the Soviet Union resorted to using humans to clean up the radioactive debris, particularly the graphite from the core of reactor 4, on top of the power plant's roof. Of course, as with anything shown in the Chernobyl miniseries, one of the first questions viewers ask is, did that really happen? And considering everything that occurred in the aftermath of the Chernobyl nuclear disaster, the answer is yes.
Spanning several months after the immediate crisis management at Chernobyl, episode 4 depicts the clean-up phase that took place towards the end of 1986. Before placing the sarcophagus over the Chernobyl Power Plant, the debris and graphite needed to be removed or at least placed back into the core so that construction could begin to cover all of it up. At first, actual robots such as the STR-1 and Mobot were used to remove the debris in certain areas. Some robots, of course, didn't work at all, such as the German MF-2 and MF-3.
As a last resort, the Soviet Union and the Chernobyl Commission ended up using humans - "biorobots" as they were called - to literally shovel the debris off the roof. According to the book, Chernobyl: Confessions of a Reporter, by author Igor Kostin, the vast majority of liquidators (people responsible for managing the crisis in its aftermath) who were tasked with removing the radioactive material from the third roof were middle-aged. Furthermore, they could only be on the roof for a very short period of time.
Just as Jared Harris' Valery Legasov mentions in Chernobyl episode 4, staying on the roof for more than a minute or two would be detrimental to a liquidator's life expectancy. So in order to further protect the biorobots, their uniforms/protective gear would be discarded after single-use, since the material would be highly radioactive. And this process went on for quite some time. Throughout the summer of 1986, 3,828 biorobots shoveled the radioactive debris off of Chernobyl's roof. At first, it was believed that approximately 3,400 men did this job, but the real number came out at a later point. In fact, this part of the process was the subject of a 2011 Ukranian documentary, titled Chernobyl.3828.
All in all, much of what happened after the explosion of the RBMK reactor at Chernobyl was done as a last resort. Something like this had never occurred before, and everyone involved was trying to figure out one problem at a time. This is evident with the use of the "biorobots" when the radio-operated robots failed to perform as needed.