Yes. 'Chernobyl' on HBO is a true story. It shows what happened in 1986 at the Chernobyl nuclear power plant in the Soviet Union. The series tells about the explosion, the heroism of the firefighters and other workers who tried to deal with the situation, and also the cover - up attempts by the Soviet authorities at that time. It's a very powerful and realistic portrayal of a huge disaster.
To a large extent, it is. The show aims to depict the Chernobyl disaster and its aftermath as accurately as possible, drawing from historical records and accounts. However, for the sake of storytelling, there could be some minor fictional elements or condensations.
The explosion at the Chernobyl nuclear power plant is a main event. Also, the initial response of the firefighters who rushed in not fully aware of the danger. And the later attempts to contain the radiation, like building the concrete sarcophagus.