To record a unique score for the show, composer Hildur Guðnadóttir went to the decommissioned power plant Ignalina in Lithuania, where a lot of the show was filmed, to record unique ambient sounds with the help of sound recording specialist Chris Watson and score producer Sam Slater. Then, back in the studio they listened to hours of recordings, sampling sounds from them. She composed most of the music for the show's soundtrack from those recordings.
The city of Pripyat - about 1.2 miles (2 km) from the power plant - sits almost exactly as it was left on April 27, 1986, at 2 p.m. Soviet authorities initially ordered a temporary three-day evacuation just three hours in advance, and advised residents to pack only their vital personal belongings. Believing they would be returning shortly, the city was essentially abandoned in place. During the clean-up operation, though, most of the furniture, cars and other belongings were looted and illegally removed from the exclusion zone. When the people of Chernobyl were evacuated, they were informed that they would only be going away for a few weeks while the Power Plant was fixed. That turned out to not be what happened, and so the city sits exactly as it was left in 1986.
Parallel to the show, after each episode's release, HBO released a podcast for each episode, in which creator/writer Craig Mazin talks with Peter Sagal about the episode in question. During those, Mazin revealed many behind-the-scenes details about the writing and the production and explained more about the history and real events behind the episode's storyline and the characters. It's called "The Chernobyl Podcast."
On screen the actors speak English in their natural accents. However, all speech that is heard through artificial means - through the radio, emergency telephone call recordings, Soviet television news, and announcements made through public address systems - is in Russian.
Initial filming started on May 13, 2018, in Fabijoniskes, a residential district in Vilnius, Lithuania, which was used to portray the Ukrainian city of Pripyat, since the district maintained an authentic Soviet atmosphere. At the end of March, production moved to Visaginas, Lithuania, to shoot both the exterior and interior of the Ignalina Nuclear Power Plant, a decommissioned nuclear power station that is sometimes referred to as "Chernobyl's sister" due to its visual resemblance and the nuclear reactor design used at both Chernobyl and Ignalina (RBMK nuclear power reactor).
Veteran British sound engineer Chris Watson - a regular recordist on the acclaimed documentaries of David Attenborough such as The Life of Birds (1998), The Life of Mammals (2002) and The Life of Mammals (2002) - assisted Icelandic composer Hildur Guðnadóttir with her efforts to record the interior sounds of the decommissioned Ignalina Nuclear Power Plant in Lithuania before the filming crew actually arrived on location. According to Hildur, she and Watson were both required to wear protective gear before exploring the plant, which was still being cleaned by numerous uniformed personnel as they 'sampled' the sound ambience in the vast labyrinth of corridors throughout the facility.
As a result of the series' depiction of the accident, the Russian government has announced it will do a version of its own. They call it the "patriotic version" and it follows a conspiracy theory according to which the power plant in Chernobyl exploded due to a bomb put by CIA agents.
The trivia items below may give away important plot points.
The last lines, spoken in voiceover by Legasov (Jared Harris), are from the tapes that he records in the beginning of episode 1 - "What is the cost of lies?" The show ends with that line too, coming full circle.
Lyudmila Ignatenko (played by Jessie Buckley), the pregnant wife of doomed firefighter Vasily Ignatenko (Adam Nagaitis) is the subject of a Swedish documentary titled The Voice of Ljudmila (2001). The young couple, who married in 1983, had planned to travel to Belarus to visit Vasily's parents on that fateful Saturday morning of April 26, 1986.