It was part of the story -- miners were brought in to dig a tunnel under the reactor by hand to install an emergency cooling system so as to avert a meltdown and second explosion. Lacking any ventilation, they worked in the nude.
In context, the episode added to the surreal air of the disaster. This made the heroism of the miners and many others stand out even more.
7 posted on 06/04/2019 4:35:02 PM PDT by Rockingham