You’d think safety would be the main concern for managers at nuclear power plants. But in Illinois, they seem to be just as worried about tattoos.

Electrical Workers Local 15 has filed unfair labor practices charges against Commonwealth Edison, owner of five plants, over its decision to prohibit workers from wearing union tattoos and to ban union reps from its plants.

The dispute erupted when members of Electrical Workers Local 15 began wearing temporary tattoos in a campaign against company plans to create a two-tiered pension program.

The tattoos said “Solidarity in Unity” and “Local 15.”

In August, managers ordered workers to remove the tattoos, claiming they were a “distraction” in a plant control room. When they refused, over 100 workers were sent home and docked a day’s pay.