Plasma is a fluid added by NuclearCraft.
It is created during the operation of a Fusion Reactor and when the reactor is operating correctly, is perfectly safe. However, if the reactor's Electromagnets lose power, Plasma may begin to leak, causing catastrophic structural failure (an explosion).
Plasma has no crafting recipe and cannot be created directly by the player. If spawned into the game, plasma will set a single block on fire with no other effects.