It is a nuclear variant of a landmine. The nuke mine operates in all respects as other mines do although its explosion is more akin to that of a mini nuke. It deals both normal damage and radiation exposure damage. The mine also leaves behind a radiation exposure area effect for a short time after detonation. It appears to have three detonators located around the outside of the mine.
The only guaranteed (fixed) unarmed nuke mine in the base game is located on the road between Longneck Lukowski's Cannery and Crater house, near an intersection at Kingsport Lighthouse. Another armed one is very close by, just a little up the road to the lighthouse.