With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Plutonium reacts with nitrogen.
text_B: The Olentangy Indian Caverns are a series of natural underground caves , passages , and rooms occupying three different levels .. The caverns were formed millions of years ago by an underground river that cut through the limestone rock .. They were used by the Wyandotte Indians as a refuge from the weather and from their enemies the Delaware Indians .. Wyandotte Indians. Wyandotte Indians. Delaware Indians. Delaware Indians. The Olentangy Indian Caverns are located at 1779 Home Road , Delaware , Ohio and are open seasonally for tours .
not_related.