Assertion: neptunium's life | /r/HasProperty | 2.14 million years
Facets:
Source sentences:
text: Neptunium-237 is a transuranic radioactive material with a long physical half-life (2.14 million years).
text: This amount declines slowly as the americium decays into neptunium-237, a different transuranic element with a much longer half-life (about 2.14 million years).