Yes, TRUNCATION is a Scrabble word!

Letter values in Scrabble US: T 1, R 1, U 1, N 1, C 3, A 1, T 1, I 1, O 1, N 1.

Is it a valid word?

TRUNCATION is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the property of being truncated or short
the replacement of an edge or solid angle (as in cutting a gemstone) by a plane (especially by a plane that is equally inclined to the adjacent faces)
the act of cutting short