Yes, ARBITRATION is a Scrabble word!

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

Is it a valid word?

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

(law) the hearing and determination of a dispute by an impartial referee agreed to by both parties (often used to settle disputes between labor and management)
the act of deciding as an arbiter; giving authoritative judgment

Not playable in Scrabble US: ARBITREMENT.