Yes, ISOLATION is a Scrabble word!

Letter values in Scrabble US: I 1, S 1, O 1, L 1, A 1, T 1, I 1, O 1, N 1.

Is it a valid word?

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

a state of separation between persons or groups
a feeling of being disliked and alone
the act of isolating something; setting something apart from others
(psychiatry) a defense mechanism in which memory of an unacceptable act or impulse is separated from the emotion originally associated with it
a country's withdrawal from international politics

Also: closing off.