Yes, CONTINUATION is a Scrabble word!

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

Is it a valid word?

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

the act of continuing an activity without interruption
a part added to a book or play that continues and extends it
a Gestalt principle of organization holding that there is an innate tendency to perceive a line as continuing its established direction
the consequence of being lengthened in duration

Also: good continuation, law of continuation.