Yes, SPIRAL is a Scrabble word!

Letter values in Scrabble US: S 1, P 3, I 1, R 1, A 1, L 1.

Is it a valid word?

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

a plane curve traced by a point circling about the center but at increasing distances from the center
a curve that lies on the surface of a cylinder or cone and cuts the element at a constant angle
a continuously accelerating change in the economy
ornament consisting of a curve on a plane that winds around a center with an increasing distance from the center
a structure consisting of something wound in a continuous series of loops
flying downward in a helical path with a large radius