Yes, SCINTILLATION is a Scrabble word!

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

Is it a valid word?

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

(physics) a flash of light that is produced in a phosphor when it absorbs a photon or ionizing particle
a rapid change in brightness; a brief spark or flash
a brilliant display of wit
the quality of shining with a bright reflected light
the twinkling of the stars caused when changes in the density of the earth's atmosphere produce uneven refraction of starlight