Yes, STERILIZATION is a Scrabble word!

Letter values in Scrabble US: S 1, T 1, E 1, R 1, I 1, L 1, I 1, Z 10, A 1, T 1, I 1, O 1, N 1.

Is it a valid word?

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

the act of making an organism barren or infertile (unable to reproduce)
the procedure of making some object free of live bacteria or other microorganisms (usually by heat or chemical means)

Not playable in Scrabble US: STERILISATION.