Yes, CASTRATION is a Scrabble word!

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

Is it a valid word?

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

neutering a male animal by removing the testicles
surgical removal of the testes or ovaries (usually to inhibit hormone secretion in cases of breast cancer in women or prostate cancer in men)
the deletion of objectionable parts from a literary work