Yes, INVERSIONS is a Scrabble word!

Letter values in Scrabble US: I 1, N 1, V 4, E 1, R 1, S 1, I 1, O 1, N 1, S 1.

Is it a valid word?

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

the layer of air near the earth is cooler than an overlying layer
abnormal condition in which an organ is turned inward or inside out (as when the upper part of the uterus is pulled into the cervical canal after childbirth)
a chemical process in which the direction of optical rotation of a substance is reversed from dextrorotatory to levorotary or vice versa
(genetics) a kind of mutation in which the order of the genes in a section of a chromosome is reversed
the reversal of the normal order of words
(counterpoint) a variation of a melody or part in which ascending intervals are replaced by descending intervals and vice versa
a term formerly used to mean taking on the gender role of the opposite sex
turning upside down; setting on end
the act of turning inside out

Also: sexual inversion.