Yes, INS is a Scrabble word!

Letter values in Scrabble US: I 1, N 1, S 1.

Is it a valid word?

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

an agency in the Department of Justice that enforces laws and regulations for the admission of foreign-born persons to the United States
a unit of length equal to one twelfth of a foot
a rare soft silvery metallic element; occurs in small quantities in sphalerite
a state in midwestern United States

Also: immigration and naturalization service, atomic number 49, hoosier state.

Not playable in Scrabble US: INDIANA.