Yes, NICAD is a Scrabble word!

Letter values in Scrabble US: N 1, I 1, C 3, A 1, D 2.

Is it a valid word?

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

a rechargeable battery with a nickel cathode and a cadmium anode; often used in emergency systems because of its low discharge rate when not in use

Also: nickel-cadmium accumulator.