Yes, SWEEPER is a Scrabble word!

Letter values in Scrabble US: S 1, W 4, E 1, E 1, P 3, E 1, R 1.

Is it a valid word?

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

an employee who sweeps (floors or streets etc.)
a cleaning implement with revolving brushes that pick up dirt as the implement is pushed over a carpet
little-known nocturnal fish of warm shallow seas with an oblong compressed body

Also: carpet sweeper.