Yes, PEACEMAKERS is a Scrabble word!

Letter values in Scrabble US: P 3, E 1, A 1, C 3, E 1, M 3, A 1, K 5, E 1, R 1, S 1.

Is it a valid word?

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

someone who tries to bring peace
a belt-fed machine gun capable of firing more than 500 rounds per minute; used by United States troops in World War II and the Korean War

Also: make-peace, browning machine gun.