radioactive series

18 LETTERS · STARTS WITH R

radioactive series is a valid 18-letter word worth 23 points in Scrabble and 25 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

R1A1D2I1O1A1C3T1I1V4E1S1E1R1I1E1S1

1 + 1 + 2 + 1 + 1 + 1 + 3 + 1 + 1 + 4 + 1 + 0 + 1 + 1 + 1 + 1 + 1 + 1 =23 PTS

DOUBLE WORD → 46TRIPLE WORD → 69

MEANING

What does radioactive series mean?