Wikipedia is our friend here:
Fukushima Daini (Daini means second or two)
Unit First criticality Reactor Architecture Construction
1 31/07/1981 Toshiba Toshiba Kajima
2 23/06/1983 Hitachi Hitachi Kajima
3 14/12/1984 Toshiba Toshiba Kajima
4 17/12/1986...