A rim seal assembly includes an annular seal element circumscribing an engine centerline or axis and mounted on an annular platform including a radially inwardly extending annular platform flange disposed between and connected to forward and aft flanges at distal ends of forward and aft annular elements respectively. Annular forward and aft outer rim cavities radially disposed between the forward and aft annular elements and the platform are axially separated by the platform flange. Cooling slots extend radially across axially facing forward and aft surfaces of the forward and aft flanges. The platform flange and the forward and aft flanges are bolted together. The annular seal element may include seal teeth in sealing relationship with an annular seal land such as in a labyrinth seal. The rim seal assembly may be incorporated in a low pressure turbine use a compressor as a source of cooling air.