Turbine stator vane segment having internal cooling circuits

A turbine stator vane includes outer and inner walls (20, 28) each having outer and inner chambers and a vane (18) extending between the outer and inner walls. The vane includes first, second, third, fourth and fifth cavities (34, 36, 38, 40, 42) for flowing a cooling medium. The cooling medium enters the outer chamber of the outer wall, flows through an impingement plate (60) for impingement cooling of the outer band wall defining in part the hot gas path and through openings (64, 66, 68) in the first, second and fourth cavities for flow radially inwardly, cooling the vane. The spent cooling medium flows into the inner wall and inner chamber for flow through an impingement plate (84) radially outwardly to cool the inner wall. The spent cooling medium flows through the third cavity (38) for egress from the turbine vane segment from the outer wall. The first, second or third cavities contain inserts (70, 72, 74) having impingement openings for impingement cooling of the vane walls. The fifth cavity (42) provides air cooling for the trailing edge.