Turbine disc assembly

A turbine disc assembly comprising a turbine disc mounted coaxially on a shaft and, in use, arranged in the path of a hot work fluid flow, a cover plate axially displaced from the turbine disc in a direction upstream with respect to the work fluid flow and an annular seal plate arranged adjacent an outer rim of the turbine disc to prevent the hot work fluid flow from penetrating a space axially adjacent the turbine disc, the cover plate comprising a radially inner annular disc component and a radially outer annular disc component, the annular disc components arranged coaxially with each other and arranged so as to permit relative axial and/or radial movement of the radially inner annular disc component and the radially outer annular disc component with respect to one another.