A steam turbine system comprising a first turbine section and a downstream turbine section, each of the first and downstream turbine section having a rotating member including a shaft, and a stationary member surrounding the rotating member and defining a steam flow path, wherein the first turbine section is one of a high pressure section or an intermediate pressure section and the downstream turbine section is one of an intermediate pressure section or a low pressure section, wherein the downstream turbine section has a pressure below a pressure of the first turbine section, whereby each of a first and a second end of the shaft of the first turbine section is at a pressure greater than atmospheric pressure, and wherein the first turbine section comprises a shaft sealing system, the shaft sealing system comprising a plurality of seals disposed about each of the first end and the second end of the shaft of the first turbine section, the plurality of seals comprising a main seal (180, 181) disposed about each of the first end and the second end of the shaft of the first turbine section, a steam seal (182, 183) disposed about each of the first end and the second end of the shaft and disposed axially outboard of the innermost main seal (180, 181), and an air seal (184, 185) disposed axially outboard of each of the steam seals (182, 183), wherein a first annulus is disposed between the first main seal and the first steam seal, a second annulus is disposed between the second main seal and the second steam seal, a third annulus is disposed between the first air seal and the first steam seal, and a fourth annulus is disposed between the second air seal and the second steam seal, the shaft sealing system further comprising a first and second connection line (200, 270), wherein the first connection line is configured to conduct steam from the first turbine section to the downstream turbine section and fluidly connects the first and second annulus (230, 240) to a first stage of the downstream turbine section, and wherein the second connection line fluidly connects the third and fourth annulus (250, 260) to a second stage of the downstream turbine section, the second stage having a lower pressure than the first stage, characterized in that the shaft sealing system is a self-contained shaft sealing system and further comprises a first buffer seal disposed axially outboard of the first air seal and a second buffer seal disposed axially outboard of the second air seal, each of the main seals (180, 181), steam seals (182, 183) and air seals (184, 185) comprises a hydrodynamic non-contacting seal, wherein the hydrodynamic non-contacting seal further comprises one of a segmented circumferential seal or a face seal and wherein the hydrodynamic non-contacting seal further comprises carbon, and in that the steam turbine system further comprises a filtered air supply in fluid communication with each of a first cavity disposed between the first buffer seal and the first air seal and a second cavity disposed between the second buffer seal and the second air seal through a filtered air supply line providing filtered air to each of the first cavity and the second cavity.