Patent ID: 7744343

Claim:
A steam turbine comprising: a rotor; a plurality of bucket stages coupled to said rotor, each said bucket stage comprising a plurality of circumferentially spaced buckets coupled to said rotor, each said bucket comprising a base portion and a tip portion; a diaphragm assembly surrounding said rotor and said bucket stages; and an outer casing disposed about said rotor and diaphragm assembly; said diaphragm assembly comprising: a plurality of nozzle stages located between said bucket stages; a circumferentially extending groove, said groove located upstream from one of said bucket stages and between said bucket stage and an adjacent nozzle stage positioned upstream from said bucket stage; a circumferentially extending extraction chamber; at least one first bore extending from said groove to said extraction chamber, said at least one first bore providing bi-directional fluid communication between said groove and said extraction chamber; and at least one second bore extending from said extraction chamber through an outer surface of said diaphragm assembly; said at least one second bore providing bi-directional fluid communication between said extraction chamber and an area between said outer surface of said diaphragm assembly and said outer casing.