A turbine assembly comprising: a rotor with a rotational axis ; a casing enclosing the rotor to form a flow passage therebetween; a first rotating blade row having a plurality of circumferentially adjacent first rotating blades each with a first shroud , at a first rotating blade end that is distal from the rotor and blade airfoils extending into the flow passage ; a first sealing means located between the casing and the first shroud ; a stationary vane row axially adjacent and downstream of the first rotating blade row, having a plurality of circumferentially adjacent stationary vanes each with a base member and a vane airfoil extending into the flow passage ; a second rotating blade row in the flow passage axially adjacent and downstream of the stationary vane row having a plurality of circumferentially adjacent second rotating blades each with a second shroud , at a second rotating blade end that is distal from the rotor ; and a second sealing means located between the casing and the second shroud , wherein a first cavity is formed by the first shroud , the first sealing means and the base member and a second cavity is formed by the second shroud , the base member and the second sealing means , characterised by a bypass-passage extending from a first end at the first cavity to a second end at the second cavity so as to bypass the flow passage and the vane airfoil . a rotor with a rotational axis ; a casing enclosing the rotor to form a flow passage therebetween; a first rotating blade row having a plurality of circumferentially adjacent first rotating blades each with a first shroud , at a first rotating blade end that is distal from the rotor and blade airfoils extending into the flow passage ; a first sealing means located between the casing and the first shroud ; a stationary vane row axially adjacent and downstream of the first rotating blade row, having a plurality of circumferentially adjacent stationary vanes each with a base member and a vane airfoil extending into the flow passage ; a second rotating blade row in the flow passage axially adjacent and downstream of the stationary vane row having a plurality of circumferentially adjacent second rotating blades each with a second shroud , at a second rotating blade end that is distal from the rotor ; and a second sealing means located between the casing and the second shroud , a first rotating blade row having a plurality of circumferentially adjacent first rotating blades each with a first shroud , at a first rotating blade end that is distal from the rotor and blade airfoils extending into the flow passage ; a first sealing means located between the casing and the first shroud ; a stationary vane row axially adjacent and downstream of the first rotating blade row, having a plurality of circumferentially adjacent stationary vanes each with a base member and a vane airfoil extending into the flow passage ; a second rotating blade row in the flow passage axially adjacent and downstream of the stationary vane row having a plurality of circumferentially adjacent second rotating blades each with a second shroud , at a second rotating blade end that is distal from the rotor ; and a second sealing means located between the casing and the second shroud , wherein a first cavity is formed by the first shroud , the first sealing means and the base member and a second cavity is formed by the second shroud , the base member and the second sealing means , characterised by a bypass-passage extending from a first end at the first cavity to a second end at the second cavity so as to bypass the flow passage and the vane airfoil . <EOS>