Patent ID: 9534690
Date: 2017-01-03
CPC Classifications: F04D,F16J,G21C,Y02E

Claim:
1. A leakage prevention seal sealing a space between a rotating shaft rotating about an axis and a housing surrounding the rotating shaft from a radial outer side so as to regulate a flow of high-temperature pressurized water in the space from the upstream side to the downstream side in an axial direction, the leakage prevention seal comprising: a first seal ring which surrounds the rotating shaft and which contacts with an upstream side surface of the housing along a circumferential direction in the rotating shaft; a second seal ring, which, on the upstream side of the first seal ring, surrounds the rotating shaft and which contacts with an upstream surface of the first seal ring along the circumferential direction in the rotating shaft; and a heat-driven section which, when high-temperature pressurized water reaches the heat-driven section, reduces the diameter of both the first seal ring and the second seal ring and causes the inner peripheral surfaces of both the first seal ring and the second seal ring to be in contact with the rotating shaft, wherein the first seal ring has a closed loop shape to form a first gap extending over a first range in a circumferential direction between the rotating shaft and the first seal ring during the reduction in diameter, wherein the second seal ring forms a second gap, which allows the high-temperature pressurized water to leak to the downstream side, over a second range in the circumferential direction during the reduction in diameter, and wherein the circumferential positions of both the first range and the second range are different.