Leakage prevention seal, and pump for nuclear reactor cooling material

Patent metadata

Field	Value
Publication number	US-2016010749-A1
Application number	US-201314769714-A
Country	US
Kind code	A1
Filing date	Dec 24, 2013
Priority date	Mar 19, 2013
Publication date	Jan 14, 2016
Grant date	—

Abstract

This leakage prevention seal is provided with: a first seal ring which surrounds a rotating shaft and which is in circumferential contact with the surface of a housing which faces the upstream side; a second seal ring, which, on the upstream side of the first seal ring, surrounds the rotating shaft and which is in circumferential contact with the first seal ring; 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. The circumferential positions of both a first range between the first seal ring and the rotating shaft and a second range formed by the second seal ring are different.

First 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 is in circumferential contact with the surface of the housing which faces the upstream side; a second seal ring, which, on the upstream side of the first seal ring, surrounds the rotating shaft and which is in circumferential contact with the first seal ring; 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.

2 . The leakage prevention seal according to claim 1 , further comprising a first gap positioning unit determining the circumferential position of the first range where the first gap is formed by applying a force in a radial direction to the first seal ring.

3 . The leakage prevention seal according to claim 2 , further comprising a pressing unit pressing the second seal ring toward the first seal ring.

4 . The leakage prevention seal according to claim 3 ,
wherein the first seal ring includes: a ring main body extending in the circumferential direction of the rotating shaft; and a pair of soft members disposed at both respective ends of the ring main body, formed of a material softer than the material of the ring main body, and brought into contact with each other during the reduction in diameter.

5 . The leakage prevention seal according to claim 4 ,
wherein the heat-driven section reduces the diameter of the first seal ring at a first temperature and reduces the diameter of the second seal ring at a second temperature, and wherein the first temperature is lower than the second temperature.

6 . The leakage prevention seal according to claim 5 ,
wherein the second seal ring has a closed loop shape when reduced in diameter, and wherein the second gap extends over the second range between the second seal ring and the rotating shaft.

7 . The leakage prevention seal according to claim 6 , further comprising a second gap positioning unit determining the circumferential position of the second range where the second gap is formed by applying a force in the radial direction to the second seal ring.

8 . The leakage prevention seal according to claim 5 ,
wherein the second seal ring has a C shape for both circumferential ends to face each other in the circumferential direction during the reduction in diameter, and wherein the second gap is formed between both of the ends of the second seal ring.

9 . A pump for a nuclear reactor cooling material comprising:
a rotating shaft rotating about an axis; a housing surrounding the rotating shaft from a radial outer side; and a leakage prevention seal according to claim 8 sealing a space between the rotating shaft and the housing so as to regulate a flow of high-temperature pressurized water in the space from the upstream side to the downstream side in the axial direction.

10 . The pump for a nuclear reactor cooling material according to claim 9 ,
wherein an annular groove recessed to the radial outer side and extending in a circumferential direction is formed in an inner peripheral surface of the housing, wherein the first seal ring and the second seal ring are arranged to be accommodated in the annular groove, and wherein the surface of the annular groove facing the upstream side is an abutting surface.

Assignees

• Mitsubishi Heavy Ind Ltd

Inventors

• Kafuku Hidetaka
• Uehara Hidekazu
• Sakaguchi Yukihiro

Classifications

• F16J15/008

  with provision to put out of action at least one sealing; One sealing sealing only on standstill; Emergency or servicing sealings (F16J15/164 takes precedence) · CPC title

• F04D7/08

  the fluids being radioactive · CPC title

• F04D29/126

  especially adapted for liquid pumps · CPC title

• F16J15/164 Primary

  the sealing action depending on movements; pressure difference, temperature or presence of leaking fluid · CPC title

• G21C15/02

  Arrangements or disposition of passages in which heat is transferred to the coolant; {Coolant flow control devices (G21C19/04 takes precedence; coolant flow control through fuel assemblies, e.g. flow restrictors G21C3/322)} · CPC title