JP2013151922A - Nuclear reactor coolant pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nuclear reactor coolant pump capable of controlling circulation of pressurized water of high temperature and high pressure in abnormal circumstances.SOLUTION: A nuclear reactor coolant pump is provided with a rotary shaft 1, a housing which surrounds the rotary shaft 1, and a leakage preventing seal 30 which is installed so as to demarcate a gap between the rotary shaft 1 and the housing and controls the circulation of high temperature pressurized water in abnormal circumstances. The leakage preventing seal 30 includes: a C-shaped seal ring 31 extending in a circumferential direction of the rotary shaft 1 so as to surround the rotary shaft 1, and having a first end part 41 and a second end part 51 which face each other in the circumferential direction; and a thermal actuator 60 which is driven by the high temperature pressurized water as heat source and reduces a diameter of the seal ring 31 by bringing the first end part 41 and the second end part 51 close to each other.

Description

  The present invention relates to a reactor coolant pump, and more particularly, to a reactor coolant pump that can avoid leakage of high-temperature pressurized water during an abnormality.

  The nuclear reactor primary coolant pump includes a rotating shaft that rotates about an axis extending in the vertical direction, and a housing that surrounds the rotating shaft. A space between the rotating shaft and the housing is provided with a plurality of stages of shaft seals that are spaced apart in the vertical direction. And by these multi-stage seals, pressure reduction is performed so that the high-pressure pressurized water on the lower side becomes atmospheric pressure on the upper side (see, for example, Patent Document 1).

Japanese Utility Model Publication No. 63-22397

  By the way, in the reactor primary coolant pump, it is expected that, for example, 70 ° C. pressurized water rises to 300 ° C. during normal operation when there is an abnormality such as loss of all alternating current power supply (SBO: Station Black Out). At this time, high-temperature and high-pressure pressurized water (hereinafter referred to as high-temperature pressurized water) may break through the shaft seal located at the lowermost position among the plurality of shaft seals and reach the second shaft seal from the lowermost position. .

Here, the second shaft seal device from the bottom can be designed to withstand the high-temperature pressurized water, but the heat-resistant O-ring arranged around the shaft seal device was damaged by the high-temperature pressurized water. In this case, the primary coolant may leak to the outside.
Therefore, in order to avoid the high temperature pressurized water reaching the second shaft sealing device from the bottom when all AC power is lost, the high temperature pressurized water flows in the gap between the rotating shaft and the housing between the sealing devices. It is preferable to have a configuration that can regulate the above.

  This invention is made | formed in view of the said subject, Comprising: It aims at providing the reactor coolant pump which can control distribution | circulation of the high temperature / high pressure pressurized water at the time of abnormality.

In order to solve the above problems, the present invention provides the following means.
That is, the reactor coolant pump according to the present invention is provided so as to partition in the axial direction a rotating shaft that rotates around an axis, a housing that surrounds the rotating shaft, and a gap between the rotating shaft and the housing. A leakage prevention seal that restricts the flow of high-temperature pressurized water from one side of the axial direction to the other side in the event of an abnormality, and the leakage prevention seal extends in the circumferential direction of the rotation shaft so as to surround the rotation shaft Then, a C-shaped seal ring having a first end portion and a second end portion facing each other in the circumferential direction, and driving the high-temperature pressurized water as a heat source, the first end portion and the second end portion are And a thermoactuator that reduces the diameter of the seal ring by being close to each other.

  According to the reactor coolant pump having such a feature, when high-temperature pressurized water reaches the leakage prevention seal at the time of abnormality, the thermoactuator is driven using the high-temperature pressurized water as a heat source. By this driving, the thermoactuator reduces the diameter of the seal ring by bringing the first end and the second end of the seal ring close to each other. As a result, the gap between the seal ring and the rotating shaft is reduced in the circumferential direction, or the seal ring is in close contact with the rotating shaft in the circumferential direction.

  Moreover, it is preferable that the reactor coolant pump according to the present invention includes a biasing unit that biases the first end portion and the second end portion of the seal ring so as to be separated from each other.

  As a result, when the thermoactuator is not driven, the seal ring is expanded in diameter by separating the first end and the second end by the biasing means. Therefore, a gap between the seal ring and the rotating shaft in the normal state can be secured, and smooth rotation of the rotating shaft can be maintained.

  Furthermore, in the reactor coolant pump of the present invention, it is preferable that the first end is pressed radially inward and toward the second end by driving the thermoactuator.

  Thus, when the seal ring is pressed radially inward, the seal ring is easily reduced in diameter so as to embrace the rotating shaft. Accordingly, the gap between the seal ring and the rotation shaft can be more reliably reduced over the entire circumferential direction, or the seal ring can be reliably adhered to the rotation shaft over the entire circumferential direction.

  Furthermore, in the reactor coolant pump of the present invention, the seal ring is accommodated in an annular groove that is annularly recessed from the inner peripheral surface of the housing that faces the outer peripheral surface of the rotating shaft, and the annular groove is It is preferable to have a counterbore portion for introducing the high-temperature pressurized water into the radially outer side of the seal ring when the seal ring is reduced in diameter.

  As a result, when the high-temperature pressurized water reaches the leakage prevention seal in an abnormal state, the diameter of the seal ring is reduced, and as a result, the high-temperature pressurized water circulates outward in the radial direction of the seal ring through the counterbore portion of the annular groove. . As a result, the seal ring is pressed radially inward by high-temperature pressurized water. Accordingly, the gap between the seal ring and the rotation shaft can be more reliably reduced over the entire circumferential direction, or the seal ring can be reliably adhered to the rotation shaft over the entire circumferential direction.

  According to the reactor coolant pump of the present invention, when the thermoactuator is driven using high-temperature pressurized water as a heat source to reduce the diameter of the seal ring, the gap with the rotation shaft is reduced in the circumferential direction, or the seal ring is in the circumferential direction. In close contact with the rotating shaft. This makes it possible to regulate the distribution of high-temperature pressurized water at the time of abnormality.

It is a figure which shows the longitudinal cross-sectional view and its systematic diagram of the nuclear reactor coolant pump which concerns on 1st embodiment of this invention. It is the figure which looked at the leak prevention seal in the nuclear reactor coolant pump which concerns on 1st embodiment of this invention from the axial direction of the rotating shaft. It is AA sectional drawing of FIG. It is the figure which looked at the leakage prevention seal | sticker of the reactor coolant pump which concerns on 2nd embodiment of this invention from the axial direction of the rotating shaft. It is the figure which looked at the leakage prevention seal | sticker of the reactor coolant pump which concerns on the modification of 2nd embodiment of this invention from the axial direction of the rotating shaft. It is the figure which looked at the leakage prevention seal | sticker of the reactor coolant pump which concerns on the modification of 3rd embodiment of this invention from the axial direction of the rotating shaft in normal time. It is the figure which looked at the leakage prevention seal | sticker of the reactor coolant pump which concerns on the modification of 3rd embodiment of this invention from the axial direction of the rotating shaft at the time of abnormality.

Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3.
First, the overall configuration of the reactor coolant pump 100 according to the first embodiment will be described. As shown in FIG. 1, the reactor coolant pump 100 includes a rotating shaft 1 disposed so as to be rotatable around an axis line 0 extending in the vertical direction, and a housing 2 disposed so as to surround the rotating shaft 1. ing. A plurality of shaft seals 10 are provided in the space between the rotary shaft 1 and the housing 2 and are spaced apart in the direction of the axis 0.

  In this embodiment, three sets of shaft seals 10 are provided. These shaft seals 10 are a first shaft seal 10A, a second shaft seal 10B, and a third shaft seal 10C from the bottom to the top. Yes. The first shaft seal 10A is a leakage limiting type seal, and the second shaft seal 10B and the third shaft seal 10C are mechanical seals.

  The first shaft seal 10 </ b> A is a first runner 11 </ b> A that is integrally fixed to the outer peripheral surface of the rotary shaft 1 and has a disk shape that projects radially outward, and a ring shape that is fixed to the housing 2. And a first ring 12A that forms a slight gap therebetween. A first secondary seal (not shown) is provided between the first ring 12A and the housing 2.

  Further, the second shaft seal 10B is provided above the first shaft seal 10A, and is fixed to the outer peripheral surface of the rotating shaft 1 integrally, and a second runner 11B having a disk shape projecting radially outward. And a second ring 12B slidably contacting the second runner 11B in a ring shape fixed to the housing 2. A second secondary seal (not shown) is provided between the second ring 12B and the housing 2.

  Further, the third shaft seal 10C is provided above the second shaft seal 10B, is fixed to the outer peripheral surface of the rotary shaft 1 integrally, and is a third runner 11C having a disk shape projecting radially outward. And a second ring 12B which forms a ring fixed to the housing 2 and forms a gap in sliding contact with the third runner 11C. A third secondary seal (not shown) is provided between the third ring 12 </ b> C and the housing 2.

  The reactor primary coolant is high-temperature water of 200 to 300 ° C., and high-pressure pressurized water (seal water) is placed under the first shaft seal 10A by a filler pump 15 so that the high-temperature water does not rise in the housing 2. ) Is supplied. This pressurized water is supplied from the volume control tank 16. The pressurized water that leaks through the first shaft seal 10A and reaches the lower side of the second shaft seal 10B is returned to the volume control tank 16 through the shielding valve 17 and the flow meter 18.

Pure water called purge water is supplied to the space below the third shaft seal 10C, that is, the space between the third shaft seal 10C and the second shaft seal 10B. This purge water is supplied from a purge water head tank 19 provided at a high place via a throttle and a flow meter 20 (not shown). Note that the pure water prepared in the pure water makeup tank 21 is supplied to the purge water head tank 19 via the pure water pump 22 and the refill valve 23. The replenishing valve 23 is controlled by a level control device 24 that detects the head height of pure water in the purge water head tank 19, whereby the head height of the purge water head tank 19 is maintained at a predetermined value. ing.
The purge water lubricates and cools the second shaft seal 10B and the third shaft seal 10C, and is collected in the drain tank 27 via the flow meter 25 and the stand pipe 26.

  The temperature of the pressurized water below the first shaft seal 10A is 70 ° C., and the pressure is about 15.5 MPa. In the first shaft seal 10A, this pressurized water is depressurized to about 0.3 MPa, that is, the pressure of the pressurized water in the space below the second shaft seal 10B is about 0.3 MPa. In the second shaft seal 10B, the pressure of about 0.3 MPa is reduced to about 0.03 MPa, and in the third shaft seal 10C, the pressure is reduced to atmospheric pressure.

  Here, when all AC power is lost, it is assumed that pressurized water at 70 ° C. during normal operation below the first shaft seal 10A is heated to about 300 ° C. by being heated by the reactor primary coolant. When the first shaft seal 10A is broken through by such high-temperature pressurized water (hereinafter referred to as “high-temperature pressurized water”), the high-temperature pressurized water reaches the second shaft seal 10B and may cause leakage of the high-temperature pressurized water. On the other hand, in the present embodiment, for example, a leakage preventing seal 30 is provided to avoid reaching the second shaft seal 10B of high-temperature pressurized water having a temperature of 300 ° C. and a pressure of about 19 MPa.

  This leakage prevention seal 30 is provided in the gap between the housing 2 and the rotary shaft 1 between the first shaft seal 10A and the second shaft seal 10B. In this embodiment, as shown in FIG. 2 is provided so as to be accommodated in an annular groove 3 provided in 2.

  The annular groove 3 is formed so as to be recessed from the inner peripheral surface of the housing 2 in the radial direction of the rotary shaft 1 (hereinafter simply referred to as the radial direction). , Simply referred to as the circumferential direction). Further, the annular groove 3 has an upper inner wall surface 4 facing downward (one side in the axis 0 direction), a lower inner wall surface 5 facing the upper inner wall surface 4 and facing upward (the other side in the axis 0 direction), and a diameter. It has a bottom wall surface 6 that faces the inner side in the direction and is connected to the upper inner wall surface 4 and the lower inner wall surface 5.

  Further, the lower inner wall surface 5 in the annular groove 3 is provided with a counterbore portion 7 that is recessed downward from the lower inner wall surface 5 and opens inward in the radial direction with an interval in the circumferential direction. The counterbore 7 is formed so as to be recessed radially outward from the bottom wall surface 6.

The leak prevention seal 30 of this embodiment includes a seal ring 31 and a thermoactuator 60.
As shown in FIGS. 2 and 3, the seal ring 31 extends in the circumferential direction of the rotary shaft 1 so as to surround the rotary shaft 1 from the periphery. That is, the seal ring 31 has an annular shape with the axis 0 as the center.

Further, the seal ring 31 is a ring body 32 whose outer peripheral portion is made of, for example, stainless steel. The lower surface of the ring body 32 is in contact with the lower inner wall surface 5 of the annular groove 3.
Further, a resin ring 34 made of, for example, a resin having heat resistance is provided on the inner peripheral side of the ring main body 32. That is, as shown in FIG. 3, a mounting groove 33 is formed on the surface facing the radially inner side of the ring body 32 so as to be recessed toward the radially outer side over the entire circumferential direction, and the resin ring 34 is formed in the mounting groove 33. The outer peripheral side portion is fitted.

  In this way, the resin ring 34 protrudes radially inward from the ring body 32, and the seal ring 31 is configured in which the ring body 32 and the resin ring 34 are fixedly integrated. The dimension of the resin ring 34 in the axis 0 direction is set smaller than the dimension of the ring body 32 in the axis 0 direction.

  Further, in the normal state, that is, in a state where the high-temperature pressurized water does not reach the leakage prevention seal 30 (hereinafter referred to as an initial state), the inner diameter of the resin ring 34 is set slightly larger than the outer diameter of the rotating shaft 1. Thus, a slight gap is formed between the inner peripheral surface of the resin ring 34 and the outer peripheral surface of the rotary shaft 1.

  As shown in FIG. 2, the seal ring 31 has a first end 41 and a second end 51 that are independent from each other in the extending direction, that is, in the circumferential direction. That is, the seal ring 31 does not have an annular shape extending integrally around the entire circumference, but has a first end portion 41 and a second end portion 51 that are not joined to each other.

  Further, the seal ring 31 extends so that the first end portion 41 side and the second end portion 51 side face each other in the circumferential direction. As a result, the seal ring 31 has a C-shape as a whole.

  The first end portion 41 and the second end portion 51 can be moved relative to each other in the circumferential direction. That is, when the first end portion 41 and the second end portion 51 are relatively moved so as to be close to each other in the circumferential direction, the seal ring 31 is reduced in diameter as a whole. On the other hand, when the first end portion 41 and the second end portion 51 are relatively moved so as to be separated from each other in the circumferential direction, the diameter of the seal ring 31 is increased as a whole.

Further, a first projecting portion 44 projecting so as to extend radially outward is integrally formed with the ring body 32 at a portion of the seal ring 31 on the first end portion 41 side.
Further, a second projecting portion 54 that projects so as to extend radially outward is formed integrally with the ring body 32 at a portion on the second end 51 side of the seal ring 31.

The thermoactuator 60 is an actuator configured to be driven using high-temperature pressurized water as a heat source, and includes a cylinder 61 and a rod 62 as shown in FIG.
The cylinder 61 is a member having an outer cylindrical shape, and the inside thereof is sealed with wax that expands when reaching a set temperature. In this embodiment, it is comprised so that a wax may expand | swell at the temperature of high temperature pressurized water, for example, 200 to 300 degreeC.

  When the wax inside the cylinder 61 expands, the rod 62 is configured to protrude from the end surface of the cylinder 61 that forms a columnar shape. Therefore, when the hot pressurized water reaches the thermoactuator 60, the wax expands using the hot pressurized water as a heat source, and the rod 62 of the thermoactuator 60 protrudes. In other words, the thermoactuator 60 of the present embodiment is configured such that the rod 62 protrudes by being driven using high-temperature pressurized water as a heat source.

  The thermoactuator 60 is not limited to the above configuration, and may be a configuration using a bimetal formed by bonding two metal plates having different thermal expansion coefficients, for example. In this case, the rod 62 protrudes from the cylinder 61 when the set temperature is reached by utilizing the property that the bimetal bending changes according to the temperature change.

  The tip of the rod 62 of the thermoactuator 60 is connected to the first protrusion 44 of the ring body 32 in the seal ring 31. More specifically, the tip of the rod 62 is connected to the first protrusion 44 from the side opposite to the second protrusion 54 side. The cylinder 61 is integrally fixed to the housing 2 in a state of being housed in a housing portion (not shown) formed in the housing 2. As a result, the rod 62 protrudes when the thermoactuator 60 is driven, so that the rod 62 presses the first protrusion 44 toward the second protrusion 54. That is, the first end portion 41 approaches the second end portion 51 due to the protrusion of the rod 62.

The surface of the seal ring 31 facing the upper side of the ring body 32 and the upper inner wall surface 4 of the annular groove 3 are in close contact with each other in the entire circumferential direction.
Further, the surface of the seal ring 31 facing the lower side of the ring body 32 and the lower inner wall surface 5 of the annular groove 3 are in close contact with each other in the entire circumferential direction.
Further, in a normal state, the surface facing the radially outer side of the ring body 32 and the bottom wall surface 6 of the annular groove 3 are in close contact with each other in the entire circumferential direction.

Next, the operation of the leakage prevention seal 30 in the reactor coolant pump 100 having the above configuration will be described.
When the pressurized water below the first shaft seal 10A is heated to become high-temperature pressurized water, when the high-temperature pressurized water breaks through the first shaft seal 10A and reaches the leakage prevention seal 30, the thermoactuator of the leakage prevention seal 30 60 is heated by hot pressurized water.

  Thus, when the wax inside the thermoactuator 60 reaches a predetermined temperature using the high-temperature pressurized water as a heat source, the wax expands, and the rod 62 of the thermoactuator 60 protrudes from the cylinder 61.

  Then, the rod 62 of the thermoactuator 60 presses the first projecting portion 44 of the seal ring 31 toward the second projecting portion 54, and the first end portion 41 of the seal ring 31 approaches the second end portion 51. To do. As a result, the circumferential dimension of the seal ring 31 is reduced, that is, the diameter of the seal ring 31 is reduced.

  When the diameter of the seal ring 31 is thus reduced, a gap is formed between the surface of the seal body 31 that faces the outer side in the radial direction of the ring body 32 and the bottom wall surface 6 of the annular groove 3. Then, high-temperature pressurized water flows into this gap, that is, radially outward of the seal ring 31 through the counterbore portion 7. Thereby, the seal ring 31 is pressed radially inward by the high-temperature pressurized water over the entire circumferential direction, and the diameter reduction of the seal ring 31 is promoted.

  The gap between the seal ring 31 and the rotary shaft 1 is reduced by the reduced diameter of the seal ring 31, or the inner peripheral surface of the seal ring 31, that is, the inner peripheral surface of the resin ring 34 is the rotary shaft. It adheres to the outer peripheral surface of 1 Thereby, the flow from the lower side to the upper side of the hot pressurized water is restricted.

  As described above, according to the reactor coolant pump 100 of the present embodiment, when the high-temperature pressurized water reaches the leakage prevention seal 30 at the time of abnormality, the thermoactuator 60 is driven using the high-temperature pressurized water as a heat source. The thermoactuator 60 reduces the diameter of the seal ring 31 by this driving, so that the gap between the seal ring 31 and the rotary shaft 1 is reduced in the circumferential direction, or the seal ring 31 is in close contact with the rotary shaft 1 in the circumferential direction. Therefore, it is possible to regulate the flow of high-temperature and high-pressure pressurized water at the time of an abnormality, and for example, it is possible to avoid leakage of the primary coolant to the outside within 72 hours, which is assumed to be the maximum duration of all AC power loss.

  Further, when the hot pressurized water reaches the leakage prevention seal 30 in an abnormal state and the diameter of the seal ring 31 starts to be reduced by driving the thermoactuator 60, the hot pressurized water passes through the counterbore 7 of the annular groove 3 and It wraps around the radially outer gap. Thereby, since the seal ring 31 is pressed radially inward by the high-temperature pressurized water, the gap between the seal ring 31 and the rotary shaft 1 can be more reliably reduced over the entire circumferential direction, or the seal The ring 31 can be more closely contacted with the rotating shaft 1 over the entire circumferential direction.

  Further, since the seal ring 31 is composed of a ring body 32 made of stainless steel and a resin ring 34 made of resin provided on the inner peripheral side of the stainless steel, the seal ring 31 is made durable by the ring body 32. Adhesiveness to the rotating shaft 1 can be ensured by a resin having higher flexibility than metal, while ensuring the property.

Next, a reactor coolant pump 100 according to a second embodiment of the present invention will be described with reference to FIG. About 2nd embodiment, the same code | symbol is attached | subjected to the component similar to 1st embodiment, and detailed description is abbreviate | omitted.
In the reactor coolant pump 100 of the second embodiment, in addition to the configuration of the first embodiment, the first end 41 and the second end 51 of the seal ring 31 are urged so as to be separated from each other. A spring member 70 is provided as a biasing means.

That is, the spring member 70 is a member such as a coil spring having a spring element that can contract in the circumferential direction of the seal ring 31, and includes a first end 41 and a second end 51 of the seal ring 31. In the present embodiment, the first protrusion 44 and the second protrusion 54 are provided between the first protrusion 44 and the second protrusion 54. The spring member 70 is not limited to a coil spring, and other members having a spring constant may be used.
One end of the spring member 70 is connected to the first end portion 41, and the other end is connected to the second end portion 51. In a normal state, the spring member 70 is in a compressed state between the first end portion 41 and the second end portion 51, and the first end portion 41 and the second end portion 51 are connected to each other. The urging forces that are separated from each other in the direction are generated.

  In this embodiment, the pressing force of the first end 41 by the rod 62 when the thermoactuator 60 is driven is set to be larger than the urging force of the spring member 70.

  In the reactor coolant pump 100 of the second embodiment, the spring member 70 normally separates the first end portion 41 and the second end portion 51 by the biasing force, so that the diameter of the seal ring 31 is reliably increased. State. As a result, the seal ring 31 is in close contact with the bottom wall surface 6 of the annular groove 3, and a gap between the seal ring 31 and the rotary shaft 1 can be secured. Therefore, the rotation of the rotating shaft 1 during normal operation is not hindered, and erroneous contact between the rotating shaft 1 and the seal ring 31 can be avoided.

  When the hot pressurized water reaches the leakage prevention seal 30, the thermoactuator 60 is driven using the hot pressurized water as a heat source, and presses the first end 41 of the seal ring 31 toward the second end 51. At this time, since the pressing force of the rod 62 of the thermoactuator 60 is set larger than the biasing force of the spring member 70, the first end portion 41 and the second end portion 51 are resisted against the biasing force of the spring member 70. Can be reliably brought close to each other.

  Therefore, the dimension of the seal ring 31 in the circumferential direction can be reduced, that is, the diameter of the seal ring 31 can be reliably reduced. As a result, as in the first embodiment, the gap between the seal ring 31 and the rotary shaft 1 is reduced, or the inner peripheral surface of the seal ring 31, that is, the inner peripheral surface of the resin ring 34 is the outer peripheral surface of the rotary shaft 1. It is possible to regulate the flow from the lower side to the upper side of the hot pressurized water.

  As a modification of the second embodiment, for example, as shown in FIG. 5, the seal ring 31 itself separates the first end 41 and the second end 51 of the seal ring 31, that is, It may act as a spring element that generates a biasing force so as to expand the diameter of the seal ring 31. In this modification, the seal ring 31 is configured as a C-shaped spreading spring, and the seal ring 31 itself has a role as an urging means.

  Even in this manner, as in the second embodiment, the gap between the seal ring 31 and the rotary shaft 1 can be secured in the normal time, while the flow from the lower side to the upper side of the hot pressurized water is restricted in the abnormal time. Can do.

Next, a reactor coolant pump 100 according to a third embodiment of the present invention will be described with reference to FIGS. About 3rd embodiment, the same code | symbol is attached | subjected to the component similar to 1st embodiment, and detailed description is abbreviate | omitted.
The third embodiment is configured such that the first end 41 of the seal ring 31 is pressed radially inward and toward the second end 51 by driving the thermoactuator 60.

  That is, in the third embodiment mobile phone, the thermoactuator 60 is arranged so as to be inclined and extend in a plane perpendicular to the axis 0 from the tangential direction of the seal ring 31. As a result, when the rod 62 of the thermoactuator 60 protrudes, the first end 41 is pressed radially inward and toward the second end 51.

  A first guide surface 81 extending along the extending direction of the thermoactuator 60 is formed in the storage portion 80 of the thermoactuator 60. In the present embodiment, a part of the surface that defines the storage unit 80 is the first guide surface 81. The first guide surface 81 is inclined from the first end portion 41 toward the second end portion 51 as it goes radially inward.

  Further, a second end extending in parallel with the first guide surface 81 on the second end 51 side with respect to the first guide surface 81 so as to be shifted outward in the radial direction by one step from the first guide surface 81. A guide surface 82 is formed. The step surface connecting the first guide surface 81 and the second guide surface 82 is a first abutment surface 83 on which the normal second protrusion 54 can abut. Further, a second contact surface 84 connected to the second guide surface 82 is provided on the opposite side of the second contact surface 82 to the first contact surface 83 so as to face the first contact surface 83. Is formed. The second protrusion 54 comes into contact with the second contact surface 84 at the time of abnormality.

  The first guided surface 81 is slidably in contact with a first guided surface 86 which is a surface facing the radially outer side of the first projecting portion 44 of the seal ring 31. The second guided surface 82 is slidably in contact with a second guided surface 87 that is a surface facing the radially outer side of the second protruding portion 54 of the seal ring 31.

Next, the operation of the leakage prevention seal 30 in the reactor coolant pump 100 of the third embodiment will be described.
In a normal state, as shown in FIG. 6, the first end 41 and the second end 51 of the ring body 32 of the seal ring 31 are in a state of being separated from each other, and the second protrusion 54 is in the first contact. It is in contact with the surface 83. Further, the first guided surface 86 in the first protrusion 44 is in contact with the first guide surface 81, and the second guided surface 87 in the second protrusion 54 is in contact with the second guide surface 82.

  As in the first embodiment, when the thermoactuator 60 of the leakage prevention seal 30 is heated by the high-temperature pressurized water and the wax inside the thermoactuator 60 reaches a predetermined temperature, the wax expands, and the rod of the thermoactuator 60 62 protrudes from the cylinder 61.

  As a result, the first protrusion 44 of the ring body 32 in the seal ring 31 is pressed radially inward and toward the second protrusion 54, that is, the first end 41 is radially inward and the second end 51. Pressed to the side. Then, the first end portion 41 of the seal ring 31 approaches the second end portion 51 while being directed radially inward.

  At this time, the first guided surface 86 of the first projecting portion 44 in the ring body 32 is guided along the first guiding surface 81, so that the first end portion 41 is smoothly radially inward and the second end portion. Move toward 51.

  When the first end portion 41 approaches the second end portion 51 in this way, the entire seal ring 31 moves in the pressing direction of the rod 62, so that the second end portion 51 becomes the first end portion 41. The second contact surface 84 is moved toward the second contact surface 84 side. Then, when the second projecting portion 54 comes into contact with the second contact surface 84, the first end portion 41 and the second end portion 51 finally come into contact as shown in FIG. As a result, the inner diameter of the seal ring 31 is reduced from the beginning.

  In the process in which the second protrusion 54 moves from the first contact surface 83 to the second contact surface 84, the second guided surface 87 of the second protrusion 54 guides along the second guide surface 82. As a result, smooth movement is realized.

Thus, the diameter reduction operation of the seal ring 31 is completed, and the gap between the seal ring 31 and the rotary shaft 1 is reduced, or the inner peripheral surface of the seal ring 31, that is, the inner peripheral surface of the resin ring 34 is rotated. The shaft 1 is in close contact with the outer peripheral surface. Thereby, the flow from the lower side to the upper side of the hot pressurized water is restricted.
In particular, in the present embodiment, since the first end 41 is pressed radially inward and toward the second end 51 by driving the thermoactuator 60, the seal ring 31 can be easily held in the rotary shaft 1. Reduce to diameter. Thereby, the adhesiveness of the seal ring 31 and the rotating shaft 1 can be improved.

The embodiment of the present invention has been described above, but the present invention is not limited to this, and can be appropriately changed without departing from the technical idea of the present invention.
For example, in the embodiment, the thermoactuator 60 is configured to drive the first end 41 closer to the second end 51 by driving the thermoactuator 60, but in reverse, that is, the second end 51 is connected to the first end 41. It is good also as a structure made to approach toward.

  Moreover, it is good also as a structure which arrange | positions the thermoactuator 60 between the 1st end part 41 and the 2nd end part 51, and this thermoactuator 60 shrink | contracts by a drive. Also by this, the first end portion 41 and the second end portion 51 can be brought close to each other at the time of abnormality, and the seal ring 31 can be reliably reduced in diameter.

  Further, in the third embodiment, the first projecting portion 44 and the second projecting portion 54 are configured to be guided by the first guide surface 81 or the second guide surface 82. Instead, for example, a groove is formed in the housing 2. A convex portion that is formed and engages with the groove may be provided on the seal ring 31. Accordingly, when the first end 41 side of the seal ring 31 is pressed by the rod 62, the convex portion of the seal ring 31 is guided by the groove of the housing 2, so that the diameter of the seal ring 31 can be reduced smoothly. Can be realized.

DESCRIPTION OF SYMBOLS 1 Rotating shaft 2 Housing 3 Annular groove 4 Upper inner wall surface 5 Lower inner wall surface 6 Bottom wall surface 7 Counterbore part 10 Shaft seal 10A First shaft seal 11A First runner 12A First ring 10B Second shaft seal 11B Second runner 12B Second ring 10C Third shaft seal 11C Third runner 12C Third ring 15 Filler pump 16 Volume control tank 17 Shielding valve 18 Flow meter 19 Purge water head tank 20 Flow meter 21 Pure water makeup tank 22 Pure water pump 23 Replenishment Valve 24 Level control device 25 Flow meter 26 Stand pipe 27 Drain tank 30 Leak prevention seal 31 Seal ring 32 Ring body 33 Mounting groove 34 Resin ring 41 First end portion 44 First protrusion 51 Second end 54 Second protrusion 60 Thermoactuator 61 Cylinder 62 Rod 70 Spring member (biasing means)
80 Storage portion 81 First guide surface 82 Second guide surface 83 First contact surface 84 Second contact surface 86 First guided surface 87 Second guided surface 100 Reactor coolant pump

Claims (4)

A rotation axis that rotates about an axis,
A housing surrounding the rotating shaft;
A leakage preventing seal that is provided so as to partition the gap between the rotating shaft and the housing in the axial direction, and regulates the flow of high-temperature pressurized water from one side to the other side in the axial direction at the time of abnormality,
The leakage prevention seal is
A C-shaped seal ring extending in the circumferential direction of the rotary shaft so as to surround the rotary shaft and having a first end and a second end facing each other in the circumferential direction;
A reactor coolant pump, comprising: a thermoactuator that is driven by using the high-temperature pressurized water as a heat source and reduces the diameter of the seal ring by bringing the first end and the second end close to each other.   2. The reactor coolant pump according to claim 1, further comprising a biasing unit that biases the first end portion and the second end portion of the seal ring so as to be separated from each other.   The reactor coolant pump according to claim 1 or 2, wherein the first end portion is pressed radially inward and toward the second end portion by driving the thermoactuator. The seal ring is accommodated in an annular groove that is annularly recessed from the inner peripheral surface of the housing facing the outer peripheral surface of the rotating shaft,
The said annular groove has a counterbore part which introduces the said high temperature pressurization water to the radial direction outer side of this seal ring when the said seal ring is diameter-reduced. Reactor coolant pump.

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