JP2013160695A - Water supply pipe for steam generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water supply pipe for a steam generator, capable of suppressing thermal stratification inside a pipe.SOLUTION: A water supply pipe for a steam generator includes: an insertion pipe 21 inserted to a through-hole 112 of an outer shell member; and an in-generator pipe 22 connected to the insertion pipe. The in-generator pipe includes: a duct; and an outflow part 25 for allowing cooling water inside the duct to flow out to a space 40 in the steam generator. The duct includes: a first inclination part 24c where not a side close to the insertion pipe but a side far from the insertion pipe in a flow direction is positioned on an upper side in a vertical direction; and a second inclination part that is positioned to be farther from the insertion pipe than the first inclination part and where not a side close to the insertion pipe but a side farther from the insertion pipe in a flow direction is positioned on a lower side in a vertical direction. In at least a partial section in a flow direction in a duct 234a between the first inclination part and the second inclination part, a lower end 234b of a cross section of the duct is positioned to be upper in a vertical direction than a horizontal surface 30 passing an upper end 21a of an inner wall surface of the insertion pipe in a connection part between the insertion pipe and the in-generator pipe.

Description

  The present invention relates to a water supply pipe for a steam generator.

  Conventionally, a water supply pipe for supplying cooling water into a steam generator such as a pressurized water reactor is known. In the water supply pipe, a thermal stratification phenomenon may occur due to the inflow of steam or hot internal water into the pipe. The thermal stratification phenomenon is not preferable because it causes a stress of a fatigue source.

  Patent Document 1 discloses a technology of a water supply pipe of a steam generator in which a cough is attached to an inner upper wall of a water supply pipe bent so as to lift a water supply ring.

Japanese Utility Model Publication No. 61-121304

  There is still room for study on the suppression of thermal stratification in the water supply pipe. The objective of this invention is providing the feed pipe for steam generators which can suppress thermal stratification in a pipe | tube.

  The steam generator water supply pipe of the present invention is inserted into a through-hole penetrating the outer shell member of the steam generator, and is connected to the insertion pipe part extending in the horizontal direction, the insertion pipe part, and the steam generator. An internal pipe part of the generator, the internal pipe part of the generator is formed in the axial direction of the internal pipe part of the generator, and the outside of the steam generator via the insertion pipe part A pipe through which the cooling water supplied from the pipe flows, and an outflow part through which the cooling water in the pipe flows out from the pipe to the space in the steam generator. A first inclined portion having an inclination in which a side larger than a side having a small distance from the insertion tube portion along the water flow direction is located on the upper side in the vertical direction, and along the flow direction more than the first inclined portion. The insertion tube portion that is located on the side where the distance from the insertion tube portion is large and extends along the flow direction A second inclined portion having an inclination whose lower side is located on the lower side in the vertical direction, and the side of the pipe line between the first inclined portion and the second inclined portion. In at least a part of the flow direction, the lower end of the cross section of the pipe line orthogonal to the flow direction is the upper end of the inner wall surface of the insertion pipe part at the connection part between the insertion pipe part and the generator inner pipe part. It is characterized by being above the horizontal plane passing through the vertical direction.

  According to the water supply pipe for a steam generator, a decrease in the water level of the insertion pipe portion is suppressed, so that thermal stratification due to generation of a steam pool in the insertion pipe portion is suppressed. In addition, when cooling water having a different temperature flows into the cooling water in the insertion pipe part, the high-temperature cooling water flows out to the generator internal pipe part, thereby suppressing thermal stratification.

  In the steam generator feed pipe, the section in which the first inclined portion is formed in the generator inner pipe portion preferably does not have the outflow portion.

  According to this water supply pipe for a steam generator, even if the cooling water level in the steam generator is lowered, it is possible to suppress a drop in the water level of the insertion pipe portion.

  In the water supply pipe for a steam generator, the generator inner pipe section includes a ring-shaped pipe section extending in a ring shape along an inner peripheral surface of the outer shell member, and a ring branched from the ring-shaped pipe section. A connecting pipe part connecting the tubular pipe part and the insertion pipe part, wherein the first inclined part is the pipe line formed in the connecting pipe part, and the second inclined part is the ring It is preferable that the pipe is formed on the both sides in the axial direction of the ring-shaped pipe part with the connection pipe part interposed therebetween.

  According to this water supply pipe for a steam generator, it is possible to form the first inclined portion and the second inclined portion while suppressing interference with other structures in the steam generator.

  In the steam generator feed pipe, in the ring-shaped pipe portion, a horizontal line that is the pipe line extending in the horizontal direction on the opposite side to the insertion pipe portion side than the second inclined portion in the flow direction. A ring-shaped pipe line is formed, and an upper end of a cross section perpendicular to the flow direction in the horizontal ring-shaped pipe line is an inner part of the insertion pipe part at a connection part between the insertion pipe part and the generator internal pipe part. It is preferable that it exists in the vertical direction lower side than the horizontal surface which passes along the upper end of a wall surface.

  According to this water supply pipe for a steam generator, the occurrence of steam accumulation in the horizontal ring pipe is suppressed by suppressing the ring-shaped pipe portion from being exposed when the cooling water level in the steam generator is lowered. The

  In the steam generator feed pipe, in the ring-shaped pipe portion, a horizontal line that is the pipe line extending in the horizontal direction on the opposite side to the insertion pipe portion side than the second inclined portion in the flow direction. A ring-shaped pipe is formed, and the upper end of the cross section perpendicular to the flow direction in the horizontal ring-shaped pipe is vertically lower than the lower limit in the control target of the coolant level in the space in the steam generator. Preferably it is on the side.

  According to this water supply pipe for a steam generator, even if the cooling water level in the steam generator is lowered to the lower limit in the control target of the water level, the occurrence of steam accumulation in the horizontal ring-shaped pipeline is suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, thermal stratification in the pipe | tube of the water supply pipe for steam generators can be suppressed.

FIG. 1 is a schematic diagram of a steam generator according to an embodiment. Drawing 2 is a sectional view showing the feed pipe for steam generators concerning an embodiment. FIG. 3 is a perspective view showing a water supply pipe for a steam generator according to the embodiment. Drawing 4 is a perspective view showing the important section of the feed pipe for steam generators concerning an embodiment. FIG. 5 is a cross-sectional view showing an example of a water supply pipe that can suppress thermal stratification in the insertion pipe portion. FIG. 6 is a perspective view showing an example of a water supply pipe capable of suppressing thermal stratification in the insertion pipe part.

  Hereinafter, a water supply pipe for a steam generator according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

(Embodiment)
The embodiment will be described with reference to FIGS. 1 to 6. The present embodiment relates to a water supply pipe for a steam generator. FIG. 1 is a schematic view of a steam generator according to the present embodiment, FIG. 2 is a cross-sectional view showing a water supply pipe for a steam generator according to the embodiment, and FIG. 3 is a perspective view showing a water supply pipe for the steam generator according to the embodiment. Drawing 4 is a perspective view showing the important section of the feed pipe for steam generators concerning an embodiment. Note that FIG. 2 shows a cross section of the steam generator water supply pipe viewed horizontally in the direction I of FIG.

  The steam generator 1 is used, for example, in a pressurized water reactor (PWR). The pressurized water reactor uses light water as a reactor coolant and neutron moderator. In a pressurized water reactor, high-temperature and high-pressure light water that does not boil over the entire core is sent to the steam generator 1 as primary cooling water. The steam generator 1 transmits the heat of the high-temperature and high-pressure primary cooling water to the secondary cooling water, and generates water vapor in the secondary cooling water. Then, the steam generator is rotated by this steam to generate electricity.

  The steam generator 1 has a hollow cylindrical shape that extends in the up-down direction and is hermetically sealed, and has a trunk portion 2 in which the lower half is slightly smaller in diameter than the upper half. The body 2 is an outer shell member of the steam generator 1. A tube group outer cylinder 3 having a cylindrical shape is provided in the lower half portion of the trunk portion 2 and is arranged at a predetermined interval from the inner wall surface of the trunk portion 2. The lower end portion of the tube group outer tube 3 extends to a position directly above the tube plate 4 disposed below the lower half of the body portion 2. In the tube group outer cylinder 3, a heat transfer tube group 51 including a plurality of heat transfer tubes 5 having an inverted U shape is provided. Each of the heat transfer tubes 5 is arranged with a U-shaped arc portion facing upward, an end portion facing downward is supported by the tube plate 4, and an intermediate portion is supported by a plurality of tube support plates 6. A large number of through holes (not shown) are formed in the tube support plate 6, and the heat transfer tubes 5 are inserted and supported in the through holes.

  A water chamber 7 is provided at the lower end of the body 2. The water chamber 7 is divided into an entrance chamber 71 and an exit chamber 72 by a partition wall 8. One end of each heat transfer tube 5 is connected to the entrance chamber 71, and the other end of each heat transfer tube 5 is connected to the exit chamber 72. Further, the entrance chamber 71 has an inlet nozzle 711 that communicates with the outside of the trunk portion 2, and the exit chamber 72 has an exit nozzle 721 that communicates with the exterior of the trunk portion 2. The inlet nozzle 711 is connected to a cooling water pipe (not shown) through which primary cooling water is sent from the pressurized water reactor, while the outlet nozzle 721 is supplied with the primary cooling water after heat exchange. A cooling water pipe (not shown) to be sent to the type reactor is connected.

  In the upper half of the body portion 2, an air / water separator 9 that separates water vapor into steam and hot water, and a moisture separator 10 that removes the moisture of the separated steam and makes it close to dry steam. Is provided. Between the steam separator 9 and the heat transfer tube group 51, a steam generator water supply pipe (hereinafter simply referred to as “water supply pipe”) 20 for supplying secondary cooling water into the body 2 from the outside. Has been inserted. Further, a steam discharge port 12 is formed at the upper end portion of the body portion 2. Further, in the lower half portion of the body portion 2, the secondary cooling water supplied from the water supply pipe 20 into the body portion 2 is caused to flow down between the body portion 2 and the tube group outer tube 3, and the tube plate 4. The water supply path 13 is provided that is folded back and raised along the heat transfer tube group 51. The steam outlet 12 is connected to a steam supply passage (not shown) for sending steam to the turbine, and the steam used in the turbine is cooled to the water supply pipe 20 by a condenser (not shown). A cooling water pipe (not shown) for supplying secondary cooling water is connected.

  In such a steam generator 1, the primary cooling water heated in the pressurized water reactor is sent to the entrance chamber 71 and reaches the exit chamber 72 through a large number of heat transfer tubes 5. On the other hand, the secondary cooling water cooled by the condenser is sent to the water supply pipe 20 and supplied into the trunk portion 2 through the water supply pipe 20. In the present embodiment, the secondary cooling water is also simply referred to as “cooling water”. The cooling water supplied into the body portion 2 rises along the heat transfer tube group 51 through the water supply path 13. At this time, heat exchange is performed between the high-pressure and high-temperature primary cooling water and the secondary cooling water in the trunk portion 2. Then, the cooled primary cooling water is returned from the outlet chamber 72 to the pressurized water reactor. On the other hand, the secondary cooling water subjected to heat exchange with the high-pressure and high-temperature primary cooling water rises in the body portion 2 and is separated into steam and hot water by the steam separator 9. The separated steam is sent to the turbine after moisture is removed by the moisture separator 10.

  The water supply pipe 20 has a pipe line through which cooling water supplied from the outside of the steam generator 1 flows, and an outflow part (from FIG. 2) through which the cooling water in the pipe flows out of the pipe into the space 40 in the steam generator 1. 4 (see reference numeral 25 in FIG. 4). The water supply pipe 20 is arranged so that the cooling water can flow out under the surface of the cooling water in the space 40 during operation of the steam generator 1. Thermal stratification occurs in the water supply pipe 20 when the supply of cooling water from the outside of the steam generator 1 is stopped or when the supply of cooling water is started, such as when the reactor plant is stopped or started. There are things to do. For example, when low-temperature cooling water is supplied to the water supply pipe 20 at a small flow rate in a state where high-temperature cooling water or steam is present in the pipe, thermal stratification occurs between the low-temperature cooling water and the high-temperature cooling water in the pipe, Thermal stratification may occur due to steam and cooling water. If thermal stratification occurs in the pipe, stress that becomes a fatigue source is generated, which is not preferable. It is preferable that thermal stratification in the pipe of the water supply pipe 20 can be suppressed, and in particular, thermal stratification can be suppressed in a portion inserted into the through-hole penetrating the trunk portion 2 in the water supply pipe 20.

  In the water supply pipe 20 of the present embodiment, as will be described below with reference to FIGS. 2 to 4, a through-hole penetrating through the trunk part 2 in the generator internal pipe part 22 disposed in the steam generator 1. It is bent so as to be lifted from the insertion tube portion 21 inserted into 112 (see, for example, reference numeral 24 in FIG. 2), and further bent so as to be lowered (see, for example, reference numeral 233 in FIG. 2). By being bent so that the downstream side of the insertion pipe portion 21 in the flow direction of the cooling water supplied from the outside is lifted, the thermal stratification phenomenon passes through the insertion pipe portion 21 in a short time, and the heat in the trunk portion 2 Generation of stress is suppressed. Further, by bending the water supply pipe 20 bent once so as to be lifted on the downstream side thereof, the design flexibility in the arrangement of the water supply pipe 20 with other structures in the steam generator 1, The design freedom of the elevation with respect to the water level is secured.

  As shown in FIG. 2, the water supply pipe 20 includes an insertion pipe part 21 and a generator internal pipe part 22. The insertion tube portion 21 and the generator internal tube portion 22 are both tubular members having a circular cross section. Pipe lines are formed in the insertion pipe part 21 and the generator internal pipe part 22 in the axial direction, respectively. Cooling water supplied from the outside of the steam generator 1 flows into the pipe line of the generator internal pipe section 22 via the insertion pipe section 21. The cooling water flowing through the pipe line of the generator inner pipe part 22 flows out from the pipe line of the generator inner pipe part 22 into the space 40 in the steam generator 1 through an outlet pipe 25 described later.

  The body 2 has a nozzle 11. The nozzle 11 has a protruding portion 111 that protrudes outward in the radial direction of the body portion 2. Further, the nozzle 11 is formed with a through hole 112 that penetrates the nozzle 11 in the axial direction of the protruding portion 111. The insertion tube portion 21 is fitted into the through hole 112 from the inside in the radial direction of the body portion 2. The insertion tube portion 21 is fixed to the nozzle 11 by welding or the like with the outer peripheral surface of the insertion tube portion 21 and the inner peripheral surface of the protruding portion 111 facing each other. That is, the insertion tube portion 21 is inserted into the through hole 112 that penetrates the trunk portion 2 of the steam generator 1. The center axis of the nozzle 11, that is, the center axis of the through hole 112 is horizontal, and the insertion tube portion 21 extends in the horizontal direction correspondingly. Further, the insertion tube portion 21 extends linearly, and the extending direction thereof is the radial direction of the body portion 2.

  The generator inner pipe portion 22 is disposed inside the trunk portion 2, that is, inside the steam generator 1. As shown in FIGS. 2 and 3, the generator internal tube portion 22 includes a ring-shaped tube portion 23 extending in a ring shape, a branch from the ring-shaped tube portion 23, and the ring-shaped tube portion 23 and the insertion tube portion 21. And a connecting pipe portion 24 for connecting the two. The ring-shaped tube portion 23 extends in the circumferential direction of the body portion 2 along the inner wall surface 2a of the body portion 2 shown in FIG. The ring-shaped tube portion 23 is disposed coaxially with the central axis 50 of the trunk portion 2, for example. As shown in FIG. 2, the ring-shaped tube portion 23 is supported by the inner wall surface 2 a of the trunk portion 2 via the stay 14. The ring-shaped tube portion 23 includes a horizontal ring-shaped tube portion 231 and an upper ring-shaped tube portion 232 that is lifted upward in the vertical direction with respect to the horizontal ring-shaped tube portion 231.

  The horizontal ring tube portion 231 extends in the horizontal direction. Further, as shown in FIG. 2, a horizontal ring-shaped pipe line 231a which is a pipe formed in the axial direction in the horizontal ring-shaped pipe portion 231 also extends in the horizontal direction. That is, in the horizontal ring-shaped pipeline 231a, the upper end 231b of the cross section orthogonal to the flow direction of the cooling water has the same vertical position in any cross section. Further, in the horizontal ring pipe 231a, the lower end 231c of the cross section orthogonal to the flow direction of the cooling water has the same vertical position in any cross section. In other words, the horizontal ring-shaped conduit 231a is a conduit having a central axis extending on the same horizontal plane and a uniform diameter. The horizontal ring-shaped pipe part 231 in which the horizontal ring-shaped pipe line 231a is formed is located on the opposite side of the ring-shaped pipe part 23 to the insertion pipe part 21 side with respect to the inclined pipe part 233 in the flow direction of the cooling water. That is, the horizontal ring-shaped pipe line 231a is downstream of the pipe line 233e of the inclined pipe part 233 in the flow direction of the cooling water when the cooling water is supplied from the outside of the steam generator 1.

  As shown in FIG. 3, the upper ring-shaped tube portion 232 has two inclined tube portions 233 and an upper horizontal tube portion 234. The inclined pipe part 233 is connected to the insertion pipe part 21 via the upper horizontal pipe part 234 and the connection pipe part 24. That is, the inclined pipe portion 233 is located on the side where the distance from the insertion pipe portion 21 along the flow direction of the cooling water in the generator inner pipe portion 22 is larger than the connection pipe portion 24. In other words, the length of the flow path from the insertion pipe part 21 to the inclined pipe part 233 is larger than the length of the flow path from the insertion pipe part 21 to the connection pipe part 24.

  The upper horizontal pipe portion 234 is a straight pipe portion extending in the horizontal direction. The connecting pipe part 24 branches off from the upper horizontal pipe part 234. The connecting pipe part 24 branches off from the lower part of the upper horizontal pipe part 234 toward the outer side in the radial direction of the body part 2. The end of the connection pipe 24 opposite to the side connected to the upper horizontal pipe 234 is connected to the insertion pipe 21. That is, the connecting pipe part 24 branches from the ring-shaped pipe part 23 and connects the ring-shaped pipe part 23 and the insertion pipe part 21. The connecting pipe part 24 has an inclination in which the side with the larger distance from the insertion pipe part 21 is located on the upper side in the vertical direction than the side with the smaller distance from the insertion pipe part 21 along the flow direction of the cooling water. That is, the connecting pipe part 24 has an inclination in which the end part 24b side connected to the upper horizontal pipe part 234 is located on the upper side in the vertical direction than the end part 24a side connected to the insertion pipe part 21. Correspondingly, the pipe path 24c formed in the connecting pipe part 24 is such that the side where the distance from the connecting pipe part 21 is larger than the side where the distance from the insertion pipe part 21 along the flow direction of the cooling water is small is vertical. It has a slope located above the direction. The pipe line 24c formed in the connection pipe part 24 corresponds to the first inclined part. In the pipe line 24c, the gradient of the flow path increases from the side where the distance from the insertion pipe part 21 is small toward the side where the distance is large.

  The inclined tube portion 233 is formed on both sides of the ring-shaped tube portion 23 in the axial direction with the connecting tube portion 24 interposed therebetween. One inclined tube portion 233 connects one end of the upper horizontal tube portion 234 and one end of the horizontal ring tube portion 231, and the other inclined tube portion 233 is connected to the other end of the upper horizontal tube portion 234 and the horizontal ring tube portion 231. The other end of the unit 231 is connected. The inclined pipe part 233 has an inclination in which the side with the larger distance from the insertion pipe part 21 is located on the lower side in the vertical direction than the side with the smaller distance from the insertion pipe part 21 along the flow direction of the cooling water. . That is, as shown in FIG. 4, the inclined tube portion 233 has the end portion 233 b side connected to the horizontal ring-shaped tube portion 231 on the lower side in the vertical direction than the end portion 233 a side connected to the upper horizontal tube portion 234. It has a slope that is located. Correspondingly, the pipe line 233e formed in the inclined pipe part 233 is such that the side where the distance from the insertion pipe part 21 is larger than the side where the distance from the insertion pipe part 21 along the flow direction of the cooling water is small is vertical. It has a slope located below the direction. This pipe line 233e corresponds to the second inclined portion.

  The inclined pipe part 233 of this embodiment has two elbow parts 233c and 233d connected in series. One elbow part 233c heading upward in the vertical direction from the connection part 233g of both elbow parts is bent toward one side in the circumferential direction, and the other elbow part 233d going from the connection part 233g to the lower side in the vertical direction is circumferential. It is bent toward the other side. As described above, the inclined tube portion 233 is bent so as to be lowered from the upper horizontal tube portion 234 and connected to the horizontal ring-shaped tube portion 231. Further, as shown in FIG. 2, the inclined pipe portion 233 has an inclination in which the lower side in the vertical direction is directed outward in the radial direction of the body portion 2 from the upper side in the vertical direction. That is, in the inclined pipe portion 233, the lower side in the vertical direction is closer to the inner wall surface 2a of the trunk portion 2 than the upper side in the vertical direction. In this way, even when another structure is disposed in the radially inner region of the body portion 2, the ring-shaped tube portion 23 is disposed so as to avoid interference with the structure. Can do. In addition, the radial inclination in the inclined pipe part 233 is not limited to this. The inclination direction of the inclined pipe portion 233 may be determined as appropriate so that interference between other structures and the ring-shaped pipe portion 23 can be avoided.

  Further, the first inclined portion that is the raised portion of the pipe line is formed in the connecting pipe portion 24 as the pipe line 24c, and the second inclined portion that is the lowered portion of the pipe line is formed in the ring-shaped pipe portion 23 as the pipe line 233e. As a result, the degree of freedom of arranging the raised portion and the lowered portion of the pipe line is increased. The generator internal pipe portion 22 of the present embodiment is branched from the connection pipe portion 24 to both sides in the circumferential direction to form a ring-shaped pipe portion 23. When both the first inclined portion that is the lifted portion and the second inclined portion that is the lifted portion are formed in the connecting tube portion 24 before branching to the ring-shaped tube portion 23, a large space is required. If it is going to form both the 1st inclination part and the 2nd inclination part in the connecting pipe part 24, it will bend the connecting pipe part 24 in U shape or V shape, and the connecting pipe part 24 is the diameter of the trunk | drum 2. Projects greatly toward the center of the direction. For this reason, the connecting pipe portion 24 easily interferes with other structures.

  On the other hand, since the pipe line 233e as the second inclined portion is formed in the ring-shaped tube portion 23 branched from the connecting tube portion 24, it is easy to secure a space for forming the second inclined portion. . According to the method of forming the second inclined portion (pipe 233e) by inclining a part of the ring-shaped tube portion 23 as in the present embodiment, the second inclined portion can be extended in the circumferential direction. . That is, the second inclined portion can be formed while avoiding interference with the structure disposed on the radial center side in the body portion 2. Therefore, the freedom degree which arrange | positions a 2nd inclination part becomes high. For example, as described above, in the inclined pipe portion 233, it is possible to avoid the interference with other structures by inclining the lower side in the vertical direction toward the radially outer side of the trunk portion 2 than the upper side in the vertical direction. Become.

  The tube diameters (inner diameters) of the insertion tube portion 21, the connection tube portion 24, and the ring-shaped tube portion 23 can be constant in each. In the present embodiment, the tube diameter of the insertion tube portion 21 is equal to the tube diameter of the connection tube portion 24, and the tube diameter of the ring-shaped tube portion 23 is smaller than the tube diameter of the connection tube portion 24.

  The ring-shaped pipe portion 23 has an outflow pipe 25. The outflow pipe 25 functions as an outflow part through which cooling water in the pipe formed in the ring-shaped pipe part 23 flows out from the pipe into the space 40 in the steam generator 1. The outflow pipe 25 is a hollow cylindrical member, and a plurality of outflow pipes 25 are arranged along the direction in which the ring-shaped pipe part 23 extends with respect to the ring-shaped pipe part 23. As shown in FIG. 4, the cylindrical portion of the outflow pipe 25 is formed with a plurality of through holes 25 a that penetrate the cylindrical portion of the outflow pipe 25 in the radial direction. Further, one end of the outflow pipe 25 in the axial direction is connected to a pipe line of the ring-shaped pipe portion 23 through a communication hole (not shown) formed in the ring-shaped pipe section 23. This communication hole is formed at the top of the ring-shaped tube portion 23. That is, the outflow pipe 25 is connected to the upper end of the pipe line formed in the ring-shaped pipe portion 23 when viewed in the axial direction. The end of the outflow pipe 25 on the upper side in the vertical direction, that is, the end opposite to the side connected to the ring-shaped pipe 23 is closed.

  When cooling water is supplied from the outside of the steam generator 1 to the ring-shaped tube portion 23 via the insertion tube 21, the cooling water flows into the outflow tube 25 from the pipe line of the ring-shaped tube portion 23, and passes through the through hole 25a. To the internal space 40 of the steam generator 1. In the outflow pipe 25, a large number of through holes 25a are equally arranged in the circumferential direction and the axial direction. For this reason, the cooling water flows out uniformly from the outflow pipe 25 to the periphery. In addition, the outflow pipe 25 is not provided in the section in which the 1st inclination part in the connection pipe part 24, ie, the generator internal pipe part 22, was formed.

  Since the communication hole that connects the pipe line of the ring-shaped pipe part 23 and the outflow pipe 25 is formed in the ridge part of the ring-shaped pipe part 23, the steam generator until the ring-shaped pipe part 23 is exposed on the water surface. Even if the water level of the cooling water in 1 falls, the water level fall in the pipe line of the ring-shaped pipe part 23 is suppressed. Thereby, generation | occurrence | production of the steam pool in the pipe line of the ring-shaped pipe part 23 is suppressed.

  Moreover, in the water supply pipe 20 of this embodiment, the lower end 234b of the cross section in the pipe line 234a formed in the upper horizontal pipe part 234 is located vertically above the upper end 21a of the inner wall surface of the insertion pipe part 21. . Thereby, as will be described below, the occurrence of thermal stratification in the insertion tube portion 21 is suppressed.

  As shown in FIG. 2, the lower end 234 b of the cross section orthogonal to the flow direction of the cooling water in the pipe 234 a formed in the upper horizontal pipe part 234 is the insertion pipe in the connection part between the insertion pipe part 21 and the connection pipe part 24. It is above the upper end 21 a of the inner wall surface of the portion 21 in the vertical direction. In other words, the cross section orthogonal to the flow direction of the cooling water in the pipe line 234a does not intersect the horizontal plane 30 passing through the upper end 21a of the inner wall surface of the insertion pipe part 21 at the connection part between the insertion pipe part 21 and the connection pipe part 24. The lower end 234b of the cross section is on the upper side in the vertical direction from the horizontal plane 30. Thereby, even if the water level of the cooling water in the steam generator 1 is lowered, the drop in the water level in the pipe is suppressed closer to the insertion pipe part 21 than the upper horizontal pipe part 234 in the water supply pipe 20. Specifically, it is possible to suppress the cooling water level from lowering than the lower end 234b of the pipe 234a, and to maintain the state where the insertion pipe portion 21 is filled with the cooling water. Therefore, in the insertion pipe part 21, generation | occurrence | production of a steam pool is suppressed in a pipe | tube, and generation | occurrence | production of the thermal stratification in the insertion pipe part 21 is suppressed. In particular, the connecting pipe portion 24 of this embodiment does not have the outflow pipe 25. Thereby, it is suppressed more reliably that the water level of cooling water falls rather than the lower end 234b of the pipe line 234a.

  Unlike the water supply pipe 20 of the present embodiment, the insertion pipe part 21 and the ring-shaped pipe part 23 are horizontal without having a raised part such as the connecting pipe part 24 and a lowered part such as the inclined pipe part 233. In the water supply pipe extending flatly, when the cooling water supply is started from the state where the water level in the water supply pipe is lowered, such as when the operation of the steam generator 1 is started, the entire water supply pipe is filled with the cooling water. It takes a certain amount of time. Until the water level in the water supply pipe rises, the steam and the cooling water exist in a layered manner in the insertion pipe portion 21, so that stress of a fatigue source continues to be generated in the insertion pipe portion 21. Further, when the cooling water touches the steam, a water hammer phenomenon may occur. It is desirable to be able to suppress the occurrence of such thermal stress and water hammer phenomenon in the vicinity of the nozzle 11 as a boundary.

  According to the water supply pipe 20 of the present embodiment, when the supply of cooling water is started from a state where the water level in the water supply pipe 20 is lowered, the insertion pipe portion 21 is first filled with cooling water, and the water level further rises. Cooling water is supplied from the connecting pipe part 24 to the horizontal ring-shaped pipe part 231 through the upper ring-shaped pipe part 232. Thereby, it becomes possible to shorten the time for which the steam layer and the cooling water layer are stratified in the insertion tube portion 21, thereby suppressing the generation of stress of the fatigue source in the insertion tube portion 21.

  Moreover, according to the water supply pipe 20 of this embodiment, it becomes easy to avoid the state in which the cooling water having different temperatures exists in the pipe in the insertion pipe portion 21 as described below.

  For example, when low-temperature cooling water is supplied at a low flow rate from the outside of the steam generator 1 in a state where high-temperature cooling water remains in the pipe of the water supply pipe 20, or the space 40 outside the water supply pipe 20. When high-temperature cooling water flows into the pipe from the bottom, thermal stratification occurs in which the low-temperature cooling water and the high-temperature cooling water are separated into layers. At this time, in the water supply pipe in which the insertion pipe part 21 and the ring-shaped pipe part 23 extend flat in the horizontal direction, this thermal stratification is also easily maintained in the insertion pipe part 21.

  According to the water supply pipe 20 of the present embodiment, when low-temperature cooling water is supplied from the outside of the steam generator 1 with a small flow rate in a state where the high-temperature cooling water remains in the water supply pipe 20, The inside of the insertion tube portion 21 is quickly filled with the cooling water supplied from the outside, and the high-temperature cooling water in the insertion tube portion 21 is transferred from the connection tube portion 24 to the upper ring-shaped tube portion 232 and the horizontal ring-shaped tube portion 231. leak. Thereby, in the water supply pipe 20 of this embodiment, the thermal stratification in the insertion pipe part 21 is a short time compared with the case of the water supply pipe in which the insertion pipe part 21 and the ring-shaped pipe part 23 are extended flat in a horizontal direction. It will be resolved.

  In this embodiment, the pipe line 234a formed in the upper horizontal pipe part 234 corresponds to the pipe line between the first inclined part and the second inclined part. In this embodiment, the lower end 234b of the cross section orthogonal to the flow direction of the cooling water is on the upper side in the vertical direction with respect to the horizontal plane 30 in all sections of the pipe 234a. In at least a part of the cooling water flow direction in 234 a, the lower end 234 b of the cross section of the pipe line 234 a orthogonal to the cooling water flow direction may be located above the horizontal plane 30 in the vertical direction.

  Here, as a water supply pipe capable of suppressing thermal stratification in the insertion pipe part 21, a water supply pipe 120 having a shape in which the entire ring-shaped pipe part 123 is lifted with respect to the insertion pipe part 21 as shown in FIGS. . FIG. 5 is a cross-sectional view showing an example of a water supply pipe capable of suppressing thermal stratification in the insertion pipe part, and FIG. 6 is a perspective view showing an example of a water supply pipe capable of suppressing thermal stratification in the insertion pipe part. FIG. In this water supply pipe 120, the ring-shaped pipe part 123 does not have the inclined pipe part 233 as in the present embodiment. As shown in FIG. 5, in the pipe 123 a formed in the ring-shaped pipe portion 123, the position of the upper end 123 b of the cross section orthogonal to the flow direction of the cooling water is in the vertical direction regardless of the position in the flow direction of the cooling water. In the same position. That is, the upper end 123b of the cross section orthogonal to the flow direction of the cooling water in the pipe line 123a is on the same horizontal plane regardless of the position in the flow direction of the cooling water.

  As shown in FIG. 6, the ring-shaped tube portion 123 has a tapered portion 123c. The taper portion 123 c is formed in the vicinity of the connection portion of the ring-shaped tube portion 123 with the connection tube portion 124. The tapered portion 123c is formed on both sides in the circumferential direction with respect to the connection portion with the connection tube portion 124 in the ring-shaped tube portion 123. The tapered portion 123c has a tapered shape in which the side farther from the side closer to the connecting tube portion 124 in the cooling water flow direction of the ring-shaped tube portion 123 has a smaller diameter. In the taper portion 123c, the flow path cross-sectional area of the pipe line 123a gradually decreases as the distance from the connection pipe part 124 increases. Corresponding to the difference in diameter at both ends of the taper portion 123c, the ring-side tube portion 123 has a diameter of the ring-side connection tube portion 123d, which is a portion closer to the connection tube portion 124 than the taper portion 123c. It is larger than the diameter of the part 123e on the opposite side to the connecting pipe part 124 side than 123c. The connecting pipe part 124 is the same as the connecting pipe part 24 of the water supply pipe 20, and the distance from the insertion pipe part 21 is larger than the side where the distance from the insertion pipe part 21 along the flow direction of the cooling water is small. The side has an inclination located on the upper side in the vertical direction.

  The ring-side connecting pipe portion 123d is a straight pipe portion having a constant diameter. As shown in FIG. 5, the lower end 123f of the cross section orthogonal to the flow direction of the cooling water in the ring side connecting pipe portion 123d is the inner wall surface of the inserting pipe portion 21 in the connecting portion between the inserting pipe portion 21 and the connecting pipe portion 124. It is above the upper end 21a in the vertical direction.

  Even with such a water supply pipe 120, it is possible to suppress the generation of thermal stress that becomes a fatigue source by suppressing the occurrence of thermal stratification in the insertion pipe portion 21 or by eliminating the thermal stratification at an early stage. it can. However, when the entire ring-shaped tube portion 123 is lifted with respect to the insertion tube portion 21, the ring-shaped tube portion 123 is likely to be exposed to the air layer when the water level in the steam generator 1 is lowered.

  On the other hand, in the water supply pipe 20 of the present embodiment, as shown in FIGS. 3 and 4, the generator internal pipe section 22 bent so as to be lifted at the connection pipe section 24 with respect to the insertion pipe section 21. Is bent so as to be lowered at the inclined tube portion 233. Thereby, the position in the vertical direction of the horizontal ring-shaped tube portion 231 is lowered, and the horizontal ring-shaped tube portion 231 is suppressed from being exposed from the cooling water surface. As shown in FIG. 2, the upper end 231 b of the cross section orthogonal to the flow direction of the cooling water in the pipe line 231 a of the horizontal ring-shaped pipe part 231 is the insertion pipe part 21 in the connection part between the insertion pipe part 21 and the connection pipe part 24. It is located on the lower side in the vertical direction than the horizontal plane 30 passing through the upper end 21a of the inner wall surface. Thereby, even if the cooling water level in the steam generator 1 is lowered to a level at which the insertion pipe part 21 starts to be exposed, the pipe 231a of the horizontal ring-shaped pipe part 231 is below the water surface. Since the horizontal ring-shaped pipe portion 231 becomes difficult to be exposed from the cooling water, the occurrence of steam accumulation in the pipe line 231a is suppressed.

  The position in the vertical direction of the pipe 231a formed in the horizontal ring-shaped pipe portion 231 is not limited to this and can be arbitrarily set. For example, in the present embodiment, the upper end 231 b of the cross section orthogonal to the flow direction of the cooling water in the pipe 231 a is located below the central axis X of the insertion pipe portion 21 in the vertical direction. Thus, in the water supply pipe 20 of this embodiment, the position in the vertical direction of the pipe line 231a of the horizontal ring-shaped pipe part 231 is arbitrarily set while maintaining the effect of suppressing thermal stratification in the insertion pipe part 21. It becomes possible.

  In the present embodiment, the upper horizontal pipe portion 234 is provided with an outflow pipe 251 (25). Thereby, when the cooling water level in the steam generator 1 falls, it is suppressed that the cooling water in the insertion pipe part 21 is sucked out to the horizontal ring-shaped pipe part 231 side. For example, when the outflow pipe 251 is not provided in the upper horizontal pipe section 234, the cooling water level is lowered until the horizontal ring-shaped pipe section 231 is exposed, and the supply of cooling water from the outside to the water supply pipe 20 is stopped. And the cooling water in the insertion pipe part 21 in a high position with respect to the horizontal ring-shaped pipe part 231 may be sucked out toward the horizontal ring-shaped pipe part 231 side. In this embodiment, since the outflow pipe 251 is provided in the upper horizontal pipe section 234, the outflow pipe 251 is exposed and the pipe 234a is opened when the cooling water level in the steam generator 1 is lowered. . Thereby, it is suppressed that the cooling water in the insertion pipe part 21 is attracted | sucked toward the horizontal ring-shaped pipe part 231. FIG.

  In addition, the position in the vertical direction of the horizontal ring-shaped pipe portion 231 may be set based on a predetermined control target of the coolant level in the space 40 in the steam generator 1. The target water level of the cooling water is determined depending on the control parameters of the nuclear power plant having the steam generator 1. For example, when a lower limit is set for the control target water level, the upper end 231b of the cross section orthogonal to the flow direction of the cooling water in the pipe 231a is positioned below the vertical direction below the lower limit water level. Also good. In this way, if the cooling water level in the steam generator 1 is equal to or higher than the lower limit of the target water level, the pipeline 231a is under the surface of the cooling water, and the occurrence of steam accumulation in the pipeline 231a is suppressed. .

  Further, the position of the horizontal ring-shaped pipe portion 231 in the vertical direction is, for example, even when cooling water is supplied at a low temperature and at a low flow rate, such as when the plant is started and stopped at a low temperature. You may set so that the pipe line 231a of the horizontal ring-shaped pipe part 231 may be located below rather than the cooling water level in the space 40 in the steam generator 1. FIG.

  In this embodiment, the pipe part having the outflow pipe 25 is the ring-shaped pipe part 23 extending in a ring shape, but the shape of the pipe part having the outflow pipe 25 is not limited to this.

  As described above, the water supply pipe for a steam generator according to the present invention is suitable for suppressing thermal stratification in the pipe.

DESCRIPTION OF SYMBOLS 1 Steam generator 2 Trunk part 11 Pipe stand 112 Through-hole 20 Water supply pipe 21 Insertion pipe part 22 Generator internal pipe part 23 Ring-shaped pipe part 231 Horizontal ring-shaped pipe part 232 Upper ring-shaped pipe part 233 Inclined pipe part 234 Upper horizontal part Pipe part 24 Connection pipe part 25 Outflow pipe 30 Horizontal plane

Claims (5)

An insertion pipe portion inserted in a through-hole penetrating the outer shell member of the steam generator and extending in a horizontal direction;
A generator internal pipe connected to the insertion pipe and disposed inside the steam generator;
With
The generator inner pipe part is formed in the axial direction of the generator inner pipe part, and a pipe line through which cooling water supplied from the outside of the steam generator flows through the insertion pipe part; And an outflow part from which the cooling water flows out from the pipe into the space in the steam generator,
The pipe has a first inclined part having an inclination in which a side larger than a side having a small distance from the insertion pipe part along the flow direction of the cooling water is located above the vertical direction, and the first inclined part. An inclination is located on the side where the distance from the insertion tube part along the flow direction is large, and the side where the distance from the insertion tube part along the flow direction is smaller than the side where the distance is small is located below the vertical direction. A second inclined portion having
In at least a part of the flow direction in the pipe line between the first inclined part and the second inclined part, a lower end of a cross section of the pipe line orthogonal to the flow direction is the insertion pipe part. The steam generator water supply pipe, which is above a horizontal plane passing through an upper end of an inner wall surface of the insertion pipe part in a connection part with the generator inner pipe part. The water supply pipe for steam generators according to claim 1, wherein a section in which the first inclined portion is formed in the generator inner pipe portion does not have the outflow portion. The generator inner tube section includes a ring-shaped tube section extending in a ring shape along an inner peripheral surface of the outer shell member, and the ring-shaped tube section and the insertion tube section branched from the ring-shaped tube section. And a connecting pipe part for connecting
The first inclined part is the pipe line formed in the connection pipe part,
The said 2nd inclination part is the said pipe line formed in the said ring-shaped pipe part, Comprising: It forms in the both sides of the axial direction of the said ring-shaped pipe part on both sides of the said connection pipe part. A water supply pipe for a steam generator as described in 1. Of the ring-shaped pipe part, a horizontal ring-shaped pipe line that is the pipe line extending in the horizontal direction is formed on the side opposite to the insertion pipe part side than the second inclined part in the flow direction. And
The upper end of the cross section perpendicular to the flow direction in the horizontal ring-shaped pipe line is perpendicular to the horizontal plane passing through the upper end of the inner wall surface of the insertion pipe part at the connection part between the insertion pipe part and the generator inner pipe part. The water supply pipe for steam generators according to claim 3, which is on the lower side. Of the ring-shaped pipe part, a horizontal ring-shaped pipe line that is the pipe line extending in the horizontal direction is formed on the side opposite to the insertion pipe part side than the second inclined part in the flow direction. And
The steam according to claim 3, wherein an upper end of a cross section perpendicular to the flow direction in the horizontal ring pipe line is vertically below a lower limit in a control target of a coolant level in the space in the steam generator. Generator water supply pipe.

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