JP5089485B2 - Jet pump and reactor - Google Patents

Description

  The present invention relates to a jet pump and a nuclear reactor, and more particularly, to a jet pump and a nuclear reactor suitable for application to a boiling water reactor.

  A conventional boiling water reactor (BWR) has a jet pump installed in a reactor pressure vessel (hereinafter referred to as RPV) to which a recirculation system pipe is connected. The jet pump includes a nozzle, a bell mouth, a throat, and a diffuser. The cooling water whose pressure has been increased by driving the recirculation pump passes through the recirculation system piping and is jetted from the nozzle into the throat as drive water. The nozzle increases the speed of the driving water. The cooling water present around the nozzle in the RPV is sucked into the bell mouth as driven water by the action of the jetted driving water, and flows into the diffuser through the throat. The cooling water discharged from the diffuser is supplied to the core through the lower plenum in the RPV (see, for example, Japanese Patent Laid-Open Nos. 59-188100, 7-119700, and 2007-285165). ).

  The jet pumps described in JP 59-188100 A, JP 7-119700 A, and JP 2007-285165 A have a plurality of nozzles. When the area of the spout is the same, increasing the number of nozzles increases the contact area between the driving water and the driven water, promotes the mixing of the driving water and the driven water, reduces the mixing loss, and the jet pump Efficiency is improved.

JP 59-188100 A JP 7-119700 A JP 2007-285165 A

  The performance of the jet pump is expressed by the M ratio, N ratio, and efficiency as shown below. The M ratio is a ratio of the flow rate Qs of the driven water (cooling water) flowing into the throat portion with respect to the flow rate Qn of the drive water (recirculation water) at the nozzle portion, and is expressed by equation (1).

M ratio = Qs / Qn (1)
The N ratio is the total pressure ratio of the driven water to the driving water, and is expressed by equation (2).

N ratio = (Pd−Ps) / (Pn−Pd) (2)
Here, Pd is the total pressure in the diffuser section, Ps is the total pressure around the jet pump, and Pn is the total pressure in the nozzle section. The efficiency η is the ratio of the energy of the driven water to the driving water, and is represented by the product of the M ratio and the N ratio as shown in the equation (3).

η = M ratio × N ratio (3)
As a jet pump, it is desirable that the M ratio, the N ratio, and the efficiency η are large. If the flow rate of the cooling water discharged from the jet pump can be increased efficiently by using a small-capacity recirculation pump, the recirculation system can be made compact and the installation space of the recirculation system can be reduced.

  For example, when the power is improved in an existing nuclear reactor (for example, BWR), the increase in the reactor power can be expanded by increasing the core flow rate to increase the cooling capacity of the core. Further, by expanding the control range of the core flow rate during the operation of the BWR, the range of change in the void ratio in the core can be increased, and the fuel economy can be improved. In order to increase the core flow rate in this way, it is conceivable to improve the recirculation pump and the jet pump. The inventors have found that in the modification of an existing nuclear reactor for the purpose of improving the output, the improvement of the jet pump is more effective than the modification or replacement of a large-sized device such as a recirculation pump. Since the performance of the jet pump greatly depends on the shape of the mixing portion of the driving water and the driven water, the performance may be improved by improving the nozzle that ejects the driving water.

  The inventors found that when a plurality of nozzles are arranged on the nozzle pedestal based on detailed numerical analysis, a vortex of driven water is generated on the nozzle surface on the central axis side of the nozzle pedestal, and energy loss due to the vortex is reduced. It has been found that by reducing the amount, the driven fluid can be sucked in more and the jet pump efficiency is improved.

  An object of the present invention is to provide a jet pump and a nuclear reactor that can further increase the efficiency.

A feature of the present invention that achieves the above-described object is that the nozzle device includes a nozzle pedestal member that forms a protrusion at the axial center of the nozzle device, and a plurality of nozzle devices that are disposed around the protrusion and are attached to the nozzle pedestal member. the nozzle, and have a rectifying member which is disposed toward the axis from the nozzle, a plurality of rectifying members are arranged radially toward the plurality of nozzles from the protrusion is disposed around the protrusion are they there to Rukoto.

Each rectifying member disposed around the protrusion and radially disposed from the protrusion toward each of the plurality of nozzles is in the flow of the driven fluid passing between the nozzles and toward the axis of the nozzle device . Occurrence of vortices near the outer surface of the nozzle projection can be suppressed, and energy loss of the driven fluid due to the vortices can be reduced. For this reason, the efficiency of the jet pump is further improved.

  The above object can also be achieved by a plurality of nozzles provided in the nozzle device forming a plurality of dimples on the outer surface on the axial center side of the nozzle device. This is because each dimple formed on the outer surface of the nozzle moves the separation of the flow of the driven fluid to the downstream side, so that the generated vortex is reduced and the energy loss is reduced.

  Preferably, it is desirable that the nozzle form a plurality of throttle portions that reduce the cross-sectional area of the driving fluid passage formed in the nozzle.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the vortex of a driven fluid can be suppressed and the efficiency of a jet pump can further be increased.

  A jet pump installed in a boiling water reactor that is an embodiment of the present invention will be described below with reference to the drawings.

  A jet pump according to embodiment 1 which is a preferred embodiment of the present invention will be described below. Before describing the structure of the jet pump of this embodiment, the schematic structure of a boiling water reactor to which this jet pump is applied will be described below with reference to FIGS.

  A boiling water reactor (BWR) has a reactor pressure vessel (reactor vessel) 1, and a reactor core shroud 3 is installed in the reactor pressure vessel 1. The reactor pressure vessel is hereinafter referred to as RPV. A core 2 loaded with a plurality of fuel assemblies (not shown) is disposed in a core shroud 3. A steam separator 4 and a steam dryer 5 are disposed above the core 2 in the RPV 1. A jet pump 10 is disposed in an annular downcomer 6 formed between the RPV 1 and the core shroud 3. The recirculation system provided in the RPV 1 includes a recirculation system pipe 7 and a recirculation pump 8 installed in the recirculation system pipe 7. One end of the recirculation piping 7 is connected to the downcomer 6. The other end of the recirculation pipe 7 is connected to a lower end of a riser pipe 9 disposed in the downcomer 6. The upper end of the riser pipe 9 is connected to the branch pipe 26, and the branch pipe 26 is connected to the nozzle device 12 of the jet pump 10. The feed water pipe 17 and the main steam pipe 42 are connected to the RPV 1. The nozzle device 12 is attached to the bell mouth 20 by a plurality of support plates 26 and is integrated with the bell mouth 20.

  Cooling water (driven fluid, coolant) 23 that is driven water present in the upper portion of the RPV 1 is mixed with water supplied to the RPV 1 from the water supply pipe 17 and descends in the downcomer 6. The cooling water 23 is sucked into the recirculation system pipe 7 by driving the recirculation pump 8, and is pressurized by the recirculation pump 8. The raised cooling water 24 is referred to as driving water (driving fluid) for convenience. The driving water 24 flows through the recirculation system pipe 7, the riser pipe 9, and the branch pipe 26, reaches the nozzle device 12 of the jet pump 10, and is ejected from the nozzle device 12. The cooling water 23 that is driven water existing around the nozzle device 12 is sucked into the throat 21 from the bell mouth 20 by the ejection of the driving water 24. The cooling water 23 descends in the throat 21 together with the driving water 24 and is discharged from the lower end of the diffuser 22. The cooling water (including the driven water 23 and the driving water 24) discharged from the diffuser 22 is referred to as cooling water 25 for convenience. The cooling water 25 is supplied to the core 2 through the lower plenum 7. The cooling water 25 is heated when passing through the core 2 and becomes a gas-liquid two-phase flow containing water and steam. The steam / water separator 4 separates the gas / liquid two-phase flow into steam and water. The separated steam is further dehumidified by the steam dryer 5 and discharged to the main steam pipe 42. This steam is guided to a steam turbine (not shown) to rotate the steam turbine. A generator connected to the steam turbine rotates to generate electric power. The steam discharged from the steam turbine is condensed into water by a condenser (not shown). This condensed water is supplied into the RPV 1 through the water supply pipe 17 as water supply. The water separated by the steam separator 4 and the steam dryer 5 falls and reaches the downcomer 6 as cooling water 23.

  The jet pump 10 having the nozzle device 12, the bell mouth 20, the throat 21 and the diffuser 22 as main components sucks in the cooling water 23 existing around the nozzle device 12, and thereby has a large flow rate with a small amount of driving water 24. Cooling water 25 can be supplied to the core. When the kinetic energy of the driving water 24 provided by the recirculation pump 8 effectively acts on the cooling water 23, the cooling water 23 is driven and the flow rate of the cooling water 25 further increases. The jet pump 10 reduces the static pressure in the throat 21 by ejecting the driving water 24 ejected from the nozzle device 12 into the throat 21 at a high speed. Thereby, the cooling water 23 can be sucked into the throat 21, and a necessary core flow rate can be secured with a small amount of power. The diffuser 22 gradually expands toward the downstream side so that the flow does not cause separation, and the kinetic energy of the cooling water is converted into pressure by the diffuser 22. In the diffuser 22, the pressure of the driven water 23 is higher than the pressure at the position sucked into the bell mouth 20. The channel cross-sectional area of the bell mouth 20 increases toward the upstream.

  The bell mouth 20, the throat 21 and the diffuser 22 are connected and integrated in this order. The integrated bell mouth 20, throat 21 and diffuser 22 are a jet pump body. The nozzle device 12 is disposed above the bell mouth 20.

  A detailed configuration of the nozzle device 12 in the jet pump 10 of the present embodiment will be described below with reference to FIGS. 1 and 2. The nozzle device 12 includes a nozzle pedestal (nozzle pedestal member) 15, six nozzles 13, and six rectifying plates (rectifying members) 18. The nozzle base 15 of the nozzle device 12 is attached to and integrated with the bell mouth 20 by a support plate 26 and is connected to the branch pipe 26. The nozzle device 12 is disposed above the bell mouth 20. The nozzle pedestal 15 has a protrusion 16 that extends downward at the axial center. The six nozzles 13 are annularly attached to the nozzle pedestal 15 and are arranged around the protrusions 16. These nozzles 13 extend from the nozzle base 15 toward the bell mouth 20. Each rectifying plate 18 is arranged radially from the protruding portion 16 toward each nozzle 13, and is attached to the protruding portion 16 and the nozzle 13.

  FIG. 5 shows a vertical cross-sectional shape of the rectifying plate 18 at a position where the rectifying plate 18 is attached to the nozzle 13. The cross-sectional area in the longitudinal cross section on the nozzle 13 side of the rectifying plate 18 decreases from the root portion 17 of the nozzle 13 where the nozzle 13 is attached to the nozzle base 15 toward the tip of the nozzle 13. That is, the relationship between the plate thickness L1 of the rectifying plate 18 at the base portion 17 on the nozzle 13 side and the plate thickness L2 of the rectifying plate 18 on the tip side of the nozzle 13 is L1> L2.

  FIG. 6 shows a vertical cross-sectional shape of the rectifying plate 18 at a position where the rectifying plate 18 is attached to the nozzle base 15. The cross-sectional area in the vertical cross section of the rectifying plate 18 on the nozzle pedestal 15 side decreases from the base portion 17 toward the tip of the projection portion 16. That is, the relationship between the plate thickness L3 of the rectifying plate 18 at the base portion 17 on the nozzle pedestal 15 side and the plate thickness L4 of the rectifying plate 18 on the distal end side of the protruding portion 16 is L3> L4. In such a nozzle device 12, the flow passage cross-sectional area of the cooling water flow passage 19 formed between the adjacent rectifying plates 18 is changed from upstream to downstream (from the root portion 17 toward the tip of the nozzle 13). Can be gradually enlarged. For this reason, it is possible to suppress an increase in pressure loss due to a rapid change in the flow path cross-sectional area.

  The driving water 24 boosted by the recirculation pump 8 flows into the nozzle base 15 of the nozzle device 12 from the branch pipe 26 and is guided into the ejection passages (driving fluid passages) 27 formed in the nozzles 13. The driving water 24 is ejected into the bell mouth 20 of the jet pump 10 from the ejection port 14 formed in each nozzle 13. The jet port 14 is formed at the tip of the jet passage 27. The jet flow 28 of the drive water 24 jetted from the jet port 14 reaches from the bell mouth 20 into the throat 21. This jet flow 28 reduces the static pressure in the throat 21, and the cooling water 23 in the downcomer 6 existing around the nozzle device 12, that is, the driven water 29 passes through the suction channel 30 and enters the throat 21. Sucked. The suction passage 30 is formed between each nozzle 13 and the bell mouth 20. A part of the driven water 29 to be sucked is guided into the cooling water flow path 19 through a gap 31 (see FIG. 2) between the nozzles 13. The driven water 29 that has flowed into the cooling water passage 19 descends along the flow straightening plate 18 and flows into the bell mouth 20 through the region inside the jet flow 28.

  In order to confirm the function of the rectifying plate 18, the inventors first examined the flow state of the driven water 29 around the nozzle 13 when the rectifying plate 18 does not exist in the nozzle device 12. That is, the inventors clarified by analysis the flow state of the driven water 29 on the protruding portion 16 side of the nozzle 13 when there is no rectifying plate 18 using the general-purpose fluid analysis code. The result is shown in FIG. FIG. 7 shows a 1/6 region in the circumferential direction of the nozzle device 12 around the protrusion 16 in consideration of symmetry. Due to the flow of the driven water 29 toward the protrusion 16 along the outer surface of the nozzle 13, a vortex is generated near the outer surface of the nozzle 3 on the protrusion 16 side downstream from the separation point (see FIG. 7). Since generation of vortices generally loses fluid energy, the efficiency of the jet pump can be improved by reducing vortices generated near the outer surface of the nozzle 3 on the protrusion 16 side. Further, the vortex generated unsteadily may cause the nozzle 13 to vibrate and adversely affect the soundness of the BWR structural member.

  The inventors of the present invention are directed to the nozzle device 12 of the jet pump 10 to which the rectifying plate 18 is attached, and the flow state of the driven water 29 toward the protrusion 16 along the outer surface of the nozzle 13 does not exist. As in the case, analysis was performed using a general-purpose fluid analysis code. The analysis result is shown in FIG. FIG. 8 also shows a 1/6 region in the circumferential direction of the nozzle device 12 around the protrusion 16 in consideration of symmetry, as in FIG. By attaching the rectifying plate 18, the vortex (see FIG. 7) generated when the rectifying plate 18 is not present disappears. For this reason, the driven water 29 passing between the adjacent nozzles 13 smoothly flows toward the protrusions 16 along the outer surface of the nozzles 13 (see FIG. 8).

  The relationship between the M ratio and the jet pump efficiency η in the jet pump 10 including the nozzle device 12 having the rectifying plate 18 is shown by a solid line in FIG. This relationship is a characteristic obtained by analysis. The relationship of a conventional jet pump having a nozzle device having a configuration in which the rectifying plate 18 is removed from the nozzle device 12 is also shown in FIG. 9 by a broken line. Since the present embodiment has the current plate 18, when the driven water 29 passing between the adjacent nozzles 13 flows toward the protrusion 16, the outer surface of the nozzle 13 on the protrusion 16 side is near the outer surface. As described above, no vortex is generated. For this reason, the efficiency (solid line in FIG. 9) of the jet pump 10 of this embodiment is improved over that of the above-described conventional jet pump that does not have the rectifying plate 18 (broken line in FIG. 9). This efficiency improvement is brought about by the generation of vortices of the driven water 29 and the energy loss of the driven water 29 being reduced by the installation of the rectifying plate 18. Further, in this embodiment, energy loss is reduced, and the driven water 29 is easily sucked into the bell mouth 20 through the nozzles 13, so that the efficiency of the jet pump is increased in a region where the M ratio is high. Significantly larger.

  Since the present embodiment can suppress the generation of vortices as described above by installing the rectifying plate 18, the vibration of each nozzle 13 can be suppressed and the soundness of the structural member of the BWR can be improved. Can do.

  The thickness of the rectifying plate 18 in the vertical cross section is reduced from the base portion 17 of the nozzle 13 toward the tip (lower end) of the nozzle 13. Since the thickness is reduced at the tip of the nozzle 13, the generation of vortices below the tip can be suppressed. Therefore, the pressure loss of the flow of the driven water 29 that passes between the nozzles 13 and reaches the bell mouth 20 can be reduced, and the flow rate of the driven water 29 sucked into the throat 21 increases. Further, since the thickness of the rectifying plate 18 is not stepwise in the axial direction but continuously decreases toward the tip of the nozzle 13, there is no abrupt change in the cross-sectional area of the driven water 29 and the pressure loss is reduced. Further reduced.

  The thickness of the rectifying plate 18 is thinner on the protrusion 16 side of the nozzle base 15 than on the nozzle 13 side. Therefore, the generation of vortex in the vicinity of the outer surface of the nozzle 13 facing the protrusion 16 is suppressed, and the flow passage cross-sectional area of the cooling water passage 19 in the vicinity of the protrusion 16 can be increased. This increase in the flow path area reduces the pressure loss of the driven water 29 descending the cooling water flow path 19. Reduction of the pressure loss increases the flow rate of the driven water 29 sucked by the throat 21.

  The BWR controls the flow rate of the cooling water 25 (core flow rate) supplied to the core 2 by changing the flow rate of the jet flow 28 from each nozzle 13 of the nozzle device 12 by adjusting the rotational speed of the recirculation pump 8. By doing so, the reactor power can be controlled. The BWR equipped with the jet pump 10 of the present embodiment can expand the control range of the core flow rate by improving the efficiency of the jet pump 10, and can increase the increase range of the reactor power in improving the output of the BWR. The improvement in the efficiency of the jet pump 10 can increase the burnup of the fuel assembly loaded in the core 2 and improve the fuel economy.

  In the present embodiment, the jet pump 10 with improved jet pump efficiency can be realized by replacing the nozzle device of the conventional jet pump with the nozzle device 12 having the rectifying plate 18. For this reason, by using the jet pump 10 of the present embodiment, the core flow rate corresponding to the improvement of the BWR output can be secured without changing the capacity of the recirculation pump 8, so that the recirculation pump 8 has a high performance. There is no need to replace it with a recirculation pump.

  A jet pump according to embodiment 2, which is another embodiment of the present invention, will be described below with reference to FIGS. The jet pump 10 </ b> A according to the present embodiment is also applied to the BWR similarly to the jet pump 10.

  The jet pump 10A has a configuration in which the nozzle device 12 in the jet pump 10 is replaced with a nozzle device 12A. The nozzle device 12 </ b> A uses a rectifying plate 18 </ b> A in which the length of the nozzle device in the radial direction is shortened in place of the rectifying plate 18 in the nozzle device 12. The other structure of the jet pump 10A is the same as that of the jet pump 10. The rectifying plate 18 </ b> A has one end surface in the radial direction attached to the nozzle 13 and the upper end surface attached to the nozzle pedestal 15. The other end face of the rectifying plate 18 in the radial direction (end face located on the axial center side of the nozzle device 12 </ b> A) is separated from the protrusion 16, and a gap 32 is formed between the end face and the protrusion 16.

  Also in this embodiment, since the current plate 18A is provided, the effect produced in the first embodiment can be obtained. In the present embodiment, since the gap 32 is formed between the rectifying plate 18A and the projecting portion 16, the flow passage cross-sectional area of the cooling water flow passage 19 in the vicinity of the axial center of the nozzle device 12A can be increased as compared with the first embodiment. it can. For this reason, the pressure loss of the cooling water channel 19 can be reduced as compared with the first embodiment.

  A jet pump according to embodiment 3, which is another embodiment of the present invention, will be described below with reference to FIGS. The jet pump 10 </ b> B of the present embodiment is also applied to the BWR like the jet pump 10.

  The jet pump 10B has a configuration in which the nozzle device 12 in the jet pump 10 is replaced with a nozzle device 12B. The nozzle device 12 </ b> B has a large number of dimples 33 (see FIG. 13) formed on the outer surface of each nozzle 13 in place of the rectifying plate 18 in the nozzle device 12. The dimple 33 is a small depression. These dimples 33 are present in a dimple formation region 34 formed on the outer surface of each nozzle 13 facing the axial center side of the nozzle device 12B. That is, these dimples 33 are formed on the outer surface of each nozzle 13 facing the axial center side of the nozzle device 12B. The dimple formation region 34 occupies less than half of the outer surface in the circumferential direction of the nozzle 13. The dimples 33 are depressions having a spherical bottom as shown in FIG. 13A, and are arranged in a staggered arrangement as shown in FIG. 13 (B). As the dimple, a cylindrical dimple 33A as shown in FIG. 14 may be formed.

  The operation of the dimple 33 formed on the outer surface of the nozzle 13 will be described below. In the conventional jet pump, as shown in FIG. 7, the swirl of the driven water 29 is generated in the vicinity of the outer surface of the nozzle 13 on the axial center side of the nozzle base. This vortex is generated because the driven water 29 flowing along the outer surface of the nozzle 13 is separated on the outer surface on the axial center side of the nozzle device having six nozzles. In the present embodiment, the plurality of dimples 33 formed on the outer surface of the nozzle 13 cause a slight disturbance in the driven water 29 that flows along the outer surface of the nozzle 13. Since the separation position of the flow of the driven water 29 moves to the downstream side due to this minute disturbance, the generated vortex is reduced, and the energy loss of the flow of the driven water 29 can be reduced. Accordingly, the efficiency of the jet pump 10B in which the dimples 33 are formed can be improved. By arranging the dimples 33 in a staggered manner, slight disturbance of the driven water 29 can be uniformly formed on the outer surface of the nozzle 13. By forming a minute flow uniformly, it is possible to effectively suppress unsteady vortices.

  The plurality of dimples 33 are formed in a dimple formation region 34 located on the outer surface of the nozzle 13 on the axial center side of the nozzle device 10B. The reason for adopting such a configuration will be described. The dimple 33 has an effect of reducing energy loss by moving the separation of the flow of the driven water 29 to the downstream side. When the dimple 33 is formed on the outer surface of the nozzle 13 in a region where the flow of the driven water 29 is not separated, energy loss is not a little caused by the occurrence of slight disturbance. Therefore, it is desirable from the viewpoint of energy loss reduction that the dimple 33 is formed on the outer surface of the nozzle 13 slightly upstream from the flow separation position.

  In order to move the peeling position shown in FIG. 7 to the downstream side, the dimple 33 may be formed slightly upstream of the peeling point, that is, on the axis side of the nozzle device 12B of the nozzle 13. The dimple 33 is not formed on the outer surface of the nozzle 13 that does not face the protruding portion 16. For this reason, energy loss due to the dimples 33 does not occur on the outer surface of the nozzle 13 that does not face the protrusion 16.

  According to the results of a plurality of numerical analyzes with different conditions performed by the inventors, the separation point of the flow of the driven water 29 is downstream of the intermediate point of the outer surface of the nozzle 13 shown in FIG. It turns out. Therefore, the dimple 33 may be formed on the outer surface of the nozzle 13 on the axial center side of the nozzle device 12B from the midpoint of the outer surface of the nozzle 13. The six nozzles 13 provided in the nozzle device 12B are arranged on a circle (a broken-line circle shown in FIG. 2) whose axis is centered on the axis of the nozzle device 12B. The above-described intermediate point is the intermediate point shown in FIG. 7, and is the position of the intersection between the above-described circle (broken circle shown in FIG. 2) and the outer surface of the nozzle 13 in the cross section of the nozzle 13.

  As is apparent from the above description, the jet pump 10B of this embodiment suppresses the generation of vortices of the driven water 29 by forming the dimple 33 on the outer surface of the nozzle 13 on the axial center side of the nozzle device 12B. Thus, energy loss can be reduced. For this reason, in this embodiment, the suction amount of the driven water 29 is increased, and the efficiency of the jit pump can be improved in a region where the M ratio is large.

  A jet pump applied to a BWR according to embodiment 4 which is another embodiment of the present invention will be described below with reference to FIGS. The jet pump 10C of the present embodiment has a configuration in which the nozzle 13 of the nozzle device 12 in the jet pump 10 is replaced with a nozzle 13A. The jet pump 10C has the same configuration as the jet pump 10 except that the nozzle 13A is different. The six nozzles 13 extend downward from the nozzle base 15 and are arranged at equal intervals in the circumferential direction.

  The nozzle device 12C includes six nozzles 13A. A detailed configuration of the nozzle 13A will be described with reference to FIG. When the nozzle inner diameter, which is the passage diameter of the ejection passage 27A formed inside, is sequentially defined as D1, D2, D3 from the upstream end to the downstream end of the nozzle 13A, these inner diameters have a relationship of D1> D2> D3. have.

  That is, in the nozzle device 12C used in the jet pump 10C, the nozzle 13A includes a nozzle straight pipe portion 36, a nozzle throttle portion 37, a nozzle straight pipe portion 38, a nozzle throttle portion 39, and a nozzle lower end portion 40. The nozzle straight pipe portion 36 located at the most upstream has a constant inner diameter of D1. The first stage nozzle restricting portion 37 connected to the downstream end of the nozzle straight pipe portion 36 has an internal flow path cross-sectional area that decreases toward the downstream, an inner diameter at the upper end is D1, and an inner diameter at the lower end is D2. The length is L1. The nozzle straight pipe portion 38 connected to the downstream end of the nozzle restricting portion 37 has a constant inner diameter of D2. The second stage nozzle restricting portion 39 connected to the lower end of the nozzle straight pipe portion 38 has an internal flow passage cross-sectional area that decreases in the downstream direction, an inner diameter at the upper end is D2, and an inner diameter at the lower end is D3. Is L2. The nozzle lower end portion 40 connected to the lower end of the nozzle restricting portion 39 and located on the most downstream side of the nozzle 13A has an inner diameter of D3 and has an outlet 14 formed therein.

  In the nozzle 13 </ b> A, the ejection passage 27 </ b> A is throttled at two locations of the nozzle throttle portions 37 and 39. The aperture angle θ1 of the nozzle aperture 37 and the aperture angle θ2 of the nozzle aperture 39 can be calculated by the following equations (4) and (5), respectively.

θ1 = tan ⁻¹ ((D1−D2) / 2 / L1) (4)
θ2 = tan ⁻¹ ((D2−D3) / 2 / L2) (5)
The nozzle aperture angle θ2 of the nozzle aperture 39 near the jet nozzle 14 is larger than the aperture angle θ1 of the nozzle aperture 37 (θ2> θ1). A nozzle straight pipe portion 36 having a large flow path cross-sectional area is arranged upstream of the nozzle throttle portion 37, and a nozzle straight pipe portion 38 having a small flow path cross-sectional area is arranged downstream of the nozzle throttle portion 37.

  It is desirable to arrange a straight pipe nozzle lower end portion 40 having an inner diameter D3 and a jet port 14 formed at the tip thereof at the lowermost end portion located on the most downstream side of the nozzle 13A. However, in order to improve the flow velocity of the jet flow 28 ejected from the jet port 14, a nozzle throttle portion in which the flow passage cross-sectional area gradually decreases toward the downstream end may be used instead of the nozzle lower end portion 40 of the straight pipe. good.

  In the case where a nozzle restricting portion in which the flow path cross-sectional area gradually decreases toward the downstream end is used as the nozzle lower end portion 40, the spread of the jet flow 28 from the jet outlet 14 of the nozzle lower end portion 40 is suppressed within a desired range. Therefore, it is desirable that the aperture angle θ of the nozzle aperture is a small angle of less than about 2 degrees.

  The driving water 24 that has flowed into the nozzle pedestal 15 of the nozzle device 12C from the branch pipe 26 is guided to the ejection flow path 27A in each nozzle 13A. The flow passage cross-sectional area of the ejection passage 27A depends on the inner diameters of the nozzle straight pipe portion 36, the nozzle throttle portion 37, the nozzle straight pipe portion 38, the nozzle throttle portion 39, and the nozzle lower end portion 40 arranged from the upstream side to the downstream side. It has changed. The driving water 24 that has flowed into the ejection passage 27 </ b> A passes through the nozzle straight pipe portion 36, the nozzle throttle portion 37, the nozzle straight pipe portion 38, and the nozzle throttle portion 39, and reaches the nozzle lower end portion 40. The driving water 24 descending in the ejection passage 27 </ b> A is gradually accelerated by the nozzle restricting portion 37 and accelerated more rapidly than the nozzle restricting portion 37 by the nozzle restricting portion 39. The accelerated driving water 24 is ejected from the ejection port 14 into the throat 21.

  A velocity component toward the central axis of the nozzle 13 </ b> A is given to the driving water 24 in the nozzle restricting portion 39. However, since the fluid has a property of flowing along the wall surface, the ejection flow 28 having the diameter D3 is ejected from the ejection port 14 formed at the tip of the nozzle lower end portion 40 with the diameter D3. As the throttle angle θ2 of the nozzle restricting portion 39 is larger, there is a momentum toward the nozzle central axis, so that the spread of the jet flow 28 ejected from the jet port 14 is suppressed, and the jet flow 28 is a distance downstream from the jet port 14. It is possible to reduce the diameter D4 of the jet flow 28 at the point of advance by L3 within a desired range. The diameter D4 of the ejection flow 28 is the flow path width of the ejection flow 28, and the velocity of the ejection flow 28 increases as the diameter D4 of the ejection flow 28 decreases.

  If the jet flow 28 is ejected from the nozzle 13A into the throat 21 while the expansion of the jet flow 28 is suppressed and the speed is maintained, the static pressure in the throat 21 is further reduced, and therefore exists around the nozzle device 12C. More driven water 29 is drawn into the bell mouth 20 through the suction channel 30.

  A case is assumed where the nozzle lower end portion 40 is not disposed downstream of the nozzle restricting portion 39. In this case, the diameter of the ejection flow 28 becomes smaller even after ejection due to the momentum of the driving water 24 directed toward the central axis of the nozzle 13A given by the nozzle restricting portion 39. That is, since the straight pipe portion of the nozzle lower end portion 40 does not exist, the jet flow 28 ejected from the jet port 40 formed at the lower end of the nozzle portion 39 is affected by the nozzle restricting portion 39. For this reason, the diameter D4 of the jet flow 28 at the distance L3 from the jet port 14 is smaller than the inner diameter D3 of the jet port 14, the jet velocity is increased, and the acceleration loss is increased. Decrease.

  For this reason, by installing the nozzle lower end part 40 which is a straight pipe part in the downstream of the nozzle throttle part 39, the diameter of the jet flow 28 ejected from the jet outlet 14 is the inner diameter D3 of the nozzle lower end part 40 which is a straight pipe. The flow rate of the driving water 24 is prevented from decreasing due to an increase in acceleration loss.

  In addition, by providing two or more nozzle throttling portions on the nozzle 13A, it is possible to widen the flow path of the driven water 29 between the nozzles 13A while reducing the pressure loss in the nozzle 13A.

  Next, the nozzle 14 is formed in the nozzle 13A with the inner diameter of the nozzle 14 fixed at D3 and the nozzle restricting portion 37 as a straight tube, and the inner diameter of the nozzle straight portion 36 and the nozzle restricting portion 37 formed into a straight tube as D2. Let us consider a case where the throttle part is provided at one location of the nozzle throttle part 39. If the length L2 of the nozzle restricting portion 39 is not changed, the flow path of the driving water 24 flowing inside the nozzle straight pipe portion 36 and the nozzle restricting portion 37 formed into a straight pipe becomes narrow and friction is increased. The loss increases and the flow rate of the driving water 24 decreases. In addition, when the length L2 of the nozzle restricting portion 39 is increased to increase the upstream flow passage cross-sectional area of the nozzle restricting portion 39, the outer diameter of the nozzle 13A is increased and formed between the plurality of nozzles 13A. Therefore, the amount of the driven water 29 sucked into the bell mouth 20 is reduced.

  Therefore, by providing the nozzle 13A with two or more nozzle restricting portions, the flow passage cross-sectional area of the ejection passage 27A in the nozzle 13A becomes narrower on the ejection outlet 14 side, and the flow velocity of the driving water 24 flowing in the ejection passage 27A is reduced. To increase. As a result, the region in which the friction loss increases in the ejection passage 27A can be reduced. Further, since the outer diameter of the nozzle 13A can be reduced below the nozzle throttle portion 37, the width of the gap 31 formed between the nozzles 13A can be made wider than that in the first embodiment, and the cooling water flow The flow rate of the driven water 29 sucked into the passage 19 can be increased. As a result, the flow rate of the driven water 29 sucked into the throat 21 increases.

  As described above, the driving water 24 that has flowed into the ejection passage 27 </ b> A is accelerated in the ejection passage 27 </ b> A by the nozzle throttling portions 37 and 39, and is ejected into the throat 21 from the ejection port 14 as the ejection flow 28. In this embodiment, since the spread of the jet flow 28 can be suppressed, the speed of the jet flow 28 that has reached the throat 21 is increased, and the static pressure in the throat 21 is further reduced. As a result, more driven water 29 can be sucked into the throat 21.

  In the present embodiment, the rectifying plate 18 is provided in the same manner as in the first embodiment. Therefore, the axial center of the nozzle device 12 </ b> C is provided along the outer surface in the vicinity of the outer surface of the nozzle 13 </ b> A facing the axial center of the nozzle device 12 </ b> C. It is possible to suppress the generation of vortices due to the flow of the driven water 29 toward the side. For this reason, the present embodiment can obtain the effects produced in the first embodiment. Furthermore, since the present embodiment includes the nozzle 13A having the two nozzle throttling portions 37 and 39, the driven water 29 that is sucked into the throat 21 more than the first embodiment by the action of the nozzle 13A described above. The flow rate can be increased. For this reason, the flow rate of the cooling water 25 discharged from the jet pump 10 </ b> C is larger than that of the jet pump 10. The efficiency of the jet pump 10 </ b> C in the region where the M ratio is high is improved as compared with that of the jet pump 10.

  The jet pump 10C according to the present embodiment has a throttle portion and a straight pipe portion that are throttled in one stage described in JP-A-59-188100 even when the rectifying plate 18 is not installed. Compared with a conventional jet pump having five nozzles, the jet pump efficiency is improved.

  In this embodiment, the throttle angle θ2 of the nozzle throttle unit 39 is larger than the throttle angle θ1 of the nozzle throttle unit 37, so that the spread of the jet flow 28 is suppressed and the speed of the driving water 24 at the inlet of the throat 21 is reduced. In addition, the nozzle lower end portion 40 that forms the ejection port 14 is provided to prevent the speed of the driving water 29 from excessively increasing due to the restriction and greatly increasing the pressure loss of the nozzle 13A.

  Since the speed of the driving water 24 at the throat 21 does not drop much from the speed at the position of the jet outlet 14, the static pressure in the throat 21 is further reduced, and the amount of suction of the driven water 29 into the throat 21 increases. The M ratio and efficiency of the jet pump can be improved.

  In the jet pump 10B according to the third embodiment, the nozzle 13 may be replaced with the nozzle 13A, and the dimple formation region 34 may be formed on the outer surface of each nozzle 13A facing the axial center of the nozzle device 12B. In the dimple formation region 34, a plurality of dimples 33 are arranged in a staggered manner.

It is a longitudinal cross-sectional view of the nozzle device vicinity of the jet pump of Example 1 applied to BWR which is one suitable Example of this invention. It is II sectional drawing of FIG. It is a perspective view of the jet pump of Example 1 to which the nozzle device shown in FIG. 1 is applied. It is a longitudinal cross-sectional view of the boiling water reactor to which the jet pump of Example 1 shown in FIG. 3 is applied. It is a longitudinal cross-sectional view by the side of the nozzle of the baffle plate shown in FIG. It is a longitudinal cross-sectional view by the side of the projection part of the nozzle base of the baffle plate shown in FIG. It is explanatory drawing which shows the flow state of the to-be-driven water in the nozzle vicinity of the conventional jet pump. It is explanatory drawing which shows the flow state of the driven water in the nozzle vicinity of the jet pump of Example 1. FIG. It is a characteristic view which shows the relationship between M ratio and the jet pump efficiency in the jet pump of Example 1, and the conventional jet pump. It is the longitudinal cross-sectional view of the nozzle apparatus vicinity of the jet pump of Example 2 applied to BWR which is another Example of this invention. It is XI-XI sectional drawing of FIG. It is a partial side view of the nozzle device of the jet pump of Example 3 applied to BWR which is another Example of this invention. It is explanatory drawing which shows the dimple formed in the outer surface of the nozzle shown in FIG. 12, (A) is a fragmentary sectional view of the nozzle in the part in which the dimple was formed, (B) is explanatory drawing which shows the arrangement | sequence of a dimple. It is. It is a local sectional view of a nozzle in a portion in which dimples having other shapes are formed. It is the longitudinal cross-sectional view of the nozzle apparatus vicinity of the jet pump of Example 4 applied to BWR which is another Example of this invention. It is XVI-XVI sectional drawing of FIG. FIG. 16 is an enlarged vertical sectional view of the nozzle shown in FIG. 15.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel, 2 ... Core, 3 ... Core shroud, 6 ... Downcomer, 10, 10A, 10B, 10C ... Jet pump, 12, 12A, 12B, 12C ... Nozzle device, 13, 13A ... Nozzle, 14 ... Jet port, 15 ... Nozzle base, 16 ... Projection, 18, 18A ... Rectifying plate, 19 ... Cooling water flow path, 20 ... Bell mouth, 21 ... Throat, 22 ... Diffuser, 24 ... Drive water (drive fluid), 27 ... Jet passage, 29 ... driven water (driven fluid), 30 ... suction passage, 33, 33A ... dimple, 34 ... dimple formation region, 36, 38 ... nozzle straight pipe portion, 37, 39 ... nozzle throttling portion, 40 ... The lower end of the nozzle.

Claims (8)

A nozzle device that ejects a driving fluid, a driven fluid that is sucked in by the ejection of the driving fluid, exists around the nozzle device, and a discharge port that mixes the driving fluid and discharges the mixed fluid A pump body,
The nozzle device includes a nozzle pedestal member in which a protrusion is formed at the axial center of the nozzle device, a plurality of nozzles arranged around the protrusion and attached to the nozzle pedestal member, and the nozzle have a rectifying member which is disposed toward the axial center,
The plurality of the rectifying member, a jet pump which is characterized that you have arranged radially toward each of the plurality of nozzles from said protrusion is disposed around the protrusion.   The jet pump according to claim 1, wherein the nozzle forms a plurality of throttle portions that reduce a cross-sectional area of a driving fluid passage formed in the nozzle.   The jet pump according to claim 1, wherein the rectifying member is attached to the nozzle and the nozzle base member.   The jet pump according to claim 3, wherein a gap is formed between the rectifying member and the protrusion.   The jet pump according to any one of claims 1 to 4, wherein a thickness of the rectifying member is thinner on a tip end side of the nozzle than on a side where the nozzle is attached to the nozzle pedestal member.   The jet pump according to any one of claims 1 to 5, wherein a thickness of the rectifying member is thinner on the axis side than on the nozzle side. 3. The jet pump according to claim 2, wherein the nozzle forms a straight pipe portion on the distal end side of the throttle portion located on the distal end side of the nozzle among the plurality of throttle portions . A reactor vessel and a plurality of jet pumps installed in the reactor vessel and supplying coolant to a core formed in the reactor vessel;
Reactor in which the jet pump, characterized in that a jet pump according to any one of claims 1 to 7.

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