JP5642515B2 - Plant with piping having valve stem and boiling water nuclear power plant - Google Patents

Description

  The present invention relates to a plant including a pipe having a valve stem and a boiling water nuclear power plant.

  In a boiling water nuclear power plant (hereinafter referred to as a BWR plant), when the flow rate of main steam supplied from a reactor pressure vessel to a turbine is excessively increased, pressure fluctuations in the main steam system increase, There is a possibility of giving vibration. In order to reduce pressure fluctuation, measures such as optimizing the flow path shape of the main steam system are taken. Such cases and countermeasures are disclosed in G. Deboo, et al., “Quad cities unit 2 main steam line acoustic source identification and load reduction”, Proceedings of ICONE 14, ICONE14-89903 (2006).

  As one of the causes of pressure fluctuations in the main steam system in the BWR plant, a hydroacoustic resonance phenomenon is considered in a branch pipe such as a valve pedestal installed in a main steam pipe to which a steam relief safety valve is attached. In hydrodynamic resonance, the vortex generated by the separation of the flow of gas (for example, steam) flowing in the main steam pipe at the front edge (upstream side edge) of the branch pipe at the junction with the main steam pipe is the main steam. Pressure fluctuation (sound wave) is generated when it collides with the rear edge (downstream side edge) of the branch pipe at the junction with the pipe, and the sound wave propagates upstream to separate the flow at the front edge of the branch pipe. This is a phenomenon having a so-called feedback mechanism that generates a vortex when excited.

  The wavelength of the sound wave generated by the hydrodynamic resonance becomes shorter as the steam flow velocity in the main steam pipe increases. However, when the wavelength of the sound wave becomes equal to about four times the length of the branch pipe, a 1/4 wavelength is fixed in the branch pipe due to interference between the sound wave generated at the root of the branch pipe and the sound wave reflected at the end of the closed branch pipe. A standing wave is formed, and a large pressure fluctuation is generated as compared with a pressure fluctuation that is normally generated. The detailed mechanism is disclosed in S. Ziada, "A flow visualization study of flow-acoustic coupling at the mouth of a resonant side-branch", Journal of Fluids and Structures, 8, pp.391-416 (1994). ing. When the main steam flow rate is increased in the BWR plant, it is considered that the steam flow velocity in the main steam pipe increases, a standing wave is formed in the valve stem, and the pressure fluctuation increases.

  Such hydroacoustic resonance is organized by the Strouhal number St defined by the branch pipe inner diameter d, the branch pipe resonance frequency f, and the average velocity U of the main pipe.

St = f × d / U (1)
The strength of the hydroacoustic resonance is arranged by the Strouhal number St. Generally, when the Strouhal number St falls within the range of 0.3 to 0.6, the hydroacoustic resonance becomes strong (see FIG. 6).

  As a countermeasure for suppressing the pressure fluctuation of the BWR plant due to the hydroacoustic resonance, for example, Japanese Patent Application Laid-Open No. 2006-153869 has a pressure sensor and a Helmholtz resonance pipe installed in the steam dome of the reactor pressure vessel or the main steam pipe. A method for effectively suppressing pressure fluctuation is disclosed.

  In addition, Shiro Takahashi et al., “The hydroacoustic vibration of boiling water reactor steam dryer”, Journal of the Japan Society of Mechanical Engineers, B, 75, pp.597-603 (2009) A method is described in which a Helmholtz resonance pipe is installed in a valve nozzle provided in the main steam pipe, and acoustic fluctuation is suppressed to reduce pressure fluctuations generated in the valve nozzle.

  More generally, a method of providing a vortex generator or a spoiler upstream of the branch pipe is known as a method for suppressing hydrodynamic resonance. Further, for example, in Japanese Patent Laid-Open No. 7-301386, in order to disturb the excitation frequency of a vortex serving as a sound source, a sound reduction plate is provided in the vicinity of an inlet on the pipe side of a branch pipe connected to a pipe through which a gas flows. Discloses a method for preventing the occurrence of hydroacoustic resonance.

  Japanese Patent Application Laid-Open No. 53-86997 describes that in FIG. 5, an annular expansion cylinder is provided in a valve nozzle for installing a steam relief safety valve installed in a main steam pipe. The internal space of the expansion cylinder is communicated through the opening with a flow path that is communicated with the main steam pipe and formed in the valve stem. In the axial direction of the valve stem, both the first surface on the main steam pipe side and the second surface on the steam relief valve side of the inner space are flat. The dimension of the opening in the internal space in the axial direction of the valve stem is the distance between the first surface and the second surface, and the opening is formed continuously in the circumferential direction of the valve stem. Yes. During operation of the nuclear reactor, the pressure wave generated when the main steam isolation valve installed in the main steam pipe is closed is attenuated in the expansion cylinder. The hopping phenomenon that pushes up can be prevented.

JP 2006-153869 A JP-A-7-301386 JP-A-53-86997

G. Deboo, et al., "Quad cities unit 2 main steam line acoustic source identification and load reduction", Proceedings of ICONE 14, ICONE14-89903 (2006) S. Ziada, "A flow visualization study of flow-acoustic coupling at the mouth of a resonant side-branch", Journal of Fluids and Structures, 8, pp.391-416 (1994) Shiro Takahashi et al., 8 "Hydroacoustic Vibration of Boiling Water Reactor Steam Dryer", Transactions of the Japan Society of Mechanical Engineers, B, 75, pp.597-603 (2009)

  As described above, Japanese Patent Laid-Open No. 2006-153869 discloses a method of effectively suppressing pressure fluctuation due to hydroacoustic resonance in a BWR plant using a Helmholtz resonance tube. However, the Helmholtz resonance tube suppresses pressure fluctuations by using hydroacoustic resonance in the resonance pipe, and therefore only suppresses pressure fluctuations at frequencies that match the Helmholtz resonance frequency determined by the resonance tube shape. There is. For this reason, in order to apply a Helmholtz resonance tube in order to suppress pressure fluctuations caused by hydroacoustic resonance in a BWR plant, a pressure sensor for detecting the frequency of the pressure fluctuations generated, a Helmholtz resonance frequency as a pressure In order to match the frequency of variation, it is necessary to combine devices that adjust the shape of the resonant tube. The application of the Helmholtz resonance pipe complicates the structure of the main steam system of the BWR plant, and the installation of the Helmholtz resonance pipe in the existing BWR plant is based on the steam dome of the reactor pressure vessel or the main steam system including the main steam pipe. A major remodeling of is required.

  As described above, if the Helmholtz resonance tube is installed in the valve mount on which the vapor relief safety valve is attached, the resonance frequency can be shifted using acoustic resonance in the resonance tube to suppress pressure fluctuation. However, a new acoustic resonance mode is generated in which the length of the path from the root of the branch pipe to the end of the Helmholtz resonance tube is ¼ wavelength, and the Strouhal number is 0.3 to 0.3 with respect to the resonance frequency f ′. Hydrodynamic acoustic resonance occurs at a steam flow velocity U ′ of 0.6, and the pressure fluctuation increases. When the flow velocity of the steam flowing through the main steam pipe is U, it is assumed that hydroacoustic resonance having a resonance frequency f is generated at the joint between the valve stem and the main steam pipe when the Helmholtz resonance pipe is not installed. . When the resonance frequency when the Helmholtz resonance tube is installed and when it is not installed and the flow velocity of each steam in the main steam pipe when the hydroacoustic resonance occurs, the resonance frequency is f. > F ′ and the vapor flow velocity is U> U ′.

  As described above, the method of providing a vortex generator or spoiler on the upstream side of the branch pipe and the method of providing a sound reduction plate near the branch pipe inlet are effective for suppressing hydroacoustic resonance, but both are mainly used. In addition to complicating the structure of the steam system, the structure is installed in the main steam flow of the main steam pipe, which increases the pressure loss of the main steam pipe. Moreover, since the structure to install is exposed to the flow of the main steam in various steam piping which has a large density, it is necessary to consider the soundness of the structure.

  In addition, the inventors examined the effect of suppressing pressure fluctuations generated by hydroacoustic resonance by the expansion cylinder provided in the valve stem described in JP-A-53-86997. As a result, the internal space formed in the enlarged cylinder provided in the valve nozzle has a dimension in the axial direction of the valve nozzle that is the distance between the first surface and the second surface. Since the opening formed continuously in the circumferential direction of the valve is connected to the flow path in the valve nozzle, a new acoustic resonance mode is generated via the expansion cylinder, and the resonance frequency f ″ at this time is The inventors have found a new problem that hydroacoustic resonance occurs at a steam flow velocity U ″ where the Strouhal number is 0.3 to 0.6, and the pressure fluctuation cannot be suppressed. The resonance frequency f ″ is the resonance frequency of the sound wave that has been found by the inventors and propagates along the inner surface of the expansion cylinder and reaches the valve body of the vapor relief safety valve.

  When the flow velocity of the steam flowing through the main steam pipe is U, the resonance frequency f is obtained at the junction between the valve stem and the main steam pipe when no expansion cylinder is installed (the Helmholtz resonance pipe is not installed). Assume that hydroacoustic resonance occurs. Comparing the resonance frequency when the expansion cylinder is installed and when the expansion cylinder is not installed and the flow velocity of each steam in the main steam pipe when the hydroacoustic resonance occurs, the resonance frequency is f> f ″ and the steam flow rate is U> U ″. As with the installation of the Helmholtz resonance tube, the installation of the expansion cylinder on the valve stem shifts the resonance frequency using acoustic resonance in the expansion cylinder to suppress pressure fluctuations.

  In the installation of the Helmholtz resonance tube and the expansion cylinder, the pressure fluctuation is suppressed by shifting the resonance frequency. However, even if the Helmholtz resonance tube and the expansion tube are installed, depending on the acoustic resonance mode generated at the joint between the valve stem and the main steam pipe, the Strouhal number is 0.3 to 0.3 with respect to the resonance frequency as described above. Hydroacoustic resonance occurs at a steam flow rate of 0.6, and a new problem arises that the pressure fluctuation cannot be suppressed.

  An object of the present invention is to provide a plant and a boiling water nuclear power plant with piping having valve stems that can suppress the occurrence of hydroacoustic resonance with a simple configuration regardless of the flow velocity of gas flowing in the piping. Is to provide.

A feature of the present invention that achieves the above-described object is that, in a plant having a pipe nozzle to which a valve is attached and a pipe through which steam flows, the valve nozzle is connected to the pipe inside. There is a sound wave attenuating chamber formed outside the flow path, and a partition wall that partitions the internal space of the sound wave attenuating chamber and the flow path is provided in the valve nozzle, and the flow path communicates with the internal space. A through hole is formed in the partition ,
A plurality of through holes are formed in the partition wall in the circumferential direction of the valve stem,
There exists in the mutually different space | interval in the circumferential direction of a valve nozzle of the some through-hole formed in the partition .

A partition wall that partitions the internal space of the sound wave attenuation chamber and the flow path in the valve stem is provided in the valve stem, and a through hole that communicates the flow path and the internal space is formed in the partition wall. When the sound wave generated at the joint portion is propagated from the flow path to the internal space and from the internal space to the flow path, the sound wave passes through the through-hole formed in the partition wall. For this reason, it is possible to generate more sound wave components having a phase difference between each other, and a plurality of sound wave components having a phase difference between the vortices generated at the upstream end of the joint between the pipe and the valve stem. Therefore, the generation of hydroacoustic resonance can be remarkably suppressed regardless of the flow velocity of the gas flowing in the pipe. Therefore, as described above, the hydroacoustic resonance is achieved with a simple configuration in which the internal space of the sound wave attenuation chamber and the flow path in the valve stem are partitioned by a partition wall formed with a through hole that communicates the internal space and the flow path. Can be remarkably suppressed. In addition, since the plurality of through holes formed in the partition wall have different intervals in the circumferential direction of the valve stem, each of the through holes formed in the partition wall is surrounded by the partition wall and connected to the pipe. Each component of the sound wave propagated to the internal space of the sound wave attenuation chamber through the through hole has a different propagation distance in the internal space and returns to the flow path surrounded by the partition wall with a phase difference between the components. As a result, the generation of the hydroacoustic resonance is further suppressed.

  According to the present invention, generation of hydroacoustic resonance can be suppressed with a simple configuration regardless of the flow velocity of the gas flowing in the pipe.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an enlarged longitudinal sectional view of a vicinity of a valve stem of a boiling water nuclear power plant provided with a pipe having a valve stem of Example 1 which is a preferred embodiment of the present invention. It is II-II sectional drawing of FIG. It is a block diagram of the boiling water nuclear power plant provided with piping which has a valve stem of Example 1. FIG. It is a characteristic view which shows the relationship between the pressure fluctuation which generate | occur | produces in the valve nozzle which attaches a steam relief safety valve shown in FIG. 1, and a straw hull number. It is a characteristic view which shows the time change of the pressure fluctuation which generate | occur | produces in the valve nozzle which attaches a steam relief safety valve shown in FIG. It is a characteristic view which shows the relationship between the pressure fluctuation and the Strouhal number which generate | occur | produce in the valve nozzle which installs the steam relief safety valve provided in the main steam piping of the conventional boiling water nuclear power plant. It is a characteristic view which shows the time change of the pressure fluctuation which generate | occur | produces in the valve nozzle which attaches the steam relief safety valve provided in the main steam piping of the conventional boiling water nuclear power plant. It is an expanded longitudinal cross-sectional view of the vicinity of the valve nozzle of a boiling water nuclear power plant provided with piping which has the valve nozzle of Example 2 which is another Example of this invention. It is an expanded longitudinal cross-sectional view of the vicinity of the valve stem of the boiling water nuclear power plant provided with piping which has the valve stem of Example 3 which is another Example of this invention. It is an expanded longitudinal cross-sectional view of the vicinity of the valve nozzle of the boiling water nuclear power plant provided with piping which has the valve nozzle of Example 4 which is another Example of this invention. It is XI-XI sectional drawing of FIG. It is XII-XII sectional drawing of FIG. It is an expanded longitudinal cross-sectional view of the vicinity of the valve nozzle of the boiling water nuclear power plant provided with piping which has the valve nozzle of Example 5 which is another Example of this invention. It is XVI-XVI sectional drawing of FIG. It is an expanded longitudinal cross-sectional view of the vicinity of the valve nozzle of a boiling water nuclear power plant provided with piping which has the valve nozzle of Example 6 which is another Example of this invention. It is XVIII-XVIII sectional drawing of FIG. It is an expanded longitudinal cross-sectional view of the vicinity of the valve stem of the conventional boiling water nuclear power plant provided with piping which has a valve stem.

  FIG. 17 shows the details of the mechanism of hydroacoustic resonance that occurs in the valve stem that is attached to the steam relief valve provided in the main steam pipe of the BWR plant. The main steam pipe in which the main steam 28 flows is shown in FIG. The valve nozzle 13F to which the steam relief safety valve 21 provided in 11 is attached will be described in detail. The steam 28 discharged from the reactor pressure vessel and flowing in the main steam pipe 11 is an upstream end (upstream edge) 25 of the joint portion between the main steam pipe 11 and the straight pipe portion 14B of the valve stem 13F. The flow is separated and a vortex is generated. The vortex flows downstream with the steam 4 and collides with the downstream end (downstream edge) 26 of the joint between the main steam pipe 11 and the straight pipe portion 14B. A sound wave is generated when the generated vortex collides with the downstream end portion 26. The sound wave propagates through the flow path 27 formed in the valve nozzle 13F, and is reflected by the valve body 24 of the steam relief safety valve 21 that closes the valve nozzle 13F. The flow path 27 is connected to a steam flow path through which the steam 28 in the main steam pipe 11 flows. The sound wave reflected by the valve body 24 reaches the upstream end 25 of the joint between the main steam pipe 11 and the straight pipe portion 14B. The sound wave that has reached the upstream end 25 serves to strengthen the vortex generated at the upstream end 25.

The wavelength of the sound wave thus generated is formed in the length L (the joint portion between the main steam pipe 11 and the valve stem 2 to which the steam relief safety valve 21 is attached, and the valve stem 13F. Is generated at the downstream end 26 of the joint between the main steam pipe 11 and the valve nozzle 13F when it becomes equal to about four times the shortest distance between the valve body 24 and the valve body 24 closing the flow path 27. The standing wave of ¼ wavelength is formed in the flow path 27 of the valve nozzle 13F by the interference between the sound wave to be generated and the sound wave reflected by the valve body 24 that closes the valve nozzle 13F, and is formed in the main steam pipe 11. As a result, a larger pressure fluctuation occurs than a pressure fluctuation that normally occurs. The above is the generation mechanism of the hydroacoustic resonance at the joint of the main steam pipe 11 of the valve stem 13F of the steam relief safety valve 21.
The strength of the hydrodynamic resonance is a straw defined by the inner diameter d of the valve nozzle 13F, the resonance frequency f of the flow path 27 composed of the valve nozzle 13F and the steam relief safety valve 21, and the average flow velocity U of the main steam 28. When the Hull number St is arranged and the Straw Hull number St falls within the range of 0.3 to 0.6, the hydroacoustic resonance becomes strong (see FIG. 6).

  When the flow rate of the steam 28 flowing in the main steam pipe 11 is excessively increased, it is generated based on the hydroacoustic resonance generated at the downstream end portion 26 of the joint portion of the main steam pipe 11 and the valve stem 13F. The pressure fluctuation is a fluctuation close to a sine wave having a characteristic frequency (see FIG. 7). It is important to suppress such pressure fluctuations in order to maintain the soundness of the equipment of the BWR plant.

  The inventors diligently studied measures for suppressing pressure fluctuations caused by hydroacoustic resonance generated at the junction between the main steam pipe and the valve stem.

  The inventors conducted an experiment in which a valve nozzle having an enlarged cylinder described in JP-A-53-86997 was installed in a pipe and air was allowed to flow through the pipe to confirm the function of the enlarged cylinder. . In the valve stem with the enlarged cylinder, the energy of the sound wave is reduced by expanding and contracting the sound wave front by the enlarged cylinder, and vortex is generated at the leading edge (upstream end) of the junction between the valve nozzle and the main steam pipe. It is possible to suppress hydroacoustic resonance by weakening. However, in the case of using the valve stem having an enlarged cylinder described in JP-A-53-86997, sound waves generated at the rear edge of the branch pipe follow the enlarged cylinder in the inner space of the enlarged cylinder. The existence of a new acoustic mode was confirmed that propagated and reflected to the valve body via the propagation path and reached the joint between the valve stem and the pipe. The resonance frequency f 'of the acoustic mode passing through the internal space of the expansion cylinder is smaller than the frequency f. For this reason, as described above, when the gas flows in the pipe at a flow velocity U 'lower than U, the Strouhal number falls within the range of 0.3 to 0.6, and hydroacoustic resonance occurs. An increase in pressure fluctuation due to the generation of such hydroacoustic resonance was confirmed in the inventors' experiments.

  Therefore, the inventors can suppress the occurrence of hydroacoustic resonance at the joint between the valve stem and the gas flow pipe, regardless of the flow velocity of the gas flowing in the pipe provided with the valve stem. We examined the structure of the plant with a pipe with a base, especially the valve base. As a result, the inventors provided a sound wave attenuation chamber disposed outside the flow path formed in the valve nozzle and connected to the pipe in the valve nozzle installed in the pipe through which the gas flows. A partition wall that partitions the internal space of the attenuation chamber and the flow path is provided in the valve nozzle, and a plurality of through holes (through flow paths) that communicate the flow path and the internal space (for example, the through holes 18, 19, It was found that by forming 20) on the partition wall, the occurrence of hydroacoustic resonance at the joint between the valve stem and the pipe can be suppressed regardless of the flow velocity of the gas flowing in the pipe.

  A part of the sound wave generated by the hydroacoustic resonance generated at the joint between the valve nozzle and the pipe propagates through the flow path in the valve nozzle and passes through the plurality of through holes formed in the partition wall. It enters the internal space, is reflected by the inner surface of the sound wave attenuation chamber in the internal space, passes through the plurality of through holes, passes through the flow path in the valve base, and reaches the joint between the valve base and the pipe. In the valve stem having such a structure, the sound wave is reflected by the inner surface of the sound wave attenuation chamber as in the case of the enlarged cylinder described in JP-A-53-86997, thereby reducing the energy of the sound wave. In the valve stem having such a structure, the sound wave passes through the plurality of through holes formed in the partition wall when entering the internal space of the sound wave attenuation chamber and when going outside the internal space of the sound wave attenuation chamber. The energy of the sound wave is reduced by the fluid viscosity (expansion / contraction of the sound wave surface) generated when the sound wave passes through the plurality of through holes. Also, since the sound wave enters and leaves the sound wave attenuation chamber through a plurality of through holes, that is, a plurality of paths having different lengths, the energy of the sound wave is dispersed into a plurality of frequencies, and the individual frequencies are dispersed. The energy of each sound wave component is reduced.

  By dividing the flow path in the valve nozzle and the internal space of the sound attenuation chamber by a partition wall having a through hole, the fluid viscosity due to the through hole when the sound wave enters and exits the internal space, and the sound wave by the inner surface of the sound attenuation chamber The energy of the sound wave can be reduced by the reflection. In addition, since the energy of the sound wave is dispersed to a plurality of frequencies by the plurality of through holes, even if the sound wave having a certain frequency reaches the upstream end 25 and strengthens the vortex, the sound wave having a different frequency is upstream. Since the vortex is disturbed and collapsed one after another, the vortex reaching the downstream end 26 that causes the hydroacoustic resonance is reduced, resulting in the occurrence of the hydroacoustic resonance. Is suppressed. Therefore, by dividing the flow path in the valve nozzle and the internal space of the sound wave attenuation chamber by a partition wall having a plurality of through holes, the valve nozzle and the pipe can be connected regardless of the flow velocity of the gas flowing in the pipe. Generation of hydroacoustic resonance at the joint can be significantly suppressed.

  Examples of the present invention obtained in consideration of the above examination results will be described below.

  A plant including a pipe having a valve nozzle according to the first embodiment which is a preferred embodiment of the present embodiment will be described with reference to FIGS. 1, 2, and 3. A plant provided with piping having the valve nozzle of the present embodiment is a BWR plant 1. The BWR plant 1 includes a nuclear reactor 2, a main steam pipe 11, a turbine 12, a condenser (not shown), and a water supply pipe.

  The reactor 2 has a reactor pressure vessel (hereinafter referred to as RPV) 3 and a core disposed in the RPV 3. A large number of fuel assemblies (not shown) are loaded in the core. A removable lid 4 is attached to the RPV 3. In the RPV 3, a steam / water separator (not shown) is installed above the core, and a steam dryer 5 having a corrugated plate 6 is installed above the steam / water separator. The main steam pipe 11 is connected to a nozzle 9 formed in the RPV 3 and communicates with a steam dome 7 formed in the RPV 3 above the steam dryer 5. A turbine 12 is connected to the main steam pipe 11. The valve stem 13 has a straight pipe portion 14 and a sound wave attenuation chamber 15, and the straight pipe portion 14 is connected to the main steam pipe 10, whereby the valve stem 13 is installed in the main steam pipe 10. A flow path 27 formed in the straight pipe portion 14 communicates with the main steam pipe 11. A steam relief valve 21 is attached to the end face of the valve stem 13. The steam relief safety valve 21 is provided with a valve body 24 in a valve casing 22, and the valve body 24 blocks the flow path 27 during normal operation of the BWR plant 1.

  A vent pipe (not shown) is connected to a flange 23 provided in the valve casing 22 of the steam relief safety valve 21. This vent pipe extends into a pressure suppression chamber (not shown) provided in a reactor containment vessel (not shown) containing the nuclear reactor 2, and the tip thereof is used as pool water in the pressure suppression chamber. Soaked.

  An annular sound attenuation chamber 15 surrounding the flow path 27 is provided on the outer surface of the annular side wall that defines the flow path 27 formed inside the valve stem 13, that is, the straight pipe portion 14. A valve stem 13, that is, a partition wall 17 that is a part of the side wall of the straight pipe portion 14 divides the flow path 27 and the internal space 16 formed in the sound wave attenuation chamber 15. The internal space 16 is an annular space surrounding the flow path 27. A plurality of through holes, that is, through holes 18, 19, and 20 are formed in the partition wall 17, and these through holes communicate the flow path 27 and the internal space 16. The through holes 18, 19 and 20 are arranged at different positions in the circumferential direction of the partition wall 17 (see FIG. 2). The inner diameters of the through holes 18, 19 and 20 are equal. These through holes are arranged in the circumferential direction of the partition wall 17 so as to have different intervals. For example, the distance between the through hole 18 and the through hole 19 in the circumferential direction is different from the distance between the through hole 18 and the through hole 20 in the circumferential direction.

  In the axial direction of the valve stem 13, the first surface of the internal space 16 on the main steam pipe 11 side and the second surface on the steam relief safety valve 21 side are both flat, and the through holes 18, 19 and 20 Each inner diameter is smaller than the dimension of the space between the first surface and the second surface of the internal space 16 in the axial direction of the valve nozzle 13. In the present embodiment, the through holes 18, 19, and 20 are disposed at a position that is ½ of the interval between the first surface and the second surface of the internal space 16 in the axial direction of the valve stem 13.

  By driving a recirculation pump (not shown), the cooling water in the RPV 3 is pressurized and ejected from a nozzle of a jet pump (not shown) installed in the RPV 3. By the jetted cooling water flow, the cooling water existing around the nozzle is sucked into the jet pump and discharged from the jet pump. The discharged cooling water is supplied to the core. This cooling water is heated by the heat generated by the nuclear fission of the nuclear fuel material in the fuel assembly while ascending the core, and a part thereof becomes steam 28. Water contained in the steam 28 is removed by the steam separator and the steam dryer 5. The steam 28 from which moisture has been removed is guided to the turbine 12 through the main steam pipe 11 and rotates the turbine 12. A generator (not shown) connected to the turbine 12 rotates to generate electric power. The steam 28 discharged from the turbine 12 is condensed into water by a condenser (not shown). This water is pressurized as a feed water by a feed water pump (not shown), and supplied into the RPV 3 through a feed water pipe (not shown). The reactor 2 of the BWR plant is a steam generator. The water separated by the steam dryer 5 is guided to a region formed between the steam-water separators below the steam dryer 5 through the drain pipe 8.

  If the pressure in the RPV 3 becomes higher than the set value, the valve body 24 of the steam relief safety valve 21 is automatically pushed up and the steam relief safety valve 21 is opened. The steam 28 in the RPV 3 passes through the main steam pipe 11, the flow path 27 in the nozzle 13 and the steam relief safety valve 21, is discharged into the pool water in the pressure suppression chamber through the vent pipe, and is condensed. Thereby, the pressure in the RPV 3 is suppressed to a set value or less, and the safety of the nuclear reactor 2 is ensured.

  In a normal operation state of the BWR plant 1, the steam 28 discharged from the RPV 3 flows through the main steam pipe 10. When the flow rate of the steam 28 flowing in the main steam pipe 11 increases excessively, at the upstream end (upstream edge) 25 of the joint portion between the main steam pipe 11 and the straight pipe portion 14 of the valve stem 13. Then, the flow of the vapor 28 is separated and a vortex is generated. The generated vortex flows along with the flow of the steam 28 toward the downstream in the main steam pipe 11 and collides with the downstream end (downstream edge) 26 of the joint portion between the main steam pipe 11 and the straight pipe section 14. To do. A sound wave is generated when the generated vortex collides with the downstream end portion 26.

  A part of the generated sound wave propagates in the flow path 27 toward the valve body 24 closing the flow path 27 formed in the straight pipe portion 14 and is reflected by the valve body 24. The sound wave reflected by the valve body 24 and reduced in energy propagates through the flow path 27 and reaches the upstream end 25. Further, the remaining sound wave generated at the downstream end 26 passes through the through holes 18, 19 and 20, reaches the internal space 16, and is reflected by the inner surface of the sound wave attenuation chamber 15 that defines the internal space 16. . This sound wave again passes through the through holes 18, 19 and 20, propagates in the flow path 27, and reaches the upstream end 25.

  The sound waves that have propagated through the flow path 27 and reached the through holes 18, 19, and 20 reach the through holes almost simultaneously. The sound wave propagates to the internal space 16 through each of the through holes 18, 19 and 20. Part of the energy of the sound wave is lost due to contraction and expansion of the wave surface of the sound wave (fluid viscosity at the through hole) when the sound wave passes through each of the through holes 18, 19 and 20. For example, a sound wave propagated through the through hole 18 into the internal space 16 is reflected by the wall surface of the internal space 16, and a part of the sound wave returns to the flow path 27 through the through hole 18 and passes through the through hole 18. The other components of the sound wave propagated into the internal space 16 propagate in the internal space 16 along the path 29 or 30, pass through the through holes 19 or 20, and return to the flow path 27. Of the sound waves that have passed through the through hole 18 and propagated into the internal space 16, the sound wave that has passed through the through hole 18 again returns to the flow path 27 in the shortest time, and then the sound wave that has passed through the through hole 20 Returning to 27, the sound wave that has finally passed through the through hole 19 returns to the flow path 27. Similarly, sound waves that have passed through each of the through holes 19 and 20 from the flow path 27 and reached the internal space 16 are also returned to the flow path 27 through the respective through holes 18, 19, and 20.

  Thus, each component of the sound wave propagated through the through holes 18, 19 and 20 into the internal space 16 passes through the through holes 18, 19 and 20, respectively, and has three frequencies. Breaks down into different components. Since these components have different propagation distances, they return to the flow path 27 with a phase difference. Each time the sound wave passes through each of the through holes 18, 19 and 20 when going from the flow path 27 to the internal space 16, and when passing from the internal space 16 to the flow path 27, each of the through holes 18, 19 and 20 Each time it passes through, the wavefront of the sound wave contracts and expands (due to the fluid viscosity of each of the through holes 18, 19 and 20), so that a part of the energy of the sound wave is lost.

  A part of each component of the sound wave having a phase difference mutually returned from the internal space 16 to the flow path 27 reaches the upstream end 25. The remainder of each component of the sound wave having a phase difference with each other returned from the internal space 16 to the flow path 27 is reflected by the valve body 24 and passes through each of the through holes 18, 19 and 20 again. Propagates to the internal space 16. With the same mechanism as the sound wave that has reached the internal space 16 described above, the components of the sound wave having a phase difference with each other further increase and pass through each of the through holes 18, 19, and 20 from the internal space 16. Returned to 27.

  In this embodiment provided with the valve stem 13 having a simple configuration having a partition wall 17 in which the flow path 27 and the internal space 16 are partitioned to form the through holes 18, 19 and 20, the through holes 18, 19 and 20 are respectively provided. Each component of the sound wave that has reached the upstream end 25 through various paths including the above is provided with a valve nozzle that does not have the partition wall 17 that partitions the flow path 27 and the internal space 16. In the 86997 publication, a considerable amount of energy is lost compared to each component of the sound wave that reaches the upstream end 25 of the joint between the valve stem having the enlarged cylinder and the pipe, and each component of the sound wave is larger than each other. Has a phase difference. For this reason, in this embodiment provided with the valve stem 13 having the partition wall 17 in which the through holes 18, 19 and 20 are formed, each component of more sound waves having different frequencies at different timings is sent to the upstream end 5. As a result, the vortex generated at the upstream end 5 is disturbed and collapsed by these sound wave components, and the vortex becomes considerably weaker than that of Japanese Patent Laid-Open No. 53-86997. As a result, the generation of vortices causing the hydroacoustic resonance is remarkably suppressed, and the occurrence of hydroacoustic resonance at the junction between the valve stem 13 and the main steam pipe 11 is remarkably suppressed.

  The relationship between the pressure fluctuation generated in the valve nozzle 13 used in this embodiment and the number of straw hulls is as shown in FIG. 4, and is generated by installing the conventional valve nozzle 13F shown in FIG. 17 on the main steam pipe 11. The increase in pressure fluctuation in the range where the Strouhal number St is in the range of 0.3 to 0.6 due to the hydroacoustic resonance performed does not occur in this embodiment. In addition, hydroacoustic resonance at different steam flow velocities (that is, different Strouhal numbers) generated by installing the Helmholtz resonance tube in the valve nozzle for installing the steam relief safety valve does not occur.

  In the present embodiment provided with the valve stem 13 having the partition wall 17 in which the flow path 27 and the internal space 16 are partitioned to form the through holes 18, 19, and 20, there is a phase difference due to the formation of the plurality of through holes. Since more sonic components can be generated, the pressure fluctuation (sound wave) generated by the hydroacoustic resonance generated at the joint between the valve stem 13 and the main steam pipe 11 is the conventional valve stem shown in FIG. Compared to the pressure fluctuation (see FIG. 7) generated by the installation of 13F on the main steam pipe 11, the waveform is disturbed as shown in FIG. 5, and the magnitude of the pressure fluctuation is also reduced.

  In the present embodiment, the valve nozzle 13 having the partition wall 17 having the through holes 18, 19 and 20 that partition the flow path 27 and the internal space 16 and communicate the flow path 27 and the internal space 16 is provided. When sound waves generated at the joint between the nozzle 13 and the main steam pipe 11 enter and leave the through holes, more sound wave components having a phase difference can be generated. For this reason, as described above, it is possible to weaken the generation of vortices at the upstream end that causes the hydroacoustic resonance, and the valve stem 13 regardless of the flow velocity of the steam 28 flowing in the main steam pipe 11. The generation of hydroacoustic resonance at the junction between the main steam pipe 11 and the main steam pipe 11 can be suppressed. As the number of through holes formed in the partition wall 17 is increased, a larger number of sound wave components having different frequencies can be generated, and the generation of vortices at the upstream end 25 can be further suppressed. This embodiment can suppress the occurrence of hydroacoustic resonance at the junction between the valve stem 13 and the main steam pipe 11 regardless of the flow velocity of the steam flowing in the main steam pipe 11.

  The plant provided with piping which has a valve nozzle of Example 2 which is another Example of a present Example is demonstrated using FIG. The plant provided with piping having the valve nozzle of the present embodiment is also a BWR plant. The BWR plant of the present embodiment has a configuration in which the valve nozzle 13 is replaced with the valve nozzle 13A in the BWR plant 1 of the first embodiment. Other configurations of the BWR plant of the present embodiment are the same as those of the BWR plant 1. The valve nozzle 13A used in the present embodiment is similar to the valve nozzle 13 used in the first embodiment in that the through holes 18, 19 and 20 formed in the partition wall 17 are separated from the partition wall 17 in the axial direction of the valve nozzle 13A. The upper end portion (the end portion of the partition wall 17 on the steam relief safety valve 21 side) is arranged. The other structure of the valve nozzle 13A is the same as that of the valve nozzle 13.

  In the present embodiment, each effect produced in the first embodiment can be obtained. In the first embodiment, the non-condensable gas contained in the main steam flowing in the main steam pipe 11 flows into the internal space 16 through the through holes 18, 19 and 20, and the partition wall 17 exists, so May stay. Since non-condensable gas is lighter than steam, it stays in the upper part of the internal space 16. In this embodiment, since the through holes 18, 19 and 20 formed in the partition wall 17 are present at the upper end of the partition wall 17, even if non-condensable gas flows into the internal space 16, the through holes 18, 19 and 20 This non-condensed gas can be easily discharged to the flow path 27 through 20. The amount of non-condensable gas remaining in the internal space 16 can be reduced.

  The plant provided with piping which has a valve nozzle of Example 3 which is another Example of a present Example is demonstrated using FIG. The plant provided with piping having the valve nozzle of the present embodiment is also a BWR plant. The BWR plant of the present embodiment has a configuration in which the valve nozzle 13 is replaced with the valve nozzle 13B in the BWR plant 1 of the first embodiment. Other configurations of the BWR plant of the present embodiment are the same as those of the BWR plant 1. The valve stem 13B used in the present embodiment is similar to the valve stem 13 used in the first embodiment except that the through holes 18, 19 and 20 formed in the partition wall 17 are connected to the lower end portion of the partition wall 17 (the main steam of the partition wall 17). It has the structure arrange | positioned at the edge part of the piping 11 side. The other structure of the valve nozzle 13B is the same as the valve nozzle 13.

  In the present embodiment, each effect produced in the first embodiment can be obtained. When the main steam flowing through the main steam pipe 11 flows into the internal space 16 through the through holes 18, 19 and 20, it is condensed to generate condensed water, and the generated condensed water can be accumulated in the internal space 16. There is sex. In this embodiment, since the through holes 18, 19 and 20 formed in the partition wall 17 exist at the lower end of the partition wall 17, even if condensed water accumulates in the internal space 16, this condensed water is passed through the through hole 18. , 19 and 20 can be easily discharged to the flow path 27.

  A plant including a pipe having a valve nozzle according to the fourth embodiment which is another embodiment of the present embodiment will be described with reference to FIGS. 10, 11, and 12. The plant provided with piping having the valve nozzle of the present embodiment is also a BWR plant. The BWR plant of the present embodiment has a configuration in which the valve nozzle 13 is replaced with the valve nozzle 13C in the BWR plant 1 of the first embodiment. Other configurations of the BWR plant of the present embodiment are the same as those of the BWR plant 1. The valve stem 13C used in the present embodiment is similar to the valve stem 13 used in the first embodiment in that the through holes 18, 19 and 20 formed in the partition wall 17 are separated from the partition wall 17 in the axial direction of the valve stem 13C. The upper end portion (the end portion of the partition wall 17 on the steam relief safety valve 21 side) (see the XII-XII cross section of FIG. 10). Furthermore, the valve stem 13C has other through holes 18, 19 and 20 arranged in the axial direction of the valve stem 13C at the lower end of the partition wall 17 (the end of the partition wall 17 on the main steam pipe 11 side) (in FIG. 10). XI-XI cross section). The other configuration of the valve nozzle 13C is the same as that of the valve nozzle 13.

  In the present embodiment, each effect produced in the second embodiment can be obtained, and even if condensed water accumulates in the internal space 16, the condensed water is easily discharged to the flow path 27 through the through holes 18, 19 and 20. can do. In this embodiment, since the number of through holes formed in the partition wall 17 is larger than that in the first embodiment, more sound wave components having different frequencies are generated than in the first embodiment. Since the vortex generated at the upstream end 25 is more disturbed, the generation of acoustic resonance is largely suppressed.

  A plant including a pipe having a valve stem in Example 5 which is another example of this example will be described with reference to FIGS. 13 and 14. The plant provided with piping having the valve nozzle of the present embodiment is also a BWR plant. The BWR plant of the present embodiment has a configuration in which the valve stem 13 is replaced with the valve stem 13E in the BWR plant 1 of the first embodiment. Other configurations of the BWR plant of the present embodiment are the same as those of the BWR plant 1. The valve nozzle 13E used in the present embodiment has a configuration in which the sound attenuation chamber 15 is replaced with the sound attenuation chamber 15A in the valve nozzle 13 used in the first embodiment. The valve stem 13E includes a straight pipe portion 14A and a sound wave attenuation chamber 15A. The straight pipe portion 14 </ b> A that forms the flow path 27 inside is joined to the main steam pipe 11, and the flow path 27 is connected to the main steam pipe 11. The cross-sectional area of the sound attenuation chamber 15A in the direction perpendicular to the axis of the valve stem is only half that of the sound attenuation chamber 15. The sound wave attenuation chamber 15A surrounds only 1/2 of the circumferential length of the outer surface of the straight pipe portion 14A. The partition wall 17 that is a part of the side wall of the straight pipe portion 14A is formed with through holes 18 and 19 that communicate the flow path 27 and the internal space 16 in the sound wave attenuation chamber 15A. The through holes 18 and 19 are arranged at a position that is half the distance between the first surface and the second surface of the internal space 16 in the axial direction of the valve stem 13E.

  In the present embodiment, each effect produced in the first embodiment can be obtained. In this embodiment, since the sound wave attenuation chamber 15A is smaller than the sound wave attenuation chamber 15 of the first embodiment, the valve nozzle 13E can be downsized.

  A plant including a pipe having a valve nozzle in Example 6 which is another example of this example will be described with reference to FIGS. 15 and 16. The plant provided with piping having the valve nozzle of the present embodiment is also a BWR plant. The BWR plant of the present embodiment has a configuration in which, in the BWR plant 1 of the first embodiment, the valve nozzle 13 is replaced with the valve nozzle 13F, and the steam relief safety valve 21 is replaced with the steam relief safety valve 21A. Other configurations of the BWR plant of the present embodiment are the same as those of the BWR plant 1. The valve nozzle 13F used in the present embodiment has the same configuration as the valve nozzle 13F used in the conventional BWR plant shown in FIG. The sound wave attenuation chamber 15 is provided in the steam relief safety valve 21A.

  The sound wave attenuation chamber 15 is provided at the lower end portion of the valve casing 22 of the steam release safety valve 21 </ b> A and surrounds the flow path formed in the valve casing 22 and connected to the flow path 27. A partition wall 17 is formed in the internal space 16 formed in the sound wave attenuation chamber 15 and the valve casing 22 to partition the flow path, and penetrates through the flow path formed in the internal space 16 and the valve casing 22. Holes 18, 19 and 29 are formed in the partition wall 17.

  A valve provided with a steam relief safety valve 21A having a partition wall 17 in which through holes 18, 19 and 20 are formed by partitioning the flow path formed in the valve casing 22 and the internal space 16 and communicating the flow path with the internal space 16. In the present embodiment having the nozzle 13F, each effect produced in the first embodiment can be obtained.

  Each of the embodiments described above includes a pressurized water nuclear plant having a steam pipe connecting the steam generator (steam generator) and the turbine, a thermal power plant having a steam pipe connecting the boiler (steam generator) and the turbine, and the like. It can apply to the plant provided with piping which has a valve stem of this and a gas (steam, air, etc.) flows.

  DESCRIPTION OF SYMBOLS 1 ... Boiling water type nuclear power plant (BWR plant), 2 ... Reactor, 3 ... Reactor pressure vessel, 5 ... Steam dryer, 11 ... Main steam piping, 12 ... Turbine, 13, 13A-13C, 13E, 13F ... Valve base, 14, 14A ... straight pipe portion, 15, 15A ... sound wave attenuation chamber, 16 ... internal space, 17 ... partition wall, 18, 19, 20 ... through hole, 21 ... main steam relief safety valve, 22 ... valve casing, 24 ... valve body, 25 ... upstream end, 26 ... downstream end, 27 ... flow path.

Claims (8)

In a plant equipped with a pipe nozzle to which a valve is attached and a pipe through which steam flows, the valve nozzle forms a flow path communicating with the pipe inside and is arranged outside the flow path. A partition wall that divides the internal space of the sound wave attenuation chamber and the flow path is provided in the valve stem, and a through hole that communicates the flow path and the internal space is formed in the partition wall. ,
A plurality of the through holes are formed in the partition wall in the circumferential direction of the valve stem,
A plant comprising a pipe having a valve nozzle, wherein the plurality of through holes formed in the partition wall have different intervals in the circumferential direction of the valve nozzle. The plant comprising a pipe having a valve nozzle according to claim 1, wherein the partition wall is a part of a side wall of the valve nozzle. The pipe having the valve nozzle according to claim 1 or 2 , wherein the through-hole is formed in at least one end of the valve-side end of the partition and the pipe-side end of the partition. Plant. The said plant is a nuclear power plant, The plant provided with piping which has a valve nozzle in any one of Claim 1 thru | or 3 . The said plant is a thermal power plant, The plant provided with piping which has the valve nozzle of any one of Claim 1 thru | or 3 . A reactor and a steam pipe connected to the reactor for guiding the steam generated in the reactor and having a valve nozzle to which a steam relief valve is attached;
The valve nozzle forms a flow path communicating with the steam pipe inside, and has a sound wave attenuation chamber disposed outside the flow path, and partitions the internal space of the sound wave attenuation chamber from the flow path. A partition wall is provided in the valve stem, and a through hole communicating with the flow path and the internal space is formed in the partition wall,
A plurality of the through holes are formed in the partition wall in the circumferential direction of the valve stem,
A boiling water nuclear plant characterized in that the plurality of through holes formed in the partition walls have different intervals in the circumferential direction of the valve stem. The boiling water nuclear plant according to claim 6 , wherein the partition wall is a part of a side wall of the valve stem. The boiling water nuclear power plant according to claim 6 or 7 , wherein the through hole is formed in at least one end of an end of the partition on the steam relief safety valve side and an end of the partition on the piping side.

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