Steam-water separator and boiling water reactor equipped therewith

Abstract

To provide: a steam separator capable, by using a simple structure, of decreasing the amount of droplets accompanying steam within an annular flow passage in a second or subsequent stage from the bottom of the steam separator having multiple stages of separating mechanisms, and reduce the carry-over under a condition of high quality; and a boiling water reactor including the same.SOLUTION: In a steam separator 105 including multiple stages of separating mechanisms, a separating mechanism in a second or subsequent stage includes vertical plates 21, 31 that divide a second-stage annular flow passage 132 / third-stage annular flow passage 138 in a circumferential direction, and that eliminate a swirl component of a mixed flow continuously occurring from a second-stage inner cylinder 129 / third-stage inner cylinder 135 to the second-stage annular flow passage 132 / third-stage annular flow passage 138.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a steam-water separator and a boiling water reactor provided with the same, and in particular, to a steam-water separator disposed above a reactor core for separating a mixed fluid of steam and water generated in the reactor core into steam and water, and a boiling water reactor provided with the same.

Background Art

[0002] As an example of a steam-liquid separator and a boiling water reactor equipped therewith that can reduce the appropriate amount of liquid entrained with steam outside the steam separator using a simple structure, while suppressing an increase in steam airflow resistance and reducing carryover under high-quality conditions, Patent Document 1 describes a standpipe that guides a two-phase gas-liquid flow from below upward, a diffuser that communicates with the upper end face of the standpipe to form a flow path and expands the flow path cross-sectional area upward from the flow path cross-sectional area of ​​the upper end face, and a first that communicates with the upper end face of the diffuser to form a flow path A stepped inner cylinder, a first-stage outer cylinder surrounding the first-stage inner cylinder at concentric intervals to form an annular flow path, a first-stage annular plate closing the inner peripheral edge of the upper end face of the first-stage outer cylinder and forming a circular hole smaller in diameter than the first-stage inner cylinder, a first-stage pick-off ring rising cylindrically downward from the inner peripheral edge forming the circular hole of the first-stage annular plate to form a circular hole as a flow path to the second-stage inner cylinder, a second-stage inner cylinder installed on the first-stage annular plate and forming a flow path, a second-stage outer cylinder surrounding the second-stage inner cylinder at concentric intervals to form an annular second-stage discharge flow path, and the upper side of the second-stage outer cylinder The diffuser comprises at least a second-stage annular plate that closes the inner periphery of its end face and has a circular hole smaller in diameter than the second-stage inner cylinder, a third-stage inner cylinder installed on the second-stage annular plate and forming a flow path, and a second-stage pick-off ring that rises cylindrically downward from the inner periphery of the second-stage annular plate that forms the circular hole and forms the circular hole as a flow path to the third-stage inner cylinder, and includes a hub that passes through the axial center of the gas-liquid two-phase flow path and a plurality of swirl vanes attached radially around the hub, the inner edges of the swirl vanes being fixed to the hub in the radial direction, and swirls against the inner wall of the diffuser or the inner wall of the first-stage inner cylinder. In a steam-water separator equipped with a swirler whose outer edge is fixed in the radial direction of the rotating blades, the second stage outer cylinder is provided with a second stage separated water outlet for discharging water that has flowed into the second stage discharge channel and a second stage steam outlet for discharging steam, and the second stage steam outlet is positioned higher than the second stage separated water outlet, and a projection is provided along the edge of the second stage steam outlet that protrudes into the second stage discharge channel, and the tip of the projection is bent in a direction that does not block the flow path of the second stage steam outlet so as to form a groove-shaped flow path between it and the second stage outer cylinder. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 5562908 [Overview of the project] [Problems that the invention aims to solve]

[0004] In a typical boiling water reactor, multiple steam-water separators are installed above the core to separate the steam-water mixture generated in the core into steam and water. In these separators, a swirling motion is imparted to the steam-water mixture by a swirling vane in the diffuser, and the difference in vapor-liquid density due to centrifugal force is used to separate the steam and water.

[0005] The separated water flows down the annular channel between the inner and outer cylinders of the steam-water separator, drains out the outlet at the bottom of the outer cylinder, returns to the down boiler, and is then sent back to the reactor core by a recirculation pump. Meanwhile, the separated steam is discharged out of the steam-water separator through the central channel, flows into the steam dryer where moisture is removed, and then sent to the turbine. In this way, as much moisture as possible is removed from the steam generated in the reactor core, resulting in efficient power generation.

[0006] Furthermore, one effective way to achieve efficient power generation is to increase the amount of steam generated by increasing the ratio of the steam flow rate to the total flow rate of steam and water at the core outlet (hereinafter referred to as quality).

[0007] When the quality of the mixed fluid of steam and water flowing into the steam-water separator changes, the steam-water separation performance also changes. Generally, as the quality improves and the amount of steam generated increases, the swirling speed imparted to the two-phase flow by the swirler increases, the centrifugal force increases, and the steam-water separation performance improves.

[0008] Here, as an example, we will describe the three-stage steam-liquid separator used in the Advanced Boiling Water Reactor (ABWR).

[0009] In the steam-water separator used in ABWRs, separated water with almost no steam contamination is discharged from a downward-facing outlet in the annular flow path between the first-stage inner cylinder and the first-stage outer cylinder. Separate water and steam are discharged from outlets located below the second and third-stage outer cylinders from the bottom of the steam-water separator.

[0010] Here, when the amount of steam generated increases at the core outlet, that is, when the steam flow rate at the steam-water separator inlet increases, the steam flow rate, and thus the steam velocity, that flows into the annular flow path separated by the pick-off rings from the second and third inner cylinders from the bottom of the steam-water separator increases.

[0011] The water separated by the second and third pick-off rings from the bottom of the steam-water separator flows down the annular channel as a liquid film or as droplets along the outer surface of the inner and outer cylinders, and is discharged from the outlet along with the steam. As the steam velocity increases, the steam creates waves on the surface of the flowing liquid film, and the droplets formed by tearing off the tips of these waves are carried along and discharged from the outlet, rising through the narrow channels between multiple steam-water separators, and potentially flowing into the steam dryer as steam with a high moisture content.

[0012] Patent Document 1 describes installing an L-shaped structure along the edge of the steam outlet as a means to prevent the liquid film flowing down within the annular flow path between the inner and outer cylinders of the second and third stages from the bottom of these steam-water separators from being carried along with the steam.

[0013] However, in Patent Document 1, which employs the above-mentioned L-shaped structure, the L-shaped structure must be installed in the narrow annular flow path between the inner and outer cylinders of the second and third stages from the bottom of a steam-water separator having multiple separation mechanisms, so there is room to improve workability. On the other hand, it is necessary to ensure a gap for steam to flow where the L-shaped structure is installed, but there is a concern that the steam velocity will increase if the gap is too narrow.

[0014] Furthermore, in a gas-water separator with multiple separation mechanisms, the water and steam separated by the pick-off ring in the second and third inner cylinders from the bottom exist in a churn flow or annular spray flow state within the annular flow path after passing through the pick-off ring, with a large amount of liquid droplets present in the steam.

[0015] Furthermore, as the vapor velocity increases, it is a concern that the surface of the liquid film flowing down the annular channel will become wavy, and the leading edges of these waves will tear off to form droplets, increasing the number of droplets carried along with the vapor.

[0016] The present invention has been made in view of the above-mentioned points, and its object is to provide a steam-water separator and a boiling water reactor equipped therewith that can reduce the amount of droplets accompanying the steam in the annular flow path from the second stage onward from the bottom of a steam-water separator having a multi-stage separation mechanism using a simple structure, thereby reducing carryover under high-quality conditions. [Means for solving the problem]

[0017] The present invention includes multiple means for solving the above problems, but to give one example, a steam-water separator equipped with a multi-stage separation mechanism, the first stage separation mechanism from the bottom includes a standpipe that guides a mixed fluid of steam and water generated in the reactor core from bottom to top, a diffuser that communicates with the upper end face of the standpipe and forms a flow path, and expands the flow path cross-sectional area upward from the flow path cross-sectional area of ​​the upper end face, a first-stage inner cylinder that communicates with the upper end face of the diffuser and forms a flow path, a hub that passes through the axial center of the flow path of the mixed flow of steam and water and a plurality of swirl vanes that are attached radially around the hub, the inner edge of the swirl vanes being fixed to the hub in the radial direction, and the outer edge being fixed to the inner wall of the diffuser or the inner wall of the first-stage inner cylinder in the radial direction of the swirl vanes, a first-stage outer cylinder that forms a first-stage outlet below the first-stage annular flow path that is formed by concentrically surrounding the first-stage inner cylinder at intervals, and a swara that closes the upper side surface of the first-stage outer cylinder and has a smaller diameter than the first-stage inner cylinder The separation mechanism comprises a first-stage annular plate with a circular hole formed therein, a first-stage pick-off ring that extends cylindrically downward from the inner peripheral edge of the first-stage annular plate forming the circular hole and forms the circular hole as a short flow path to the second-stage inner cylinder, and the second-stage and subsequent stages of the separation mechanism from the bottom consist of a second-stage and subsequent inner cylinder installed on the preceding annular plate and forming a flow path, a second-stage and subsequent outer cylinder that forms a second-stage and subsequent discharge port below the second-stage and subsequent annular flow path formed by concentrically surrounding the second-stage and subsequent inner cylinders at intervals, and the upper side of the second-stage and subsequent outer cylinders The separation mechanism for the second and subsequent stages includes a second and subsequent annular plate that seals the opening and has a circular hole smaller in diameter than the second and subsequent inner cylinders, a second and subsequent pick-off ring that extends cylindrically downward from the inner peripheral edge of the second and subsequent annular plate that forms the circular hole, forming the circular hole as a short passage or outlet passage to the next and subsequent inner cylinders, and a vertical plate that divides the second and subsequent annular passages in the circumferential direction and eliminates the swirling component of the mixed flow that continues to flow from the second and subsequent inner cylinders to the second and subsequent annular passages. Furthermore, a drainage channel forming plate shorter in length than the vertical plate is placed in a position directly opposite the surface of the vertical plate to which the mixed flow collides, to have do . [Effects of the Invention]

[0018] According to the present invention, with a simple structure, the amount of liquid droplets entrained in steam in the annular flow passages from the second stage onward from the bottom of the steam-water separator having a multi-stage separation mechanism can be reduced, and carry-over under high-quality conditions can be reduced. Problems, configurations and effects other than those described above will be clarified by the following description of examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] [Figure 1] It is a longitudinal sectional view showing a schematic structure of a boiling water nuclear reactor to which the steam-water separator of the present invention is applied. [Figure 2] It is a longitudinal sectional view showing the steam-water separator of Example 1, which is a view taken along line A-A of Fig. 3 described later. [Figure 3] It is a horizontal sectional view showing a plurality of steam-water separators of Example 1. [Figure 4] It is a longitudinal sectional view showing the portion above the second stage of the steam-water separator of Example 1. [Figure 5] It is a horizontal sectional view showing the steam-water separator of Example 1, which is a view taken along line B-B of Fig. 4. [Figure 6] It is a detailed view of portion D in Fig. 5 of the horizontal sectional view showing the steam-water separator of Example 1. [Figure 7] It is a developed view of the second or third stage of the steam-water separator of Example 1 as viewed from the outer surface of the inner cylinder toward the outer peripheral side. [Figure 8] It is a detailed view of portion C in Fig. 4 of the discharge port of the steam-water separator of Example 1. [Figure 9] It is a view showing a state where the vertical plate of the steam-water separator of Example 1 is installed on the inner surface of the outer cylinder of the second stage. [Figure 10] It is a view showing a state where the vertical plate of the steam-water separator of Example 1 is installed on the outer surface of the inner cylinder of the second stage. [Figure 11] It is a horizontal sectional view showing a modified example of the steam-water separator of Example 1. [Figure 12] It is a detailed view of portion E in Fig. 11 of the horizontal sectional view showing a modified example of the steam-water separator of Example 1. [Figure 13] It is a longitudinal sectional view showing the steam-water separator of Example 2. [Figure 14]This is a horizontal cross-section of the gas-liquid separator in Example 2, viewed from the FF arrow in Figure 13. [Figure 15] This is a horizontal cross-section showing the gas-liquid separator of Example 2, viewed from the direction of arrow GG in Figure 13. [Figure 16] This is an exploded view of the second or third stage of the gas-liquid separator in Example 2, as seen from the outer surface of the inner cylinder towards the outer circumference. [Figure 17] This is an enlarged view of section H in Figure 13, showing the details of the discharge port of the gas-liquid separator in Example 2. [Figure 18] This is a detailed diagram of the swirling flow within the second annular channel of the gas-liquid separator in Example 2. [Figure 19] This is a detailed diagram of the swirling flow in the third annular channel of the gas-liquid separator in Example 2. [Figure 20] This is a horizontal cross-sectional view showing a modified example 1 of the gas-liquid separator of Example 2. [Figure 21] This is an exploded view of the second or third stage inner cylinder as seen from the outer surface towards the outer circumference, showing a modified example 1 of the gas-liquid separator of Example 2. [Figure 22] This is a longitudinal cross-sectional view showing a modified example 2 of the gas-liquid separator of Example 2. [Figure 23] This is an exploded view showing a modified example 2 of the gas-liquid separator of Example 2, viewed from the outer surface of the inner cylinder to the inner surface of the outer cylinder of the second stage. [Figure 24] This is an exploded view showing a modified example 2 of the gas-liquid separator of Example 2, viewed from the outer surface of the inner cylinder to the inner surface of the outer cylinder of the third stage. [Figure 25] This is a longitudinal cross-sectional view showing the gas-liquid separator of Example 3. [Figure 26] This is a horizontal cross-sectional view of the gas-liquid separator in Example 3, as seen from the direction of arrow LL in Figure 25. [Figure 27] This is a horizontal cross-sectional view of the gas-liquid separator in Example 3, as seen from the MM arrow in Figure 25. [Modes for carrying out the invention]

[0020] Examples of the steam-water separator of the present invention and a boiling water reactor equipped therewith will be described below with reference to the drawings. In the drawings used herein, the same or corresponding components are denoted by the same or similar reference numerals, and repeated descriptions of these components may be omitted.

[0021] <Example 1> An example of the steam-water separator of the present invention and a boiling water reactor equipped therewith will be described with reference to Figures 1 to 12.

[0022] First, before describing the steam-liquid separator of this embodiment, we will explain the schematic structure of the boiling water reactor to which this steam-liquid separator is applied, using Figure 1. Figure 1 is a schematic diagram of the ABWR configuration.

[0023] In the improved boiling water reactor 100 shown in Figure 1, a cylindrical core shroud 102 is provided inside the reactor pressure vessel 101, and a core 103 loaded with multiple fuel assemblies is installed inside the core shroud 102.

[0024] An upper grid plate 119 is installed at the upper end of the core within the core shroud 102, and a core support plate 108 is installed at the lower end of the core within the core shroud 102. In addition, multiple fuel support fittings 109 are installed on the core support plate 108.

[0025] Furthermore, the reactor pressure vessel 101 is provided with control rod guide tubes 110 that allow multiple cross-shaped control rods to be inserted into the reactor core 103 in order to control the nuclear reaction of the fuel assemblies. A control rod drive mechanism 111 is located in a control rod drive mechanism housing installed below the bottom of the reactor pressure vessel 101, and the cross-shaped control rods are connected to the control rod drive mechanism 111.

[0026] The coolant 118 flowing into the reactor core 103 is heated by the nuclear reaction of the fuel assemblies, becoming a mixed flow of steam and water, which flows into the steam-water separator 105 located above the reactor core 103. The mixed flow that flows into the steam-water separator 105 is given a swirling speed by the swirler 122 inside the steam-water separator 105. This swirling speed causes centrifugal force to act on the mixed flow, separating it into water and steam due to the density difference between water and steam, and the water flows again as coolant 118 to the downcomer 114.

[0027] Meanwhile, the steam flows into the steam dryer 106, where it is further dried to remove moisture. In this way, the steam, with its moisture content reduced to 0.1 weight percent or less, is sent through the main steam pipe 115 to the turbine (not shown) to generate electricity.

[0028] The coolant 118, which flows into the reactor pressure vessel 101 from the feedwater piping 116 via a condenser, etc. (not shown), flows downward through the downcomer 114, which is formed between the reactor pressure vessel 101 and the core shroud 102 by the internal pump 113, and through which the water separated by the steam-water separator 105 circulates. In this way, the internal pump 113 forces the coolant 118 to circulate to the core 103 in order to efficiently cool the heat generated in the core 103. Note that a jet pump can be used instead of the internal pump 113.

[0029] Next, the configuration of the gas-liquid separator will be explained using Figures 2 and 3. This invention focuses on gas-liquid separators having two or more separation mechanisms, and Figure 2 shows a gas-liquid separator having a three-stage separation mechanism.

[0030] The gas-liquid separator 105 shown in Figure 2 is composed of a three-stage separation mechanism.

[0031] The first stage separation mechanism, located at the lowest point in the vertical direction, includes a standpipe 120, a diffuser 121, a first stage inner cylinder 123, a swirler 122, a first stage outer cylinder 124, a first stage annular plate 128, and a first stage pick-off ring 125.

[0032] The standpipe 120 guides the mixed fluid of steam and water generated in the core 103 from bottom to top. The diffuser 121 communicates with the upper end face of the standpipe 120 to form a flow path, and the flow path cross-sectional area expands upward from the flow path cross-sectional area of ​​the upper end face. The first stage inner cylinder 123 communicates with the upper end face of the diffuser 121 to form a flow path. The swirler 122 includes a hub that passes through the axial center of the flow path of the mixed steam and water flow and a plurality of swirl vanes mounted radially around the hub, with the inner edge of the swirl vanes fixed to the hub in the radial direction and the outer edge of the swirl vanes fixed to the inner wall of the diffuser 121 or the inner wall of the first stage inner cylinder 123 in the radial direction. The first stage outer cylinder 124 forms the first stage outlet 127 below the first stage annular flow path 126 which is formed by concentrically surrounding the first stage inner cylinder 123 at intervals. The first annular plate 128 closes the upper surface of the first outer cylinder 124 and forms a circular hole with a smaller diameter than the first inner cylinder 123. The first pick-off ring 125 extends cylindrically downward from the inner periphery forming the circular hole of the first annular plate 128, forming a circular hole as a short channel to the second inner cylinder 129.

[0033] The second-stage separation mechanism, located directly above the first-stage separation mechanism, comprises a second-stage inner cylinder 129, a second-stage outer cylinder 130, a second-stage annular plate 134, and a second-stage pick-off ring 131.

[0034] The second-stage inner cylinder 129 is installed on the preceding first-stage annular plate 128 and forms a flow path. The second-stage outer cylinder 130 forms a second-stage outlet 133 below the second-stage annular flow path 132 which is formed by concentrically surrounding the second-stage inner cylinder 129 at intervals. The second-stage annular plate 134 closes the upper side surface of the second-stage outer cylinder 130 and forms a circular hole with a smaller diameter than the second-stage inner cylinder 129. The second-stage pick-off ring 131 extends cylindrically downward from the inner periphery forming the circular hole of the second-stage annular plate 134, forming a circular hole as a short flow path to the third-stage inner cylinder 135.

[0035] The third-stage separation mechanism, located directly above the second-stage separation mechanism, comprises a third-stage inner cylinder 135, a third-stage outer cylinder 136, a third-stage annular plate 140, and a third-stage pick-off ring 137.

[0036] The third-stage inner cylinder 135 is installed on the preceding second-stage annular plate 134 and forms a flow path. The third-stage outer cylinder 136 forms a third-stage outlet 139 below the third-stage annular flow path 138 which is formed by concentrically surrounding the third-stage inner cylinder 135 at intervals. The third-stage annular plate 140 closes the upper side surface of the third-stage outer cylinder 136 and forms a circular hole with a smaller diameter than the third-stage inner cylinder 135. The third-stage pick-off ring 137 extends cylindrically downward from the inner periphery forming the circular hole of the third-stage annular plate 140, forming the circular hole as the gas-water separator outlet flow path.

[0037] As shown in Figure 3, multiple steam-liquid separators 105 are arranged at regular intervals, and the steam discharged from the second-stage outlet 133 and third-stage outlet 139 of each steam-liquid separator 105 rises through the inter-steam-liquid separator flow path 141 and flows into the steam dryer 106 located above the steam-liquid separators 105.

[0038] Next, the characteristic configuration of the gas-liquid separator 105 of Example 1 will be described using Figures 4 to 8. Figure 4 shows the structure of the second and third separation mechanisms from the bottom of the gas-liquid separator.

[0039] The most distinctive components of the present invention are a vertical plate 21 that circumferentially divides the second-stage annular flow path 132 between the second-stage inner cylinder 129 and the second-stage outer cylinder 130, eliminating the swirling component of the mixed flow that continues from the second-stage inner cylinder 129 to the second-stage annular flow path 132, and a vertical plate 31 that circumferentially divides the third-stage annular flow path 138 between the third-stage inner cylinder 135 and the third-stage outer cylinder 136, eliminating the swirling component of the mixed flow that continues from the third-stage inner cylinder 135 to the third-stage annular flow path 138.

[0040] As shown in Figure 4, the second stage inner cylinder 129 receives a steam-water mixture in which the proportion of water in the total flow rate of the steam-water mixture that flows into the steam-water separator 105 in the first stage inner cylinder 123 has been greatly reduced.

[0041] Inside the second-stage inner cylinder 129, the swirling flow 142 generated by the swirling vanes below the first-stage inner cylinder 123 is maintained and continues. As a result, centrifugal force acts on the steam-water mixture inside the second-stage inner cylinder 129 due to the swirling flow, causing the gas and liquid to separate due to the difference in gas-liquid density, forming a liquid film on the inner surface of the second-stage inner cylinder 129, which then moves upward.

[0042] The separated water flows from the second-stage pick-off ring 131 into the second-stage annular channel 132. Meanwhile, the steam flows from the central channel of the second-stage pick-off ring 131 into the third-stage inner cylinder 135.

[0043] The separated water also contains vapor, which exists in a churn flow or annular spray flow state within the second-stage annular channel 132 after passing through the second-stage pick-off ring 131, with a large amount of droplets present in the vapor.

[0044] As shown by the dashed lines in Figures 4 and 5, the swirling flow 142 in the second-stage inner cylinder 129 leaves a swirling flow 143 in the second-stage annular flow channel 132.

[0045] Therefore, as shown in Figure 6, by utilizing the swirling flow 143, steam containing droplets can be made to collide with a vertical plate 21 installed in the second annular flow path 132 so as to extend to the second outlet 133, thereby enabling steam-water separation.

[0046] The vertical plate 21 is connected to the inner surface of the second stage outer cylinder 130 or the outer surface of the second stage inner cylinder 129, and it is expected that water will accumulate on the inner circumference side of the second stage outer cylinder 130 due to centrifugal force. Therefore, it is more preferable that the vertical plate 21 be installed so as to be in contact with the inner surface of the second stage outer cylinder 130, but it may also be in contact with either the inner surface of the second stage outer cylinder 130 or the outer surface of the second stage inner cylinder 129.

[0047] Furthermore, the vertical end face of the vertical plate 21 is positioned at a 90-degree angle to the outer surface of the second stage inner cylinder 129 and the inner surface of the second stage outer cylinder 130.

[0048] As shown in Figure 7, the separated droplets form a liquid film 2 on the vertical plate 21 and flow downward as a downward flow 3 due to gravity. The steam that collides with the vertical plate 21 and loses its swirling component becomes a downward flow 4. At the second stage outlet 133 below the second stage outer cylinder 130, as shown in Figure 8, the liquid film 2 formed on the vertical plate 21 and flowing downward flows out of the steam-water separator 105, while the steam maintains its downward flow 4 and flows out of the steam-water separator 105, and into the steam dryer 106 above.

[0049] As described above, the vertical plate 21 allows for the separation of liquid droplets in the steam, and water and steam can be discharged separately at the second stage outlet 133 of the second stage outer cylinder 130, thereby reducing carryover from outside the steam-water separator 105 to the steam dryer 106.

[0050] Furthermore, as shown in Figure 4, in the third-stage annular passage 138, the strength of the swirling flow 144 in the third-stage inner cylinder 135 weakens, but, similar to the second stage, the swirling flow 145 remains in the third-stage annular passage 138. Therefore, by utilizing this swirling flow 145 and causing steam to collide with the vertical plate 31 installed in the third-stage annular passage 138 so as to extend to the third-stage outlet 139, steam-liquid separation can be achieved.

[0051] The vertical plate 31 is also connected to the inner surface of the third stage outer cylinder 136 or the outer surface of the third stage inner cylinder 135, and more preferably, it is installed so as to contact the inner surface of the third stage outer cylinder 136 because it is expected that water will accumulate on the inner circumference side of the third stage outer cylinder 136 due to centrifugal force. However, it may also be in contact with either the inner surface of the third stage outer cylinder 136 or the outer surface of the third stage inner cylinder 135. Similarly, the vertical end face of the vertical plate 31 is installed at a 90-degree angle to the outer surface of the third stage inner cylinder 135 and the inner surface of the third stage outer cylinder 136.

[0052] These vertical plates 21 and 31 are L-shaped when viewed from a vertical cross-section, and it is preferable in terms of guiding the liquid film out of the separation mechanism if each extends to the outer surface of the second stage outer cylinder 130 or the third stage outer cylinder 136. On the other hand, it is preferable in terms of manufacturability and installation work if they extend to the same surface as the outer surface of the second stage outer cylinder 130 or the third stage outer cylinder 136.

[0053] Next, the method for installing the vertical plates 21 and 31 on the gas-liquid separator 105 of Example 1 will be explained using Figures 9 and 10. Figures 9 and 10 describe the second-to-last separation structure of the gas-liquid separator 105 from the bottom.

[0054] The present invention can be easily realized by installing the vertical plate 21 on the inner surface of the second stage outer cylinder 130 as shown in Figure 9, or by installing the vertical plate 21 on the outer surface of the second stage inner cylinder 129 as shown in Figure 10. The same applies to the third stage separation structure from the bottom of the gas-water separator.

[0055] Modified versions of the gas-liquid separator in Example 1 are shown in Figures 11 and 12.

[0056] A key feature of this embodiment is the orientation in which the vertical plates are installed within the annular channel.

[0057] As shown in Figure 11, in the modified gas-water separator 105A, the vertical end face of the vertical plate 21A is installed or close to the outer surface of the second-stage inner cylinder 129 at an angle A less than 90 degrees with respect to the direction of the swirling flow 143 remaining in the second-stage annular flow channel 132, or the vertical end face of the vertical plate 21A installed in the second-stage annular flow channel 132 is installed or close to the inner surface of the second-stage outer cylinder 130 at an angle B greater than 90 degrees.

[0058] As a result, as shown in Figure 12, droplets or liquid films tend to accumulate in the space at angle A, and the scattering of droplets when vapor collides with the vertical plate 21A is also reduced. Furthermore, the same function can be achieved even if angles A and B are reversed, or even if only angle A or angle B is used.

[0059] Similarly, the vertical plates installed in the third-stage annular channel 138 may be installed with their vertical end faces positioned at an angle less than 90 degrees or greater than 90 degrees relative to the outer surface of the third-stage inner cylinder 135 and the inner surface of the third-stage outer cylinder 136.

[0060] Next, the effects of this embodiment will be described.

[0061] In the gas-water separator 105 equipped with a multi-stage separation mechanism of Embodiment 1 of the present invention described above, the separation mechanism from the second stage onward has vertical plates 21, 31, and 21A that divide the second-stage annular flow path 132 and the third-stage annular flow path 138 in the circumferential direction and eliminate the swirling component of the mixed flow that continues to flow from the second-stage inner cylinder 129 and the third-stage inner cylinder 135 to the second-stage annular flow path 132 and the third-stage annular flow path 138.

[0062] This allows for further steam-water separation by causing the droplet-containing steam to collide with vertical plates 21, 31, and 21A. As a result, the amount of droplets accompanying the steam can be reduced compared to conventional methods, and carryover can be reduced under high-quality conditions where the steam flow rate increases when power output is increased. Therefore, the range of operating conditions for the reactor can be broadened.

[0063] Furthermore, since the vertical ends of the vertical plates 21 and 31 are positioned at a 90-degree angle to the outer surfaces of the second-stage inner cylinder 129 and the third-stage inner cylinder 135 and the inner surfaces of the second-stage outer cylinder 130 and the third-stage outer cylinder 136, the vertical plates 21 and 31 can be easily installed.

[0064] Furthermore, since the vertical end face of the vertical plate 21A is positioned at an angle less than 90 degrees or greater than 90 degrees with respect to the outer surface of the second-stage inner cylinder 129 and the third-stage inner cylinder 135 and the inner surface of the second-stage outer cylinder 130 and the third-stage outer cylinder 136, the scattering of droplets when steam collides with the vertical plate 21A can also be reduced.

[0065] Furthermore, since the vertical plates 21, 31, and 21A are installed connected to the inner surfaces of the second-stage outer cylinder 130 and the third-stage outer cylinder 136, or to the outer surfaces of the second-stage inner cylinder 129 and the third-stage inner cylinder 135, fixing the vertical plates 21, 31, and 21A is very easy, and the possibility of liquid film accumulating between the second-stage outer cylinder 130, the third-stage outer cylinder 136, the second-stage inner cylinder 129, and the third-stage inner cylinder 135, or accumulating on the back side of the vertical plates 21, 31, and 21A, can be reduced, thereby ensuring more reliable discharge.

[0066] Furthermore, because the vertical plates 21, 31, and 21A extend to the second-stage outlet 133 and the third-stage outlet 139, the liquid film formed on the surface of the vertical plates 21, 31, and 21A can be guided to the second-stage outlet 133 and the third-stage outlet 139, thereby ensuring more reliable discharge to the outside of the gas-water separators 105 and 105A.

[0067] <Example 2> A steam-water separator according to Embodiment 2 of the present invention and a boiling water reactor equipped therewith will be described with reference to Figures 13 to 24.

[0068] Figure 13 shows the separation structure of the second and third stages from the bottom of the gas-liquid separator 105B, similar to Figure 4, and Figures 14 to 17 show the separation structure of the second stage from the bottom of the gas-liquid separator 105B, similar to Figure 5, etc.

[0069] The steam-water separator 105B of this embodiment, shown in Figures 13 to 17, further includes drainage channel forming plates 5B and 5C that are shorter in length than the vertical plates 21B and 31B, positioned directly opposite the surface where the mixed flow collides with the vertical plates 21B and 31B. The vertical plates 21B and 31B and the drainage channel forming plates 5B and 5C extend to the second-stage outlet 133 and the third-stage outlet 139, respectively, forming a drainage port for draining water that adheres to the vertical plates 21B and 31B and flows down as a liquid film, and an exhaust port for steam, respectively.

[0070] As shown in Figures 13 and 14, the flow is similar to that described in Figures 4 and 5 until the vapor containing droplets collides with the vertical plate 21B installed in the second-stage annular channel 132.

[0071] In this embodiment, a drainage channel forming plate 5B is installed below the surface on which steam collides with the vertical plate 21B, thereby providing a drainage channel. As shown in Figures 15 and 16, by providing the drainage channel 6B, droplets adhering to the vertical plate 21B form a liquid film and flow down, but the liquid film does not come into contact with the descending steam as it flows down. As a result, even when increasing output and the steam flow rate increases, the surface of the liquid film can be further suppressed from becoming wavy due to the descending steam flow.

[0072] Furthermore, as shown in Figure 17, by providing a separate drain outlet 7B for the separated water and a separate outlet for the steam, the water drained from the steam-water separator 105B is prevented from being stirred up by the steam. This reduces the amount of moisture contained in the steam rising from outside the steam-water separator 105B, thus reducing carryover.

[0073] Furthermore, as shown in Figure 13, in the third-stage annular channel 138, although the swirling speed in the third-stage inner cylinder 135 decreases, a swirling flow 145 remains in the third-stage annular channel 138, similar to the second-stage separation mechanism. Therefore, by utilizing this swirling flow 145 to cause steam to collide with the vertical plate 31B installed in the third-stage annular channel 138, steam-water separation is achieved. As shown in Figure 15, a drainage channel 6C is secured by the drainage channel forming plate 5C, and by providing separate drainage ports for water 7C and steam, the amount of liquid droplets contained in the steam can be reduced, thereby reducing the carryover of fluid that is discharged outside the steam-water separator 105B and flows into the steam dryer 106.

[0074] Furthermore, the drainage channel forming plates 5B and 5C can be easily realized by installing them on the inner surfaces of the second-stage outer cylinder 130 and the third-stage outer cylinder 136, or on the outer surfaces of the second-stage inner cylinder 129 and the third-stage inner cylinder 135, similar to the vertical plates 21 and 31 shown in Figures 9 and 10. While it is desirable to install them approximately parallel to the vertical plates 21 and 31, this is not required. Additionally, the drainage channel forming plates 5B and 5C do not need to be installed at a 90-degree vertical angle to the inner or outer cylinders; they can be installed at any angle.

[0075] A modified example 1 of the gas-liquid separator of Example 2 is shown in Figures 18 to 21.

[0076] Figure 18 is an unfolded view of the vertical plate and drain-forming plate installed in the second-stage annular flow channel, the second stage from the bottom, as seen from the outer surface of the second-stage inner cylinder to the inner surface of the second-stage outer cylinder. Figure 19 is an unfolded view of the vertical plate and drain-forming plate installed in the third-stage annular flow channel, the third stage from the bottom of the steam-water separator, as seen from the outer surface of the third-stage inner cylinder to the inner surface of the third-stage outer cylinder. Figures 18 and 19 also show the difference in the collision angle of steam with the vertical plates when steam with swirling velocity collides with the vertical plates installed in the second-stage and third-stage annular flow channels in Figure 13.

[0077] In the steam-water separator 105C shown in Figure 18, the angle K at which the steam in the third-stage annular channel 138, shown in Figure 19, collides with the vertical plate 31C is larger than the angle J at which the steam in the second-stage annular channel 132 collides with the vertical plate 21C.

[0078] This is because the swirling speed generated in the third-stage annular passage 138 is weaker than the swirling speed generated in the second-stage annular passage 132. For this reason, in the third-stage annular passage 138, where the swirling speed is weaker, it is necessary to increase the axial length of the surface into which the steam collides. However, when the output is increased and the steam flow rate increases, increasing the length of the surface into which the steam collides increases the likelihood of contact with descending steam, so it is desirable to keep the surface into which the steam collides as short as possible.

[0079] Therefore, if the steam in the third-stage annular channel 138 collides with the vertical plate 31C before the collision angle K becomes large, that is, when the collision angle is small, the same effect can be obtained with the length of the vertical plate 21C installed in the second-stage annular channel 132.

[0080] One way to achieve this is to use different numbers of vertical plates 21C and 31C. Figures 20 and 21 show structures with increased vertical plates.

[0081] As shown in Figures 20 and 21, by making the number of vertical plates 31C in the third stage and beyond separation mechanism equal to or greater than the number of vertical plates 21C in the lower stage separation mechanism, the axial length of the surface where steam collides with the vertical plates 21C, 31C installed in the second stage annular flow path 132 and the third stage annular flow path 138 of the third stage can be set to an appropriate length suitable for the flow direction of the steam flowing into each flow path, thereby more efficiently removing droplets from the steam.

[0082] A modified example 2 of the gas-liquid separator in Example 2 is shown in Figures 22 to 24.

[0083] A key feature of the gas-water separator 105D in Modification 2 of this Embodiment 2 is that the length of the vertical plate 31D installed in the third annular channel 138 is made longer than the length of the vertical plate 21D installed in the second annular channel 132 of the gas-water separator 105D. This ensures that the difference between the vertical length of the vertical plate 31D and the vertical length of the drainage channel forming plate 5C1 in the separation mechanism from the third stage onward is greater than or equal to the difference between the vertical length of the lower vertical plate 21D and the vertical length of the drainage channel forming plate 5B1.

[0084] Figure 23 shows an unfolded view of the vertical plate 21D and drainage channel forming plate 5B1 installed in the second annular channel 132 of the steam-water separator 105D, viewed from the outer surface of the second inner cylinder 129 to the inner surface of the second outer cylinder 130. Figure 24 shows an unfolded view of the vertical plate 31D and drainage channel forming plate 5C1 installed in the third annular channel 138 of the steam-water separator 105D, viewed from the outer surface of the third inner cylinder 135 to the inner surface of the third outer cylinder 136.

[0085] As shown in Figures 23 and 24, the length of the drainage channel forming plate 5B1 installed in the second annular channel 132 is made longer than the drainage channel forming plate 5C1 installed in the third annular channel 138. By making the length of the surface on which steam with swirling velocity collides with the vertical plates 21D and 31D L1 for the vertical plate 21D in the second annular channel 132 and L2 (longer than L1) for the vertical plate 31D in the third annular channel 138, the probability of the steam colliding with the vertical plate 31D can be increased compared to the probability of the steam colliding with the vertical plate 21D, and droplets in the steam can be removed more efficiently.

[0086] The other configurations and operations are substantially the same as those of the steam-water separator and boiling water reactor equipped therewith described in Example 1 above, and details are omitted.

[0087] In the steam-liquid separator and boiling water reactor equipped therewith of Example 2 of the present invention, substantially the same effects as those of the steam-liquid separator and boiling water reactor equipped therewith of Example 1 described above can be obtained.

[0088] Furthermore, by providing drainage channel forming plates 5B and 5C, which are shorter in length than the vertical plates 21B, 31B, 21C, 31C, 21D, and 31D, at positions directly opposite the surface where the mixed flow collides, it is possible to reliably discharge droplets to the outside of the gas-water separators 105B, 105C, and 105D.

[0089] Furthermore, the vertical plates 21B, 31B, 21C, 31C, 21D, 31D and the drainage channel forming plates 5B, 5C extend to the second-stage discharge port 133 and the third-stage discharge port 139, forming drainage ports for draining water that adheres to the vertical plates 21B, 31B, 21C, 31C, 21D, 31D and flows down as a liquid film, and exhaust ports for steam, respectively, thereby enabling more efficient discharge of liquid droplets to the outside of the steam-water separators 105B, 105C, 105D.

[0090] Furthermore, the number of vertical plates 31C in the third and subsequent separation mechanisms is greater than or equal to the number of vertical plates 21C in the lower separation mechanism, and the difference between the vertical length of vertical plate 31D in the third and subsequent separation mechanisms and the vertical length of drainage channel forming plate 5C is greater than or equal to the difference between the vertical length of vertical plate 21D in the lower separation mechanism and the vertical length of drainage channel forming plate 5B. This increases the probability of steam colliding with vertical plates 21C, 21D, 31C, and 31D, thereby enabling more efficient removal of droplets from the steam.

[0091] <Example 3> A steam-water separator according to Embodiment 3 of the present invention and a boiling water reactor equipped therewith will be described with reference to Figures 25 to 27.

[0092] In the gas-water separator 105E of this embodiment shown in Figures 25 to 27, the vertical plates 21E and 31E are semicircular pipes, and the drainage channel is a circular pipe structure.

[0093] As shown in the horizontal cross-sections of Figures 25 to 27, by making the vertical plates semicircular tubular vertical plates 21E, 31E, when steam with a swirling component collides with the semicircular tubular vertical plates 21E, 31E, droplet scattering can be prevented more effectively than with the flat vertical plates 21, 21A, 21B, 21C, 21D, 31, 31B, 31C, 31D shown in Examples 1 and 2.

[0094] Furthermore, by providing an additional semicircular drainage channel forming plate 5E and creating a circular pipe structure for the drainage channel 6E between it and the vertical plate 21E, a drainage channel can be easily realized. Note that the drainage channel forming plate 5E does not need to be semicircular; it may be flat.

[0095] Similarly, it is desirable to form a drainage channel 6E1 by providing a semicircular or flat drainage channel forming plate 5E1 within the third annular channel 138.

[0096] The other configurations and operations are substantially the same as those of the steam-water separator and boiling water reactor equipped therewith described in Example 1 above, and details are omitted.

[0097] In the steam-liquid separator and boiling water reactor equipped therewith of Example 3 of the present invention, substantially the same effects as those of the steam-liquid separator and boiling water reactor equipped therewith of Example 1 described above can be obtained.

[0098] <Other> It should be noted that the present invention is not limited to the embodiments described above, and includes various modifications. The embodiments described above are explained in detail for the purpose of clearly illustrating the present invention, and are not necessarily limited to those having all the configurations described.

[0099] Furthermore, it is possible to replace parts of the configuration of one embodiment with parts of the configuration of another embodiment, and it is also possible to add parts of the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with parts of other configurations.

[0100] For example, in all the embodiments described above, the vertical plates 21, 21A, 21B, 21C, 21D, 21E, 31, 31B, 31C, 31D, and 31 are shown extending straight in the vertical direction. However, the embodiment is not limited to this configuration, and the vertical plates can be installed in a direction that is approximately parallel or perpendicular to the mixed flow. When the vertical plates are installed in a direction that is approximately parallel or perpendicular to the mixed flow, it is desirable that the portion near the outlet extends straight in the vertical direction to smoothly guide the liquid film to the outlet. In this case as well, it is possible to provide a drainage channel forming plate as appropriate. [Explanation of Symbols]

[0101] 2…Liquid film formed by adhering to the vertical plate 3… Downward flow of liquid film 4… Downward flow of steam 5B, 5B1, 5C, 5C1, 5E, 5E1…Drainage channel forming plate 6B,6C,6E,6E1…Drainage channel 7B,7C…Drain port 21,21A,21B,21C,21D,21E…Vertical board (second stage) 31,31B,31C,31D,31E…Vertical board (third stage) 100...Improved boiling water reactor 101…Reactor pressure vessel 102... Core Shroud 103…Core 104... Shroudhead 105,105A,105B,105C,105D,105E...Sea water separator 106... Steam dryer 108... Core support plate 109…Fuel support bracket 110... Control rod guide tube 111...Control rod drive mechanism 113...Internal pump 114... Down Kam 115... Main steam piping 116...Water supply piping 117... Impeller 118...Coolant 119...Upper grid plate 120... Standpipe 121... Diffuser 122... Swara 123…First stage inner cylinder 124...First stage outer cylinder 125...First stage pick-up ring 126...First stage ring channel 127...First stage discharge port 128...First ring plate 129…Second stage inner cylinder (inner cylinder after second stage) 130...Second stage outer cylinder (outer cylinder from the second stage onwards) 131...Second stage pick-off ring (Second stage and beyond pick-off ring) 132...Second-stage ring channel (second-stage and subsequent ring channels) 133…Second stage discharge port (second stage and subsequent stage discharge ports) 134...Second-stage ring plate (Ring plates from the second stage onward) 135…Third stage inner cylinder (second stage and later inner cylinder) 136...Third stage outer cylinder (outer cylinder from the second stage onwards) 137...Third stage pick-off ring (Pick-off ring from the second stage onwards) 138...Third-stage ring channel (second-stage and subsequent ring channels) 139…Third stage discharge port (second stage and subsequent stage discharge ports) 140...Third-stage ring plate (ring plates from the second stage onwards) 141…Flow path between steam and water separators 142... Swirling flow inside the second stage inner cylinder 143... Swirling flow within the second outer ring channel 144... Swirling flow inside the third stage inner cylinder 145... Swirling flow within the third stage outer ring channel

Claims

1. A gas-liquid separator equipped with a multi-stage separation mechanism, The first stage of the separation mechanism from the bottom is, A standpipe that guides the mixed fluid of steam and water generated in the reactor core from below upwards. A diffuser that forms a flow path in communication with the upper end face of the standpipe, and expands the flow path cross-sectional area upwards from the flow path cross-sectional area of ​​the upper end face. A first-stage inner cylinder that communicates with the upper end face of the diffuser and forms a flow path, A swara comprising a hub passing through the axial center of the flow path of the mixed flow of steam and water, and a plurality of swirl vanes radially mounted around the hub, wherein the inner edge of each swirl vane is fixed to the hub in the radial direction, and the outer edge of each swirl vane is fixed to the inner wall of the diffuser or the inner wall of the first stage inner cylinder, Below the first stage outer cylinder, which forms the first stage outlet, a first stage outer cylinder is formed by concentrically surrounding the first stage inner cylinder at intervals. A first-stage annular plate that closes the upper side surface of the first-stage outer cylinder and has a circular hole with a smaller diameter than the first-stage inner cylinder, The first stage pick-off ring extends cylindrically downward from the inner peripheral edge forming the circular hole of the first stage annular plate, forming the circular hole as a short channel to the second stage inner cylinder, The separation mechanism from the second stage onwards from the bottom is: The second and subsequent inner cylinders are installed on the annular plate in the preceding stage and form a flow path. Below the second and subsequent inner cylinders, which are formed by concentrically spacing them to create an annular flow path from the second stage onward, the second and subsequent outer cylinders form the second and subsequent discharge ports. The second and subsequent annular plates close the upper side surface of the outer cylinder and have a circular hole with a smaller diameter than the inner cylinder, The second and subsequent pick-off rings extend cylindrically downward from the inner periphery forming the circular hole of the second and subsequent annular plates, forming the circular hole as a short channel or outlet channel to the next and subsequent inner cylinders, The separation mechanism from the second stage onward includes a vertical plate that divides the annular flow path from the second stage onward in the circumferential direction and eliminates the swirling component of the mixed flow that continues to flow from the inner cylinder of the second stage onward into the annular flow path from the second stage onward, and a drainage channel forming plate that is shorter in length than the vertical plate and is positioned on the vertical plate directly opposite the surface to which the mixed flow collides. Steam water separator.

2. A gas-liquid separator comprising a multi-stage separation mechanism, The first stage of the separation mechanism from the bottom is, A standpipe that guides the mixed fluid of steam and water generated in the reactor core from below upwards. A diffuser that forms a flow path in communication with the upper end face of the standpipe, and expands the flow path cross-sectional area upwards from the flow path cross-sectional area of ​​the upper end face. A first-stage inner cylinder that communicates with the upper end face of the diffuser and forms a flow path, A swara comprising a hub passing through the axial center of the flow path of the mixed flow of steam and water, and a plurality of swirl vanes radially mounted around the hub, wherein the inner edge of each swirl vane is fixed to the hub in the radial direction, and the outer edge of each swirl vane is fixed to the inner wall of the diffuser or the inner wall of the first stage inner cylinder, Below the first stage outer cylinder, which forms the first stage outlet, a first stage outer cylinder is formed by concentrically surrounding the first stage inner cylinder at intervals. A first-stage annular plate that closes the upper side surface of the first-stage outer cylinder and has a circular hole with a smaller diameter than the first-stage inner cylinder, The first stage pick-off ring extends cylindrically downward from the inner peripheral edge forming the circular hole of the first stage annular plate, forming the circular hole as a short channel to the second stage inner cylinder, The separation mechanism from the second stage onwards from the bottom is: The second and subsequent inner cylinders are installed on the annular plate in the preceding stage and form a flow path. Below the second and subsequent inner cylinders, which are formed by concentrically spacing them to create an annular flow path from the second stage onward, the second and subsequent outer cylinders form the second and subsequent discharge ports. The second and subsequent annular plates close the upper side surface of the outer cylinder and have a circular hole with a smaller diameter than the inner cylinder, The second and subsequent pick-off rings extend cylindrically downward from the inner periphery forming the circular hole of the second and subsequent annular plates, forming the circular hole as a short channel or outlet channel to the next and subsequent inner cylinders, The separation mechanism from the second stage onward has vertical plates that divide the annular flow path from the second stage onward in the circumferential direction and eliminate the swirling component of the mixed flow that continuously flows from the inner cylinder of the second stage onward to the annular flow path from the second stage onward. The number of vertical plates in the separation mechanism from the third stage onward is equal to or greater than the number of vertical plates in the separation mechanism below it. Steam water separator.

3. In the gas-liquid separator according to claim 1, The vertical end face of the aforementioned vertical plate is positioned at a 90-degree angle to the outer surface of the second and subsequent inner cylinders and to the inner surface of the second and subsequent outer cylinders. Steam water separator.

4. In the gas-liquid separator according to claim 1, The vertical plate is positioned such that its vertical end face is at an angle less than 90 degrees or greater than 90 degrees with respect to the outer surface of the second and subsequent inner cylinders and the inner surface of the second and subsequent outer cylinders. Steam water separator.

5. In the gas-liquid separator according to claim 1, The vertical plate is installed connected to the inner surface of the second and subsequent outer cylinders, or to the outer surface of the second and subsequent inner cylinders. Steam water separator.

6. In the gas-liquid separator according to claim 1, The aforementioned vertical plate extends from the second stage onward to the discharge port. Steam water separator.

7. In the gas-liquid separator according to claim 6, The vertical plate and the drainage channel forming plate extend from the second stage onward to the outlet, forming a drainage port for draining water that adheres to the vertical plate and flows down as a liquid film, and an exhaust port for the steam, respectively. Steam water separator.

8. In the gas-liquid separator according to claim 1, The number of vertical plates in the separation mechanism from the third stage onward is equal to or greater than the number of vertical plates in the separation mechanism below it. Steam water separator.

9. In the gas-liquid separator according to claim 6, The difference between the vertical length of the vertical plate and the vertical length of the drainage channel forming plate in the third stage and beyond of the separation mechanism is greater than or equal to the difference between the vertical length of the vertical plate on the lower side and the vertical length of the drainage channel forming plate. Steam water separator.

10. The reactor pressure vessel and A reactor core is provided within the reactor pressure vessel and is loaded with a plurality of fuel assemblies, The shroud on which the reactor core is placed, A steam-water separator is positioned above the reactor core and separates the mixed flow of steam and water generated in the reactor core into steam and water. A steam dryer located above the steam-water separator dries the moist steam separated by the steam-water separator, A main steam piping supplying steam dried in the steam dryer to the turbine, A downcomer is formed between the reactor pressure vessel and the shroud, through which the water separated in the steam-water separator circulates. The system includes a pump located below the downcomer that supplies water from the downcomer to the reactor core, The steam-water separator is the steam-water separator described in any one of claims 1 to 9. Boiling water reactor.

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