JP4481896B2 - Boiling water reactor - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a boiling water reactor, and in particular, when an increase in reactor power is carried out, vibration is generated by reducing the pressure loss in the steam circulation section of the steam / water separator having the steam dryer function and the steam dryer in the reactor. The present invention relates to a boiling water reactor designed to prevent damage and damage.

  In boiling water reactors, steam-water separators and steam dryers are used to separate the steam-water mixture from the combustion assembly loaded in the reactor pressure vessel core into steam that is sent to the turbine and water that is circulated back to the core. Is provided. FIG. 15 shows the overall configuration of the reactor pressure vessel 2 of the boiling water reactor 1 and the configurations of the steam separator 3 and the steam dryer 4 provided in the reactor pressure vessel 2.

  As shown in FIG. 15, a fuel assembly 2 a is loaded on the core 11 of the reactor pressure vessel 2, and the core 11 is surrounded by a core shroud 12. The steam / water separator 3 is configured by arranging a large number of vertically-steamed steam / water separator units 6 in parallel on an upper part of a shroud head 5 mounted on a core shroud 12. Each steam-water separator unit 6 is provided at the upper end of a stand pipe 7 that rises from the shroud head 5 and communicates with the core 11, and the steam-water mixed flow that comes out of the core 11 passes through the stand pipe 7 and separates each steam-water separation. The water flows into the lower end of the steam generator unit 6 and is given a rotational motion by an inlet vane provided in the steam-water separator unit 6, and is separated into water and steam by centrifugal force. On the other hand, the steam dryer 4 is installed above the steam / water separator 3 and removes moisture in the steam by passing the steam through a plurality of steam dryer units 8 made of parallel wave plates and changing the direction of the steam. The steam is sent out from the main steam nozzle 9 on the furnace wall provided in the reactor pressure vessel 2 to the turbine side.

  FIG. 16 shows an enlarged view of the configuration of the steam separator 3 in the conventional boiling water reactor. As shown in FIG. 16, a rim cylinder 10 is provided at the lower peripheral edge of the shroud head 5 of the steam separator 3, and a flange 13 mounted on the core shroud 12 is provided at the lower end edge of the rim cylinder 10. Is provided. As described above, the steam / water separator unit 6 is erected on the shroud head 5 via a number of stand pipes 7. The assembly of the stand pipe 7 and the steam / water separator unit 6 is supported by the lower support ring 14, the upper support ring 15, the gusset 16, and the like, and is supported so as to stand up as accurately as possible. Further, a large number of tie bars 17 made of square pipes or the like arranged in the horizontal direction are provided between the upper ends of each steam / water separator unit 6, and each steam / water separator unit is provided by this tie bar 17. 6 is held.

  FIG. 17 is a partially enlarged plan view showing the holding structure of each steam / water separator unit 6 by the tie bar 17. As shown in FIG. 17, the steam / water separator unit 6 is set to have a constant outer diameter d, and each tie bar 17 is arranged so as to intersect in three directions at an angle of 60 ° on the horizontal plane. It arrange | positions linearly between the steam-water separator units 6. FIG. Thereby, the outer peripheral surface of one steam-water separator unit 6 contacts the six tie bars 17, and each steam-water separator unit 6 and each tie bar 17 are welded at each of the six contact points a. Connected by. By this welding connection, the air / water separation units are integrally fixed and held by the tie bars 17. Conventionally, in such a configuration, for example, the outer diameter (diameter) d of the steam / water separator unit 6 is set to 324 mm, and the pitch between the steam / water separator units 6 is set to 342.9 mm. The number is 225.

  FIG. 18 shows a vertical cross section of the shroud head / rim cylinder connection support structure portion in which the steam / water separator 3 is mounted on the upper end of the core shroud 12. As shown in FIG. 18, in the conventional boiling water reactor, a plurality of downward opening holes 18 are formed along the circumferential direction at predetermined intervals on the lower end surface of the rim body 10 at the lower end of the steam separator 3. In addition, a plurality of upward opening holes 19 are formed on the upper end support surface of the core shroud 12 that supports the rim cylinder 10 in an arrangement corresponding to the downward opening holes 18 of the rim cylinder 10. The diameter of the downward opening hole 18 of the rim body 10 at the lower end of the steam separator 3 is larger than that of the upward opening hole 19 of the core shroud 12. And the earthquake-resistant pin 20 is inserted in the upward hole of the core shroud 12, respectively. When installing the steam separator 3, the steam separator 3 is suspended from above, the downward hole 18 is aligned with the seismic pin 20, and the downward hole 18 is seated on the upper end surface of the core shroud 12. And is fixedly arranged.

  FIG. 19 shows the configuration of the steam dryer 4 in a conventional boiling water reactor. As shown in FIG. 19, the steam dryer 4 includes a support ring 30, a skirt 21 that hangs down from the support ring 30 and is provided in a cylindrical shape along the upper periphery of the steam / water separator 3, and the skirt 21 A plurality of curved hoods 23 that are erected in parallel and open at the lower ends of the steam inlets 22 at the lower ends, and hoods 21 that are erected in parallel on the skirts 21 are connected to the upper ends of the hoods 23 so that the steam flows sideways. The steam dryer unit 8 is arranged in a plurality of rows to be distributed and separated to separate moisture. Adjacent ones of the steam dryer units 8 in each row are connected by an upper tie bar 24. The steam dryer unit 8 is provided with a drain pipe 25 for discharging the separated moisture to the outer peripheral surface side of the skirt 21. The drain is guided to the skirt 21 corresponding to the discharge port 26 of the drain pipe 25. A channel 27 is provided. The support ring 30 is provided with a lifting eye 28 for lifting operation and an earthquake-resistant block 51 as protection means in the event of an earthquake.

  By the way, in recent years, in a boiling water reactor, it has been studied to increase the fuel output and perform more efficient power generation. In implementing this output increase, in the conventional steam / water separator 3 described above, the flow rate increases, the pressure loss increases, and the flow rate in the system may decrease. Moreover, when the flow rate injected into the steam separator 3 and the steam dryer 4 increases, the fluid vibration may also increase.

  In this regard, as a conventional technique for reducing pressure loss, it is possible to set the ratio of the diameter of the inner cylinder in the steam / water separator unit and the hub that is the swivel means, or to set the swirler's swirl blade outlet average angle. It has been proposed (see Patent Document 1 and Patent Document 2).

In addition, regarding the steam / water separator and steam dryer, the lower part of the reactor pressure vessel is simplified by arranging it annularly in the upper space of the reactor pressure vessel, improving the steam / water separation performance, reducing pressure loss, etc. Has also been proposed (see Patent Document 3).
JP 2003-114293 A JP 2001-208301 A JP-A-6-66984

  However, in the conventional technology described above, when the output of the boiling water reactor is increased, the flow rate of the steam separator increases, the pressure loss increases, and the flow rate in the system tends to decrease. Moreover, when the flow rate injected into the steam separator increases, fluid vibration also increases, and a sufficient solution cannot always be achieved.

  In addition, in the conventional steam separator, this is dealt with by six-point welding using a long and narrow prism as an anti-sway of the upper part of the steam separator unit. This may cause the steam / water separation unit to fall down. For this reason, it is necessary to erect the air / water separation unit as accurately as possible, or to correct the tie bar and attach it between the air / water separation units.

  Further, in the conventional earthquake-resistant pin that connects the shroud head and the rim cylinder, the shroud head may move in the left-right direction after being seated on the core shroud, and the pin and the hole may be eccentric.

  Similarly, the steam dryer located at the upper part of the steam separator and further separates the moisture content of the steam from the steam separator increases pressure loss and fluid vibration.

  The present invention has been made in view of such circumstances, and at the time of increasing the reactor power, while reducing the pressure loss of the steam separator and the steam dryer, it is possible to prevent vibration, improve rigidity, reduce stress and prevent deformation. An object of the present invention is to provide a boiling water reactor that can effectively cope with an increase in power.

  According to the inventor's study, the outer diameter d of each cylindrical portion of the steam-water separator unit in the conventional boiling water reactor is 324 mm, the pitch between the steam-water separator units is 342.9 mm, When the total number is 225, the thickness of the steam / water separator unit cylinder portion is large, the flow resistance is large due to the generation of vortices at the steam inlet, etc., the turbulent flow is increased, and the pressure loss is increased. When the reactor power is increased by about 10% from the current level (for example, when the reactor power is increased from 1 million KWe to 1.1 million KWe), an increase in pressure loss is further noticeable. Therefore, when the conventional configuration is followed, as the reactor power increases, the pressure loss of the steam separator is further increased, and the effects on the rigidity, vibration, stress, deformation, etc. of the component are proportionally increased. .

  On the other hand, if the outer diameter d of each cylinder part of the steam-water separator unit is reduced and the wall thickness is reduced, the steam flow resistance in the steam-water separator is reduced, resulting in a state closer to laminar flow. Pressure loss is reduced. However, excessively reducing the diameter leads to an increase in the number of air-water separation units, problems in strength, and the like, and therefore there are certain restrictions on reducing the diameter. From the above viewpoints, the inventors examined and tested the application conditions to the reactor structure. As a result, the pressure loss was reduced by setting the outer diameter of each steam-water separator unit to 200 mm to 300 mm. It has become clear that the influence on the rigidity, vibration, stress, deformation, etc. of the material can be reduced and that the problem of construction of the steam-water separator unit can be overcome.

  In the present invention, a more desirable range for setting the outer diameter of each steam-water separator unit is 250 mm to 260 mm. The most desirable outer diameter is 254 mm.

  In addition, according to the results of the study on the upper end support structure of the steam / water separator unit, conventionally, as a steady rest for the unit, there are 6 points by a tie bar that is long and spans many steam / water separator units and uses a long and narrow prism. Since it is configured to be supported by welding, excessive contact and deficiency with the tie bar may occur due to the diameter of each steam separator unit or the deviation in position, etc., resulting in poor support of the steam separator unit. There is a possibility that it becomes sufficient or falls. In the case of reducing the outer diameter d of each cylindrical portion of the steam / water separator unit under such a configuration, the steam / water separator unit is raised as accurately as possible, or the tie bar is modified to process the steam / water. Although it is necessary to attach between the separation units, more work is required for such work.

  In addition, when applying a conventional seismic pin that connects the shroud head and rim body, the shroud head moves left and right after seating on the core shroud because of the three-member connection structure, and the pin and hole can be eccentric. There is sex. In this regard, it is possible to effectively prevent eccentricity by adopting a direct connection configuration by reducing the number of parts.

  On the other hand, a pressure loss occurs due to the generation of vortex at the steam inlet to the steam dryer, but the pressure loss further increases as the output increases. As described above, the increase in pressure loss leads to an increase in fluid vibration, and the possibility of an increase in the influence on the rigidity of the constituent members, an increase in stress and deformation, and the like increases.

Therefore, in the invention according to claim 1 , a boiling water type provided with a steam-water separator and a steam dryer having a function of separating moisture in the reactor from steam generated in the reactor above the core of the reactor pressure vessel. In the nuclear reactor, the steam dryer is erected in a parallel arrangement on a support ring provided along an upper periphery of the steam separator, a skirt hanging along the support ring, and the support ring. A plurality of curved hoods each having an upward-facing steam inlet at the lower end and a hood arranged in parallel on the support ring and opposed to the sides of the hoods to deflect steam laterally to allow moisture And a steam dryer unit that separates the hood, and a rectifying grid plate that guides the inflowing steam is attached to the steam inlet at the lower end of the hood to reduce pressure loss. To provide a child furnace.

  With such a configuration, generation of turbulent flow can be suppressed, laminar flow expansion and vortex flow reduction at the steam-water separator inlet can be achieved, and pressure loss can be reduced. As a result, the influence on the rigidity of the structural member with respect to the increase in output can be increased, and the stress and deformation can be reduced. Further, the structural strength can be increased.

In addition to the above configuration, it is desirable to reinforce the thin plate structure constituting the steam flow path in the steam dryer. Therefore, in the invention according to claim 2 , the steam dryer has a thin plate structure that forms a steam flow path, and a reinforcing member is attached to the thin plate structure to reduce stress due to fluid vibration and fluid force. A boiling water reactor is provided.

According to a third aspect of the present invention, there is provided a boiling water reactor in which the thin plate structure constituting the steam flow path is a skirt, a hood or an end plate of the steam dryer unit of the steam dryer.

  According to the present invention, the outer diameter of the steam / water separator unit is reduced to increase the number, and the flow rate of the steam / water separator unit per unit is reduced, thereby reducing pressure loss and preventing vibration and improving rigidity. Thus, stress reduction and deformation prevention can be achieved, and an increase in output can be effectively handled. In addition, by installing a rectifying grid plate that guides the incoming steam upward at the steam inlet of the steam dryer to reduce pressure loss, it is possible to prevent vibration, reduce stress, and prevent deformation, effectively increasing output. It can correspond to.

  Hereinafter, an embodiment of a boiling water reactor according to the present invention will be described with reference to FIGS. In order to simplify the description, the same components as those in the conventional example will be described using the same reference numerals as those in FIGS. Further, the overall configuration of the reactor pressure vessel is substantially the same as that shown in FIG.

  FIG. 1 is a perspective view showing the overall configuration of a steam separator 3 according to an embodiment of the present invention. As shown in FIG. 1, the steam / water separator 3 is configured by arranging a large number of vertically-steamed steam / water separator units 6 in parallel on the upper part of the shroud head 5 so as to cover substantially the entire upper surface of the core. ing. Each steam separator unit 6 is provided at the upper end of a stand pipe 7 rising from the shroud head 5. The assembly of the stand pipe 7 and the steam / water separator unit 6 is supported by a lower support ring 14, an upper support ring 15, a gusset 16, and the like.

  In such a configuration, in the present embodiment, the outer diameter d of each steam-water separator unit 6 is set to be smaller than the conventional one and set in a range of 300 mm to 200 mm. Specifically, in the case where an existing 1 million KWe type nuclear reactor is increased by 10% due to an increase in output, the outer diameter of the steam-water separator unit 6 (hereinafter referred to as “separator outer diameter”) d, gas. Regarding the pitch between the water separator units 6 (hereinafter referred to as “separator pitch”) p and the number of the steam-water separator units 6 (hereinafter referred to as “number of separators”), the following first example and second example are described. Set.

<First example>
The separator outer diameter d is φ254 mm, the separator pitch p is 304.8 mm (12 inches), and the number of separators is 297.

<Second example>
The separator outer diameter d is φ254 mm, the separator pitch p is 292.1 mm (11.5 inches), and the number of separators is 313.

  FIG. 2 is a characteristic diagram specifically showing, as a graph, the reduction in pressure loss due to the configuration of the steam separator according to this embodiment. The horizontal axis of FIG. 2 represents the separator outer diameter d, and the vertical axis represents the pressure loss. According to the characteristic line “P1” showing the relationship between the separator outer diameter and pressure loss shown in FIG. 2, a substantially linear proportional relationship is recognized. That is, as shown in the above example, when the separator outer diameter d is 254 mm, a pressure loss reduction of about 20% is recognized compared to the conventional separator outer diameter d of 324 mm.

  The configurations of the first and second examples are the most desirable settings, but in the present invention, substantially the same effect can be obtained even when the separator diameter is set in the range of 250 to 260 mm. Furthermore, good results can be obtained even when the separator outer diameter d is set in the range of 200 to 300 mm from the degree of pressure loss and from a practical standpoint.

  Therefore, according to the present embodiment, the pressure loss can be reduced by reducing the separator outer diameter d to a small diameter, increasing the number of separators, and reducing the flow rate of the steam-water separator unit 6 per unit. It is possible to effectively cope with an increase in output by preventing vibration of the structure, improving rigidity, reducing stress and preventing deformation.

  Moreover, in this embodiment, the upper end part of the mutually adjacent steam-water separator units 6 of the steam-water separator 3 is connected by the strip-shaped connection board 31, respectively. These connecting plates 31 are made of stainless steel and have a flat, thin plate shape, and are set to dimensions longer than the gaps between the steam-water separator units 6. The connecting plate 31 is installed between the upper end surfaces of the steam / water separator unit 6, and both end portions thereof are fixed to the upper end surfaces of the pair of adjacent steam / water separator units 6 by welding.

  3 and 4 show in detail the connection structure between the steam-water separator units 6 by the connection plate 31. FIG. 3 is an enlarged plan view partially showing a partial region of the connection structure of the steam-water separator unit 6 shown in FIG. 1, and FIG. 4 shows a part thereof as a section along the line AA of FIG. FIG. As shown in FIG. 3 and FIG. 4, a steam jetting opening 32 is formed at the center of the upper end portion of each steam-water separator unit 6 having a vertically long cylindrical shape. A flange-shaped upper end wall is formed horizontally. The end of the connecting plate 31 is placed on the outer peripheral portion of the upper surface of the upper end wall, and is fixed by welding. For example, when six other steam / water separator units 6 are adjacently disposed around one steam / water separator unit 6, a horizontal plane is formed from the center of the upper end surface of the one steam / water separator unit 6. Six connecting plates 31 are arranged radially at an angle of 60 ° above, and are connected to six other steam-water separator units 6 by these connecting plates 31. In this way, all the steam / water separator units 6 are connected to each other and are integrally formed.

  According to such a configuration, connection adjustment can be easily performed corresponding to the relative position of each steam-water separator unit 6, the steam-water separator unit 6 can be raised with high accuracy, and work such as correction processing can be performed. Can be greatly reduced. That is, when each steam / water separator unit 6 is held in a sandwiched state by a conventional straight and long tie bar, many positioning corrections are made in order to join all the steam / water separator units 6 to all the tie bars. However, according to the present embodiment, since the steam-water separator units 6 may be connected to each other by the strip-shaped connecting plate 31, the position of the steam-water separator unit 6 is specially corrected. They can be welded to each other without need. Therefore, by reducing the outer diameter of the steam / water separator unit 6 and adopting a joining configuration between the steam / water separator units 6, it is possible to effectively prevent eccentricity. And the pressure loss of the steam flow in the steam-water separator unit 6 can be reduced, the influence on the rigidity, vibration, stress, deformation, etc. of the constituent material can be reduced, and the increase in reactor power can be effectively handled.

  FIG. 5 is an enlarged cross-sectional view showing a configuration example of a connecting portion between the rim body 10 and the core shroud 12 of the steam / water separator 3. As shown in FIG. 5, a flange portion 33 that is wide toward the inner peripheral side is formed at the upper end portion of the core shroud 12, and the entire upper end surface including the flange portion 33 is formed horizontally. . An upward opening groove 35 having a rectangular cross section is provided over the entire circumference at a position approximately above the radial direction of the upper end surface of the core shroud 12 and above the trunk of the core shroud 12. Chamfered portions are provided on both sides of the opening edge of the groove 35. On the other hand, on the lower end surface of the rim body 10 that hangs down from the periphery of the shroud head 5 of the steam / water separator 3, a protrusion 36 having a rectangular cross-sectional shape that fits into the groove 35 of the core shroud 12 is provided over the entire circumference. Yes. The vertical length of the projection 36 of the rim body 10 is shorter than the depth of the groove 35 of the core shroud 12, and R portions are formed on both sides of the root portion of the projection 36. In addition, the radial width of the protrusion 36 is slightly narrower than the width of the groove 35.

  When the steam / water separator 3 is installed, the steam / water separator 3 is suspended from above, the protrusion 36 at the lower end of the rim body 10 is aligned with the groove 35 of the core shroud 12, and the upper end surface of the core shroud 12 is placed. The steam / water separator 3 is fixedly disposed on the core shroud 12 by being seated and fitting between the projection 36 and the groove 35.

  Note that a skirt 34 is joined to the inner peripheral side upper edge of the flange portion 33 of the core shroud 12 by a welded portion 34 a over the entire circumferential direction of the core shroud 12. The skirt 34 protrudes above the flange 33 by a predetermined height so that the steam rising from the core hits the shroud head 5 and can be stored on the upper surface side of the core shroud 12.

  According to such a connection structure between the rim body 10 and the core shroud 12 of the steam / water separator 3, the horizontal movement due to the seismic load of the steam / water separator 3 is prevented by fitting the groove 35 and the protrusion 36. The structural strength can be improved as compared with the conventional configuration using pins, the number of parts can be reduced, and the manufacture becomes easy.

  FIG. 6 is an enlarged cross-sectional view showing another configuration example of the connecting portion between the rim body 10 and the core shroud 12 of the steam / water separator 3. In this configuration example, in contrast to the configuration shown in FIG. 5, a projection 37 is provided on the upper end portion of the core shroud 12, and on the lower end surface of the rim body 10 that hangs down from the peripheral portion of the shroud head 5 of the steam separator 3. A groove 38 that fits with the projection 37 of the core shroud 12 is formed. The shape and arrangement of these protrusions 37 and grooves 38 are substantially the same as the configuration example shown in FIG.

  FIG. 7 is an enlarged cross-sectional view showing still another configuration example of the connecting portion between the rim body 10 and the core shroud 12 of the steam / water separator 3. In this configuration example, as in the configuration shown in FIG. 5, a groove 39 is provided at the upper end portion of the core shroud 12, and at the lower end surface of the rim body 10 that hangs down from the peripheral portion of the shroud head 5 of the steam / water separator 3. A protrusion 40 that fits into the groove 39 of the core shroud 12 is formed. However, unlike the case of FIG. 5, the protrusion 40 has a lower end portion on the outer peripheral surface side of the entire rim body 10 inclined downward in a direction of a small diameter, and the inner peripheral surface side is a vertical surface, so that the entire rim body 10 is The protrusion 40 is formed by reducing the wall thickness of the lower end portion.

  As described above, in this embodiment, the upper surface opening of the core shroud 12 is provided with the grooves 35 and 39 having the upper surface opening or the upward protrusion 37 on the entire circumference, while the lower end surface of the steam separator 3 is provided with the core shroud. A downward projection 36, 40 that fits with the 12 grooves 35, 39 or a groove 38 of the lower surface opening that fits with the projection 37 of the core shroud 12 is provided over the entire circumference, and these grooves and projections are fitted. By installing the air / water separator 3 on the core shroud 12 and preventing the horizontal movement of the air / water separator 3 due to the seismic load, the number of parts can be reduced, the manufacture can be facilitated, and the structural strength can be improved.

  FIG. 8 is a perspective view showing the configuration of the steam dryer 4 according to the present embodiment. As shown in FIG. 8, the steam dryer 4 is provided on a support ring 41 provided above the periphery of the steam / water separator 3, a skirt 21 depending on the support ring 41, and the support ring 41. A plurality of curved hoods 23 that are erected in parallel and have upward steam inlets 22 at their lower ends, and hoods 23 that are erected in parallel on the support ring 41 and connected to the upper ends of the hoods 23. A steam dryer unit 8 that distributes moisture by flowing the horizontally deflected steam. The hood 23 is curved facing the side surface of the steam dryer unit 8, and both side portions between the hood 23 and the steam dryer unit 8 are closed by end plates 42. A bottom plate 43 is connected to the hood 23 arranged in the peripheral portion of the steam dryer unit 8 by welding, and the bottom plate 43 is supported by a support ring 41.

  The lower end side of the space surrounded by the steam dryer unit 8, the hood 23, and the end plate 42 opens downward, thereby forming the steam inlet 22 of the steam dryer 4. A rectifying grid plate 44 that guides the inflowing steam upward is attached to each of the steam inlets 22, and the steam is circulated between the lattice gaps of the rectifying grid plate 44, so that the steam is in a laminar flow state. It is configured to increase the pressure loss of the steam.

  FIG. 9 is an enlarged perspective view showing the configuration of the rectifying grid plate 44, and FIG. 10 is an enlarged perspective view showing the configuration of the rectifying grid plate 44. As shown in these drawings, the rectifying grid plate 44 has a configuration in which a plurality of vertical plates 45 intersect to divide the upward steam inlets 22 in the horizontal direction, and each steam inlet 22 is divided into a plurality of small squares. It is divided as a steam inlet passage. The rectifying grid plate 44 is fixedly installed by welding between the lower end portion of the hood 23 and the support bottom plate 46 of the steam dryer unit 8.

  The plate thickness t of the vertical plate 45 of the rectifying grid plate 44 is, for example, 6 mm, and the height h of the vertical plate 45 is, for example, 30 cm. The vertical and horizontal dimensions x and y of the rectangular steam inlet passage 47 along the divided vertical direction are, for example, 150 cm × 450 cm.

  In FIG. 10, as indicated by an arrow e, the steam flows from the rectifying grid plate 44 arranged at the steam inlet 22 as an upward flow between the hood 23 and the steam dryer unit 8, and then flows laterally by the hood 23. The moisture is separated and removed while passing through the perforated plate 48 and the corrugated plate 49 that are converted and constitute the steam dryer unit 8. The moisture separated from the steam is dropped from the bowl-shaped support bottom plate 46 that supports the lower end of the steam dryer unit 8 to the outer surface side of the skirt 21 through the drain pipe 25.

  FIG. 11 is a plan view showing the arrangement of the rectifying grid plates 44 of the steam dryer. The rectifying grid plates 44 are arranged in two rows of steam dryer units 8 arranged on the peripheral side of the steam dryer. Indicates the state. As shown in FIG. 11, each rectifying grid plate 44 is disposed at each steam inlet 22 between each hood 23 and each steam dryer unit 8 forming a pair of each row, and each hood 23 and each steam dryer unit. 8 is set to the same length. Then, the steam that has risen through the respective rectifying grid plates 44 is knitted and circulated in the horizontal direction, and passes through the steam dryer unit 8 to remove moisture.

  Thus, by providing the rectifying grid plate 44 at the steam inlet 22 below the hood 23, the flow of the gas-liquid two-phase flow rising in the furnace can be adjusted and smoothly flowed into the steam dryer unit 8, Reduction of pressure loss can be achieved. That is, laminar flow expansion and vortex flow reduction at the steam inlet 22 can be achieved, and pressure loss can be reduced. As a result, the influence on the rigidity of the structural member with respect to the increase in output can be increased, and the stress and deformation can be reduced. Furthermore, the stress under the hood 23 can be reduced.

  FIG. 12 is a characteristic diagram shown as a graph for explaining the operation of the rectifying grid plate 44 of such a steam dryer. In FIG. 12, the horizontal axis represents a laminar or turbulent flow state, and the vertical axis represents pressure loss. According to the characteristic line “P2” shown in FIG. 12, a substantially linear proportional relationship is recognized. That is, when the pressure loss in the conventional turbulent flow state where the rectifying grid plate 44 is not provided is “s1”, the pressure loss is large in this embodiment, and it is recognized that the pressure loss moves to “s2” on the laminar flow side. It was recognized that the reduction value of the pressure loss was about ½ that of the conventional example in which the rectifying grid plate 44 was not provided.

  As described above, according to this embodiment, the rectifying grid plate 44 that guides the incoming steam upward is attached to the steam inlet 22 of the steam dryer to reduce the pressure loss, thereby preventing vibration, reducing stress, The deformation can be prevented, the output can be effectively dealt with, and the stress under the hood 23 can be reduced. Furthermore, the configuration is simple and installation is easy.

  Next, the reinforcing member 50 of the steam dryer 4 will be described with reference to FIGS. 8, 13, and 14. 8 and 13 show a configuration example of the reinforcing member mounting configuration. As described above, the steam dryer 4 is provided with the above-described rectifying grid plate 44 and the thin plate structure constituting the steam flow path. These thin plate structures are subjected to stress due to fluid vibration and fluid force during reactor operation. Therefore, in this embodiment, a reinforcing member is attached to these thin plate structures, in particular, the skirt 21, the hood 23, and the end plate 42 of the steam dryer, to reduce stress due to fluid vibration and fluid force. It is said.

  8 and 13 show a configuration in which the reinforcing member 50 is provided on the skirt 21, the hood 23, and the end plate 42 of the steam dryer 8. As shown in these drawings, the skirt 21 has a cylindrical shape depending from the support ring 41, and a plurality of upper and lower ring-shaped reinforcing members 50 along the circumferential direction are spaced in the vertical direction on the outer peripheral surface of the skirt 21. It is provided with a gap. A plurality of longitudinal reinforcing members 50 are provided on the outer peripheral surface of the skirt 21 at intervals in the circumferential direction. These reinforcing members 50 are formed of stainless steel strips having a predetermined thickness, and are integrally joined to the skirt 21 by welding. With this configuration, it is possible to increase the rigidity of the skirt 21 made of a thin plate material and reduce fluid vibration and stress due to fluid force.

  Further, on the outer surface side of the hood 23, reinforcing members 50 are provided along the vertical direction at appropriate positions at both end positions in the lateral direction and intermediate positions thereof. Further, the reinforcing member 50 of the hood 23 is also provided on the upper surface of the bottom plate 43 connected to the lower end portion of the hood 23 by welding. These reinforcing members 50 are also made of stainless steel strips having a predetermined thickness, and are integrally joined to the outer surface of the hood 23 and the upper surface of the bottom plate 43 by welding. With this configuration, the hood 23 can be prevented from bulging during operation. That is, in the conventional structure, the hood 23 bulges outward due to the differential pressure due to the vapor pressure on the inner surface. This bulge becomes even more pronounced when the output is increased. On the other hand, in this embodiment, the swelling of the hood 23 can be suppressed by providing the reinforcing member 50. Moreover, the deformation | transformation of the whole can be suppressed by providing the reinforcement member 50 also in the center part of the food | hood 23. FIG. Thereby, the stress which arises in the welding part of the food | hood 23 edge part and the end plate 42 can be reduced. Further, vibration can be prevented.

  Further, an end plate reinforcing member 50 is provided on the outer surface of the end plate 42 over the entire periphery, and a plurality of horizontally long reinforcing members 50 are provided at appropriate positions on the outer surface of the intermediate portion of the end plate 42. Yes. These reinforcing members 50 are also made of stainless steel strips having a predetermined thickness, and are integrally joined to the end plates 42 by welding. Since the end plate 42 has a flat plate shape, the end plate 42 is easily deformed into a cylindrical shape by an internal pressure. On the other hand, in this embodiment, by providing the reinforcing member 50, the deformation can be effectively suppressed. Moreover, since the hood 23 and the end plate 42 are discontinuous in shape, excessive stress is generated due to internal pressure. In the present embodiment, the stress due to the internal pressure can be reduced by providing the reinforcing member 50 at the welded portion between the hood 23 and the end plate 42.

  FIG. 14 shows a configuration in which a reinforcing member 50 is further added to the central portion of the hood 23 as another configuration example of the reinforcing member mounting configuration. In addition, in this FIG. 14, the whole arrangement configuration in the steam dryer 4 is shown as a top view. In the configuration of FIG. 14, by adding the reinforcing member 50 to the central portion of the hood 23 of each steam dryer unit 8, a further reinforcing effect can be obtained, and the mechanical strength accompanying an increase in output can be improved. it can.

The perspective view which shows one Embodiment of the boiling water reactor which concerns on this invention, and shows the structure of a steam-water separator. BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows one Embodiment of the boiling water reactor which concerns on this invention, and shows the effect | action of a steam-water separator. The expanded plan view which shows one Embodiment of the boiling water reactor which concerns on this invention, and shows a steam-water separator unit. The side view which shows one Embodiment of the boiling water reactor which concerns on this invention, and shows a part of steam-water separator unit as the AA line cross section of FIG. The expanded sectional view which shows one Embodiment of the boiling water reactor which concerns on this invention, and shows one structural example of the connection part of the rim | limb trunk | drum of a steam-water separator and a core shroud. The expanded sectional view which shows one Embodiment of the boiling water reactor which concerns on this invention, and shows the other structural example of the connection part of the rim | limb trunk | drum of a steam-water separator and a core shroud. The expanded sectional view which shows one Embodiment of the boiling water reactor which concerns on this invention, and shows the further another structural example of the connection part of the rim | limb trunk | drum and core shroud of a steam-water separator. The perspective view which shows one Embodiment of the boiling water reactor which concerns on this invention, and shows the structure of a steam dryer. The perspective view which shows one Embodiment of the boiling water reactor which concerns on this invention, and expands and shows the structure of a rectification | straightening grid plate. The perspective view which shows one Embodiment of the boiling water reactor which concerns on this invention, and expands further the structure of a rectification | straightening grid plate. The top view which shows one Embodiment of the boiling water reactor which concerns on this invention, and shows the whole structure of the rectification | straightening grid plate of a steam dryer. An embodiment of a boiling water nuclear reactor according to the present invention, illustrating an operation of a rectifying grid plate of a steam dryer. The side view which shows one Embodiment of the boiling water reactor which concerns on this invention, and shows the structure of the reinforcement member of a steam dryer. The top view which shows one Embodiment of the boiling water reactor which concerns on this invention, and shows the structure of the reinforcement member of a steam dryer. Schematic which shows the structure of the steam-water separator steam dryer of a boiling water reactor. The perspective view which expands and shows the structure of the steam-water separator in the conventional boiling water reactor. The top view which partially expands and shows the holding structure of the conventional steam-water separator unit. Sectional drawing which shows the connection structure of the steam-water separator in the conventional boiling water reactor. The perspective view which shows the structure of the steam dryer in the conventional boiling water reactor.

Explanation of symbols

2 Reactor pressure vessel 3 Steam / water separator 4 Steam dryer 5 Shroud head 6 Steam / water separator unit 7 Stand pipe 8 Steam dryer unit 10 Rim barrel 12 Core shroud 14 Lower support ring 15 Upper support ring 23 Steam inlet 31 Connection Plate 32 Opening 33 Gutter 34 Skirt 35 Groove 36 Protrusion 37 Protrusion 38 Groove 39 Groove 40 Protrusion 41 Support ring 42 End plate 44 Rectification grid plate 45 Vertical plate 46 Support bottom plate 48 Perforated plate 49 Corrugated plate 50 Reinforcing member

Claims (3)

In a boiling water nuclear reactor provided with a steam-water separator and a steam dryer having a function of separating moisture in the reactor from steam generated in the reactor above the core of the reactor pressure vessel, the steam dryer includes: A support ring provided along the upper periphery of the steam separator, a skirt hanging along the support ring, and a steam inlet standing in parallel on the support ring and having an upward steam inlet opened at the lower end. A plurality of curved hoods, and a steam dryer unit that is installed opposite to the side of each hood and deflects steam horizontally to separate moisture, and the inflowing steam is introduced into the steam inlet at the lower end of the hood. A boiling water reactor characterized in that a pressure rectifying grid plate is attached to reduce pressure loss. The boiling water mold according to claim 1, wherein the steam dryer has a thin plate structure constituting a steam flow path, and a reinforcing member is attached to the thin plate structure to reduce stress due to fluid vibration and fluid force. Reactor. The boiling water reactor according to claim 2 , wherein the thin plate structure constituting the steam flow path is a skirt, a hood or an end plate of the steam dryer unit of the steam dryer.

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