JP5858718B2 - Control rod for boiling water reactor - Google Patents

Description

  The present invention relates to a control rod for a boiling water reactor.

  A control rod used in a boiling water reactor has a cross-shaped cross section, and has four blades extending in four directions from a tie rod disposed at an axial center and having a neutron absorbing member disposed therein. In a boiling water reactor, each operation of inserting the control rod into the core and withdrawing it from the core is performed to start and stop the reactor and to control the reactor power during the operation of the reactor. The control rod is inserted between the fuel assemblies loaded in the core, specifically, between the channel boxes of the fuel assemblies arranged adjacent to each other. There are three types of control rods as the main control rods in boiling water reactors.

The first control rod has four blades each having a sheath whose cross section is U-shaped and whose both ends are joined to tie rods and a neutron absorbing member disposed in the sheath. As an example of the first control rod, there is a control rod using a plurality of neutron absorbing rods filled with boron carbide (B ₄ C), which is a neutron absorbing material, as a neutron absorbing member disposed in a sheath. Further, as another example of the first control rod, there is a control rod using a flat hafnium cylindrical body in a neutron absorbing member arranged in the sheath (see JP-A-9-61576).

  The second control rod includes a plurality of blades extending in four directions from a tie rod disposed at an axial center, and a plurality of annular members each having a square cross section arranged in a horizontal direction and coupled to each other in the annular direction. The control rod is formed by filling a neutron absorbing material in a hole extending in the direction (see Japanese Patent Laid-Open No. 1-254895).

  The third control rod includes a plate-shaped metal member and a blade extending in all directions from an axial center including a neutron absorber filled in a hole formed in the metal member in the axial direction of the blade or in a direction perpendicular to the axial direction. (Refer to FIG. 2a and FIG. 2d of JP-T-2002-533736).

  All of these control rods are inserted between a plurality of fuel assemblies loaded in the core provided in the reactor pressure vessel of the boiling water reactor. The operation of starting and stopping the reactor and adjusting the output during the operation of the reactor are performed by the operation of inserting the control rod into the core and the operation of extracting the control rod from the core.

  In recent years, a deterioration phenomenon of a sheath which is a structural member of a control rod, which is considered to be caused by irradiation-induced stress corrosion cracking (hereinafter referred to as IASCC) (IASCC) has been confirmed. IASCC may occur when the three factors of neutron irradiation dose, tensile stress, and environmental conditions overlap. Generally, the neutron irradiation amount of the control rod tends to increase as it goes toward the handle in the axial direction of the control rod. Further, as one of the generation factors of the tensile stress, the influence of the tensile residual stress generated in the sheath which is the structural member in connection with the welding operation of the structural member at the time of manufacturing the control rod can be considered. Furthermore, as an environmental condition, it is considered that a gap environment in which the cooling water in the control rod flows may be involved in IASCC. In order to suppress the potential of IASCC generation, the second control rod and the third control rod are effective from the viewpoint of avoiding the formation of a gap through which cooling water flows in the control rod.

  In the event of an earthquake, it is necessary to quickly stop all of the control rods, including the control rods that have been completely extracted from the core, and to stop the reactor urgently. The greater the magnitude of the earthquake, the greater the horizontal displacement of each fuel assembly loaded in the core, but even if such displacement occurs in each fuel assembly due to the earthquake, the control rods It is required to be rapidly inserted between the cores, that is, horizontally displaced fuel assemblies.

  As a third control rod that is favorable from the viewpoint of suppressing the occurrence of IASCC, a control rod has been proposed that further improves rapid insertion between fuel assemblies when an earthquake occurs (Japanese Patent Laid-Open No. 2011-80985). See the official gazette).

  A boiling water reactor control rod described in Japanese Patent Application Laid-Open No. 2011-80985, which is an example of a third control rod, has a cross-shaped cross section. In this boiling water reactor control rod, four blades extending in four directions from the axial center are made of a plate-shaped metal member and a neutron absorber filled in a hole formed in the metal member in the axial direction of the blade. Contains. The control rod described in Japanese Patent Application Laid-Open No. 2011-80985 has a first region including a first cross section in which four blades are coupled to each other in the axial direction, and four blades are separated from each other. A second region including two cross sections and two blades arranged side by side in one direction are joined together by a bridging portion, and the other two blades orthogonal to these blades are separated from each other And a third region including a third cross section. In the third region, the other two blades existing in the direction orthogonal to the bridging portion are not joined at the bridging portion but separated from each other.

JP-A-9-61576 JP-A-1-254895 Japanese translation of PCT publication No. 2002-533736 JP2011-80985A

  In the control rod for boiling water reactor described in JP2011-80985A, the occurrence of IASCC in the structural member is suppressed because the gap through which the cooling water flows is not formed inside the blade. This is an effective control rod because it can be easily inserted into the core.

  The inventors have examined in detail such an effective control rod described in Japanese Patent Application Laid-Open No. 2011-80985, and found that four sheets in the first region existing at the upper end portion of the neutron absorber filling portion of the blade. A new problem has been found that there is a possibility that the stress generated in the portion where the blades of the blades are joined may increase.

  An object of the present invention is to provide a boiling water reactor control rod that can reduce the stress generated at the insertion-side end of the control rod during insertion into the core in the event of an earthquake.

A feature of the present invention that achieves the above-described object is that the plurality of regions formed in the axial direction of the control rod include a first region including a first cross section that connects the four blades to each other; A plurality of second regions arranged in the axial direction of the control rod including a second cross section in which two blades are separated from each other, and a pair of four blades are coupled by a bridging portion. A pair of blades orthogonal to each other, including a third cross section separated from each other and disposed between the second regions in the axial direction thereof,
The first region is arranged closer to the insertion end side of the control rod than all the second regions and all the third regions,
The width of each gap formed between the bridging portion included in each of the plurality of third regions and the blade orthogonal to the bridging portion is determined by a plurality of bridgings connecting the pair of blades in each pair of blades. This is because the gap formed by the bridging portion located closest to the insertion end of the portion is the narrowest.

  When a control rod that has been fully pulled out of the core is quickly inserted into the core during an earthquake, the blades of the control rod are forced to displace the fuel support bracket from the fuel support bracket that supports the fuel assembly during the earthquake. Displaces in the direction of vibration due to the earthquake. However, the widths of the gaps formed between the bridging portions included in the plurality of third regions and the blades orthogonal to the bridging portions are different from each other in the pair of blades. When the control rod 1 fully pulled out from the core at the time of an earthquake is rapidly inserted into the core, the gap formed by the bridge portion present at the position closest to the insertion end of the bridge portion of In addition, even when the pair of blades joined at the bridging portion is displaced by a forced displacement applied from the fuel support bracket during an earthquake, the bridging portion present at the position closest to the insertion end portion is displaced in the horizontal direction. Movement is constrained faster than other bridges by blades orthogonal to the bridge. For this reason, the amount of movement in the horizontal direction of the bridging portion present at the position closest to the insertion end is reduced, and the pair of blades connected by the bridging portion present at the position closest to the insertion end is connected. The fixed end moment generated in the first region on the insertion end side can be reduced. As a result, it is possible to reduce the stress generated in the portion where the pair of blades are connected to the first region.

The above object is achieved by the fact that the plurality of regions formed in the axial direction of the control rod include a first region including a first cross section connecting the four blades to each other, and the four blades are separated from each other. A plurality of second regions arranged in the axial direction of the control rod including two cross sections, and a first pair of four blades of the four blades are coupled by a bridging portion and are orthogonal to the bridging portion. A plurality of third regions arranged in an axial direction including a third cross section in which a pair of two blades are separated from each other;
The first region is disposed closer to the insertion end of the control rod than the plurality of second regions and the plurality of third regions, and forms the other end of the control rod on the side opposite to the insertion end to form four blades A lower support member attached to the
Between the first pair of blades between the plurality of first bridging portions that couple the respective blades of the first pair of blades, than the first bridging portion that is located closest to the insertion end portion. Between the first pair of blades on the insertion end side and between the first pair of blades on the lower support member side of the first bridging portion located closest to the lower support member, respectively. 1 opening is formed,
A plurality of first bridging portions connecting the respective blades of the first pair of blades each form a second opening;
Between the second pair of blades connecting the respective blades of the second pair of blades, between the second pair of blades, than the second bridge portion present at the position closest to the insertion end portion. Between the second pair of blades on the insertion end side and between the second pair of blades on the lower support member side of the second bridging portion located closest to the lower support member, respectively. 3 openings are formed,
A plurality of second bridging portions connecting the respective blades of the second pair of blades respectively form fourth openings communicating with the third opening on the insertion end side of the second bridging portion;
Each second bridging portion is disposed separately through each second opening, and each first bridging portion is disposed separately through each fourth opening,
Each second bridge formed in each of the plurality of first bridges, each of the second bridges penetrating separately from the side face facing each other in the width direction of the first pair of blades and each second opening. The width of each gap formed between the first and second bridging portions is the closest to the insertion end portion among the plurality of first bridging portions that couple the first pair of blades. Is the narrowest gap formed by
Each of the fourth openings formed in the plurality of second bridges, the side faces of the fourth pair of blades facing each other in the width direction and each of the second openings separately penetrating each of the fourth openings. The width of each gap formed between the first and second bridging portions is the second bridging portion and the second bridging portion that are located closest to the insertion end portion among the plurality of second bridging portions that couple the second pair of blades. This can also be achieved by the narrowest gap formed by.

  According to the present invention, it is possible to reduce the stress generated at the insertion-side end portion of the control rod during insertion into the reactor core when an earthquake occurs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a boiling water nuclear reactor control rod according to embodiment 1, which is a preferred embodiment of the present invention. It is a perspective view of one board member which constitutes the control rod for boiling water reactors shown in FIG. It is a perspective view of two board members arrange | positioned in the direction orthogonal to the board member shown in FIG. It is a cross-sectional view of the connection part which couple | bonds four blades in the upper end part of the handle | steering_wheel of the boiling water reactor control rod shown in FIG. FIG. 2 is a cross-sectional view of the boiling water nuclear reactor control rod shown in FIG. 1 in a region where four blades are separated from each other. The other two blades of the control rod for boiling water reactor shown in FIG. 1 that are arranged in a direction orthogonal to these blades by joining two blades arranged side by side in one direction orthogonal to the axis. It is a cross-sectional view in a region where the blades are separated from each other. In the boiling water reactor control rod shown in FIG. 1, two blades arranged side by side in one direction shown in FIG. 6 are separated from each other and exist in a direction perpendicular to these blades. It is a cross-sectional view in a region where other two blades are coupled. It is TT sectional drawing of FIG. Is _S 1 -S ₁ cross-sectional view of FIG. Is _S 2 -S ₂ cross-sectional view of FIG. Is _S 3 -S ₃ cross-sectional view of FIG. Is _S 4 -S ₄ cross-sectional view of FIG. Is _S 5 -S ₅ cross-sectional view of FIG. Is _S 6 -S ₆ cross-sectional view of FIG. It is explanatory drawing which shows a deformation | transformation when the forced displacement is provided from the fuel support metal fitting at the time of an earthquake of the control rod for boiling water reactors shown in FIG. 1 fully pulled out from the core. It is explanatory drawing which shows the state to which a forced displacement is provided from the fuel support metal fitting at the time of the earthquake of the conventional control rod for boiling water reactors pulled out from the core. It is explanatory drawing which shows the deformation | transformation at the time of the forced displacement being provided from the fuel support metal fitting at the time of the earthquake of the conventional control rod for boiling water reactors fully pulled out from the core. A newly assumed control rod obtained by removing a portion where four blades are joined from the conventional boiling water reactor control rod shown in FIG. 17 is subjected to a forced displacement from the fuel support bracket during an earthquake. It is explanatory drawing which shows a deformation | transformation. It is a cross-sectional view of the control rod for boiling water reactors of Example 2 which is another Example of this invention. It is a block diagram of the control rod for boiling water reactors of Example 3 which is another Example of this invention. Is V ₁ -V ₁ cross-sectional view of there Figure 22 a configuration diagram of a boiling water nuclear reactor control rod is Example 4 in another embodiment of the present invention. A _V 2 -V ₂ cross-sectional view of FIG. 21. It is explanatory drawing which shows the characteristic of each control rod for boiling water reactors of Example 1, 3 and 4 of this invention. It is X ₁ -X ₁ cross-sectional view of there Figure 25 a configuration diagram of a boiling water nuclear reactor control rod in an exemplary 5 another embodiment of the present invention. Is _X 2 -X ₂ cross-sectional view of FIG. 24. Is a Y ₁ -Y ₁ cross-sectional view of there Figure 27 a configuration diagram of another BWR control rod of Example 6 is an embodiment of the present invention. It is a _Y 2 -Y ₂ cross-sectional view of FIG. 26. It is Z ₁ -Z ₁ cross-sectional view of there Figure 29 a configuration diagram of another embodiment in which a boiling water nuclear reactor control rod according to a seventh embodiment of the present invention. It is _Z 2 -Z ₂ cross-sectional view of FIG. 28.

  As described above, the inventors examined in detail the control rod described in Japanese Patent Application Laid-Open No. 2011-80985. As a result, the four rods in the first region existing at the upper end portion of the neutron absorber filling portion of the blade were obtained. A new problem has been found that there is a risk that the stress generated in the portion where the blades are joined may increase. The result of this examination will be described below.

  The control rod described in Japanese Patent Application Laid-Open No. 2011-80985 has a cross-shaped cross section, and a first region including a first cross section in which four blades are coupled to each other in the axial direction, A second region including a second cross section in which four blades are separated from each other, and two blades arranged side by side in one direction orthogonal to the axis of the control rod are joined together by a bridging portion; The other two blades orthogonal to these blades have a third region including a third cross section separated from each other. The control rod having such a configuration imparts an appropriate bending rigidity to the structural strength member of the control rod, thereby improving the insertability of the control rod into the core during an earthquake.

  However, at the time of rapid insertion of the control rod into the core during an earthquake, the control rod is inserted from the fuel support fitting through which the control rod passes and the control rod guide tube that guides the control rod according to the amount of insertion of the control rod into the core. Restraint changes. As shown in FIG. 16, the control rod 32 that has been completely extracted from the core is present in the control rod guide tube 39. The handle 3 </ b> A of the control rod 32 having four blades 31 passes through the fuel support fitting 38 that supports the fuel assembly 37 and reaches above the fuel support fitting 38. When an earthquake occurs in this state, the control rod 32 is given a forced displacement 30 from the fuel assembly 37, the fuel support bracket 38, and the control rod guide tube 39 displaced by the earthquake inertia force. The control rod 32 is provided with a speed limiter 36 at the lower end, and is arranged side by side in one direction orthogonal to the axis of the control rod 32 as described in Japanese Patent Application Laid-Open No. 2011-80985. The two blades 31 are coupled to each other by a bridging portion 34A at a plurality of positions in the axial direction. An opening 35 is formed between the adjacent bridge portions 34A.

The deformation of the control rod 32 given the forced displacement 30 will be described with reference to FIG. The control rod 32 has four blades 31, that is, blades 2A ′, 2B ′, 2C ′ and 2D ′. In FIG. 17, the blade 2B ′ is not shown. The blades 2A ′, 2B ′, 2C ′ and 2D ′ are connected to each other by a connecting portion 33 located at the upper end. The blades 2A ′ and 2C ′ arranged in a straight line in one direction orthogonal to the axis of the control rod 32 are joined by a bridging portion 34A at a plurality of locations in the axial direction. The blade 2B ′ and the blade 2D ′, which are linearly arranged in a direction orthogonal to the blades 2A ′ and 2C ′, are joined by a bridging portion 34B at a plurality of positions in the axial direction. The bridging portion 34B is disposed in an opening 35 formed between the blade 2A ′ and the blade 2C ′. The bridging portion 34A is also disposed in an opening (not shown) formed between the blade 2B ′ and the blade 2D ′. 8A ₁ is an opening formed in the handle 3A.

  As shown in FIG. 16, the control rod 32 that has been completely pulled out from the core is deformed by the forced displacement 30 applied from the fuel support fitting 38 during an earthquake (see FIG. 17). Due to the forced displacement 30 applied from the fuel support bracket 38, displacement occurs in the blades 2B ′ and 2D ′ orthogonal to the direction in which the forced displacement 30 is applied (the direction in which the fuel support bracket 38 vibrates due to an earthquake) The inventors have found that high bending stress may occur in the blades 2B ′ and 2D ′ in the vicinity of the connecting portion 33. The inventors considered that this high bending stress is generated due to movement of the blades 2 </ b> B ′ and 2 </ b> D ′ in the direction in which the forced displacement 30 is applied by applying the forced displacement 30. Among the bridging portions 34B connecting the blade 2A 'and the blade 2C', which are respectively disposed in a plurality of openings 35 formed between the blade 2A 'and the blade 2C' in the axial direction of the control rod 32, the handle As shown in FIG. 17, the bridging portion 34B closest to 3A moves until it collides with the side surface on the opening 35 side of the blade 2C ′. By such movement of the bridging portion 34B, the blade 2D 'and the blade 2B', which are in a state perpendicular to the handle 3A as indicated by the dotted line before the occurrence of the earthquake, are bent as indicated by the solid line. As a result, high bending stress is generated in the blades 2B 'and 2D' in the vicinity of the connecting portion 33.

Therefore, the inventors considered a new control rod 32A in communication with the opening 35 closest to the opening 8A ₁ and the handle 3A remove the coupling portion 33 in the control rod 32 shown in FIG. 17 (FIG. 18). In the control rod 32A, the blades 2A ′, 2B ′, 2C ′ and 2D ′ are coupled to each other by a connecting portion 45. As shown in FIG. 16, the control rod 32 </ b> A that has been completely pulled out from the core is deformed by the forced displacement 30 applied from the fuel support fitting 38 during an earthquake, in the same manner as the control rod 32. As shown in FIG. 18, the bridging portion 34 </ b> B closest to the handle 3 </ b> A among the bridging members 34 </ b> B that join the blade 2 </ b> B ′ and the blade 2 </ b> D ′ by applying the forced displacement 30 is similar to the control rod 32, as shown in FIG. It moves until it collides with the side surface on the opening 35 side of '. As a result, the blade 2D ′ and the blade 2B ′, which are in a state perpendicular to the connecting portion 45 of the handle 3A before the occurrence of the earthquake, are indicated by the solid line by the movement of the bridging portion 34B. To be bent.

  However, in the control rod 32A, the distance between the bridging portion 34B closest to the handle 3A and the connecting portion 45 among the bridging portions 34B connecting the blade 2B 'and the blade 2D' is the largest handle in the control rod 32 shown in FIG. Since the distance between the bridging portion 34B and the connecting portion 33 near 3A is longer, the degree of bending of the blades 2B 'and 2D' of the control rod 32A is slightly larger than the degree of bending of the blades 2B 'and 2D' of the control rod 32 Get smaller. Therefore, the bending stress generated in the vicinity of the connecting portion 45 of the blades 2B 'and 2D' in the control rod 32A is slightly smaller than the bending stress generated in the vicinity of the connecting portion 33 of the blades 2B 'and 2D' in the control rod 32. Although the bending stress is reduced, the amount of the reduction is slight, and the bending stress generated in the vicinity of the connecting portion 45 of the blades 2B 'and 2D' is also high in the control rod 32A.

  The inventors examined various measures for further reducing the bending stress generated by the blades in the vicinity of the connecting portion where the four blades 2A 'to 2D' are coupled in the control rod 32A. As a result of these studies, the inventors have a new measure that when the forced displacement 30 is applied during an earthquake, the amount of movement of the bridging portion that moves in the direction in which the forced displacement 30 is applied may be reduced. I came up with the idea. For this reason, a pair of blades (for example, blades 2A ′ and 2C ′) arranged in a straight line in one direction orthogonal to the axis of the control rod among the four blades are coupled to each other. A bridging portion (for example, bridging portion 34A) that is closest to the handle 3A among the bridging portions (for example, bridging portion 34A), and two blades (for example, blade 2B ′) orthogonal to the bridging portion The width of the gap formed between the blade 2D ′) is set such that the other bridge part (the other bridge part 34A) disposed below the bridge part and the blade (for example, the blade 2B) orthogonal to the bridge part. Narrower than the width of the gap formed between 'and blade 2D') and arranged in a direction orthogonal to the pair of blades (for example, blades 2A 'and 2C') among the four blades. In the pair of blades (for example, blades 2B ′ and 2D ′), a bridge portion (for example, the bridge portion 34B) that couples the other pair of blades is located closest to the handle 3A (for example, the bridge portion 34B). The width of the gap formed between the bridging portion 34B) and two blades orthogonal to the bridging portion (for example, the blade 2A ′ and the blade 2C ′) is disposed below the bridging portion. A structure of a new control rod that is narrower than the width of the gap formed between the other bridging portion (the other bridging portion 34B) and a blade (for example, blade 2A ′ and blade 2C ′) orthogonal to the bridging portion. The inventors have figured out.

  An embodiment of the present invention that reflects the new structure obtained by the above examination will be described below.

  A boiling water nuclear reactor control rod according to embodiment 1, which is a preferred embodiment of the present invention, will be described with reference to FIGS.

  The control rod 1 for boiling water reactor of this embodiment (simply referred to as “control rod” in the embodiment described below) 1 includes four blades 2A, 2B, 2C and 2D, a handle 3 and a lower support member 4. It has. The blades 2A and 2C and the handle element 3E which is a part of the handle 3 are constituted by a single plate member 4A. The blade 2B and the handle element 3F which is a part of the handle 3 are constituted by a single plate member 4B. The blade 2D and the handle element 3G which is a part of the handle 3 are constituted by a single plate member 4C.

The blades 2A and 2C constituted by the plate member 4A and the handle element 3E which is a part of the handle 3 will be described with reference to FIG. The plate member 4A is formed with a connecting portion 5A that is a part of the handle 3 at one end, and further, with openings 8A ₁ , 8A ₂ , 8A ₃ and 8A ₄ and a plurality of openings 8A ₅ . . The openings 8A ₁ , 8A ₂ , 8A ₃ and 8A ₄ and the plurality of openings 8A ₅ are in the axial direction of the control rod 1, that is, the other end of the plate member 4A from the connecting portion 5A in the longitudinal direction of the plate member 4A. Are arranged in this order toward the center of the plate member 4 </ b> A. The width direction of the plate member 4A is a direction orthogonal to the longitudinal direction of the plate member 4A, and is also the width direction of the blades 2A and 2C.

Have a width of WO3, the openings 8A ₅ forming the opposite sides 15 is of a rectangular shape, the long sides of the rectangle is facing the longitudinal direction of the plate member 4A. Opening 8A ₁ is rectangular, the long side of the rectangle is facing the width direction of the plate member 4A. Width of the opening 8A ₁ is Wh. The formation of the openings 8A _1, handle element 3E including connecting portion 5A is formed at one end of the plate member 4A. Forming a side 9 that faces have a width Wo1, openings 8A ₂ which is elongated in the longitudinal direction of the plate member 4A is in communication with the openings 8A _1. Opening 8A ₃ includes an opening width Wo1 that forms the opening and opposing sides 11 of the opposing width to form the sides 10 Wo2. In the opening 8A _3, the opening of the opposite sides 11 and the form which the width Wo1 is positioned in the connecting parts 5A side of the aperture width Wo2 forming the side surfaces 10 facing each other. Opening 8A ₄ includes an opening width Wo2 forming the side surfaces 14 opening and opposing wide Wo3 forming the side surfaces 13 opposed. In the opening 8A _4, the opening of the opposing width to form the sides 14 Wo2 is positioned in the connecting parts 5A side of the aperture width Wo3 forming the side surfaces 13 opposed. The widths Wo1, Wo2 and Wo3 satisfy the relationship Wo1 <Wo2 <Wo3.

Opening 8A ₃ has an opening of the aperture and the width Wo2 of width Wo1, it forms a stepped portion by the side 11 and the side surface 10 to side surface. Even if the bridging portion 6A ₁ is moved to the end portion of the plate member 4A opposite to the connecting portion 5A, the end surface of the bridging portion 6A ₁ opposite to the connecting portion 5A is positioned at the upper end position of the side surface 10. Good. Also in the opening 8A _4, the step portion is formed by the side surface 14 and side surfaces 13 on the sides. Even when the bridge portion 6A ₁ connecting parts 5A of the bridge portion 6A ₂ is moved to the end opposite to the plate member 4A, it is positioned at the position of the upper end of the side surface 13 of the end surface opposite to the connecting portion 5A Good. With such a configuration, the opening 8A ₃ and 8A ₄ becomes a rectangle, fabrication is facilitated.

In the plate members 4A shown in FIG. 2, the blades 2A is formed on the right side of the opening _{8A 1, 8A 2, 8A 3} , 8A 4 and 8A _5, blade 2C is formed on the left side of these openings.

By forming the openings 8A ₁ , 8A ₂ , 8A ₃ and 8A ₄ and the plurality of openings 8A ₅ , a plurality of bridging portions (bridging members) that join the blade 2A and the blade 2C are formed in the plate member 4A. That is, the bridge portion 6A ₁ is formed between the openings 8A ₂ and the opening 8A _3, the bridge portion 6A ₂ is formed between the openings 8A ₃ and the opening 8A _4. Furthermore, the closest bridge 6A ₃ to the handle element 3E of the three bridge portions 6A ₃ is formed between the opening 8A ₄ and the opening 8A _5. Also between each of the three openings 8A ₅ is cross section 6A ₃ are formed. The bridging portions 6A _{1 to} 6A ₃ join the blade 2A and the blade 2C.

Bridge portions 6A _1, the length in the width direction of the blade 2A, 2C is the same as the width Wo1 openings 8A _2. Bridge portions 6A _2, the length of the blade 2A, 2C width direction is the same as the width Wo2 of the portion forming the side surface 10 facing the opening 8A _3. Bridge portions 6A _3, the length of the blade 2A, 2C width direction is the same as the width Wo3 of the portion forming the side surface 13 facing the opening 8A _4. For this reason, the respective lengths of the bridging portions 6A ₁ , 6A ₂ and A ₃ in the width direction of the blades 2A and 2C are shorter in the order of the bridging portion 6A ₃ , the bridging portion 6A ₂ and the bridging portion 6A ₁ . In the bridging portions 6A ₁ , 6A ₂ and A ₃ , the length of the bridging portion close to the connecting portion 5A, that is, the handle 3, becomes shorter.

The widths of the blades 2A and 2C are the narrowest in the region h3 shown in FIG. 2 and become wider as the regions h2 and h1 and the handle 3 are closer to each other. The lengths of the regions h1 and h2 in the longitudinal direction of the plate member 4A are equal. Region h1 is the region between the lower end of the blade 2A, the upper end 16 of 2C the opening 8A ₃ sides 11. Region h2 is lower edges of the side surfaces 11, i.e., a region between the lower end of the side surface 14 of the upper end and the opening 8A ₄ sides 10. The region h3 is a region between the lower end of the side surface 14, that is, the upper end of the side surface 13 and the lower ends of the blades 2A and 2C. The width Wb3 of each of the blades 2A and 2C in the region h3, the width Wb2 of each of the blades 2A and 2C in the region h2, and the width Wb1 of each of the blades 2A and 2C in the region h1 satisfy the relationship of Wb3 <Wb2 <Wb1. ing.

  The width of the plate member 4A is W. In the region h1, (Wo1 + 2 × Wb1) has a width W, and in the region h2, (Wo2 + 2 × Wb2) has a width W. Further, in the region h3, (Wo3 + 2 × Wb3) is the width W. The plate member 4A is symmetric with respect to the central axis of the plate member 4A passing through the middle in the width direction of the plate member 4A.

  Next, the blade 2B constituted by the plate member 4B and the handle element 3F which is a part of the handle 3 will be described with reference to FIG. A connecting portion 5B that becomes a part of the handle 3 is formed at one end of the plate member 4B. An L-shaped handle element 3F including the connecting portion 5B is connected to the upper end 16 of the blade 2B.

One end portion of the plate member 4B in the width direction of the plate member 4B, i.e., the end of the shaft center side of the control rod 1, in addition to connecting portion 5B, a connecting portion 17A ₁ and 17A ₂ and a plurality of connecting portions 17A _3, They are formed in this order from the connecting portion 5B toward the other end of the plate member 4B. Connecting portions 17A ₁ and 17A ₂ and a plurality of connecting portions 17A ₃ is extends blades 2B which is formed in the plate member 4B, from the axial center side of the side surface of the control rod 1 in the width direction of the plate member 4B. The width direction of the plate member 4B is the width direction of the blade 2B.

Side 23A of the blade 2B are each present between the connecting portions 17A ₃ adjacent each other, and between the lower end of the connecting portion 17A ₃ and the blade 2B present at a position closest to the lower end of the blade 2B. One stepped portion formed in the side surface 22A of the side 21A and the blade 2B blade 2B is between connecting portions 17A ₃ present at a position closest to the connecting portion 5B of the connection portion 17A ₂ and a plurality of connecting portions 17A ₃ Formed. One stepped portion formed in the side surface 20A of the side 19A and the blade 2B blade 2B is formed between the connecting portions 17A ₁ and the connecting portion 17A _2. Side 18A of the blade 2B is present on the upper end 16 side of the blade 2B than the connecting portion 17A _1.

The length from the side face 18A and 19A to the distal end of the connecting portion 17A ₁ is L1. The length from the side face 20A and 21A to the distal end of the connecting portion 17A ₂ is L2. The length from the side face 23A and 22A to the most close coupling portion 17A ₃ distal to the connecting portion 5B of the connection portion 17A ₃ is L3. Length from the side surface 23A to the rest of the tip of each coupling portion 17A ₃ also L3. The lengths L1, L2, and L3 satisfy the relationship L1 <L2 <L3.

  In the plate member 4B, the region h1 is a region between the upper end 16 of the blade 2B and the lower end of the side surface 19A. The region h2 is a region between the lower end of the side surface 19A, that is, between the upper end of the side surface 20A and the lower end of the side surface 21A. Region h3 is the lower end of side surface 21A, that is, the region between the upper end of side surface 22A and the lower end of blade 2B. The width of the blade 2B in the region h3 including the side surface 22A and the plurality of side surfaces 23A is Wb3, the width of the blade 2B in the region h2 including the side surfaces 20A and 21A is Wb2, and further in the region h1 including the side surfaces 18A and 19A. The width of the blade 2B is Wb1. These widths Wb3, Wb2 and Wb3 satisfy the relationship of Wb3 <Wb2 <Wb1.

  The width of the plate member 4B is 1/2 of the width W of the plate member 4A and is W / 2. In the plate member 4B, (Wb1 + L1) has a width W / 2 in the region h1, and (Wb2 + L2) has a width W / 2 in the region h2. Further, in the area h3, (Wb3 + L3) has a width W / 2.

  In the control rod 1, the plate member 4C aligned with the plate member 4B in the direction orthogonal to the axis of the control rod 1 has the same shape as the plate member 4B.

  The blade 2D constituted by the plate member 4C and the handle element 3G which is a part of the handle 3 will be described with reference to FIG. A connecting portion 5C that becomes a part of the handle 3 is formed at one end of the plate member 4C. An L-shaped handle element 3G including the connecting portion 5C is connected to the upper end 16 of the blade 2D.

One end portion of the plate member 4C in the width direction of the plate member 4C, i.e., the end of the shaft center side of the control rod 1, in addition to connecting portion 5C, the connecting portion 17B ₁ and 17B ₂ and a plurality of connecting portions 17B _3, They are formed in this order from the connecting portion 5C toward the other end of the plate member 4C. Connecting portions 17B ₁ and 17B ₂ and a plurality of connecting portions 17B ₃ is extends blade 2D formed in the plate member 4C, from the axial center side of the side surface of the control rod 1 in the width direction of the plate member 4C. The width direction of the plate member 4C is the width direction of the blade 2D.

Between blades mutual coupling portion 17B ₃ side surface 23B is adjacent 2D, and exists between each of the connecting portions 17A ₃ and the blade 2D lower end present at a position closest to the lower end of the blade 2D. One stepped portion formed by the blade 2D sides 21B and the blade 2D side 22B is formed between the nearest connection portion 17B ₃ to the connecting portion 5C of the connecting portion 17B ₂ and a plurality of connecting portions 17B ₃ . One stepped portion formed by the blade 2D sides 19B and the blade 2D side 20B is formed between the connecting portions 17B ₁ and the connecting portion 17B _2. Blade 2D side 18B is present on the upper end 16 side of the blade 2D than the connecting portion 17B _1.

Length from the side surface 18B and 19B to the distal end of the connecting portion 17B ₁ is L1. Length from the side surface 20B and 21B to the distal end of the connecting portion 17B ₂ is L2. Length from the side surface 23B and 22B to the most close coupling portion 17B ₃ distal to the connecting portion 5C of the connecting portion 17B ₃ is L3. Length from the side surface 23B to the rest of the tip of each coupling portion 17B ₃ also L3. Also in the plate member 4C, the lengths L1, L2, and L3 satisfy the relationship L1 <L2 <L3.

  In the plate member 4C, the region h1 is a region between the upper end 16 of the blade 2D and the lower end of the side surface 19B. The region h2 is a lower end of the side surface 19B, that is, a region between the upper end of the side surface 20B and the lower end of the side surface 21B. The region h3 is a lower end of the side surface 21B, that is, a region between the upper end of the side surface 22B and the lower end of the blade 2D. The width of the blade 2D in the region h3 including the side surface 22B and the plurality of side surfaces 23B is Wb3, the width of the blade 2D in the region h2 including the side surfaces 20B and 21B is Wb2, and further in the region h1 including the side surfaces 18B and 19B. The width of the blade 2D is Wb1. These widths Wb3, Wb2 and Wb3 also satisfy the relationship of Wb3 <Wb2 <Wb1.

  The width of the plate member 4C is 1/2 of the width W of the plate member 4A and is W / 2. In the plate member 4C, (Wb1 + L1) has a width W / 2 in the region h1, and (Wb2 + L2) has a width W / 2 in the region h2. Further, in the area h3, (Wb3 + L3) has a width W / 2.

In the plate member 4A, the neutron absorber filling portion 7A is formed on the blade 2A, and the neutron absorber filling portion 7C is formed on the blade 2C. In the plate member 4B, the neutron absorber filling portion 7B is formed on the blade 2B. It is necessary to form the neutron absorber filling portion 7D on the blade 2D. For this reason, the plurality of neutron absorber filling holes 28 are filled with the neutron absorber filling portion 7A of the blade 2A, the neutron absorber filling portion 7B of the blade 2B, the neutron absorber filling portion 7C of the blade 2C, and the neutron absorber filling of the blade 2D. The portions 7D are formed side by side in the width direction of the blade (see FIGS. 5, 6, and 7) and extend in the longitudinal direction of each plate member. Each neutron absorbing material filling hole 28 is, for example, extends from the lower end of each blade to the position of the bridge portion 6B ₁ (or blade upper end 16 close to the position of). Each neutron absorber filling hole 28 has a square cross section and a central axis with respect to each of the plate members 4A, 4B and 4C by mechanical hole machining such as gun drilling and electric discharge machining from the lower end of each plate member. Manufactured by arranging multiple tubes with circular holes in the cross section in the width direction of the blade and bonding these tubes to each other by hot isostatic pressing (HIP). Is done.

Neutron absorbers 29 are filled in the respective neutron absorber filling holes 28 (see FIGS. 5, 6 and 7). As the neutron absorber 29, at least one of B ₄ C and hafnium is used. B ₄ C may be directly filled into the neutron absorber filling hole 28 as B ₄ C powder, or the neutron absorber filling hole as a neutron absorber rod filled with B ₄ C powder in a sealed stainless steel tube. 28 may be inserted. Hafnium is inserted into the neutron absorber filling hole 28 as a solid round bar of metal Hf. Since B ₄ C absorbs neutrons and releases helium gas, a plenum for storing helium gas is formed in each blade. Moreover, since hafnium causes irradiation elongation by neutron absorption, it is preferable to pay attention to the design of the plenum so that each blade does not deform. After each neutron absorber filling hole 28 is filled with a neutron absorber 29, a plug is inserted into the neutron absorber filling hole 28, the stopper is joined to the corresponding plate member by welding, and the neutron absorber 29 is filled. Each neutron absorber filling hole 28 is sealed.

  The plate members 4A, 4B, and 4C themselves may be made of a hafnium-based alloy, a gadolinium-based alloy, or a cadmium-based alloy having neutron absorption capability. In this case, the neutron absorber filling hole 28 is not formed in each plate member.

  The plate member 4B is disposed at the center in the width direction of the plate member 4A so that the connecting portion 5B is perpendicular to the connecting portion 5A of the plate member 4A. The connecting portion 5B is coupled to the connecting portion 5A by the welded portion 26. The plate member 4C is also arranged at the center in the width direction of the plate member 4A so that the connecting portion 5C is perpendicular to the connecting portion 5A of the plate member 4A. The connecting portion 5C is coupled to the connecting portion 5A by the welded portion 26. The upper ends of the lower support member 4 having a cross-shaped cross section are joined to the lower ends of the plate members 4A, 4B and 4C by welding. The plate members 4A, 4B, and 4C are integrated by the above welding, and blades 2A, 2B, 2C, and 2D extending in four directions from the axis of the control rod 1 are formed. Four rollers 25 are provided on the lower support member 4, and a connecting portion 12 connected to the control rod drive mechanism is provided on the lower support member 4.

Each weld connection portions 5A and the connecting portion 5B and 5C, each weld of the connection portion _17A formed in the plate member 4B 1 ~17A ₃ and the plate connecting portion _17B formed in the member 4C 1 ~17B _3, Since there is a tensile residual stress in the welded portion between the plate members 4A, 4B and 4C and the lower support member 4, peening techniques such as water jet peening and shot peening are applied to those welded portions to weld them. It is preferable to apply compressive residual stress to the parts to improve the stress of those welds. Instead of applying the peening technique, stress relaxation polishing may be applied to those welds to improve the stress of those welds.

The coupling between the coupling portion 5A and the coupling portions 5B and 5C, the coupling portions 17A _{1 to} 17A ₃ formed on the plate member 4B and the coupling portions 17B _{1 to} 17B ₃ formed on the plate member 4C, and the plate member 4A , 4B and 4C and the lower support member 4 may be joined by friction diffusion bonding instead of welding.

In the plate member 4B and 4C, connecting portions 17A ₁ and 17B ₁ are formed bridge portion 6B ₁ are joined by welds 27, the connecting portion 17A ₂ and 17B ₂ is is bonded bridge portion 6B ₂ at weld 27 is formed, the connecting portion 17A ₃ and 17B ₃ are cross-linked portion 6B ₃ is formed are joined by welds 27. A plurality of openings are formed in the plate members 4B and 4C integrated by the coupling of the respective connecting portions, like the plate member 4A, by the plurality of bridging portions formed by the coupling of the respective connecting portions. That is, the opening 8B ₂ is formed in the connecting portions 5B and 5C side of the bridge portion 6B _1, opening 8B ₃ is formed between the bridge portion 6B ₁ and bridge portion 6B _2, openings 8B ₄ is bridge formed between 6B ₂ and three nearest bridge 6B ₃ to the connecting part 5B and 5C of the bridge portion 6B _3. Two openings 8B ₅ are formed respectively between the three mutually mutually cross section 6B ₃ to next among the bridge portions 6B _3. One opening 8 </ b> B ₅ is formed between the bridge portion 6 </ b> B ₃ and the lower support member 4 that are located closest to the lower support member 4.

The filling of the neutron absorber 29 into the respective neutron absorber filling holes 28 formed in the plate members 4A, 4B and 4C may be performed before the plate members 4A, 4B and 4C are integrated by welding. The connecting portions 5B and 5C are connected to the connecting portion 5A by welding, and the connecting portions 17A _{1 to} 17A ₃ are connected to the connecting portions 17b _{1 to} 17B ₃ by welding, whereby the plate members 4A, 4B and 4C are integrated. It may be performed after conversion.

  The control rod 1 is completed by integrating the plate members 4A, 4B and 4C as described above by welding and welding the lower support member 4 to the lower ends of the plate members 4A, 4B and 4C. The handle 3 is formed by coupling of the connecting portions 5A, 5B, and 5C, that is, coupling of the handle elements 3E, 3F, and 3G.

In the control rod 1, the bridge portions 6B _{1 to} 6B ₃ and the opening portions 8B _{2 to} 8B ₄ formed by coupling the plate members 4B and 4C will be described. The bridge portion 6B _1, length in the blade 2B and 2D in the width direction is Wo1 (= 2 × L1). Bridge portions 6B _2, the length of the blade 2B and 2D in the width direction is Wo2 (= 2 × L2). Each bridge portion 6B _3, the length of the blade 2B and 2D in the width direction is Wo3 (= 2 × L3).

Opening 8B ₂ communicates with opening 8B ₁ formed by handle elements 3F and 3G. Openings 8B _2, (the dimension between the side surface 18A and the side surface 18B which faces) width of the blade 2B and 2D in the width direction is Wo1. Opening 8B ₃ includes an opening facing the width to form an opening and opposing sides 20A and 20B of a width to form the sides 19A and 19B Wo1 Wo2. In the opening 8B _3, located in the bridge portion 6B ₁ side of the aperture opening width Wo2 width Wo1. Opening 8B ₄ includes an opening facing the width to form an opening and opposing sides 22A and 22B of a width to form the sides 21A and 21B Wo2 WO3. In the opening 8B _4, located in the bridge portion 6B ₁ side of the aperture opening width Wo3 width Wo2. Openings 8B _5, (the dimension between the side surface 23A and the side surface 23B which faces) width of the blade 2B and 2D in the width direction is WO3. The widths Wo1, Wo2 and Wo3 satisfy the relationship Wo1 <Wo2 <Wo3.

In the control rod 1, the bridge portion 6A ₁ is disposed between the side surface 19A and the side surface 19B in the opening 8B _3, the bridge portion 6A ₂ is disposed between the side 21A and the side surface 21B in the opening 8B _4, respectively of the bridge portion 6A ₃ are arranged separately each opening 8B _5. Further, the bridge portion 6B ₁ is disposed in the opening 8A _2, the bridge portion 6B ₂ is disposed between the side 10 facing in the opening 8A _3, closest to the handle 3 of the bridge portion 6B ₃ The arranged bridging portion 6B ₃ is arranged between the side surfaces 13 facing each other in the opening 8A ₄ , and the remaining bridging portions 6B ₃ are arranged separately in each opening 8A ₅ .

The control rod 1 has three cross sections having different shapes in the axial direction. The first cross section exists at the position of the upper end portion (insertion end portion) of the handle 3 that is first inserted into the core and the lower support member 4. One of the first cross sections is a cross section in a region where the connecting portions 5A, 5B, and 5C are connected to each other, which connects the four blades 2A, 2B, 2C, and 2D (see FIG. 4). Another one of the first cross sections is a cross section of the lower support member 4 having a cross shape. Region forming a second cross-section, while the upper end 16 of the blade and the bridge portion 6B _1, between the bridge portion 6B ₁ and bridge portions 6A _1, between the bridge portion 6A ₁ and bridge portion 6B _2, the bridge portion 6B ₂ and between the bridge portion 6A _2, between the bridge portion 6B ₃ existing at the nearest position to the handle 3 of the bridge portions 6A ₂ and a plurality of bridge portions 6B _3, the bridge portion 6B ₃ and a plurality of bridge portions 6A ₃ Of these, between the bridging portions 6A ₃ that are closest to the handle 3, between the remaining bridging portions 6B ₃ and the remaining bridging portions 6A ₃ , and the bridging portions that are closest to the lower support member 4. 6A ₃ and the lower support member 4 are respectively present. The second cross section is a cross section in a region where the four blades 2A, 2B, 2C and 2D are separated from each other, as shown in FIG. The region forming the third cross section exists at the position of each bridging portion of the control rod 1. As shown in FIG. 6, one region forming the third cross section is a blade in which the blade 2A and the blade 2C are connected by a bridging portion (for example, the bridging portion 6A ₂ ), and arranged at right angles to these blades. It is a cross section in the field where 2B and blade 2D are separated from each other. Another region forming the third cross section is, as shown in FIG. 7, the blade 2B and the blade 2D are connected by a bridging portion (for example, the bridging portion 6B ₃ ), and arranged perpendicular to these blades. 2B is a cross section in a region where the blade 2A and the blade 2C are separated from each other.

  The control rod 1 in which the first cross section, the second cross section, and the third cross section are formed has a plurality of first regions including the first cross section, a plurality of second regions including the second cross section, and A plurality of third regions including a third cross section are provided.

  In the present embodiment, for example, in the region between the upper end 16 of the blade and the half of the axial length of the blade from the upper end 16 of the blade in the control rod 1, the bridge is opposed to the bridge. As shown in FIG. 8, the width of the gap formed between the side surfaces of the blades, that is, the side surfaces of the openings where the bridging portions are arranged becomes narrower as the handle 3 is approached. The gap formed between the bridging portion and the blade orthogonal to the bridging portion will be described with reference to FIGS.

The position of the bridge portion 6A _1, the control rod 1 has a cross-sectional shape shown in FIG. Bridge 6A attached blade 2A and the blade 2C ₁ is disposed between the blade 2B and the blade 2D that are perpendicular to the bridge portion 6A _1. In the normal state of the control rod 1 the axis of the control rod 1 is straight, the width of the gap formed between the respective bridge portions 6A ₁ and the blade 2B and 2D are both Wg1. The width of each of the blades 2A, 2B, 2C and 2D at this position is Wb1. The addition of the thickness t of the blade 2A and 2C to twice the width Wg1 of the gap is equal to the width Wo1 the opening 8B ₃ at the position where the bridge portion 6A ₁ are arranged (2 × Wg1 + t = Wo1 ).

The position of the bridge portion 6A _2, the control rod 1 has a cross-sectional shape shown in FIG. 10. Bridge 6A attached blade 2A and the blade 2C ₂ is disposed between the blade 2B and the blade 2D that are perpendicular to the bridge section 6A _2. In the normal state of the control rod 1, the width of the gap formed between the respective bridge portions 6A ₂ and the blade 2B and 2D are both Wg2. The width of each of the blades 2A, 2B, 2C, and 2D at this position is Wb2. The addition of the thickness t of the blade 2A and 2C to twice the width Wg2 of the gap is equal to the width Wo2 of the opening 8B ₄ at the position where the bridge portion 6A ₂ are arranged (2 × Wg2 + t = Wo2 ).

The position of the bridge portion 6A _3, the control rod 1 has a cross-sectional shape shown in FIG. 11. Bridge 6A attached blade 2A and the blade 2C ₃ is disposed between the blade 2B and the blade 2D that are perpendicular to the bridge portion 6A _3. In the normal state of the control rod 1, the width of the gap formed between the respective bridge portions 6A ₃ and the blade 2B and 2D are both Wg3. The width of each of the blades 2A, 2B, 2C and 2D at this position is Wb3. The addition of the thickness t of the blade 2A and 2C to twice the width Wg3 of the gap is equal to the width WO3 openings 8B ₅ the cross section 6A ₃ are arranged (2 × Wg3 + t = Wo3 ).

The position of the bridge portion 6B _1, the control rod 1 has a cross-sectional shape shown in FIG. 12. The bridging portion 6B ₁ that couples the blade 2B and the blade 2D is disposed between the blade 2A and the blade 2C that are orthogonal to the bridging portion 6B ₁ . In the normal state of the control rod 1, the width of the gap formed between the respective bridge portions 6B ₁ and the blade 2A and 2C are both Wg1. The width of each of the blades 2A, 2B, 2C and 2D at this position is Wb1. The addition of 2 fold blade 2B and 2D the thickness t of the width Wg1 of the gap is equal to the width Wo1 the opening 8A ₂ at the position where the bridge portion 6B ₁ are arranged (2 × Wg1 + t = Wo1 ).

The position of the bridge portion 6B _2, the control rod 1 has a cross-sectional shape shown in FIG. 13. Bridge portion 6B are attached to the blade 2B and the blade 2D ₂ is disposed between the blade 2A and the blade 2C are orthogonal to the bridge portion 6B _2. In the normal state of the control rod 1, the width of the gap formed between the respective bridge portions 6B ₂ and the blade 2A and 2C are both Wg2. The width of each of the blades 2A, 2B, 2C, and 2D at this position is Wb2. The addition of 2 fold blade 2B and 2D the thickness t of the width Wg2 of the gap is equal to the width Wo2 of the opening 8A ₃ at the position where the bridge portion 6B ₂ are arranged (2 × Wg2 + t = Wo2 ).

The position of the bridge portion 6B _3, the control rod 1 has a cross-sectional shape shown in FIG. 14. The bridging portion 6B ₃ that couples the blade 2B and the blade 2D is disposed between the blade 2A and the blade 2C that are orthogonal to the bridging portion 6B ₃ . In the normal state of the control rod 1, the width of the gap formed between the respective bridge portions 6B ₃ and the blade 2A and 2C are both Wg3. The width of each of the blades 2A, 2B, 2C and 2D at this position is Wb3. The addition of 2 fold blade 2B and 2D the thickness t of the width Wg3 of the gap is equal to the width WO3 openings 8A ₄ at the position where the bridge portion 6B ₃ are arranged (2 × Wg3 + t = Wo3 ).

  The gap widths Wg1, Wg2, and Wg3 satisfy the relationship of Wg1 <Wg2 <Wg3.

  During the operation of the boiling water reactor, all the control rods 1 other than the plurality of control rods 1 used for controlling the reactor power are arranged in the reactor pressure vessel so as to have a plurality of fuel assemblies. It is in a state of being completely extracted from the core in which the body is loaded. When an earthquake occurs during operation of the boiling water reactor, all the control rods 1 are rapidly inserted into the reactor core, and the boiling water reactor is urgently stopped. In particular, each control rod 1 that has been completely extracted from the core during operation of the boiling water reactor is a control rod insertion hole having a cross-shaped cross section formed in a fuel support fitting that supports the lower end of the fuel assembly. And is fully inserted between the fuel assemblies. Each fuel assembly is displaced so as to bend in the horizontal direction as shown in FIG. 16 during an earthquake. Under the influence of these horizontal displacements of the fuel assemblies, the blades of the control rod 1 inserted between the fuel assemblies facing the displacing fuel assemblies are also displaced in the horizontal direction.

  In the control rod 1, the blades 2 </ b> A, 2 </ b> B, 2 </ b> C and 2 </ b> D are connected to each other at the upper end (insertion end) and the lower end (lower support member 4) of the control rod 1. In FIG. 2, the two blades 2A and 2C and the other two blades 2B and 2D orthogonal to the bridging portion connecting these blades are separated from each other. For this reason, since the control rod 1 inserted between the fuel assemblies at the time of the earthquake can displace the blade in the horizontal direction according to the horizontal displacement of the fuel assembly at the time of the earthquake, the control rod 1 at the time of the earthquake Is smoothly inserted between the fuel assemblies, and the time required for rapid insertion of the control rod 1 is shortened.

In the present embodiment, like the control rod described in JP 2011-80985 A, a pair of blades (for example, blade 2B) in which a bridging portion (for example, bridging portion 6A ₃ ) is orthogonal to the bridging portion. , 2D) is formed with a bridging member (for example, bridging portion 6A ₃ ) when affected by the horizontal displacement of the fuel assembly. The two blades (for example, the blades 2A and 2C) are easily displaced in the horizontal direction during an earthquake. Such a configuration of the control rod 1 can smoothly insert between the fuel assemblies during an earthquake.

In addition, a bridging portion (for example, bridging portion 6A ₃ ) forms a gap (for example, width Wg3) between each of a pair of blades (for example, blades 2B and 2D) orthogonal to the bridging portion. Since the two blades face each other, the two blades (for example, blades 2A and 2C) joined by the bridge portion (for example, the bridge portion 6A ₃ ) at the time of the earthquake are displaced in the horizontal direction at the time of the earthquake. Even so, the amount of movement in the horizontal direction of the two blades (for example, the blades 2A and 2C) due to this displacement is such that the bridging portion (for example, the bridging portion 6A ₃ ) is orthogonal to the blade (for example, the blade). 2B) (see FIG. 12 of JP2011-80985A). For this reason, the control rod 1 can suppress the buckling deformation of the blade at the time of rapid insertion into the core at the time of an excessive earthquake, similarly to the control rod described in JP2011-80985A.

  The control rod 1 of the present embodiment can obtain good insertability into the core even during an excessive earthquake.

  When the control rod 1 that has been fully pulled out is rapidly inserted into the core during an earthquake, the blade of the control rod 1 is subjected to the forced displacement 30 applied from the fuel support bracket 38 during the earthquake, as described above. 38 is displaced in the direction of vibration due to the earthquake. However, in the present embodiment, a plurality of bridging portions that couple a pair of blades (for example, blades 2A and 2C) that are part of a plurality of bridging portions that couple the pair of blades and exist in the upper region of the control rod 1. The width of each gap formed between (for example, a plurality of cross-linking portions 6A) and blades (for example, blades 2B and 2D) orthogonal to these cross-linking portions (for example, cross-linking portions 6A) A position formed in a plurality of gaps formed by the above-described partial bridging portions (for example, bridging portions 6A) that couple a pair of blades (for example, blades 2A and 2C) is an insertion end portion (handle) of the control rod 1 3) The closer the gap, the narrower (Wg1 <Wg2 <Wg3). For this reason, even if the pair of blades (for example, blades 2B and 2D) of the control rod 1 are displaced by the forced displacement 30 applied from the fuel support fitting 38, as shown in FIG. As the bridging portion exists, the movement in the horizontal direction is more quickly restrained by the blades orthogonal to the bridging portion (for example, blades 2A and 2C), and the amount of movement in the horizontal direction is reduced. As a result, a pair of blades (for example, blades 2B and 2D) joined at the bridging portion are displaced in the horizontal direction and formed at the upper end of the handle 3 that joins the blades 2A, 2B, 2C, and 2D. The fixed end moment generated in the first region (the portion of the connecting portion 5A) including the first cross section to be reduced can be reduced, and a pair of blades (for example, the blades 2B and 2D) coupled at the bridging portion can be obtained. It is possible to reduce a stress generated in a portion (for example, the handle elements 3F and 3G) connected to the first region. Even when the pair of blades 2A and 2C joined at the bridge portion are displaced in the horizontal direction under the influence of the forced displacement 30 applied from the fuel support fitting 38 at the time of an earthquake, It is possible to reduce stress generated in a portion (for example, the handle element 3E) where the pair of blades (for example, the blades 2A and 2C) that are coupled to each other are connected to the first region.

  A boiling water reactor control rod according to embodiment 2, which is another embodiment of the present invention, will be described with reference to FIG. The control rod 1A of the present embodiment forms neutron absorber filling holes in regions where the width of the bridging portion and the blade is increased in the control rod 1 of the first embodiment, and the neutron absorber is placed in these neutron absorber filling holes. It has a filled configuration. Other configurations of the control rod 1A are the same as those of the control rod 1.

Will be described in detail with reference to FIG. 19 is a cross-sectional at the position where the bridge portion 6B ₂ exists. A plurality of neutron absorbing material filling hole 28A is formed in the bridge portion 6B ₂ which couples the blade 2B and the blade 2D. Neutron absorbing material filling hole 28A does not pass through the bridge portion 6B _2. Neutron absorbing material is filled in each neutron absorbing material filling hole 28A from the open end of the neutron absorbing material filling hole 28A, the open end of the neutron absorbing material filling hole 28A is by welding to the cross section 6B ₂ end plug Blocked.

Blade 2A at the position of the bridge portion 6B _2, 2B, 2C and 2D of the respective width (the width of each blade in the region h2) is greater than the width of each blade in the lower region h3 than the area h2 (Wb2-Wb3) Only getting wider. Further, the widths of the blades 2A, 2B, 2C, and 2D in the region h1 are wider by (Wb1-Wb3) than the widths of the blades in the region h3. In each of the blades 2A, 2B, 2C and 2D, a plurality of neutron absorbers are filled in a region where the width is increased by (Wb2-Wb3) in the region h2 and a region where the width is increased by (Wb1-Wb3) in the region h1. Holes 28B are respectively formed, and the neutron absorber 29 is also filled in these neutron absorber filling holes 28B. After filling with the neutron absorbing material 29, each neutron absorbing material filling hole 28B is sealed. The neutron absorber filling holes 28 provided in these bridging portions can be formed by providing holes in the bridging portions when forming the blades 2A, 2B, 2C and 2D by machining or HIP. .

  Also in other bridging portions, a plurality of neutron absorber filling holes 28A filled with neutron absorber 29 and sealed are formed.

  In the present embodiment, each effect produced in the first embodiment can be obtained. Further, in the present embodiment, the neutron absorber 29 is also filled in the region where the width of the bridging portion and the blade is increased, so that the value of the control rod of the control rod 1A can be increased more than that of the control rod 1.

  A boiling water nuclear reactor control rod according to embodiment 3, which is another embodiment of the present invention, will be described with reference to FIG. In the control rod 1B of the present embodiment, the shape of a part of the openings (openings positioned on the handle 3 side) arranged in the axial direction in the control rod 1 of the first embodiment is directed from the handle 3 to the lower support member 4. The structure is formed so as to spread. Other configurations of the control rod 1B are the same as those of the control rod 1.

The openings 40A ₁ , 40A ₂ , 40A ₃ formed in the plate member 4A forming the blades 2A, 2C have a width at the end on the lower support member 4 side that is larger than a width at the end on the handle side. It is getting bigger. Therefore, in each of the openings _{40A 1, 40A 2, 40A 3} , opposite sides is an inclined surface. Furthermore, in the openings 40A ₁ , 40A ₂ and 40A ₃ , the width of the opening 40A ₁ at the end on the lower support member 4 side, the width of the opening 40A ₂ at the end on the lower support member 4 side, and the opening 40A _3, the width of the end portion of the lower support member 4 side is wider in the order of the opening _40A 1, 40A ₂ and 40A _3. Openings 40A _2, the width at the end of the handle 3 side of the opening 40A _1, is slightly wider than the width of the end portion of the lower support member 4 side. Openings 40A _3, width at the end of the handle 3 side of the opening 40A _2, is slightly wider than the width of the end portion of the lower support member 4 side. The remaining shape of the opening 40A ₄ formed in the plate member 4A is in a rectangle extending in the axial direction of the control rod 1B.

The openings 40B ₁ , 40B ₂ , 40B ₃ formed in the plate member 4B forming the blade 2B and the plate member 4C forming the blade 2D are also end portions on the lower support member 4 side. The width at is larger than the width at the end on the handle side (see FIG. 27). Therefore, in each of the openings _{40B 1, 40B 2, 40B 3} , opposite sides is an inclined surface. Further, in the openings 40B ₁ , 40B ₂ and 40B ₃ , the width of the opening 40B ₁ at the end on the lower support member 4 side, the width of the opening 40B ₂ at the end on the lower support member 4 side, And the width of the opening 40B ₃ at the end on the lower support member 4 side becomes wider in the order of the openings 40B ₁ , 40B ₂ and 40B ₃ . The opening 40B _2, the width at the end of the handle 3 side of the opening 40B _1, and slightly wider than the width of the end portion of the lower support member 4 side. The opening 40B _3, width at the end of the handle 3 side of the opening 40B _2, are slightly wider than the width of the end portion of the lower support member 4 side. Integrated plate member 4B, the remaining shape of the opening 40B ₄ formed in 4C is in a rectangle extending in the axial direction of the control rod 1B.

The bridging portions 6B ₁ , 6B ₂ , 6B ₃ connecting the blade 2B and the blade 2D are separately arranged in the openings 40A ₁ , 40A ₂ , 40A ₃ . The bridging portions 6A ₁ , 6A ₂ , 6A ₃ connecting the blade 2A and the blade 2C are separately arranged in the openings 40B ₁ , 40B ₂ , 40B ₃ .

  Similarly to the control rod 1, the control rod 1B includes a first region including the first cross section (the integrated connecting portions 5A to 5C and the lower support member 4), and a second region including the second cross section. (A region between the bridging portions in the axial direction of the control rod) and a third region including the third cross section (each region where each bridging portion is located).

  Further, in the control rod 1B, which is a part of a plurality of bridging portions that couple a pair of blades, a plurality of bridging portions that couple a pair of blades (for example, blades 2B and 2D) that exist in the upper region of the control rod 1B. The width of the plurality of gaps formed between the blades (for example, the blades 2A and 2C) orthogonal to the bridge portions (for example, the bridge portions 6B) (for example, the plurality of bridge portions 6A) 1, the positions formed in the plurality of gaps formed by the above-described partial bridging portions (for example, bridging portions 6A) that couple the pair of blades (for example, blades 2A and 2C) are control rods 1. The gap closer to the insertion end (handle 3) is narrower.

  In the present embodiment, each effect produced in the first embodiment can be obtained.

  A boiling water reactor control rod according to embodiment 4, which is another embodiment of the present invention, will be described with reference to FIGS. In the control rod 1C of the present embodiment, an opening is formed in the bridging portion that couples a pair of blades in the control rod 1 of the first embodiment, and the width of the opening formed in the bridging portion toward the handle 3 is set to the handle 3. It has the structure which narrows the bridge | crosslinking part near. Other configurations of the control rod 1A are the same as those of the control rod 1.

  Five bridging portions that join the blade 2B and the blade 2D are formed in the axial direction of the control rod 1C on the plate members 4B and 4C that are joined and integrated. FIG. 21 shows two bridging portions 43A and 43B located on the handle 3 side among these bridging portions. The bridging portion 43A is located closer to the handle 3 than the bridging portion 43B.

Furthermore, the opening 41B ₁ is formed between the blade 2B and the blade 2D the handle 3 side of the bridge portion 43A. This opening 41B ₁ by binding the connecting portion 5C and the connecting portion 5B, and communicates with the opening 8B ₁ formed in the combined plate member 4B and 4C. Opening 41B ₃ is formed between the bridge portion 43A and the bridge portions 43B, without other bridge section (shown with an opening 41B ₅ is adjacent the lower support member 4 side bridge portion 43B of the bridge portion 43B Toko ). Openings (not shown) are also formed between three bridging portions (not shown) formed closer to the lower support member 4 than the bridging portion 43B. Opening 41B ₃ and 41B ₅ is disposed between the blade 2B and the blade 2D.

Opening 41B ₂ are formed on the bridge portion 43A, the opening 41B ₄ are formed on the bridge portion 43B. The opening 41B _2, blade 2B, the width in the width direction of the 2D is, for example, a Wo1, openings 41B _4, blade 2B, the width in the width direction of the 2D is, for example, Wo2. Openings are also formed in the remaining three bridging portions. The widths of the openings formed in the three bridging portions in the width direction of the blades 2B and 2D are the same as the width of the gap between the blades 2B and 2B, for example, Wo3. Openings 41B ₂ and the opening 41B _4, blade 2B, the width in the width direction of the 2D is narrower than the width in the width direction of the opening _41B 1, 41B ₃ and 41B _5. Moreover, the opening 41B ₂ positioned near the handle 3 from the opening portion 41B _4, blade 2B, the width in the width direction of the 2D is narrower than the width of the opening 41B _4.

Openings 41B ₁ , 41B ₂ , 41B ₃ , 41B ₄ , and 41B ₅ are formed in this order from the connecting portions 5B and 5C toward the lower support member 4. These openings are arranged on the axis of the control rod 1C. In Figure 21, the blade 2B openings _{41B 1, 41B 2, 41B 3} , 41B 4, and present in the right 41B _5, blade 2D openings _{41B 1, 41B 2, 41B 3} , 41B 4, and 41B ₅ Present to the left of

Bridge portion 43A is by the formation of the opening 41B _2, blade 2B, in the center of the 2D in the width direction to form the two bridge 44A ₁ and 44A _2. Bridge portion 43A includes a cross-linking 44A ₁ and 44A _2. Each of the height of the bridge 44A ₁ and 44A ₂ is half of the height obtained is by subtracting the height of the opening portion 41B ₂ from the height of the bridge portion 43A. Bridge portion 43B is by the formation of the opening 41B _4, the blade 2B, in the center of the 2D in the width direction to form the two bridge 44A ₃ and 44A _4. Bridge portion 43B includes a bridge 44A ₃ and 44A _4. Each of the height of the bridge 44A ₃ and 44A ₄ are half the height obtained is by subtracting the height of the opening portion 41B ₄ from the height of the bridge portion 43B.

As described above, the width in the width direction of the blades 2B and 2D of the respective openings formed in the three bridging portions located on the lower support member 4 side with respect to the bridging portion 43B is the same as that of the opening 41B ₁ or the like. It is the same as the width in the width direction. Therefore, the three bridge portions are substantially, respectively composed of two bridge having the same height as the two bridge 44A ₃ and 44A ₄ in cross section 43B.

The length in the width direction of the blade of the bridge 44A ₁ and 44A ₂ present near the bridge 44A ₃ and 44A ₄ wheel 3 than is shorter than the length in the width direction of the bridge 44A ₃ and 44A ₄ blade .

Five bridging portions that join the blade 2A and the blade 2C to the plate member 4A are formed in the axial direction of the control rod 1C. Figure 22, of these bridge portions, two bridge portions 6A ₁ and 6A ₂ located on the handle 3 side is shown. Bridge portions 6A ₁ is located on the handle 3 side of the bridge portion 6A _2.

Moreover, the opening 41A ₁ is formed between the blade 2A and the blade 2C the handle 3 side of the bridge portion 6A _1. The opening 41A ₁ communicates with the opening 8A ₁ formed in the plate member A by forming the connecting portion 5A. Openings 41A ₄ is formed between the bridge portion 6A ₁ and bridge portions 6A _2, another bridge an opening 41A ₇ is adjacent the lower support member 4 side bridge portion 6A ₂ bridge portions 6A ₂ Toko (Not shown). Opening to mutual three bridge portions which are formed on the lower support member 4 side of the bridge portion 6A ₂ (not shown) (not shown) is formed.

Openings 41A ₂ and 41A ₃ are formed on the bridge portion 6A _1, openings 41A ₅ and 41A ₃ are formed on the bridge portion 6A _2. Openings 41A ₂ communicates with the opening 41A _1, openings 41A ₃ is in communication with the opening 41A _4. Openings 41A ₅ is communicated with the opening 41A _4, the opening 41A ₆ is communicated with the opening 41A _7. Openings 41A _2, blade 2A, the width in the width direction of 2C, for example, a Wo1, the opening 41A _5, blade 2A, the width in the width direction of 2C is, for example, Wo2. The width in the width direction of each blade of the openings 41A ₂ , 41A ₃ , 41A ₅ and 41A ₆ is narrower than the width in the width direction of the blades of the openings 41A ₁ , 41A ₄ and 41A ₇ . Further, the widths of the opening portions 41A ₂ , 41A ₃ and 41A ₅ in the width direction of the respective blades become narrower in the order of the opening portions 41A ₅ , 41A ₃ and 41A ₂ . The width of each of the openings 41A ₂ , 41A ₃ , 41A ₅ and 41A ₆ in the width direction of the blade is narrower as the opening located near the handle 3 among these openings.

The three bridging portions formed on the lower support member 4 side than the bridging portion 6A ₂ do not form openings like the bridging portions 6A ₁ and 6A ₂ and have the same shape as the bridging portion 6A _{3 in the} first embodiment. have. In other words, in the three bridge portions, said two openings having the same width as the width of the opening 41B ₅ is also formed in the same manner as the bridge portions 6A ₁ and 6A _2, three bridge portions It becomes a part of opening part which exists in each handle 3 side and the lower support member 4 side.

Openings 41A ₁ , 41A ₂ , 41A ₃ , 41A ₄ , 41A ₅ , 41A ₆ and 41A ₇ are formed in this order from the connecting portion 5A toward the lower support member 4. These openings are arranged on the axis of the control rod 1C. In FIG. 22, the blade 2A is present to the right of the openings 41A ₁ , 41A ₂ , 41A ₃ , 41A ₄ , 41A ₅ , 41A ₆ and 41A ₇ , and the blade 2C is the openings 41A ₁ , 41A ₂ , 41A ₃ , 41A. ₄ , 41A ₅ , 41A ₆ and 41A ₇ are on the left.

The bridging portion 6A ₁ is formed by forming one bridging 42A ₁ between the opening 41A ₂ and the opening 41A ₃ at the center in the width direction of the blades 2A and 2C by forming the openings 41A ₂ and 41A _3. Yes. Bridge portions 6A ₁ includes a bridge 42A _1. The height of the bridge 42A ₁ is from height bridge section 6A ₁ is a height obtained by subtracting each of the height of the opening portion 41A ₂ and 41A _3, the opening 41B ₂ formed on the bridge portion 43A It is lower than the height. The bridging portion 6A ₂ is formed by forming one bridging 42A ₂ between the opening 41A ₅ and the opening 41A ₆ at the center in the width direction of the blades 2A and 2C by forming the openings 41A ₅ and 41A _6. Yes. Bridge 6A ₂ includes a bridge 42A _2. The height of the bridge 42A ₂ is from height bridge section 6A ₂ are each of height obtained by subtracting the height of the opening portion 41A ₅ and 41A _6, the opening 41B ₄ formed in the bridge portion 43B It is lower than the height.

The length in the width direction of the blade of the bridge 42A ₁ existing near the handle 3 than crosslinking 42A ₂ is shorter than the length in the width direction of the bridge 42A ₂ blades.

Blade 2A, crosslinked 42A ₁ of the bridge portion 6A ₁ to bind 2C is disposed in the opening 41B _2. Blade 2A, crosslinked 42A ₂ of the bridge portions 6A ₂ that binds 2C is disposed in an opening 41B _4. Blade 2B, crosslinking 44A ₁ of the bridge portion 43A for coupling the 2D is disposed in the opening 41A _2, bridge 44A ₂ of the bridge portion 43A is disposed in the opening 41A in _3. Blade 2B, crosslinking 44A ₃ of the bridge portion 43B for coupling the 2D is disposed in the opening 41A in _5, crosslinking 44A ₄ bridge portions 43B are disposed in an opening 41A in _6.

The width of each gap formed between the opposing side surfaces of the bridging portion 6A ₁ , specifically the bridging 42A ₁ and the opening portion 41B ₂ , is equal to the bridging portion 6A ₂ , specifically the bridging portion 42A ₂ and the opening portion. 41B ₄ is narrower than the width of each gap formed between the opposing side surfaces. Bridge portions 43B, each gap width is specifically formed between the opposite sides of the bridge 44A ₄ and the opening 41A _6, the bridge portion 43B, in particular of the crosslinked 44A ₃ and the opening portion 41A ₅ each of the gap width formed between each opposing side surfaces, bridge portion 43A, each of the gap width is specifically formed between the opposite sides of the bridge 44A ₂ and the opening 41A ₃ and, bridge portions 43A, each of the gap width is specifically formed between the opposite sides of the bridge 44A ₁ and the opening 41A ₂ is made narrower toward the handle 3 in this order.

  Similarly to the control rod 1, the control rod 1C includes a first region including the first cross section (the integrated connecting portions 5A to 5C and the lower support member 4), and a second region including the second cross section. (A region between the bridging portions in the axial direction of the control rod) and a third region including the third cross section (each region where each bridging portion is located).

  As in the first embodiment, when the control rod 1C, which has been fully extracted from the core, is inserted between the fuel assemblies in the core at the time of an earthquake, it is affected by the displacement of the fuel assemblies in the horizontal direction. A cross-linking portion (specifically, cross-linking) that connects a pair of displaced blades is orthogonal to the cross-linking portion (specifically cross-linking), that is, the cross-linking portion (specifically, cross-linking). ) Is constrained by the opposing side surfaces of the opening where the blades are disposed, so that it is possible to suppress the buckling deformation of the blade during rapid insertion into the core during an excessive earthquake. The control rod 1 of the present embodiment can obtain good insertability into the core even during an excessive earthquake.

  Also in the present embodiment, a plurality of bridging portions (for example, a plurality of bridging portions 6A) that couple a pair of blades (for example, blades 2A and 2C), which exist in the upper region of the control rod 1C, and these bridging portions (for example, , The width of the gap formed between the other bridging portions orthogonal to the bridging portion 6A) (for example, the bridging portions 43A and 43B and the blades 2B and 2D are coupled) Of the plurality of bridging portions (for example, the plural bridging portions 6A) that connect the blades (for example, the blades 2A and 2C), as described above, the gap formed by the bridging portions that are located closer to the handle 3 is narrower. It has become. For this reason, even if the pair of blades of the control rod 1C are displaced in the direction in which the fuel support bracket 38 vibrates due to the earthquake due to the forced displacement 30 applied from the fuel support bracket 38 in the event of an earthquake, the blades are close to the handle 3. As the cross-linked portion is present, the movement in the horizontal direction is more quickly restrained by other cross-linked portions orthogonal to the cross-linked portion, and the amount of movement in the horizontal direction is reduced. Therefore, similar to the control rod 1, the blades 2A, 2B, 2C and 2D are coupled to each other, and are generated in the first region including the first cross section formed at the upper end portion of the handle 3 (part of the connecting portion 5A). The fixed end moment can be reduced, and is generated at a portion (for example, handle elements 3F and 3G) where a pair of blades (for example, blades 2B and 2D) connected at the bridging portion are connected to the first region. Stress can be reduced. In the present embodiment, when an earthquake occurs, a certain bridging portion located closer to the handle 3 is more quickly restrained in the horizontal direction by another bridging portion orthogonal to the bridging portion. In Example 1, this is the same as that a certain bridging portion located closer to the handle 3 is restrained from moving in the horizontal direction earlier by a blade orthogonal to the bridging portion.

  In the present embodiment, each effect produced in the first embodiment can be obtained.

  Here, the features of the control rod 1 of the first embodiment, the control rod 1B of the third embodiment, and the control rod 1C of the fourth embodiment will be described. The features of each of these embodiments are summarized in FIG. The effect of reducing the local fixed end moment generated in the first region existing at the insertion end of the control rod (upper end of the handle) and the insertability into the core at the time of the earthquake are different in the control rod of each embodiment. No (see function in FIG. 23). In consideration of manufacturability of the opening portion 41 composed of the bridging portion 6, the bridging portion 44 and the protrusion 43 provided on the control rod, and the gap formed between the bridging portion 6 and the opening portion 41, Embodiments 1 and 3 Since each control rod can reduce gap formation, it is superior to the control rod of the fourth embodiment. Further, with respect to the displacement of the control rod with respect to the direction in which the forced displacement is applied from the fuel support fitting when the earthquake occurs, the control rod 1C of the fourth embodiment generates the same displacement regardless of the direction of the forced displacement. .

  A boiling water reactor control rod according to embodiment 5, which is another embodiment of the present invention, will be described with reference to FIGS. 24 and 25. FIG. The control rod 1D of the present embodiment has a configuration in which the handle 3 is replaced with the handle 3A in the control rod 1 of the first embodiment. Other configurations of the control rod 1D are the same as those of the control rod 1.

  The handle 3A not only forms a first region in which the connecting portions 5A, 5B and 5C are integrally connected to the upper end portion of the handle 3A, but also connects the connecting portions 33, 33A and 33B to the lower end portion of the handle 3A. The first region is formed. The upper ends of the blades 2A, 2B, 2C, and 2D are joined to the connecting portions 33, 33A, and 33B that are integrally coupled to the handle 3A by welding.

  Similarly to the control rod 1, the control rod 1 </ b> D also includes the first region including the first cross section (the integrated connecting portions 5 </ b> A to 5 </ b> C, the integrated connecting portions 33 to 33 </ b> B, and the lower support member 4. ), A second region including the second cross section (region between the bridging portions in the axial direction of the control rod) and a third region including the third cross section (each region where each bridging portion is located). Yes.

  This embodiment can also obtain each effect produced in the first embodiment. However, the reduction of the fixed end moment in the present embodiment is mainly performed on the first region which is a portion of the integrated connecting portions 33 to 33B, and is connected to the first region, and supports the fuel in the event of an earthquake. The stress generated by the pair of blades that are displaced under the influence of the forced displacement 30 applied from the metal fitting 38 can be reduced.

  A boiling water reactor control rod according to embodiment 6, which is another embodiment of the present invention, will be described with reference to FIGS. 26 and 27. FIG. The control rod 1E of the present embodiment has a configuration in which the handle 3 is replaced with the handle 3A in the control rod 1B of the third embodiment. Other configurations of the control rod 1E are the same as those of the control rod 1B.

  The handle 3A not only forms a first region in which the connecting portions 5A, 5B and 5C are integrally connected to the upper end portion of the handle 3A, but also connects the connecting portions 33, 33A and 33B to the lower end portion of the handle 3A. The first region is formed. The upper ends of the blades 2A, 2B, 2C, and 2D are joined to the connecting portions 33, 33A, and 33B that are integrally coupled to the handle 3A by welding.

  Similarly to the control rod 1B, the control rod 1E also includes the first region including the first cross section (the integrated connecting portions 5A to 5C, the integrated connecting portions 33 to 33B, and the lower support member 4). ), A second region including the second cross section (region between the bridging portions in the axial direction of the control rod) and a third region including the third cross section (each region where each bridging portion is located). Yes.

  This embodiment can also obtain each effect produced in the first embodiment. However, the reduction of the fixed end moment in the present embodiment is mainly performed on the first region which is a portion of the integrated connecting portions 33 to 33B, and is connected to the first region, and supports the fuel in the event of an earthquake. The stress generated by the pair of blades that are displaced under the influence of the forced displacement 30 applied from the metal fitting 38 can be reduced.

  A boiling water nuclear reactor control rod according to embodiment 6, which is another embodiment of the present invention, will be described with reference to FIGS. 28 and 29. FIG. The control rod 1F of the present embodiment has a configuration in which the handle 3 is replaced with the handle 3A in the control rod 1C of the fourth embodiment. Other configurations of the control rod 1E are the same as those of the control rod 1B.

  The handle 3A not only forms a first region in which the connecting portions 5A, 5B and 5C are integrally connected to the upper end portion of the handle 3A, but also connects the connecting portions 33, 33A and 33B to the lower end portion of the handle 3A. The first region is formed. The upper ends of the blades 2A, 2B, 2C, and 2D are joined to the connecting portions 33, 33A, and 33B that are integrally coupled to the handle 3A by welding.

  Similarly to the control rod 1C, the control rod 1F has a first region including the first cross section (the integrated connecting portions 5A to 5C, the integrated connecting portions 33 to 33B, and the lower support member 4). ), A second region including the second cross section (region between the bridging portions in the axial direction of the control rod) and a third region including the third cross section (each region where each bridging portion is located). Yes.

  This embodiment can also obtain each effect produced in the first embodiment. However, the reduction of the fixed end moment in the present embodiment is mainly performed on the first region which is a portion of the integrated connecting portions 33 to 33B, and is connected to the first region, and supports the fuel in the event of an earthquake. The stress generated by the pair of blades that are displaced under the influence of the forced displacement 30 applied from the metal fitting 38 can be reduced.

1～1F ... control rod, 2A, 2B, 2C, 2D ... blade, 3, 3A ... handle, 4 ... lower support portion, 4A, 4B, 4C ... plate _{member, 5A~5C, 17A 1 ~17A 3,} 17B 1 -17B ₃ , 33, 33A, 33B ... connecting part, 6A _{1 to} 6A ₃ , 6B _{1 to} 6B ₃ , 44A _{1 to} 44A ₄ ... bridging part, 7A, 7B, 7C, 7D ... neutron absorber filling part, 8A ₁ 8A ₅ , 8B _{1 to} 8b ₅ , 41A _{1 to} 41A ₆ , 41B _{1 to} 41B ₅ ... opening, 28, 28A, 28B ... neutron absorber filling hole, 29 ... neutron absorber, 37 ... fuel assembly, 38 ... Fuel support bracket.

Claims (12)

A control rod for a boiling water reactor having four blades having a neutron absorber filling region in which a neutron absorber is accommodated and orthogonal to each other,
A plurality of regions formed in the axial direction of the control rod include a first region including a first cross section connecting the four blades to each other, and a second crossing where the four blades are separated from each other. A plurality of second regions arranged in the axial direction of the control rod including the surface, and a pair of the four blades of the four blades coupled by a bridging portion, and another pair orthogonal to the bridging portion A plurality of third regions disposed between the second regions in the axial direction, including a third cross section separated from each other by the blade,
The first region is disposed closer to the insertion end of the control rod than the plurality of second regions and the plurality of third regions,
The width of each gap formed between the bridging portion included in each of the plurality of third regions and the blade orthogonal to the bridging portion is determined by the pair of blades. A control rod for a boiling water reactor, which is narrowest in the gap formed by the bridging portion located closest to the insertion end portion among the plural bridging portions to be coupled. A control rod for a boiling water reactor having four blades having a neutron absorber filling region in which a neutron absorber is accommodated and orthogonal to each other,
A plurality of regions formed in the axial direction of the control rod include a first region including a first cross section connecting the four blades to each other, and a second crossing where the four blades are separated from each other. A plurality of second regions arranged in the axial direction of the control rod including the surface, and a pair of the four blades of the four blades coupled by a bridging portion, and another pair orthogonal to the bridging portion A plurality of third regions disposed between the second regions in the axial direction, including a third cross section separated from each other by the blade,
The first region is disposed closer to the insertion end of the control rod than the plurality of second regions and the plurality of third regions,
The width of each gap formed between the bridging portion included in each of the plurality of third regions and the blade orthogonal to the bridging portion is determined by the pair of blades. A boiling water reactor control rod, wherein the gap formed by the bridge portion adjacent to the insertion end portion among the plurality of bridge portions to be coupled is narrower than the other gaps. A lower support member attached to the four blades to form the other end of the control rod opposite to the insertion end;
In each of the pair of blades, the plurality of bridging portions that couple the pair of blades are arranged on the insertion end portion side adjacent to the bridging portion that is present at a position closest to the insertion end portion. A first opening is formed between the pair of blades;
A second opening is formed between the pair of blades disposed on the side of the lower support member adjacent to the bridging portion present at the closest position;
Each side surface of the first and second openings facing each other in the width direction of the blade is an inclined surface,
The control rod for a boiling water reactor according to claim 1 or 2 , wherein the width of the first and second openings in the width direction of the blade is widened from the insertion end toward the lower support member. . A pair of said blades and the first plate member forming a first bridge portion a plurality of a plurality of bridge portions connecting these blades of the previous SL four blades, arranged orthogonal to the first plate member The second plate member that is coupled to the first plate member in the first region and forms the other one of the four blades, and is disposed perpendicular to the first plate member, The first plate member and the second plate member are coupled to the first plate member in the first region by extending in a direction opposite to the second plate member from the coupling position of the second plate member, and the remaining of the four blades A third plate member forming one of the blades;
Each of a plurality of second bridging portions that are the plurality of bridging portions that couple the blade formed on the second plate member and the blade formed on the third plate member is the second plate member. Formed by combining a part of the second bridging part formed by the remaining part of the second bridging part formed by the third plate member,
The boiling according to any one of claims 1 to 3 , wherein each of the blades has the neutron absorber filled in a plurality of neutron absorber filling holes formed in the corresponding plate member. Control rod for water reactor. A control rod for a boiling water reactor comprising four blades having a neutron absorber filling region in which a neutron absorber is accommodated and orthogonal to each other,
A plurality of regions formed in the axial direction of the control rod include a first region including a first cross section connecting the four blades to each other, and a second crossing where the four blades are separated from each other. A plurality of second regions arranged in the axial direction of the control rod including a surface, and a first pair of blades of the four blades are coupled by a bridging portion and are orthogonal to the bridging portion. A plurality of third regions arranged in the axial direction including a third cross section in which a pair of two blades are separated from each other;
The first region is disposed closer to the insertion end of the control rod than the plurality of second regions and the plurality of third regions, and the other end of the control rod on the side opposite to the insertion end A lower support member formed and attached to the four blades;
The first pair of blades that are located closest to the insertion end portion between the first pair of blades among the plurality of first bridging portions that couple the blades of the first pair of blades. Between the first pair of blades closer to the insertion end than the first bridging portion, and closer to the lower support member than the first bridging portion located closer to the lower support member, the first A first opening is formed between each of the pair of blades,
The plurality of first bridging portions connecting the respective blades of the first pair of blades each form a second opening;
Among the second pair of blades, the second pair of blades that connect the blades, and the second pair of blades are located between the second pair of blades and closest to the insertion end. Between the second pair of blades on the insertion end side with respect to the two bridging portions and on the lower support member side with respect to the second bridging portion located closest to the lower support member. A third opening is formed between each of the pair of blades,
The plurality of second bridging portions that couple the respective blades of the second pair of blades respectively have fourth openings that communicate with the third opening on the insertion end side of the second bridging portion. Forming,
Each of the second bridges is disposed separately through each of the second openings, and each of the first bridges is disposed separately through each of the fourth openings,
Each of the second openings formed in the plurality of first bridging portions, the side surfaces facing each other in the width direction of the first pair of blades, and each of the second openings separately penetrating each of the second openings. The width of each gap formed between the second bridging portions is the first of the plurality of first bridging portions that couple the first pair of blades at a position closest to the insertion end portion. The gap formed by the bridging portion and the second bridging portion is the narrowest,
Each of the fourth openings formed in a plurality of second bridging portions, which respectively penetrates the side surfaces facing each other in the width direction of the second pair of blades and the fourth openings separately. The width of each gap formed between the second bridging portions is the first of the plurality of second bridging portions that couple the second pair of blades at a position closest to the insertion end portion. A control rod for a boiling water reactor, which is narrowest in the gap formed by two bridging portions and the second bridging portion. A pair of said blades and said plurality of first first plate member forming a bridge, the first region is arranged perpendicular to the first plate member that couples the blades of the previous SL four blades A second plate member that is coupled to the first plate member and forms the other one of the four blades, and is disposed orthogonal to the first plate member, The second plate member extends from the coupling position of the second plate member in a direction opposite to the second plate member and is coupled to the first plate member in the first region to form the remaining one of the four blades. A third plate member
Each of a plurality of second bridging portions that are the plurality of bridging portions that couple the blade formed on the second plate member and the blade formed on the third plate member is the second plate member. Formed by combining a part of the second bridging part formed by the remaining part of the second bridging part formed by the third plate member,
6. The boiling water reactor control rod according to claim 5 , wherein each of the blades has the neutron absorber filled in a plurality of neutron absorber filling holes formed in the corresponding plate member. . The second plate member and the third plate member in which the pair of blades formed on the first plate member is coupled by the first bridging portion, and the third region is orthogonal to the first bridging portion. A plurality of fourth regions arranged between the second regions in the axial direction, including a fourth cross section in which the blades formed in each of the blades are separated from each other, the second plate member, and the third The blades formed on each of the plate members are coupled by the second bridging portion, and the pair of blades formed on the first plate member orthogonal to the second bridging portion are separated from each other. Including a plurality of fifth regions disposed between the second regions in the axial direction including five transverse sections;
The control rod for a boiling water reactor according to claim 4 or 6, wherein the fourth region and the fifth region are arranged at different positions in the axial direction. Handle, said four of said first coupled include blade, the second and third being disposed in said insertion end is thus formed on the plate members, according to claim 4 which is connected to each blade, The control rod for a boiling water reactor according to any one of 6 and 7 . The control rod for a boiling water reactor according to any one of claims 1 to 8 , wherein compressive residual stress is applied to a joint portion of the plurality of plate members. A lower support member attached to the four blades to form the other end of the control rod opposite to the insertion end;
The first region for connecting the four blades to each other is formed at each of an end portion on the insertion end portion side and an end portion on the lower support member side of a handle disposed at the insertion end portion,
The lower support member side end portion of the first region is the first formed, coupled to the second and third each plate member, according to claim 4, wherein the handle is connected in front Symbol four blades, The control rod for a boiling water reactor according to any one of 6 and 7 . The control rod for a boiling water reactor according to claim 10 , wherein compressive residual stress is applied to a joint portion between the plurality of plate members and a joint portion between the handle and the plurality of plate members. The boiling water reactor control rod according to any one of claims 1 to 4 , wherein the neutron absorbing material is filled in the bridging portion.

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