JPS613084A - Boiling-water type reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a boiling water reactor (hereinafter referred to as BWR) in which control rods and a control rod drive mechanism can be attached and detached by mutually rotating a predetermined angle. ) related to improvements.

[Technical Background of the Invention] As shown in FIG. 5, in a BWR, a core shroud 2 is provided inside a reactor pressure vessel 1 that accommodates a coolant (soft water), and a reactor core provided in this core shroud 2 is used. Support plate 3
A reactor core 5 is constructed by loading a large number of fuel assemblies 4 thereon. Each of the fuel assemblies 4 has a large number of fuel rods housed in a rectangular cylindrical channel box, and in a plan view, they are arranged in a matrix within the core shroud 2. The coolant flowing upward from the bottom of the pressure vessel 1 is heated by nuclear reaction heat. Further, control rods (hereinafter referred to as CR) 6 are arranged in the reactor core 5 . As shown in FIGS. 6 and 7, this CR6 is constructed by combining four fingers 6a containing a neutron absorbing material so that the cross section is cross-shaped. The fuel assemblies 4 are interposed between the fuel assemblies 4 and are arranged at a ratio of one for every four fuel assemblies 4. By inserting each CR6 from below between the fuel assemblies 4, the core output is suppressed according to the insertion amount, and by pulling out each CR6 downward from between the fuel assemblies 4, the core output is increased. The configuration is such that output control is performed during reactor operation.

In addition, 7 in FIG. 5 is a cylindrical control rod guide tube (hereinafter referred to as a CR guide tube) provided below the core 5 corresponding to each CR6, and this CR guide tube 7 is shown in FIG. As shown, each CR6 is inserted into the interior to guide the CR6 as it moves up and down during normal operation of the reactor. A control rod drive bridge (hereinafter referred to as CRD) 8 is provided below the reactor pressure vessel 1 to drive the CR 6 up and down.

The upper end of the core shroud 2 is closed by a shroud head 9, and a steam separator 10 is connected above the shroud head 9. This steam-water separator 10 separates the coolant vapor heated and evaporated in the core 5 into steam and water, and further above the steam-water separator 10 is a steam dryer 11 for drying the separated steam. is connected. The steam that has passed through the steam dryer 11 is sent to a generator-driving turbine outside the reactor vessel 1 through a main steam pipe (not shown).

The CR guide tube 7 is connected to the core support plate 3 as shown in FIG.
It penetrates through and its upper end outer peripheral part is supported by the core support plate 3,
Furthermore, its upper end is engaged with a pin 12 protruding from the upper surface of the core support plate 3, thereby inhibiting its rotation. Furthermore, fuel supports 13 are formed at the four corners of the upper end of each CR guide tube 7 to support the fuel assembly 4 from below. Furthermore, a seat surface 14 is provided at the lower end of the inner peripheral surface of the CR guide tube 7 on which the lower end of the CR 6 is seated.

The CRD 8 is housed and supported in a cylindrical control rod drive housing (hereinafter referred to as CRD housing) 15, as shown in FIG. The CRD housing 15 penetrates the bottom head plate 1a of the reactor pressure vessel 1 and is welded to the bottom head plate 1a.
6 and a motor section 17 for driving the motor section 6 up and down.
With CRD exposed below the CRD housing 15,
It is attached to the lower end flange portion 15a of the RD housing 15 with bolts or the like.

The upper end of the CRD 8 is detachably connected to the lower end of the CR 6, and there are various types of such connection mechanisms. Examples thereof are shown in FIGS. 9(a) and (b) and FIGS. 10(a) and (b). That is, at the upper end of the piston 16 of the CRD 8, four vertically long engagement pieces 1 are arranged at equal intervals in the circumferential direction.
A bayonet type connecting portion 18 consisting of 8a is provided, and a bulging portion 18b is formed at the tip of the outer surface of each engaging piece 18a. Furthermore, a support rod 18c is provided at the center of the four engaging pieces 18a to protrude upward, and this support rod 18c
This limits the amount of inward deflection of the four engaging pieces 18a. On the other hand, the connecting portion 18 is located at the lower end of CR6.
A recess 19a for accommodating the bayonet is provided, and four engaging protrusions 19b are protruded at equal intervals in the circumferential direction from the open end of the inner circumferential surface of the recess 19a so as to correspond to the respective engaging pieces 18a. A type connected portion 19 is configured. When the connecting portion 18 and the connected portion 19 are connected, the recess 1
The bottom surface of CR 9a comes into contact with support rod 18c, and the weight of CR6 comes to be supported by support rod 18c.

Therefore, the attachment and detachment of the CR6 and the CRD 8 is performed with the CR6 lowered further than the operating range during nuclear reactor operation, and with the lower end of the CR6 seated on the seat surface 14 of the CR guide tube 7. That is, the connection between CR6 and CRD8 is
First, seat the CR6 on the seat surface 14 of the CR guide tube 7,
The piston 16 of CRD8 is raised. At this time C
The engaging piece 18a on the RD8 side passes through the engaging protrusion 19b till as shown in FIGS.
10(a) and 10(b), the bulging portion 18b of each engaging piece 18a is engaged with the retaining protrusion 19b in the recess 19a. To disconnect the CR6 and CRD8, first connect the CR6 to the seat surface 14 of the OR guide tube 7.
from the state shown in Figures 10(a) and (b).
8 by approximately 45 degrees to remove the bulging portion 18b of each engaging piece 18a from the retaining protrusion 19b in the recess 19a as shown in FIGS. 9(a) and 9(b), and the engaging piece 18a is engaged. The engagement piston 16 is lowered so as to pass between the protrusions 19b.

[Problems with Background Art] In a BWR in which the CR and CRD can be attached and detached by mutually rotating them by a predetermined angle, when the CR is lowered to a position where it is seated on the seat surface of the OR guide tube, Since the upper ends of the OR fingers are interposed between adjacent fuel assemblies, rotation is prohibited by these fuel assemblies, but each finger is thin and long (approximately 4 m), so the CRD When using the @ theory, there was a problem with workability and soundness due to rotational force at the lower end.

[Object of the invention] The present invention was made based on the above circumstances, and
The purpose of this is to enable the CR and CRD to be attached and detached by rotating them by a predetermined angle.
Even if rotational force is applied to the lower end of the OR when attaching and detaching the CRD and the I
The objective is to improve workability and CR soundness during IH.

[Summary of the Invention] In order to achieve the above object, the present invention provides a CR that is inserted into the reactor core and operates after the morning to control the output during reactor operation, and a CR that is inserted into the reactor core to control the output during reactor operation. an OR guide tube that has a guiding function for the OR that moves up and down during reactor operation and has a seat surface at its lower end for seating the OR; and an OR guide tube that is connected to the lower end of the OR and that allows the CR to move up and down inside the OR guide tube during reactor operation. , one removal of the CR is performed by rotating the OR at a predetermined angle relative to the CR with the OR seated on the seat surface of the OR guide tube. It is provided so that it can be fitted in a concave and convex manner from the top and bottom directions, and the C when the CR and CRD are attached and detached.
It is configured to include an engaging part and an engaged part that prohibit rotation of R.

[Embodiment of the invention] Figures 1 to 4 show an embodiment of the present invention,
FIG. 1 shows a schematic configuration of a BWR. That is, the coolant (
A core shroud 102 is provided inside the reactor pressure vessel 101 that accommodates soft water).
A core 105 is constructed by loading a large number of fuel assemblies 104 onto a core support plate 103 provided within the core 102. Each of the fuel assemblies 104 is made up of a large number of fuel rods housed in a rectangular cylindrical channel box, and is arranged in a matrix shape in the core shroud 102 in a plan view, and the reactor pressure The coolant flowing upward from the bottom of the container 101 is heated by nuclear reaction heat.

Further, an OR 10B is arranged in the reactor core 105. This CR10G is constructed by combining four fingers containing a neutron absorbing material so that the cross section becomes cross-shaped, and each of the four fingers is interposed between adjacent fuel assemblies 104. One fuel assembly per fuel assembly 104 is arranged. By inserting each CR106 from below between the fuel assemblies 104, the core output is suppressed according to the insertion amount, and by pulling out each CR106 downward from between the fuel assemblies 104, the core output is increased. The configuration is such that output control is performed during reactor operation.

In addition, 107 in the figure indicates each CRIO 6 below the core 105.
This OR guide tube 107 is a cylindrical OR guide tube provided correspondingly to each C and R106, and is used to guide the OR106 that moves up and down during normal operation of the reactor. A CHD 108 is provided below the reactor pressure vessel 101 to drive the CR 106 up and down.

The upper end of the core shroud 102 is the shroud head 1
09, and a steam/water separator 110 is connected above this shroud header 09.

This steam/water separator 110 separates the coolant vapor heated and evaporated in the core 105 into steam and water, and furthermore, a steam dryer 111 is connected above the steam/water 1110 to dry the separated steam. has been done. and steam dryer 11
The steam that has passed through the reactor vessel 101 is sent to a generator-driving turbine outside the reactor vessel 101 through a main steam pipe (not shown).

The OR guide tube 107 passes through the core support plate 103 and has its upper end outer periphery suspended on the core support plate 103, and further has its upper end engaged with a bottle protruding from the upper surface side of the core support plate 103. Its rotation is prohibited. Also, each CR
Fuel supports that support the fuel assembly 104 from below are formed at the four corners of the upper end of the guide @ 107, respectively. Furthermore, a seat surface 112 is provided at the lower end of the inner circumferential surface of the OR guide tube 101, as shown in FIG. 2, on which the lower end of the CR 106 is seated. Furthermore, a locking portion 113 is provided at the lower end of the OR guide tube 101.

The CRD 108 is housed and supported in a cylindrical CRD housing 114 that passes through the bottom end plate 101a of the reactor pressure vessel 101 and is welded to the bottom end plate 101a. In this CRD housing 114, the OR
The locking portion 113 of the guide tube 107 is introduced from above.

The CRD 108 has a locked portion 11 at the upper end of an outer tube 115 that fits into the inner periphery of the CRD housing 114.
6, and this locked portion 116 and the OR guide tube 101
The locking portion 113 constitutes a bayonet connection mechanism that can be freely engaged and detached from each other. Roughly CRD 1H is a piston 11 that moves up and down inside the outer tube 115.
7. Motor section 118 that drives the piston 117 up and down
(See FIG. 1), and is attached to the lower end flange portion 114a of the CRD housing 114 with bolts or the like, with the motor portion 118 exposed below the CRD housing 114.

The upper end of the piston 117 of the CR0108 is provided with a bayonet type connecting portion 119 consisting of four vertical engagement pieces 119a arranged at equal intervals in the circumferential direction, and each engagement piece 11
A bulge 119b is formed at the tip of the outer surface of 9a. Furthermore, a support rod 119C is provided in the center of the four retaining pieces 119a to protrude upward, and this support rod 119
C limits the amount of inward deflection of the four retaining pieces 119a. On the other hand, a recess 120a for accommodating the connecting portion 119 is provided at the lower end of the CR10B, and each of the engaging pieces 119a is provided at the open end of the inner peripheral surface of the recess 120a.
The bayonet type connected portion 120 is configured by projecting four locking protrusions 120b at equal intervals in the circumferential direction so as to correspond to the above. When the connecting portion 119 and the connected portion 120 are connected, the bottom surface of the recess 120a is connected to the support rod 119.
C, and the weight of the CR 106 comes to be supported by the support rod 119C.

At the outer periphery of the lower end of the Q R106, there are
As shown in the figure, an engaging portion 121 formed of one or more convex portions (the figure shows an example in which two convex portions are provided) is provided in a protruding manner. On the other hand, at the bottom of the OR guide tube 107, CR1
A cylindrical portion 122 is provided at a position surrounding the portion where the above-mentioned engaging portion 121 of 06 is provided, and the inner peripheral surface of this cylindrical portion 122 has convex portions corresponding to each convex portion of the above-mentioned engaging portion 121. Engaged portions 123 made up of the same number of recesses are provided. As shown in FIG. 2, these engaging portions 121 and engaged portions 123
When lowered to the position where the seat 2 is seated, they fit into each other from above and below.

Therefore, to attach and detach CR106 and CRD 108, use CR1
06 is further lowered than the operating range during reactor operation, and the lower end of the CR 106 is seated on the seat surface 112 of the CRD guide tube 107.

That is, to connect the CR 106 and the CRD 108, first the CR 1013 is seated on the seat surface 112 of the OR guide tube 107, and the piston 117 of the CHD 108 is raised. At this time, the engagement piece 119a on the CRD 108 side is made to pass through the engagement protrusion 120b, and the support rod 119
When C contacts the bottom of the recess 120a, CRD 1
0B is rotated about 45 degrees to engage the bulging portion 119b of each engagement piece 119a with the engagement protrusion 120b in the recess 120a. Also, to disconnect CRioa and CRD 108, first connect CR106 to seat surface 1 of OR guide tube 107.
12, and rotate the CRD 108 by about 45 degrees so that the bulge 8I1119b of each engagement piece 119a is aligned with the recess 120a.
The engagement piston 11 is removed from the inner engagement protrusion 120b, and the engagement piece 119a passes between the engagement protrusions 120b.
7 will be lowered.

When attaching and detaching the CR100 and the CRD 108 in this manner, the lower end of the CR106 is prohibited from rotating due to the engagement between the engaging portion 121 and the engaged portion 123, so the CR0108 is not connected to the CR106. Even when rotated, the lower end of the CR 106 does not rotate following the CRD 108, and no twisting or the like occurs. Therefore, the workability when attaching and detaching the CR 106 and the CRD 108 is improved, and the soundness of the CR 106 is also improved.

In the above embodiment, the engaging portion 121 on the CR106 side is a convex portion, and the engaged portion 123 on the CR0108 side is a concave portion, but the relationship between the convex portion and the concave portion may be reversed.

Furthermore, the number of these convex portions and concave portions can also be set arbitrarily.

[Effects of the Invention] As described in detail above, according to the BWR of the present invention, the lower end of the CR and the upper end of the OR guide tube are provided so as to be able to engage with each other in a recessed and recessed manner from the vertical direction, and the CR and CRD are By providing an engaging portion and an engaged portion that prohibit rotation of the CR during attachment/detachment, even if a rotational force is applied to the lower end of the CR when detaching the CR and the CRD, the CR will not be twisted. There is no occurrence of this problem, and the workability during attachment and detachment and the soundness of the CR can be improved.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention,
Figure 1 is a sectional view showing the schematic configuration of BWR, Figure 2 is OR
A cross-sectional view of the area around the connection between the guide tube and CRD, Figure 3 is
11 in the figure, FIG. 4 is a perspective view showing the relationship between the engaging part of the CR and the secured part of the OR guide tube, and FIGS. 5 to 10 are for explaining the background art. The figure is a sectional view showing the schematic configuration of BWR, FIG. 6 is a Vl-VT sectional view of FIG. 8,
Fig. 7 is a sectional view taken along the line ■-■ in Fig. 8, Fig. 9 (a) is a sectional view showing a disconnected state of CR and CRD, and Fig. 9 (b) is an IN-IX cross section in Fig. 8 (a). Figure 10(a) is a sectional view showing the connection state of CR and CRD, and Figure 10(b) is the same figure (
It is a XX sectional view of a). 105...Reactor core, 106...CR (control rod), 1
07...OR guide tube (control rod), 108...CR
D (control rod drive mechanism), 112... seat surface, 1
21... Engaging portion, 123... Engaged portion. Applicant's Representative Patent Attorney Takehiko Suzue Figure 2 Figure 3 Figure 4 Figure 6 Figure 7 Figure 8

Claims (2)

[Claims] (1) A control rod that is inserted into and pulled out of the reactor core to control output during reactor operation, and a control rod that is inserted inside and has a guiding function for the control rod that moves up and down during reactor operation, and the lower end A control rod guide tube having a seat surface on which a control rod is seated; and a control rod guide tube connected to the lower end of the control rod so that the control rod is raised and lowered inside the control rod guide tube during reactor operation, and attachment and detachment to the control rod is controlled. a control rod drive mechanism that rotates the rod at a predetermined angle relative to the control rod while seated on the seat surface of the control rod guide tube; and a lower end of the control rod and a lower end of the control rod guide tube. Boiling water characterized by comprising an engaging part and an engaged part that are provided so as to be able to engage with each other in a concave and convex manner from above and below, and that prohibit rotation of the control rod when the control rod and the control rod drive mechanism are attached and detached. type reactor. (2) A convex portion is provided at the lower end of the outer periphery of the control rod to serve as the engaging portion, and a concave portion is provided at the upper end of the control rod guide tube to serve as the engaged portion. boiling water reactor.