JPS6147586A - 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 (generally referred to as A8WR) in which control rods and a control rod drive mechanism are connected by a bayonet mechanism, and in particular, The present invention relates to a boiling water nuclear reactor (hereinafter referred to as BWR) in which rods and a control rod drive mechanism can be attached and detached from either side of the control rods or the control rod drive mechanism.

[Technical Background of the Invention] As shown in FIG. 4, a BWR includes a core shroud 2 provided inside a reactor pressure vessel 1 that accommodates a coolant (soft water), and a reactor core provided within this core shroud 2. Support plate 3
A reactor core 5 is depicted with a large number of fuel assemblies 4 loaded 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. 5 and 6, this CR6 has four blades 6a containing a neutron-absorbing material assembled in a cross-shaped cross section, and has a socket 6a at the lower end. The blades 6a are interposed between adjacent fuel assemblies 4, and are arranged at a ratio of one for every four fuel assemblies 4. By inserting each CR6 into the four fuel assemblies from below, the core output is suppressed according to the insertion claw, and by pulling out each CR6 downward from between the four fuel assemblies, the core output is increased. The configuration is such that output control is performed during reactor operation.

In addition, 7 in FIG. 24 indicates a cylindrical control rod guide tube (hereinafter referred to as OR) provided below the core 5 corresponding to each CR6.
This OR guide tube 7 allows each CR 6 to pass therethrough as shown in FIG. 6, and guides the CR 6 as it moves up and down during normal operation of the reactor. A control rod drive rock (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 to the shroud head 9. This steam separator 10 is a core 5
A steam dryer 11 is connected above the steam separator 10 to dry the separated steam. The steam that has passed through the steam dryer 11 is sent to a power generation hall driving turbine outside the reactor vessel 1 through a main steam pipe (not shown).

The OR 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 OR 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 circumferential surface of the OR guide tube 7 on which the lower end of the CR6 is seated, and a blade 6 of the CR6 is provided at a substantially mid-height position on the inner circumferential surface of the OR guide tube 7.
A rotation preventing portion 7a is provided that engages with the rotation stopper 7a and prohibits rotation of the CR6.

The CR[) 8 is housed and supported in a cylindrical control rod drive housing (hereinafter referred to as CHD housing) 15, as shown in Figure R7. The CRD housing 15 penetrates through the bottom head plate 1a of the reactor pressure vessel 1 and connects it to the bottom head plate 1a.
The CRD 8 has a piston 16 housed in the CRD housing 15 and a motor section 17 that drives the piston 16 up and down.
7 is positioned below the CRD housing 15,
It is attached to the lower end flange portion 15a of the CRD 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. Especially those that adopt bayonet l-14ffi are A B W
It is called R (Advance B W R),
Fig. 8(a)(b>) and F91ffl(a)(b) show the concrete (8 structure, that is, CRI) 8 piston 16 at the upper end with four holes arranged at equal intervals in the circumferential direction. A bayonet type connecting portion 18 consisting of a long engaging piece 18a is provided, and a bulging portion 18b is provided at the tip of the outer surface of each engaging piece 18a.
is formed. Furthermore, a support rod 18c is provided at the center of the four engagement pieces 18a to project upward, and this support rod 18c allows the four engagement pieces 18a to deflect inwardly m.
I'm trying to limit it.

On the other hand, the socket 6b at the lower end of the CR6 is provided with a recess 19affi for accommodating the connecting portion 18, and the inner peripheral surface nO line end of the recess 19a has four engaging portions corresponding to each of the engaging pieces 1aa. The bayonet-type connected portion 19 is configured by protruding protrusions 19b at equal intervals in the circumferential direction. When the connecting portion 18 and the connected portion 19 are connected, the bottom surface of the recess 19a comes into contact with the support rod 18c, and the weight of the CR6 is supported by the support rod 18c.

Soko T: CR6 to CRD 8 to (7) Arrival J] j2
C. This is carried out with the CR6 being lowered further than the operating range that is available during reactor operation, and the lower end of the CR6 being seated on the seat surface 14 of the OR guide tube 7. That is, CR6
and CRD8, first set CR6 to CR guide 7.
The person is seated on the seat surface 14, and the piston 1G of the CRD8 is raised. At this time, the engagement piece 18a on the CRD 8 side is made to pass between each engagement protrusion 5 as shown in FIGS. Rotate about 45 degrees and make the image shown in Figure 9(a) (
b) As shown in FIG.
and the inner engaging protrusion 19b. At this time, CR6
The rotation of the CR 6 is prohibited by the engagement between each blade 6a of the CR 6 and the rotation stopper 7a. To separate the CR6 and CRD8, first seat the CR6 on the seat surface 14 of the CRR inner tube 7, and then remove the CRD8 from the state shown in FIGS.
° Rotate each engaging piece 18a as shown in FIGS. 8(a) and (b).
The bulging portion 18b of the engaging protrusion 19 in the recess 19a]) J:
Then, the engaging screws 1 to 16 are lowered so that the engaging piece 18a passes between the engaging protrusions 19b.

Note that even when performing the release l152 operation, the CR6 is prohibited from rotating due to the engagement between each blade 6a and the rotation stopper 7a.

[Problems with the Background Art] In a conventional BWR in which the CR and CRD can be attached and detached by mutually rotating a predetermined angle, the rotation of the CR is
Since this is prohibited by the rotation stopper provided at approximately the mid-height position of the RR inner tube, the attachment and detachment of both is performed exclusively by rotating the CRD. For this reason, even if only the CR was to be removed, the CRD had to be removed from the CRDR housing each time. For this reason, it takes a long time to remove the CRD, and the work inside the pedestal takes a long time, causing damage to the workers. ! There was a problem that 1ffi increased. It is also conceivable to rotate the CR and remove it without removing the CRD. However, C
In order to rotate R, it must be done with the piston of the CRD raised above the rotation stopper, and since the rotation stopper is located at a fairly high position, the CRD piston will be tilted, causing In reality, it would have been extremely difficult for the two parties to leave under such conditions.

[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 at a predetermined angle relative to each other. In particular, the objective is to greatly reduce the radiation exposure of workers by making it possible to remove the CR in a short time without removing the CRD from the OR housing.

[Summary of the invention] In order to achieve the above object, the present invention provides a CR that performs power control during reactor operation by inserting and withdrawing wJ (wJ) from the reactor core.
A CRR inner pipe is inserted into the inside of the CR and has a guiding function for the CR that moves up and down during reactor operation, and a CRR inner pipe is connected to the lower end of the CR to guide the CR during reactor operation.
The CRD is raised and lowered inside the RR inner tube, and the CR is attached and detached by rotating it at a predetermined angle relative to the CR.
It is configured to include a rotation stopper provided at the lower end of the RR inner tube and fitted into the lower end from above to prevent rotation of the CR.

[Embodiment of the invention] Figures 1 to 3 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 a reactor pressure vessel 101 that accommodates soft water).
A reactor core 105 is constructed by loading a large number of fuel assemblies 104 onto a core support plate 103 provided within the reactor core 105 . 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, a CR 106 is arranged in the reactor core 105. This CR106 combines four blades 106a containing a neutron absorbing material so that the cross section is cross-shaped, and has a socket 1oeb (see Figure 2) at the lower end. The fuel assemblies 104 are interposed between the fuel assemblies 104 and arranged at a ratio of one for every four fuel assemblies 104. By inserting each CR10G from below between the fuel assemblies 104, the core output is suppressed according to the insertion amount, and each CR10G is
6 from between the fuel assemblies 104 to the lower side, the core output is increased and the output is controlled during nuclear P operation.

In addition, 101 in the figure indicates each 0RIO6 below the core 105.
This OR guide tube 107 is a cylindrical OR guide tube provided correspondingly to each CR106.
It guides the CR106 that moves up and down during normal reactor operation. A CRD 108 is provided below the reactor pressure vessel 101 to drive the QR 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 head 109.

This steam-water separator 110 separates the coolant vapor heated and evaporated in the core 105 into steam and water, and further above the steam-water separator 110 is a steam dryer 111 for drying the separated steam. is connected. and steam dryer 1
The steam that has passed through the reactor vessel 101 is sent to a power generating 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 OR
Fuel assemblies 1 are provided at the four corners of the upper end of the guide tube 101, respectively.
A fuel support is formed to support 04 from below. Furthermore, at the lower end of the inner circumferential surface of the OR guide tube 107, as shown in FIG.
12 are provided. Furthermore, a locking portion 113 is provided at the lower end of the OR guide tube 107.

In addition, as shown in R1 diagram and FIG. 2, the 0RD10
8 is a cylindrical CRD that penetrates the bottom head plate 101a of the reactor pressure vessel 101 and is welded to the bottom head plate 101a.
It is housed and supported in a housing 114.

The locking portion 113 of the OR guide tube 107 is introduced into the CRD housing 114 from above.

CR0108 has a locked portion 11G at the upper end of the outer tube 115 that fits into the inner periphery of the CRD housing 114.
and a bayonet connection 01 that can be freely engaged and detached from each other by the locked portion 11G and the locking portion 113 of the OR guide tube 107.
13 INs have been created. And further CRD108
has a piston 117 that moves up and down inside the outer tube 115, and a motor section 118 (see FIG. 1) that drives the piston 117 up and down.
While positioned below the housing 114, it is attached to the lower end flange portion 114a of the CRD housing 114 with bolts or the like.

At the upper end of the piston 111 of the CHD 108, a bayonet type connecting portion 119 consisting of four vertically long engagement pieces 119a arranged at equal intervals in the circumferential direction is provided.
A bulge 119b is formed at the tip of the outer surface of 19a. Further, a support rod 119C is provided in the center of the four engaging pieces 119a to protrude upward.
9C limits the amount of inward deflection of the four retaining pieces 119a. On the other hand, the socket 106b at the lower end of the CR10G has a recess 120a that accommodates the connecting portion 119.
is provided, and four engaging protrusions 1 are provided at the frontage end of the inner peripheral surface of the recess 120a so as to correspond to the respective engaging pieces 119a.
20b project at equal intervals in the circumferential direction to form the bayonet-type connected portion 120. When the connecting portion 119 and the connected portion 120 are connected, the bottom surface of the recess 120a comes into contact with the support rod 119C, and the weight of the CR 106 is supported by the support rod 119c.

A rotation stopper 122 is provided at the lower end of the OR guide tube 107, into which the lower end of each blade 106a of the CR 106 is fitted from above. This rotation prevention part 122 has a structure in which four fitting grooves 123 are formed at equal intervals in the upper part of a cylindrical body, and each one fitting groove 123 has a width dimension that allows the blade 106a of the CR106 to fit therein. , each fitting groove 12
An inclined surface 123a is formed on the upper half of the inner surface of the blade 3. The inclined surface 123a serves as a guide when the blade 106a is fitted from above. And each blade 106a of CR10G is fitted with 1M
123 is the socket 10 of CR106 as shown in Figure 2.
6b is lowered to a position where it is seated on the seat surface 112 of the OR guide tube 107, and they are engaged with each other in the vertical direction J: in a concave-convex manner.

Therefore, the following two steps are required to attach and detach CR106 and CRD 108.
You can do it the same way.

The first method is to rotate the CRD 108. This lowers the CR10G further below the operating range during reactor operation, and lowers the lower end of the CR10G (socket 1
013b) is seated on the seat surface 112 of the CRD guide tube 107. That is, CRioe and O
To connect with the RD 108, first the CR 106 is seated on the seat surface 112 of the OR guide tube 107, and the screw 117 of the CRD 108 is raised. At this time, CRD 1
The engagement piece 119a on the 08 side passes between the engagement protrusions 120b, and when the support rod 119C comes into contact with the bottom of the recess 120a, rotate the entire CRD 108 by about 45 degrees, and rotate each engagement piece 119a. The bulge 119b and the recess 120a
The CRD 108 is attached to the CRD housing 114 with bolts.

Also, when separating CR106 and CRD 108, first
R106 is seated on the seat surface 112 of the OR guide tube 107, and to attach the ORD 108 to the CRD housing 114, remove the bolts, rotate the entire CRD 108 by about 45 degrees, and fit the bulges 119b of each engagement piece 119a into the recess. 12
0a, and the engagement piston 117 is lowered so that the engagement piece 119a passes between the engagement protrusions 120b.

When attaching and detaching the OR 10G and the CRD 108 in this manner, the CR 106 is prohibited from rotating due to the engagement between the lower end of the blade 106a and the fitting groove 123 of the rotation stopper 122.
It can be easily rotated against the

Next, the second method is to rotate CR10G.
This is particularly effective when only the CR106 needs to be removed while leaving the RD10g. This is performed with the CRioe slightly raised from the lowest position by the piston 117 of the CRD 108, and the lower end of the blade 106b of the CRioe is disengaged from the fitting groove 123 of the rotation stopper 122. That is, first connect CR106 to CRD108 through screws 1-
The blade 106b of CR10G is raised slightly by
With the cap 1 removed, rotate the CR 106 by about 45 degrees to remove the concave 1 from the bulge 119b of each engagement piece 119a.
Remove the engagement protrusion 120b in 20a and continue CR
10'6 upwards. In this case CRD
Since the piston 117 of 108 is prohibited from rotating within the CRD housing 114, the CR 106 can be easily rotated.

Therefore, the above (in the above case, CR10G and CRD1
08 can be attached and detached from either side of CR106 or ORD 108, and in particular, the removal work of CR10G can be done in a short time without removing CHD 108 from OR housing 114, reducing the radiation exposure of workers. m can be significantly reduced.

[Effects of the Invention] As detailed above, according to the present invention, in a BWR in which the CR and the CRD can be attached and detached by mutually rotating a predetermined angle, the attachment and detachment of the CR and the CRD can be carried out by either the CR or the CRD. It can be done from either side of the
The removal work of R can be carried out in a short time without removing the CRD from the OR housing, and the radiation dose to workers can be significantly reduced.

[Brief explanation of drawings]

1 to 3 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
The ■-■ arrow view in the figure, and FIGS. 4 to 9 show conventional examples. FIG. 4 is a sectional view showing the schematic structure of the BWR, and FIG.
The figure is a cross-sectional view taken along the line V-V in Figure 7, and Figure 6 is a VI - in Figure 7.
8(a) is a sectional view showing the disconnected state of CR and CHD, FIG. 8(b) is a sectional view taken along the line ■-■ of FIG. FIG. 3(b) is a sectional view taken along the line rX-■ in FIG. 1(a). 105...Reactor core, 106-CR (control rod), 10
Cra...Blade, 106b...Socket, 10
7...OR guide tube (control rod guide tube), 108...C
RD (control rod drive structure), 122... rotation stopper,
123...mating) Oh. Applicant's agent Patent attorney Takehiko Suzue Figure 5 jI6 Figure 7

Claims (2)

[Claims] (1) Control rods that are inserted into and pulled out of the reactor core to control output during reactor operation, and control rods that are inserted into the core and have a guiding function for the control rods that move up and down during reactor operation. A control rod that is connected to a guide tube and the lower end of the control rod, and that the control rod is moved up and down inside the control rod guide tube during reactor operation, and that attachment and detachment from the control rod is performed by rotating a predetermined angle with respect to the control rod. Boiling water characterized by comprising: a drive mechanism; and a rotation stopper provided at the lower end of the control rod guide tube and fitting the lower end of the control rod from above to prevent rotation of the control rod. type reactor. (2) The boiling water nuclear reactor according to claim 1, wherein the rotation stopper has four fitting grooves into which the lower ends of the four blades of the control rod are respectively fitted.