JPH03596B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a structure for mounting a rotary plug in a roof slab of a nuclear reactor, and more particularly to a structure capable of suppressing vertical displacement of a rotary plug during an earthquake.

Figure 1 shows the overall structure of a conventional nuclear reactor. The roof slab 1 is a donut-shaped ring, and a reactor vessel 3, in which a reactor core 2 is disposed in the center and filled with liquid metal sodium as a coolant, is fixed to the lower surface of the roof slab 1. Note that the reactor core 2 is supported by a container 3 via a support member (not shown). The roof slab 1 is equipped with a large number of heavy equipment such as an intermediate heat exchanger 4 for extracting heat from the reactor core 2 and a pump 5 for circulating sodium. The roof slab 1 is also provided with a rotary plug mounting hole 8, and a core upper mechanism 6 that includes control rods and a control rod drive mechanism for controlling the output of the reactor core 2.
A rotating plug is loaded.

Further, the roof slab 1 is provided with a heat insulating structure to prevent heat from the reactor core 2 from leaking to the outside through the roof slab, and a radiation shield to shield radiation.

As described above, the roof slab 1 mounts and supports a large number of heavy equipment, and the roof slab 1 itself also has functions for shielding heat and radiation, so its own weight and loading load are extremely large. Further, the roof slab 1 is provided with a through hole for suspending the intermediate heat exchanger 4 and the pump 5 in the furnace, and has a structure in which rigidity tends to decrease.

However, when looking at the roof slab 1 from the perspective of seismic design, the control rod drive mechanism that controls the output of the reactor core 2 is mounted on the rotating plug 7, but when the roof slab 1 vibrates in the vertical direction, the rotating plug The control rod mounted on 7 will also vibrate up and down. Such vertical vibration of the control rods is undesirable from the viewpoint of core power control.

An object of the present invention is to provide a rotary plug mounting structure in a roof slab of a nuclear reactor that exhibits less vibration in the vertical direction even during an earthquake.

The present invention forms slopes on the contact surfaces of both the roof slab and the rotating plug, and attempts to suppress the deformation of the roof slab during an earthquake by the frictional force on the slope where the roof slab and the rotating plug contact. .

First, before describing embodiments of the present invention, the principle by which deformation of the roof slab can be suppressed will be explained based on FIGS. 2 and 3, which have simplified structures.

In FIG. 2, the side peripheral wall of the rotary plug mounting hole 8 of the roof slab 1 has a mortar shape, while the outer periphery of the rotary plug 7 has a truncated cone shape to fit into the roof slab. Roof slab 1 shown in Figure 2
FIG. 3 shows the deformation pattern when the tip of the roof slab 1 attempts to move upward when an earthquake force is applied in the vertical direction to the nuclear reactor structure having the rotating plug 7. In Fig. 3, when the tip 1a of the roof slab 1 tries to deform upward, the roof slab 1 originally tries to deform in a longitudinal section as shown by the dashed line in the figure, but as shown by the arrow A in the figure. The deformation of the roof slab 1 is restrained by the frictional force at the contact surface between the roof slab 1 and the rotating plug 7, and the roof slab 1 deforms as shown by the solid line in the same figure. Deformation can be kept small.

Incidentally, a concave shoulder for plug locking may be provided on the slope of the mounting hole 8 of the roof slab 1, and the rotating plug 7 may be provided with a convex shoulder that engages with this concave shoulder.

FIG. 4 shows the configuration of an embodiment according to the present invention, which is constructed so that the deformation can be restrained even when the tip 1a of the roof slab 1 moves downward. It is something. In other words, in order to restrain the deformation of the tip 1a from moving downward, the inclination of the contact surface between the roof slab 1 and the rotary plug 7 must be symmetrical with respect to the inclination shown in FIG. 2 with respect to the axial direction of the reactor vessel. It is sufficient if it is formed.

The embodiment shown in FIG. 4 embodies this knowledge, and the mounting holes 8 of the roof slab 1 are
A first inclined surface 11 that opens upward and a recess 20 that opens upward are provided, and a wall surface of the recess 20 on the center side of the mounting hole has a second inclined surface 12 that opens upward. has been done. On the other hand, a first inclined surface 11 is formed on the side peripheral wall of the rotary plug 7.
A third inclined surface 13 that engages with the second inclined surface 12 and a convex portion 30 that fits into the recess 20 are formed.A third inclined surface 13 that engages with the second inclined surface 12 is formed on the wall surface of the convex portion 30 on the center side of the plug. Four inclined surfaces 14 are formed.

In this way, if the roof slab and rotating plug have a contact structure that combines two types of slopes with different directions of inclination (i.e., a slope that opens upwards and a slope that opens downwards), the roof slab and rotation during an earthquake will be prevented. The vertical displacement of the plug can be reduced.

As described above, the structure of the rotary plug attachment part in the roof slab of a nuclear reactor according to the present invention includes a roof slab attachment hole side circumferential wall, a side circumferential wall of a rotating plug that engages with the first and second inclined surfaces, The third and fourth slopes, as well as fitting recesses and protrusions, are formed, and the vertical movement of the roof slab and rotating plug, as well as the vertical movement of the control rod, during an earthquake is controlled by the contact between the roof slab and the rotating plug. It can be suppressed by using the frictional force acting on the surface.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view showing the structure of a conventional rotary plug mounting part, Figure 2 is a cross-sectional view showing the basis of the function and effect of the structure according to the embodiment, and Figure 3 is the plug shown in Figure 2 during an earthquake. FIG. 4 is a schematic diagram showing a modification of , and FIG. 4 is a sectional view showing a structure according to an embodiment of the present invention. 1...Roof slab, 2...Reactor core, 3...Reactor vessel, 4...Intermediate heat exchanger, 5...Pump, 6
... Core upper mechanism, 7 ... Rotating plug, 8 ... Mounting hole, 11 ... First slope, 12 ... Second slope, 13 ... Third slope, 14 ... Fourth slope,
20... Concave portion, 30... Convex portion.

Claims (1)

[Scope of Claims] 1. A first inclined surface that opens upwardly and a recess that opens upwardly are provided in at least a part of the side peripheral wall of the rotary plug mounting hole of the roof slab,
and a second inclined surface that opens upwardly is formed on the wall surface of the recess on the center side of the mounting hole, and is engaged with the first inclined surface on the side circumferential wall of the rotary plug to be mounted in the mounting hole. A third sloped surface and a convex portion that fits into the recess are formed, and a fourth sloped surface that engages with the second slope is formed on a wall surface of the convex portion on the plug center side. A rotary plug attachment structure in a nuclear reactor roof slab characterized by: 2. The roof slab is equipped with at least an intermediate heat exchanger and a sodium circulation pump,
and claim 1 in which the reactor vessel is suspended.
Structure described in section. 3. The structure according to claim 1 or 2, wherein the nuclear reactor is a fast breeder reactor.