JPS6242397Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a nuclear reactor structure in which a reactor vessel lid and its upper structure are integrated into an integrated structure.

The seismic conditions of the reactor are severe, and the temperature of the Sakamo reactor vessel lid rises to about 300℃ during operation, causing a large thermal expansion compared to normal temperature, while the upper structure remains almost unchanged during operation. Since they are at room temperature, there will be a difference in the amount of thermal elongation at the joint due to the temperature difference between the two. Further, since each of the structures has a circular cross section, this difference in thermal expansion spreads radially.

Therefore, in terms of seismic design, it is necessary to support and restrain the joints where this thermal elongation occurs by so-called pin support.

Furthermore, from an engineering point of view, it is important to note that, as modern nuclear reactors have become enormous, the equipment and support structures are now among the largest construction scales in terms of size and weight. Mechanisms currently in use that can withstand small loads are no longer able to cope with this problem.

That is, in the design of a nuclear reactor, which is a heavy, large-sized seismic structure that undergoes thermal changes, the following conditions must be easily met.

(a) Capable of absorbing large thermal expansion.

(b) The method of working large-sized sheet metal structures must be able to be constructed with precision.

(c) Since it is dangerous to perform adjustment work with the superstructure suspended temporarily, the adjustment work must be able to be performed with the superstructure in place.

(d) For earthquake resistance, the joints must have a pin function in any condition.

This project was proposed to satisfy these requirements, and the upper structure is installed between the vertical parts of the U-shaped mounting bracket fixed to the upper surface of the reactor vessel lid or the lower surface of its superstructure. Insert the vertical part of the inverted T-shaped mounting bracket fixed to the lower surface of the object or the upper surface of the reactor vessel lid, and insert the lower end of the vertical part of one of the two mounting brackets that protrudes from the upper structure. is supported by the horizontal part of the other mounting bracket fixed to the reactor vessel lid, and a gap is left between the horizontal part of the one mounting bracket and the vertical part of the other mounting bracket. , loosely insert a pin into the horizontal elongated hole of each vertical piece of each of the mounting brackets, and connect the lower and upper surfaces of the pin to the lower surface of the horizontal elongated hole of the vertical piece of one of the mounting brackets and the other mounting bracket, respectively. This relates to a nuclear reactor characterized in that the vertical piece is brought into contact with the upper surface of the horizontal elongated hole in the nuclear reactor.

Figure 1 shows a basic model of the structure that requires the adoption of the present invention, in which two structures a and b are stacked one on top of the other with a joint c interposed between them. dimensional relative deviations may occur due to differences in thermal elongation. If thermal elongation occurs in the lower structure b, a slide bed e is often interposed between it and the foundation d. This proposal is applicable whether the structure with a large elongation is the upper structure a or the lower structure b, and this proposal relates to the structure of the part shown as the joint c in the figure. It is.

In seismic analysis, overturning moment M is applied to superstructure a.
When this occurs, floating occurs on the upstream side. This floating development greatly affects and reduces the natural frequency of the upper structure a. Therefore, it is said that the seismic design of a structure is preferably designed at a point where the response acceleration to earthquake motion appears to be significantly large, that is, in a rigid region adjacent to the so-called resonance region between the dominant frequencies. When the natural frequency of the structure decreases due to floating development, it approaches the resonance point.

To suppress this uplift, if there is no relative dimensional deviation between the upper and lower structures, bolts or fixing pins can be used to achieve the desired purpose, but if there is a relative deviation, internal stress will occur and this Such measures must be avoided.

Figure 2 shows the details of the joint part of the reactor according to the present proposal proposed in view of the above-mentioned circumstances. At the same time, weld the horizontal parts 3 of the U-shaped mounting bracket C, each of which has a horizontal elongated hole 2, to a pair of vertical parts 1, and attach the mounting bracket C on the lower surface of the upper structure B having a circular cross section. Weld the horizontal part 6 of the inverted T-shaped mounting bracket D, which has a horizontal elongated hole 5 in the vertical part 4, to the corresponding position of the inverted T-shaped mounting bracket D.
The vertical piece 4 of the U-shaped mounting bracket C is inserted between the pair of vertical pieces 1, 1 of the U-shaped mounting bracket C, and its lower end surface is supported by the horizontal piece 3 of the U-shaped mounting bracket C, and thus the upper structure B is supported by the reactor vessel lid A, and _a gap of
be left behind.

Further, horizontal elongated holes 5 in each of the vertical pieces 1, 4, 1,
2 and 5 from the side, and the pin 7 is inserted into the vertical part 4 of the inverted T-shaped mounting bracket D.
The horizontal elongated hole 5 of the U-shaped mounting bracket C is in contact with its lower surface p, and the upper surface thereof is such that a gap X ₂ is left, and the pin 7 is in contact with the horizontal elongated hole 2 of each vertical piece 1 of the U-shaped mounting bracket C on its upper surface. q, and the lower surface is such that a gap X ₃ remains.

In the case of a large structure, the processing accuracy of the horizontal elongated holes 2 and 5 cannot be expected to be very high, so it is preferable to adjust only the parallelism of the horizontal planes p and q of the horizontal elongated holes 2 and 5. This simplest adjustment method can be easily achieved by interposing an adjustment piece such as a shim or liner.
At this time, it is preferable that the gaps X ₁ , X ₂ , and X ₃ other than the surfaces p and q are made somewhat larger.

Even with the above method, there are cases where the pin 7 and the surfaces p and q of the horizontal elongated holes 2 and 5 do not come into precise contact with each other. In this case, when the pin 7 has a shape as shown in FIGS. 6 and 7, a high-precision contact relationship can be easily achieved by grinding the contact surface of the pin 7 with a grinder or the like. can get. This contact surface alignment is achieved by supporting the upper structure B at the contact surface r of the horizontal piece 3 of the U-shaped mounting bracket C of the reactor vessel lid A with the vertical piece 4 of the inverted T-shaped mounting bracket D. This can be easily done without having to rehang the superstructure B.

Therefore, the levitation force due to the overturning moment acting on the superstructure B during an earthquake is applied to the pin 7 through the p-plane of the horizontal elongated hole 5 of the vertical piece 4 of the inverted T-shaped mounting bracket D. transmitted as a pulling force,
Furthermore, this transmission force is transmitted to the U-shaped fitting C and then to the reactor vessel lid A through the pin 7 and the q-plane of the horizontal elongated hole 2 in each vertical piece 1 of the U-shaped fitting C, and the same atomic The pin 7 is held in place by the reactor vessel lid A, thus preventing the upper structure B from floating up.

Further, the pin 7 is a U-shaped mounting bracket C disposed on each concentric circumference of the reactor vessel lid A and the upper structure B.
and the horizontal elongated holes 2 and 5 provided in the vertical parts 1 and 4 of the inverted T-shaped mounting bracket D and extending in the cross-sectional radial direction of each of the structures, so that the same elongated holes 2 , 5, the relative displacement in the cross-sectional radial direction due to the difference in thermal expansion between the front reactor vessel lid A and the upper structure B is absorbed. The joint always constitutes a pin joint, and the generation of excessive internal stress is suppressed.

The pin 7 may be fixed to either the inverted T-shaped mounting bracket D or the U-shaped mounting bracket C. In this case, the pin 7 has a horizontal length with upper and lower parallel surfaces as shown in FIG. 3 or 5. A pin 7 is formed in the hole 2 or 5 and held in the same elongated hole, and in this case, the pin 7 can move by a distance Y as shown in FIG. This distance Y is determined by the difference in thermal elongation between B and B. The shape of the horizontal long hole is the contact surface S of the pin 7.
As long as there is a parallel part, the shape may be rectangular, elliptical, or semicircular, and the shape can be selected in consideration of workability. Therefore, the pin 7 is attached to the horizontal elongated hole in the vertical part of the mounting bracket on the side that is not fixed, leaving a gap between the lower surface or the upper surface of the same elongated hole.
This makes processing easier.

In this proposal, when joining the reactor vessel lid and the upper structure, a U-shaped mounting bracket and an inverted T-shaped mounting bracket, which are configured separately from the main structure, are fixed to each of the structures. , by supporting the vertical part of one of the fittings protruding from the lower surface of the superstructure on the horizontal part of the other fitting attached to the top surface of the reactor vessel lid. The weight of the upper structure is supported by the reactor vessel lid, thus making the function of supporting the large weight of the structure independent and limiting the surface that receives the load. By leaving a gap between the vertical part of the other mounting bracket, construction is made easier, and the desired purpose can be achieved with the precision of machining of large-sized sheet metal structures. be.

According to this proposal, with the upper structure supported by the reactor vessel lid, the insertion and adjustment work of the pins into the horizontal elongated holes in the vertical parts of each of the mounting brackets is performed, making the work safe and easy. It is to be carried out. Accordingly, in this case, the lower and upper surfaces of the pin are configured to abut against the lower surface of the horizontal elongated hole in the one mounting bracket and the upper surface of the horizontal elongated hole in the vertical piece of the other mounting bracket, respectively. Therefore, by inserting an adjustment piece into the horizontal elongated hole or grinding the pin as described above,
Adjustment work can be easily performed, and the upper structure can be prevented from floating during an earthquake.

Further, the pins are loosely inserted into horizontal elongated holes in the vertical parts of each of the mounting fittings, and form a pin joint between the upper structure and the reactor vessel lid vessel, thereby preventing excessive damage to the structure. In addition to suppressing the generation of internal stress, thermal elongation can be effectively absorbed by the relative displacement between the pin and the horizontal elongated hole.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the basic model of the structure to which this proposal is applied, Figure 2 is a vertical sectional view of the main part of an embodiment of the nuclear reactor according to this proposal, and Figure 3 is an inverted T-shaped mounting bracket. FIG. 4 is a vertical cross-sectional view, and FIG. 5 is a front view of a horizontal elongated hole provided in the vertical part of the mounting bracket.
6 and 7 are longitudinal sectional views of the pin, respectively. A...Reactor vessel lid, B...Superstructure, C...
...U-shaped mounting bracket, D...Inverted T-shaped mounting bracket, 1...
Vertical piece, 2...Horizontal elongated hole, 3...Horizontal piece, 4
...Vertical piece, 5...Horizontal elongated hole, 6...Horizontal piece, 7...Pin.

Claims (1)

[Scope of utility model registration request] An inverted T-shaped mounting bracket fixed to the lower surface of the upper structure or the upper surface of the reactor vessel lid, between the vertical parts of both sides of the U-shaped mounting bracket fixed to the upper surface of the reactor vessel lid or the lower surface of its superstructure. , and the lower end of the vertical part of one of the two mounting brackets protruding from the superstructure with the horizontal part of the other mounting bracket fixed to the reactor vessel lid. At the same time, a gap is left between the horizontal part of the one mounting bracket and the vertical part of the other mounting bracket, and a pin is loosely inserted into the horizontal elongated hole of each vertical part of each of the mounting brackets. , and the lower and upper surfaces of the pin are brought into contact with the lower surface of the horizontal elongated hole of the vertical piece of the one mounting bracket and the upper surface of the horizontal elongated hole of the vertical piece of the other mounting bracket, respectively. nuclear reactor.