JPS6120892A - Earthquakeproof supporter for vessel of nuclear 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 provides a system for absorbing displacement due to thermal expansion of a nuclear reactor vessel housing a reactor core cooled by circulation of liquid metal and related equipment therein; The present invention relates to an earthquake-resistant support device for a nuclear reactor vessel that can safely support the reactor vessel during an earthquake.

[Technical background of the invention and its problems]

As is well known, in a nuclear reactor cooled by liquid metal, the reactor core 1, core support structure 2, etc. are housed in a reactor vessel 3, as shown in FIG.
is supported by placing its upper flange 4 on a pedestal 5 extending from the wall of the reactor building.

When the volume of a nuclear reactor vessel increases as power generation capacity increases, its natural vibration frequency decreases, making its seismic design extremely difficult.

For example, if the structure is rigid, the horizontal seismic force for seismic design is 100
0 gat, but if it is not a rigid structure and its natural vibration frequency is small, the value will be 5000 to 6000 gat, which is an extremely difficult condition in terms of design. For this purpose, in the conventional structure, for example, as shown in FIG. 5, an earthquake-resistant support device is provided with oil dampers 6 at several locations radially around the lower outer periphery of the reactor vessel 3 to increase the natural frequency of the reactor vessel 3. Especially reactor vessel 3
Measures are being taken to reduce the seismic force acting on the earthquake.

However, when a so-called seismic vibration isolator such as a mechanical snapper or an oil snapper/S is used as an earthquake-resistant support device, the following problems occur.

(1) As the reactor vessel becomes larger, a large-capacity snapper that can withstand large earthquake reaction forces is required.

(2) A snapper that can cope with an increase in thermal displacement due to an increase in the size of the reactor vessel is required, which complicates the structure.

(3) It is necessary to perform maintenance and repair work such as inspecting moving parts and changing oil under high radiation levels.

[Purpose of the invention]

The present invention was made to solve the above problems, and its purpose is to have a simple structure that can withstand large earthquake reaction forces, absorb thermal displacement due to thermal expansion of the reactor vessel, and be able to operate under high radiation conditions. An object of the present invention is to provide an earthquake-resistant support device for a nuclear reactor vessel that can reduce maintenance and inspection work in a nuclear reactor vessel.

[Summary of the Invention] In order to achieve the above-mentioned object, the present invention provides a nuclear reactor vessel whose upper flange is provided protruding from the outer periphery of the lower part of the reactor vessel, which is supported by being placed on a pedestal extending from the wall of the reactor building. A radial key, a slit provided vertically in the protruding end surface of the radial key, and an inner surface of a guard vessel that faces both sides of the radial key at a predetermined interval and covers the outer periphery of the reactor vessel. It is equipped with an attached radial key holder.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a sectional view of a tank-type fast breeder reactor showing one embodiment of the present invention. Reactor vessel 3 of this tank-type fast breeder reactor
is supported by placing its upper flange 4 on a pedestal 5 extending from the reactor building wall via a ring gutter 7.

A roof slab 10 consisting of a fixed plug 8 and a rotating plug 9 is installed at the upper end opening of the reactor vessel 3, and closes the upper end opening of the reactor vessel 3. The roof slab 10 is equipped with an intermediate heat exchanger 11, a circulation pump 12, a core upper mechanism 13, a fuel exchanger 14, etc., and the intermediate heat exchanger 11 and the circulation pump 12 operate in the circumferential direction of the roof slab 10. Multiple units are installed alternately. The core support structure 2 is suspended from the roof slab 10 via a cylindrical suspension shell 15, and accommodates and supports the core 1 made up of a large number of fuel assemblies. Also,
The inside of the reactor vessel 3 is divided into an upper high temperature Na part (hot pool) 17 and a lower low temperature Na part (cold pool) 18 by a partition wall 16 connected to the outer wall of the suspended shell 15 and the inner wall of the reactor vessel 3. It's partitioned off. Coolant inside the reactor vessel 3 (
Liquid sodium) is usually 35 in coldsol 18
The temperature is about 0° C., and it is sucked in through the inflow hole 19 of the circulation pump 12 and sent to the high-pressure plenum structure 20 below the reactor core. The coolant injected into the high-pressure plenum structure 20 passes through the reactor core 1 and rises, and at this time, the temperature rises to about 500°C due to the heat of the nuclear reaction in the reactor core 1, and the coolant is heated to a temperature of about 500° C. leaks to. The coolant discharged from the hot pool zyKi passes through the flow hole 21 formed in the suspension shell 15, enters the inlet hole 22 of the intermediate heat exchanger 1, and exchanges heat with the coolant on the secondary side to reach approximately 350°C. After being cooled to a certain degree, it is returned to the cold pool 18 through the outlet nozzle 23.

Furthermore, an earthquake-resistant support device 100 according to the present invention is provided between the lower outer periphery of the reactor vessel 3 and the guard vessel 24. As shown in FIG. 2, this seismic support device 100 is provided with a plurality of layers at equal pitches along the circumferential direction of the reactor vessel 3.
It has a radial key structure. That is, as shown in FIGS. 3 and 4, this seismic support device 100 has a radial key 1 protruding from the lower outer periphery of the reactor vessel 3.
01 and the radial key receiver 102 facing both sides of this radial key 101, this radial key 1
02 is attached to a guard vessel 24 that covers the outer periphery of the reactor vessel. Furthermore, a plurality of sleeves 703 are provided on the protruding end surface of the radial key 101 along the vertical direction. An L-shaped spacer 104, 1 is provided between the radial key 10 and the radial key receiver 102.
04 is inserted, maintaining a predetermined gap width g with the side surface 101a of the radial key 10. Note that the spacer 10
4 is a mounting bolt 105 on the top surface of the radial key receiver 102
Fixed by

Next, the effect will be explained. The reactor vessel 3 is at a high temperature during operation, and the temperature is several tens of ffi in both the vertical and radial directions of the reactor vessel.
Thermal expansion is approximately ++. If this thermal expansion is restricted, a large amount of stress will be generated in the reactor vessel 3, so
As an earthquake-resistant support device, it is necessary to allow the reactor vessel 3 to thermally expand freely. Seismic support device 1 according to the present invention
In 00, radial key 101 and radial key receiver 10
2 with a predetermined gap width g, the vertical and radial thermal expansion of the reactor vessel 3 is not restricted in any way, so no thermal expansion reaction force is generated in the reactor vessel 3. Therefore, it is possible to sufficiently absorb an increase in the amount of thermal displacement due to an increase in the size of the reactor vessel 3.

Next, the effects during an earthquake will be explained with reference to the second illustration.

When a horizontal seismic force acts in the direction shown by the arrow in Figure 2 due to an earthquake, the entire reactor vessel 3 first moves in the 270° direction due to the gap width g between the radial key 101 and the radial key receiver 102.
When the radial keys 101a and 101m in the 0° and 180° directions and the radial key receiver 1θ
2a and 102'm collide with each other, restraining the horizontal movement of the reactor vessel 3. With this, Shirasial Key 101m,
101m and the radial key receivers 102a and 102rn, and when the amount of displacement of the radial key due to the reaction force exceeds V-Δθ, the next radial key 10 l
b, 1011 and the radial key receivers 102b, 1021 start operating. From then on, the earthquake load will be distributed in order according to the mounting angle of the radial key. With conventional solid radial keys, the rigidity of the key is extremely high, so it takes a huge force for the first key to be displaced, resulting in supporting the earthquake reaction force with a small number of keys. It had become. On the other hand, in the radial #-101 provided with the slit 103 according to the present invention, the slit 103 reduces the machinability of the sillial key, and since the slit 103 causes displacement with a small force, the number of keys that share the earthquake load increases. Our radial key can significantly reduce the seismic reaction force.

〔Effect of the invention〕

As explained above, according to the present invention, the earthquake reaction force that should be shared by the radial keys is flattened in order to disperse and support the reaction force during an earthquake without restricting the deformation of the reactor vessel due to thermal expansion. This makes it possible to significantly reduce some of the radial stress. In addition, the local stress generated in the reactor vessel to which the radial key is attached is significantly reduced, increasing design latitude in terms of structural strength. Furthermore, in the conventional radial key structure, in order to equalize the load, it was necessary to take measures such as reducing the gear width between the key and the key receiver as much as possible and increasing the number of keys. According to the present invention, the above-mentioned measures are not required, the installation work is easy, and the amount of materials can be reduced. Furthermore, since the structure is entirely mechanical and static, it is highly reliable and has fewer causes of failure. Therefore, there is no need for periodic maintenance work, and only simple inspection work is required, so the work under radiation can be done in an extremely short time, which has great effects.

[Brief explanation of drawings]

Figures 1 to 4 are diagrams showing an embodiment of the present invention, in which Figure 1 is a cross-sectional view of a tank-type fast breeder reactor, and Figure 2 is a horizontal cross-section of the reactor vessel showing the installation state of the seismic support device. Figure 3 is an enlarged sectional view showing part A in Figure 2, Figure 4 is 1 in Figure 3.
5 is a sectional view of a fast breeder reactor showing a conventional example. DESCRIPTION OF SYMBOLS 1...Reactor core, 3...Reactor vessel, 100...Earthquake support device, 101...Radial key, 102...Radial key receiver, 103...Slit. Figure 1 Figure 2 Figure 3 L Figure 4 Figure 5

Claims (1)

[Claims] A radial key is provided protruding from the outer periphery of the lower part of the reactor vessel, the upper part of which is placed and supported on a pedestal projecting from the wall of the reactor building, and a radial key is provided along the vertical direction on the end surface of the protruding side of the radial key. and a radial key receiver attached to the inner surface of a guard vessel that faces both sides of the radial key at a predetermined interval and covers the outer periphery of the reactor vessel. Support device.