JPS59126992A - 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 nuclear reactor that uses liquid metal as a secondary coolant and is constructed in the form of a tank.

[Technical background of the invention]

Fast breeder reactors generally use liquid metal as the coolant) I
It uses liquid metal, typically Jium, and operates at higher temperatures than light water reactors. Therefore, in such a fast breeder reactor, in order to prevent the ft vessel, core equipment, piping, etc. from being damaged by thermal stress when starting or stopping reactor operation, the walls of these structural members are usually A method is used to reduce the thickness.

However, reducing the thickness of the nuclear reactor components as described above inevitably makes them weaker in terms of strength against vibration loads such as earthquakes.

In particular, it is a safety problem to make the primary piping system through which the liquid metal coolant flows thin.

By the way, 2. In order to solve these problems, a nuclear reactor is designed to eliminate piping as much as possible, specifically, a primary heat exchanger that exchanges heat between the primary coolant and the secondary coolant. A so-called tank-type nuclear reactor structure is being considered, in which the reactor is installed inside the main reactor vessel. As shown in FIG. 1, this tank-type nuclear reactor houses a reactor core 2, a core upper mechanism 6, and a coolant 4 inside a reactor main vessel 1, as well as a primary heat exchanger 3 and a pump 5. It has a structure in which the upper end opening is covered with a so-called lid body 7. The reactor main vessel 1 uses the lid body 7 as a support member, and the bit 9 provided on the floor 8 of the building through the lid body 7.
suspended inside. The core 2 is a core support mechanism lO
An inlet 11 connected to a pump 5 is located at the lower end of the reactor core 2 . Further, the fire heat exchanger 3 is formed in a vertical shape, and is supported and fixed to the lid body 7. An outlet Z2 for the primary coolant is located at the lower end of this thermal heat exchanger 3, and an inlet 13 for the secondary coolant is located halfway, and an outflow pipe 14 and an inflow pipe for the secondary coolant are located at the upper end. Z5 is installed in each.

In a nuclear reactor having such a configuration, the coolant 4 present in the lower part of the reactor main vessel 1 is transferred to the inlet 1 by the action of the pump 53.
1 into the core 2, heated by the core 2, and then exited from the upper part of the core to form a free liquid level while the primary heat exchanger 3
flows into the primary heat exchanger 3 from the inlet 13 of the
The coolant then exchanges heat with the coolant to achieve a low temperature, flows out from the outlet 12 to the lower part of the reactor main vessel 1, and circulates to the inlet 12.

The secondary coolant, which has reached a high temperature by exchanging heat with the above-mentioned secondary coolant, flows from the outflow pipe 14 to a two-fire heat exchanger (not shown), exchanges heat, and then returns to the primary heat exchanger through the inflow pipe 15. 3
circulates inside.

By using such a tank-type nuclear reactor, piping for the -fire heat exchanger system can be eliminated, and the safety level against earthquakes can be improved.

[Problems with background technology]

However, even reactors employing the tank-type reactor structure described above cannot be said to be sufficient against seismic vibration loads. The main vessel 1 is supported on the floor 8 around the lid 7 and suspended in the bit 9, so if this reactor is reduced to a mechanical model, the above reactor The system of
It can be considered as a cantilever structure with fixed support at one end. Therefore, when an external impact is applied to the reactor main vessel 1 in the horizontal direction, bending and shear vibrations as shown in FIG. 2 occur. The natural frequency of this vibration is determined by the bending rigidity of the reactor main vessel 1 and the total volume of the reactor main vessel 1 that accommodates internal members such as the reactor core 2 and the thermal heat exchanger 3. In the tank-type nuclear reactor structure described above, the side wall of the reactor main passenger unit 1 is made thin, so the above-mentioned bending rigidity is small, and the primary heat exchanger 3, pump 5, etc. are housed inside, so the reactor The weight of the main container 1 as a whole is heavy. Therefore, the natural frequency of the tank-type nuclear reactor structure is lower than that of the loop-type nuclear reactor in which the -fire heat exchanger is installed outside the reactor main vessel. When actually divided, the natural frequency of the mechanical model shown in Figure 2 is several hertz, and this value almost matches the predominant frequency of the ground during an earthquake. Therefore, when an earthquake occurs, the reactor main vessel 1 exhibits a resonant state, and a large bending shear stress may occur in the vicinity of the connecting portion of the lid 7 of the reactor main vessel 1.

Further, since the coolant 4 forms a free liquid level within the reactor main vessel 1, fluid vibrations such as sloshing occur when the reactor vessel 1 vibrates during an earthquake. This fluid vibration may damage the reactor main vessel 1 and the ladder housed therein.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to prevent damage to the tank-type retainer, without complicating the entire structure, and to provide protection in the event of an earthquake, etc. It is possible to reduce the vibration of the reactor main vessel,
The objective is to provide a nuclear reactor that can improve safety.

[Structure of the invention]

In the present invention, the floor of the building and the roof slab of the reactor main vessel,
It is characterized by interposing an elastic material with a vibration-proofing function between it and the so-called lid body.

〔Effect of the invention〕

With the above configuration, the reactor main vessel is suspended from the floor into the pit via an elastic material with a vibration-isolating function, which reduces the inherent thermal frequency of the system including the reactor main vessel. It is possible to make the earthquake much lower than that of a conventional tank-type nuclear reactor, and to deviate it from the predominant earthquake frequency. Therefore, when an earthquake occurs, the system containing the reactor main body light does not exhibit a resonance state, so the reactor main vessel (arch) vibrates greatly.As a result, the reactor main vessel It is possible to reduce the bending shear stress generated in the vicinity of the connecting portion.

In addition, it is possible to dampen the vibration amplitude of the above-mentioned reactor and sub-reactor main vessels due to the viscous action of the elastic control system with vibration isolation, which further reduces the occurrence of the above-mentioned bending shear stress. It can be reduced.

In addition, since the vibration of the reactor main vessel can be reduced, it is possible to prevent the side pieces of the reactor main vessel from sliding due to the fluid vibration of the cooling system sloshing housing in the upper N12 reactor main guest vessel. be able to.

As described above, by installing an elastic material with a vibration-proofing function, it is possible to provide a nuclear reactor that can further improve safety than a conventional nuclear reactor with a tank-type structure.

[Embodiments of the invention]

A practical example of the present invention will be described with reference to the drawings.

FIG. 3 is a sectional view showing a schematic configuration of a nuclear reactor according to the present invention, and the same parts as in FIG. 1 are designated by the same symbols. Therefore, the explanation of the overlapping parts will be omitted.

In this embodiment, a cylindrical anti-vibration rubber N16 is provided between the lid 7 and the floor 8. The anti-vibration rubber layers 16 are arranged at equal intervals in the circumferential direction of the reactor main vessel 10. The rest of the configuration is the same as the conventional nuclear reactor shown in FIG.

In such a configuration, the rigidity of the vibration-proof rubber layer 16 is sufficiently smaller than that of the side wall of the reactor main vessel 1. Since the reactor main vessel 1 is suspended in the bit 9 via the vibration-proof rubber layer 16, when placed in the mechanical model shown in FIG. 2, the reactor system of the example is Think of it as a cantilever structure with one end fixed and supported, with low rigidity at the base. Therefore, the bending rigidity of the entire beam is low, and the natural frequency of this beam is lower than the natural frequency of the beam when a conventional nuclear reactor is replaced with a mechanical model. Therefore, the horizontal natural frequency of the system including the reactor main vessel 1 of the nuclear reactor in which the vibration-proof rubber layer 16 is installed is lower than that of a conventional nuclear reactor.

That is, the above natural frequency does not match the predominant frequency of the ground during an earthquake. Therefore, when an earthquake occurs, the reactor main vessel 1 does not exhibit a resonance state, and therefore does not vibrate significantly.

As a result, large bending shear stress is not generated on the side wall of the reactor main vessel 1 in the vicinity of the lid 7. - Furthermore, since the vibration-proof rubber layer 16 also has a viscous effect, it suppresses the amplitude of vibration of the reactor main vessel 1. therefore,
In addition to the above-mentioned effects, the bending shear stress is further reduced when an earthquake occurs.

In addition, as mentioned above, the vibrations of the reactor main vessel 1) 1- are reduced, so that the above-mentioned vibrations due to fluid vibrations such as sloshing of the coolant 4 existing in the reactor main vessel 1 forming a free liquid level are reduced. Damage to the side wall of the reactor main vessel 1, the side wall of the -fire heat exchanger 3, the inner wall of the lid 7, etc. can be prevented from occurring.

By killing the vibration-proof rubber layer 16 as described above, it is possible to reduce the bending shear stress on the side wall of the reactor main vessel 1 and prevent damage to the side wall, etc. of the reactor main vessel 1. The safety of nuclear reactors can be improved.

Incidentally, when an earthquake occurs, vibrational strain (displacement) concentrates on the vibration-proof comb layer 16, but this is particularly problematic because the vibration-proof rubber layer 16 can absorb even relatively large strains.

An example of the vibration response when foaming occurs in the reactor main vessel of a nuclear reactor using a seismic rubber kite as an elastic material is shown below.

To simplify calculations, the combined shape of the reactor main vessel and lid 7 is assumed to be a cylindrical shape with an inner diameter of 22 m and an outer diameter of 22.1 m, and the entire Kyoto area including the parts inside the reactor main vessel is approximately 130
00 tons. The anti-vibration rubber layer has a diameter of 1 tn p
A disk-shaped vulcanized rubber with an FJ of 0.1 m is used, and this disk is 10
The anti-vibration rubber layer is formed by stacking two layers. The anti-vibration rubber layers are arranged at 24 evenly spaced locations on the circumference of the reactor main vessel. With this configuration, the horizontal and vertical spring constants of one anti-vibration rubber layer are 7.8 x 103 ton/m and 2.7, respectively.
If X 10' ton/m, the spring constants of the entire 24 vibration-proof rubber layers in the horizontal direction and the flat bending direction are each 1.9.
X105ton/m *6.5X104ton
/m. Since a structure with a weight of 13,000 tons is connected to this spring, the horizontal and vertical natural frequencies of this system are 1.9 Hz and 1.1, respectively.
Hz. The natural frequency in the horizontal direction is approximately 1 compared to the natural frequency when the conventional anti-vibration rubber layer is not used.
/4 value. Therefore, the natural frequency of the reactor main vessel can be shifted from the predominant frequency of the ground during an earthquake.

In the case of the above numerical example, the horizontal strain (shear strain) and vertical strain (compressive strain) of the vibration isolating rubber layer are each 30 inches or less, which is within the allowable range of normal vibration isolating rubber. enter. In the shunted nuclear reactor with the above configuration, the reactor main vessel is installed on the floor via a vibration-proof rubber layer, so the displacement of the reactor main vessel with respect to the floor is large, and this displacement is in the horizontal direction. So there will be 9 people and 19 crn Wado. However, it is possible to design a nuclear reactor plant in which equipment that is affected by the above-mentioned displacement, such as secondary coolant piping, etc., is not damaged by the above-mentioned displacement.

FIG. 4 shows the horizontal seismic response spectrum of the nuclear reactor in the above-mentioned numerical example.

In the figure, A is the frequency characteristic of acceleration on the floor surface when an earthquake occurs, and B is the frequency characteristic of acceleration on the surface of the reactor main vessel under the same conditions.

As can be seen from the figure, the acceleration characteristics on the surface of the reactor main vessel are reduced by about 22 cm compared to the acceleration characteristics on the floor surface. If the seismic response waveform at the floor surface, which is the vibration input to the reactor main vessel, is close to a sine wave due to the filter effect of the building, by shifting the above-mentioned natural frequency from the dominant frequency, the reactor main vessel The bending shear stress of the side wall is
can be expected to decrease to

Note that the present invention is not limited to the embodiments described above. In the embodiment, vibration-proofing rubber is used as the elastic phase having a vibration-proofing function, but other vibration-proofing elastic phases may be used.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing the schematic configuration of a conventional tank-type nuclear reactor, Figure W2 is a diagram illustrating the vibration mode of the conventional main reactor vessel during an earthquake, and Figure 3 is a cross-sectional view showing the schematic configuration of a conventional tank-type nuclear reactor. FIG. 4 is a cross-sectional view showing a schematic configuration of a nuclear reactor according to one practical example. FIG. 4 is a diagram showing an example of seismic response characteristics of a nuclear reactor in the same example. ... core, 3 ... - formation heat exchanger, 4 ... coolant, 5 ... pump, 6 ... core upper mechanism, 7 ... lid body, 8 ... floor, 9 ... Bit, 16 ... Anti-vibration rubber layer. Applicant's representative Patent attorney Takehiko Suzue Figure 3 Figure 4

Claims (1)

[Claims] A nuclear reactor using liquid metal as a primary coolant, the reactor comprising:
A heat exchanger for exchanging heat between the secondary coolant and the secondary coolant is located in the reactor main vessel, and the reactor main vessel is connected to the reactor main vessel via a support member connected to the upper part of the reactor main vessel. In a tank-type nuclear reactor that is installed suspended in a bit provided on the floor so as to be supported by the floor of the building, an elastic material having a vibration-proofing function is installed between the floor and the support member. A nuclear reactor characterized by being made by intervening.