JPS5831805B2 - Gensuikouzou Seigiyoban - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control panel for a nuclear power plant, and more particularly to a control panel with a damping structure suitable for maintaining the functions of instruments attached to the panel during an earthquake.

The demand for seismic resistance of nuclear power plant control panels is becoming stronger and stronger, and there is a need for safer earthquake-resistant control panels.

Earthquake resistance in nuclear power plants is essential and an important issue from the perspective of preventing radiation disasters.

The seismic resistance of a control panel is a more important issue than its strength, as maintaining the functionality of the equipment attached to the control panel is more important than its strength.

In other words, to prevent the control panel from falling or being damaged during an earthquake, it is sufficient to check the strength of the anchor bolts used to secure the control panel to the building, but it is sufficient to check the strength of the anchor bolts used to secure the control panel to the building. It is extremely difficult to consider how to carry out the intended purpose and maintain the functionality for safe reactor shutdown.

For example, the conventional control panel has an integral structure using welding instead of bolts, and has a rigid structure with many beams, which allows control of vibrations at frequencies far away from the vibration frequency of the building (2 to 1oHz) during an earthquake. It was used as a board.

However, there are limits to the rigid structure. On the other hand, because it is made of steel, the damping rate is very small.

Steel materials have a damping constant of about 1, but the control panel has a damping constant of about 3 to 8 because a frictional damping force acts between it and the base.

In other words, a small damping factor of the panel means that the response magnification near the natural frequency of the control panel is large, and even though the control panel has a rigid structure and has a frequency far away from the building frequency, However, it is undesirable because it responds sensitively to the natural frequency component of the control panel of the seismic frequency.

FIG. 1 shows typical vibration characteristics of a conventional rigid structure control panel.

The vibration characteristic F of this rigid structure control panel is the natural frequency f.

The peak value A is reached by the acceleration response magnification that is pressed.

On the other hand, the building frequency is fl, and by making the control panel a rigid structure, the natural frequency of the control panel is located at a distance from fl.

The model of the vibration system of an actual control panel is complicated, but if we consider the generally adopted damping rate, the damping constant of this control panel can be expressed as 100/2A (@).

That is, the damping constant and the acceleration response magnification are inversely proportional.

An object of the present invention is to provide a damping structure control panel with a high natural frequency and a large damping constant.

A feature of the present invention is that a material having a damping constant larger than that of the upholstery is attached inside a rigid control panel and on the exposed surface of the upholstery constituting the control panel.

The control panel of the present invention has a high natural frequency, so it does not resonate with the vibration frequency of an earthquake, and the damping constant is large, so the acceleration response rate during an earthquake is small. Acceleration can be reduced.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 2 is a structural diagram of the damping structure board.

The control panel PNL consists of pillar 1, front plate 2, and side plate 3, which are the covering materials.
The rubber 4 is attached to the inside of the control panel.

In other words! It has a structure in which rubber 4 is attached to the exposed surface of each of the above-mentioned covering materials inside the lJ# board.

When installing rubber here, be careful not to get in the way when placing equipment inside the control panel.

FIG. 3 shows the vibration characteristics of this damping structure control panel.

In the damping structure control panel equipped with this rubber, the peak value A1 is extremely low, about 50%, so the damping constant of the control panel equipped with rubber can be reduced to about 20%, and the response at the natural frequency is The magnification can be increased to about 2.5 times.

That is, in the event of an earthquake, the acceleration that the equipment attached to the control panel receives is about the same value as the floor on which the control panel is installed.

This is because seismic waves generally have various frequency components, but when they enter a building, they are filtered, and the building's natural frequency components are emphasized and input to the control panel.

The natural frequency of a building is often about 2 to 10 Hz, and the input to the control panel has few frequency components of 10 Hz or higher.

However, as the damping constant of the control panel increases, the degree of increase in acceleration in seismic waves also decreases, and with the damping structure control panel of the present invention, if the natural frequency is 15H or above, The acceleration of the control panel is only the same value as the floor.

In the embodiment of the present invention, rubber 4 is used to increase the damping constant of the control panel, but the same effect can be obtained by using other materials having a large damping coefficient.

For example, a square piece made of nylon is attached to the inside of the front plate 2 and side plate 3.

Since the damping constant of nylon is as large as 50 da, the increase in acceleration of the control panel is significantly suppressed.

Moreover, the nylon squares can be used in place of the fixtures in the control panel.

According to the present invention, by installing a material having a damping constant smaller than that of the covering material inside the control panel, the acceleration received by the equipment attached to the control panel during an earthquake can be reduced from the floor on which the control panel is installed. It can be reduced to the same extent as the above.

Furthermore, since the natural frequency of the control panel is high, resonance with the earthquake frequency can be avoided.

Improving the seismic resistance of the control panel in this way has significant practical and economical effects.

[Brief explanation of drawings]

FIG. 1 is a graph showing the vibration characteristics of a conventional structure, FIG. 2 is a structural diagram showing an embodiment of the present invention, and FIG. 3 is a graph showing the vibration characteristics. Explanation of symbols, PNL...Control panel, 1...Column, 2...
・Front plate, 3...Side plate, 4...Rubber.

Claims (1)

[Claims] 1. A damping device characterized in that a material having a damping constant larger than the damping constant of the covering material is attached inside a rigid structure control panel composed of a plurality of covering materials and on the exposed surface of the covering material. Structural control panel.