JPS6144273B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure tube type nuclear reactor, and is particularly suitable for preventing swinging of a pressure tube assembly having a long lower extension pipe that is prone to swinging, and also improves installation work during construction. The present invention also relates to a vibration isolation plate structure for a pressure pipe assembly that takes into account alignment workability and removal workability during maintenance.

Figure 1 shows a conventional pressure tube reactor.

This reactor consists of a calandria tank 1 that holds heavy water as a moderator, a ferrous water shield 2 that shields radiation and heat, nuclear fuel, and light water that serves as a coolant. The pressure pipe assembly 3 is made up of a pressure pipe assembly 3 that passes through the pressure pipe assembly 2 and stands in a lattice shape.

The pressure pipe assembly 3 is supported (fixed) by a support bolt 5 to a flange-type tip of a ferrous-water sleeve 4 protruding from the ferrous-water shield 2 . In addition, an inlet pipe 7-1 for supplying light water, which is a coolant, is connected to the lower extension pipe 6 extending downward from the support point (fixed point), and due to the arrangement, they overlap each other. It is connected.

In addition, in the process of flowing through the pressure tube assembly from the bottom to the top, the cooling water becomes a two-layer flow of steam and water due to the nuclear reaction of the nuclear fuel contained in the pressure tube assembly and exits from the outlet pipe 7-2. go. After that, steam and water are separated and contribute to power generation.

In addition, in conventional pressure tube reactors, the output is small and the number of pressure tube assemblies 3 is small, so the length of the lower extension tube 6 (from the position supported by the support bolt 5 to the lower end of the lower extension tube) ) was short, so it was difficult to shake, and there was no need to take any special measures to prevent shake.

However, when increasing the size of the furnace, the number of pressure pipe assemblies 3 inevitably increases, and the piping space L due to the arrangement of the piping 7.
1 and the piping support space L2 tend to increase and become longer.

For example, if the number of pressure tube assemblies 3 is approximately tripled compared to a conventional furnace in order to increase the size of the furnace, L1 and L2 of the lower extension tube 6 will be
The length of the structure increases proportionally, creating a problem that the structure tends to swing easily.

An object of the present invention is to provide good vibration prevention by providing a two-piece vibration isolation plate on the lower outer periphery of the lower extension tube 6, which is becoming longer as pressure tube reactors become larger. It is an object of the present invention to provide a vibration isolating plate that takes into consideration installation workability during construction, alignment workability, and removal workability during maintenance.

The present invention provides a groove on the lower outer circumferential surface of the lower extension tube of each pressure tube assembly, and this groove has a two-part structure, and the portions that fit into the outer circumferential groove of the lower extension tube are semicircular. On the other hand, a steel plate with a rectangular outer shape is hugged, a notch is provided at both ends of each of the two split steel plates, and a hole that can be tightened with bolts is provided in that part, and both steel plates are tightened with bolts to form a lower extension pipe. In addition, the steel plates attached to the adjacent pressure pipe aggregates are arranged so that they are in contact with each other on their square external surfaces, and are further supported by vibration isolator supports provided through the building wall. It is characterized by what it did.

FIG. 2 shows an overall view of an embodiment of the vibration isolation structure according to the present invention. The details are shown in Figure 3, which is a plan view of Figure 2.
The explanation will be made based on FIG. 4, which is a detailed view of section A in FIG. 2, and FIG. 5, which is a plan view of FIG. 4.

The vibration isolating plate 8 is designed in consideration of installation workability and centering workability during construction, and removal workability during maintenance.
It has a split structure, and while the parts that fit into the lower extension tube 6 are semicircular, the outer shape is square, and the outer shape is provided with a notch. are steel plates 9-1, 9-2 with bolt holes, and steel plates 9-1, 9 split in two.
-2 is made up of a bolt 10 that is tightened while being held in the outer periphery of a groove 11 provided below the lower extension tube 6.

Next, the construction method of the present invention during construction and maintenance will be described.

First, the case during construction is shown below.

The pressure pipe assembly 3 at the time of construction is structurally the third
Install in sequence from row A to row B to row C as shown in the figure. Next, the installation method of the present invention in the process of installing the pressure tube assembly 3 will be described.

First, after installing the pressure pipe assembly 3 of row A, the two halves of the steel plates 9-1 and 9-2 are held in the groove 11 provided below the lower extension pipe 6, and the lower extension pipe is tightened with bolts 10. Fix it to the outer periphery of 6. In addition, steel plate 9-
1 and 9-2 are positioned within the reach of the worker from the lower end of the lower extension pipe 6.

Next, install the pressure pipe assembly 3 of row A 2, and align the vibration isolation plates 9-1, 9-2 with the surface of the steel plate 9-1 of the existing pressure pipe assembly 3 of row A 1. Similarly, it is fixed to the outer periphery of the groove 11 of the lower extension tube 6 of the pressure tube assembly 3 in row A 2.

Thereby, it is possible to adjust the pitch L3 of the pressure tube assembly 3 by the vibration isolating plate 8 due to the fall of the pressure tube assembly 3 from the support point where the pressure tube assembly 3 is supported by the support bolt 5. .

All pressure tube assemblies 3 shall be installed using the installation method described above.

The vibration isolating plate 8 attached to the lower extension pipe 6 of the outermost pressure pipe assembly 3 shown in FIG. It is fixed at.

Thereby, swinging of the lower extension tube 6 can be prevented.

Next, we will discuss the case during maintenance.

During maintenance, since the work is done under radiation, it is necessary to minimize the amount of work.
9-2 must be able to be installed and removed. Therefore, in the present invention, a bolted structure is used, and two
We decided to adopt a vibration isolation plate 8 with a splittable structure.

The method for removing and installing it will be described below.

(1) Using a tool, remove the bolts 10 (2 pieces) from the gaps at the lower ends of the lower extension pipes 6 arranged in a grid pattern.

(2) Push up the steel plates 9-1 and 9-2 from below to a position where there is no contact with the surrounding vibration isolation plates (this state is shown by the dashed-dotted line in Figure 4) and remove them.

Therefore, the length of the groove 11 of the lower extension tube 6 is
It needs to be at least twice the thickness of the steel plates 9-1 and 9-2.

As described above, remove the vibration isolating plate 8 within the range that allows the space required for maintenance to be secured.

In addition, when installing, follow the above-mentioned procedure in reverse.

According to the present invention, it is possible to prevent the lower extension tube 6 from swinging out, and at the same time, it is possible to easily attach and detach the vibration isolation plate 8 within a minimum range during alignment and maintenance of the lower extension tube 6.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing an overall schematic diagram of a conventional pressure tube nuclear reactor, FIG. 2 is a side sectional view of a reactor showing an embodiment of the vibration isolation structure according to the present invention, and FIG.
These figures are a plan view of FIG. 2, FIG. 4 is a detailed view of section A in FIG. 2, and FIG. 5 is a plan view of FIG. 4. 6...Lower extension pipe, 8...Vibration isolation plate, 9-1...
Steel plate, 9-2... Steel plate, 10... Bolt, 13...
...Support for vibration isolation plate.

Claims (1)

[Claims] 1. In the vibration isolation structure of pressure tube aggregates that penetrate the reactor body of a pressure tube reactor and are arranged in a lattice pattern, a groove is provided on the lower outer periphery of the lower extension pipe of each pressure tube aggregate, and this groove is divided into two parts. In the structure, the parts that fit into the outer circumferential groove of the lower extension pipe are semicircular, but the outer shape is square steel plates, and cutouts are provided at both ends of each of the two split steel plates. Furthermore, a hole is provided in that part for bolting, and by tightening both steel plates with bolts, it is fixed to the lower extension pipe, and furthermore, the steel plates attached to the adjacent pressure pipe aggregates are in contact with each other on their rectangular external surfaces. A vibration isolating plate structure for a pressure pipe assembly, characterized in that the vibration isolating plate structure is such that the vibration isolating plate supports are provided through a building wall.