JPS5930473Y2 - Core support device in fast breeder reactor - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a core support device for a fast breeder reactor using liquid metal as a coolant.

A core support device for a fast breeder reactor generally has a structure as shown in FIGS. 1 and 2.

That is, a coolant inlet pipe 2 is installed at the bottom of the reactor vessel 1.
However, coolant outlet pipes 3 are formed in the upper part and are buttoned, and a core support plate 5 of a core support device 4 is horizontally stretched between the pipes 2 and 3 in the vertical direction. has been done.

A box body 6 is connected below this core support plate 5, and a partition wall 1 stretched horizontally within this box body 6 connects the inside of the box body 6 with a high-pressure coolant chamber 8 and a low-pressure coolant chamber 8. It is partitioned into a coolant chamber 9.

The core support plate 5 is formed with a large number of openings 11, 11, .
A large number of flow rate adjusting pipes 12, 12, .

Additionally, a large number of openings 13, 13, .

The entrance nozzle 14 of the fuel assembly 10, which is composed of a core fuel assembly, a blanket fuel assembly, a control rod, a reflector, etc., is inserted into the flow rate adjustment tube 12 through the opening 11 of the core support plate 5, and the lower end is supported facing into the low pressure coolant chamber 9 from the opening 13 of the partition wall 7.

Additionally, as shown in detail in FIG. 2, the high-pressure cooling chamber 8 of the box body 6
There are many coolant inlets 15, 15 and 15 in the circumferential direction on the outer periphery of the
... is formed.

The coolant introduced into the reactor vessel 1 from the inlet pipe 2 flows from the coolant inlet 15 through the high-pressure coolant chamber 8 in the fuel assembly 10 in a direction opposite to the direction of gravity, and flows into the outlet pipe 3. However, since the upward force due to the pressure loss of the coolant flowing within the fuel assembly 10 is greater than the weight of the fuel assembly 100, the fuel assembly 10 tends to float.

For this reason, conventionally, as shown in FIG.
Horizontal holes 17, 17... are formed in 4, and these horizontal holes 1
7 into the fuel assembly 10, and as mentioned above, the low pressure coolant chamber 9 is communicated with the lower part of the high pressure coolant chamber 8, and the fuel assembly 10 is held hydraulically.

By the way, the orifice hole 16 of the flow rate adjustment tube 12 is different for each flow rate adjustment tube 12, and the coolant flowing into the high pressure coolant chamber 8 from the coolant inlet 15 has a coolant flow rate based on the nuclear thermal design. The heat generated by the internal fuel pins 18, 18, . . . is cooled by distributing it to each fuel assembly 10.

In the past, the flow rate of the coolant distributed to the fuel assemblies 10 arranged inside the reactor vessel 1 was distributed to the fuel assemblies 1 arranged outside.
It flows inward at a flow rate of several meters through the gaps between the flow rate adjustment pipes 12 in the high-pressure coolant chamber 8, with some of it flowing into the nearby flow rate adjustment pipes 12, and flows into all the flow rate adjustment pipes 12 in the high-pressure coolant chamber 8. Flow rate is distributed.

The coolant flowing through the gaps between the tube groups of the flow rate adjustment tubes 12 causes a pressure loss proportional to the flow velocity and the number of rows, so the pressure decreases as it moves toward the inside.

The pressure distribution caused by the pressure loss of the coolant flowing in the high-pressure coolant chamber 8 causes an error in flow rate distribution.

button, fuel assembly 1 due to increase in thermal output of fast breeder reactor
00, but this also increases the error in the flow rate distribution of the coolant.

The present invention eliminates the drawbacks of the conventional ones mentioned above,
The purpose of this system is to provide a core support device that reduces errors in coolant flow distribution and cools all fuel assemblies to an almost isothermal state. A baffle plate extending in the axial direction of the flow rate adjustment tube is installed at the location where the material collides with the flow rate adjustment tube to delay the separation of the boundary layer on the surface of the flow rate adjustment tube, thereby reducing the wake behind the adjustment tube and reducing the pressure. This reduces losses, thereby reducing the pressure distribution in the high-pressure coolant chamber and reducing errors in flow distribution.

The present invention will be explained below with reference to the embodiments shown in FIGS. 4 and 5.

Since there is no change in the overall configuration of the core support device already described with reference to FIGS. 1 and 2, only the main parts that are different from the conventional device will be described.

FIGS. 4A and 4B show the first embodiment of the present invention, and the axis of the flow rate adjustment tube 12 is shown at the collision position of the coolant on the outer periphery of the flow rate adjustment tube 12, that is, in the direction in which the coolant flows. A pair of baffle plates 19.19 are provided projecting in the direction, and these baffle plates 19.19 are positioned at an angle of approximately 20°.

According to the above-described configuration, as shown in FIG.
will occur.

In addition, swirls are generated at the back of the baffle plate 19, 19 and the back of the flow rate adjustment tube 12, and the separation of the boundary layer on the outer surface of the tube 12 is delayed compared to the case of a simple circular tube, so the flow rate is adjusted. The wake generated at the back of the tube 12 is reduced.

Therefore, the flow rate adjustment pipe 12 has a stagnant portion a1 of the coolant.
It is replaced by a virtual elliptical cylinder d as an envelope surface for a large and small number of vortices, c>, and a turbulent boundary layer, the resistance is clearly reduced, and the pressure loss of the coolant is small.

Therefore, the error in the flow rate distribution of the coolant is small, and each fuel assembly 10 can be uniformly cooled.

The theory of resistance reduction mentioned above is explained in detail on pages 570 to 575 of the Proceedings of the Japan Society of Mechanical Engineers, published in August 1955.

6A and 6B show a second embodiment of the present invention,
A baffle plate 12 extending in the axial direction is provided at a position on the outer periphery of the flow rate adjusting pipe 12 where the coolant collides with the baffle plate 12 .

A certain degree of effect can also be obtained with such a configuration.

As explained above, the core support device for a fast breeder reactor according to the present invention has a protruding baffle plate extending in the axial direction of each flow rate adjustment tube, so that the pressure loss in the high pressure coolant chamber is reduced, and each This has the excellent effect of reducing errors in the flow rate distribution of coolant flowing into the fuel assembly, and improving the operational performance and integrity of the fast breeder reactor.

[Brief explanation of drawings]

Figure 1 is a longitudinal cross-sectional view of a half part showing a general core support device;
Figure 2 is an enlarged cross-sectional view of the main part of Figure 1, Figure 3 is a vertical cross-sectional view partially showing the vicinity of the flow rate adjustment tube of a conventional core support device, and Figure 4A is a main part of the main part. FIG. 4B is a cross-sectional view taken along the line IV-IV of FIG. 4A, and FIG. FIG. 6A is a front view showing a second embodiment of the core support device according to the present invention, and FIG. -V
FIG. 1...Reactor vessel, 4...Core support device, 6...Box, 8...High pressure coolant chamber, 9...・Low pressure coolant chamber, 10...Fuel assembly, 12...Flow rate adjustment pipe, 14...
- Entrance nozzle, 15... Coolant inlet, 19... Baffle plate.

Claims (1)

[Scope of utility model registration request] A high-pressure coolant chamber with a large number of flow rate adjustment pipes into which the entrance nozzle of the fuel assembly is inserted and a coolant inlet on the side, and a partition wall formed below this high-pressure coolant chamber. a low-pressure coolant chamber, and a baffle plate extending in the axial direction of each flow rate adjusting tube is provided protrudingly at a position where the coolant collides with each of the flow rate adjusting tubes. Core support device in a breeder reactor.