JPH025277B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to the core structure of a gas-cooled nuclear reactor, and particularly to the structure of a high-temperature plenum block that supports stacked columns of fuel blocks from below.

In the core of the gas-cooled nuclear reactor mentioned above, which is composed of a stack of various blocks, differences in level occur between the high-temperature plenum blocks that support columns of fuel blocks due to unbalanced temperature distribution within the reactor. Even in such a case, it is desired that the core structure is such that the step does not interfere with columns such as fuel blocks and disturb the posture of the columns.

[Prior art and its problems] First, FIGS. 1 to 3 show the conventional structure of a high-temperature gas reactor, which is a type of gas-cooled nuclear reactor.
In the figure, reference numeral 1 indicates one control block 2, each of which is a regular hexagonal block, and six standard fuel blocks 3 surrounding this control block, which are stacked up and down to a height of more than ten levels, and further combined with a movable reflector 8 to form a column. The unit core structure made up of
4 is a regular hexagonal high-temperature plenum block corresponding to each unit core structure 1 arranged in parallel at the bottom of the core so as to support the assembly of unit core structures 1 from below; 5 is a hearth insulation block; 6 1 is a high temperature plenum section defined between the hearth insulation block 5 and the high temperature plenum block 4, 7 is a cooling gas outlet pipe connected to the high temperature plenum section, and 9 is a fixed section surrounding the assembly. The reflector 10 is a diamond grid supporting the entire weight of the core, and 11 is a gas sealing member between the high temperature plenum blocks 4. The figure shows only the main parts, and the core barrel surrounding the reactor core, core restraint mechanism, reactor pressure vessel, etc. are not omitted. In the above configuration, as is well known, the cooling gas flows from above the core into a channel in the fuel block, where it is heated to a high temperature and then transferred to the high temperature plenum block 4.
The gas flows down through the gas passage holes 12 and is collected in the high-temperature plenum section 6, from where it flows out of the furnace through the outlet pipe 7.

By the way, as shown in the figure, the unit core structure 1 is composed of laminated columns including a control block 2, a fuel block 3, a movable reflector 9, etc., and each structure has a dowel pin on the upper surface of the corresponding high-temperature plenum block 4. Supported through. The illustrated reference numeral 13 indicates a pin hole of the dowel pin. In this case, as understood from FIG. 3, one high-temperature plenum block 4 has one unit core structure corresponding to the plenum block, that is, a control block 2, six standard fuel blocks 3 and The total amount of each column of movable reflectors 8 combined with this is supported. Therefore, the planar shape of the unit core structure 1 formed by combining a total of seven regular hexagonal blocks is a star shape with an uneven outer periphery as shown in the figure, and a part of the periphery is a regular hexagonal block as shown by the symbol P. It protrudes from the area of the rectangular high-temperature plenum block 4 and overhangs to the side, enters the area of the adjacent high-temperature plenum block, and comes to straddle the upper surface of that plenum block. Figures 6A and 6B show the stacked state of the core constituent blocks according to this conventional structure. That is, if the upper surface levels of adjacent high-temperature plenum blocks 4 correctly match and are lined up on the same plane as shown in FIG. There is no problem even if they come into contact with each other.
On the other hand, if a step H occurs between adjacent blocks due to an imbalance in the temperature distribution inside the furnace during operation of the furnace, as shown in FIG. is pushed upward, and its blocking posture is tilted, causing disturbance in the blocking posture of the column. As a result, gaps are locally formed between the laminated blocks, which deteriorates the sealing performance in those areas, causing problems such as a bypass flow of cooling gas.

[Purpose of the invention]

This invention was made in consideration of the above points, and eliminates the drawbacks of the conventional structure, and even if a step occurs between adjacent high-temperature plenum blocks, the step does not interfere with the columns of the unit core structure. ,
The purpose is to provide a core structure that does not disturb the stacked position of the blocks.

[Key points of the invention]

In order to achieve the above object, the present invention provides a structure in which an adjacent high-temperature plenum block is provided with A notch recess having approximately the same shape as the protruding portion is formed in the upper peripheral edge of the block, and this notch recess is used as an escape to create a step between the high temperature plenum blocks and the constituent blocks of the unit core structure. avoid interference with
This is designed to prevent disturbances in the stacked orientation of the core constituent blocks.

[Embodiments of the invention]

4 and 5 show the structure of an embodiment of the present invention, in which a cutout recess 14 having a triangular planar shape is formed in a part of the upper peripheral edge of the high temperature plenum block 4. FIG. This notch recess 14 is
The cutout recess 14 is formed so as to coincide with a portion facing the protruding portion P of the unit core structure 1 that protrudes from the area of the adjacent high-temperature plenum block, and the depth h of the notch recess 14 is equal to that of the reactor. The dimensions are determined to be slightly larger than the level difference H between the high temperature plenum blocks expected from the operating conditions. The regular hexagonal high-temperature plenum block has six notches 14 in total, one on each top side of each block.

With the above configuration, even if a level difference H occurs between the high temperature plenum blocks as shown in FIG. 7B, from the state where there is no level difference between adjacent high temperature plenum blocks as shown in FIG. This effectively prevents interference between the protruding portion P and the adjacent high-temperature plenum block 4. Therefore, there is no fear that the constituent blocks of the unit core structure 1 supported on the upper surface of each high-temperature plenum block 4 will be disturbed in their posture, and a stable column posture will be maintained.

〔Effect of the invention〕

As described above, according to the present invention, a notched recess having approximately the same shape as the protruding portion is formed at the upper peripheral edge of the high-temperature plenum block, and the unit supported on the adjacent high-temperature plenum block is formed using this notched recess as a relief. By avoiding interference with the protruding parts of the core structure, even if a step occurs between high-temperature blocks, this step does not disturb the stacked posture of the core constituent blocks, and maintains stable core function. can be achieved.

[Brief explanation of drawings]

Figure 1 is a partial vertical cross-sectional view showing the core structure of a conventional high-temperature gas reactor, Figure 2 is a plan view of one high-temperature plenum block in Figure 1, and Figure 3 is the core structure of Figure 1. A partially cutaway cross-sectional plan view, FIGS. 4 and 5 are a partial plan view and a perspective view showing the structure of an embodiment of the present invention, and FIGS.
Figures A and B are explanatory diagrams showing stacked postures of unit core structures with respect to changes in the state of juxtaposition between high-temperature plenum blocks according to the prior art and the embodiment of the present invention, respectively. 1... unit core structure, 2... control block,
3... Standard fuel block, 4... High temperature plenum block, 8... Movable reflector, 14... Notch recess,
P...protrusion, H...step between high temperature plenum blocks.

Claims (1)

[Claims] 1 A control block and a plurality of standard fuel blocks surrounding it are stacked vertically, and a movable reflector is further combined to form a unit core structure, and the assembly of these core unit structures is individually stacked with each unit core structure. In a gas-cooled nuclear reactor stacked and supported on regular polygonal high-temperature plenum blocks juxtaposed at the bottom of the reactor core corresponding to the A gas-cooled nuclear reactor characterized in that a notch recess having substantially the same shape as the projecting part is formed in the upper peripheral edge of an adjacent high-temperature plenum block, facing the projecting part of the unit core structure projecting out.