JPS59220672A - Gas cooled 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 [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 the columns of fuel blocks due to imbalances in the temperature distribution inside 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, Figures 1 to 3 show the conventional structure and meaning 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 piled up in several levels in the upper and lower middle levels, and are further combined with a movable reflector 8. A unit core structure 1 constitutes a column, ・l is a regular hexagonal shape corresponding to each unit core structure 1 juxtaposed at the lower part of the core so as to support the assembly of unit core structures 1 from below; A high-temperature plenum block, 5 a hearth insulation block, 6 a high-temperature plenum section defined between the hearth insulation block 5 and the high-temperature plenum block 4, and 7 a cooling gas outlet piped in communication with the high-temperature plenum section. 9 is a fixed reflector that surrounds the assembly; IO is a diagonal grid that supports the entire weight of the core; 11 is a gas sealing member between high-temperature plenum blocks 4; only the main parts are shown in the figure. The core barrel surrounding the reactor core, core restraint mechanism, reactor pressure vessel, etc. are omitted and are not shown in brown. In the above configuration, as is well known, the cooling gas flows upward into the reactor core into channels/channels in the fuel flock, where it is heated to a high temperature and then flows down through the gas passage hole 12 of the hot plenum head 4. It is collected in the high-temperature plenum section 6, from where it flows out of the furnace through the outlet vibe 7.

By the way, as shown in the figure, control block 2. A unit core structure 1 composed of stacked columns such as a fuel block 3 and a movable reflector 9 is supported by dowel pins on the upper surface of a high temperature plenum block 4 corresponding to each structure. 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 includes one unit core structure corresponding to the plenum block, a block control block 2, and six standard fuel blocks 3. The total amount of each column of the movable reflector 8 combined therewith is supported.

As shown in the figure, the planar shape of the unit core structure 1, which is made up of a combination of seven regular hexagonal plates, is a star shape with an uneven outer periphery, and part of its periphery is designated by the symbol P. As shown, it protrudes from the area of the regular hexagonal high-temperature plenum block 4 and extends to the side, enters the area of the adjacent high-temperature plenum block, and comes to straddle the upper surface of that plenum block. FIGS. 6(a) and 6(b) show the stacked state of core constituent blocks according to this conventional structure. In other words, 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 are in contact with each other across the top surface. On the other hand, if a step H occurs between adjacent blocks due to an unbalanced temperature distribution in the furnace during operation of the furnace, as shown in FIG. The portion P is pushed upward and its blocking attitude is tilted, causing disturbance in the blocking attitude of the column. As a result, gaps are created locally between the laminated blocks, resulting in problems such as a decrease in sole properties in those areas and the occurrence of bypass flow of cooling gas.

[Purpose of the invention]

This invention has been made in consideration of the above points, and eliminates the drawbacks of the conventional structure, and eliminates the problem that even if a step occurs between adjacent high-temperature plenum blocks, the step does not interfere with the column of the unit core structure. The purpose of the present invention 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 is directed to the projecting portion of the unit core structure that protrudes from the block area of each high-temperature plenum block and extends into the area of the adjacent high-temperature plenum block. A notch recess having approximately the same shape as the protruding portion is formed at the upper peripheral edge of the high-temperature gnome protrusion.

The high-temperature plenum block uses the notch recess as an escape to avoid interference between the high-temperature plenum block and the constituent blocks of the unit core structure in the event of a step between the high-temperature plenum block and the unit core structure block, thereby preventing disturbances in the stacked posture of the core constituent blocks. It was designed to do so.

[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. . This notch recess 14 is formed so as to coincide with a location facing the protruding portion P of the unit core structure 1 that protrudes from the area of the adjacent high-temperature plenum block. The depth dimension of No. 14 is determined to be slightly larger than the amount of step H between the high-temperature Blenheim grooves, which is assumed based on the operating conditions of the furnace. In addition, the regular hexagonal high-temperature plenum block has one on each top side for each plate.
Notch recesses 14 are formed at six locations in total.

With the above configuration, υ, even if a level difference H occurs between the high temperature plenum blocks as shown in Figure 7 (b) from the state of no level difference between adjacent high temperature plenum blocks as shown in Figure 7 (a), the above-mentioned The cutout recess 14 effectively functions as a relief, and no interference occurs 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 notch 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 recess is supported on the adjacent high temperature plenum block using the notch recess as a relief. By avoiding interference with the protruding parts of the unit core structure, even if there is a step between the high-temperature blocks, this step will not disturb the stacking posture of the core constituent blocks, allowing stable core function to be maintained. can be achieved.

[Brief explanation of the drawing]

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. B) is an explanatory diagram showing the stacking posture of the unit core structures with respect to changes in the state of juxtaposition between high-temperature Blenheim reactors and reactors according to the conventional method 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
Steps between hot 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 formed into a unit core structure. In a gas-cooled nuclear reactor in which hot plenum blocks of regular polygonal shape are juxtaposed at the bottom of the reactor core and individually corresponding to the core, each hot plenum block has an adjacent hot plenum that protrudes from its block area. Gas cooling characterized in that a notch recess having approximately the same shape as the protruding part is formed in the upper peripheral edge of the adjacent high temperature plenum block, facing the protruding part of the unit core structure extending into the area of the block. shaped nuclear reactor.