JPS5979180A - Fast breeder - 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 1. Technical Field of the Invention The present invention relates to a fast breeder reactor, and particularly relates to the structure of the reactor core in (a).

1. Technical Background of the Invention J General (The core of a fast breeder reactor is often cylindrical or close to the cylinder, surrounded by a cylinder.

Here (the nuclear fuel fit loaded into the reactor core is uranium agglomerated or uranium enriched with plu-1 to nium), and the blanket absorbs neutrons leaking from the core and converts them into useful fissile material. It is loaded with natural uranium or reduced-membered uranium.

Figure 1 shows the core of a normal homogeneous reactor. In the core of this homogeneous reactor, a diameter blanket 1 is formed at the outermost periphery, and the inner upper and lower parts of this diameter blanket 1 are respectively 3 is formed into the upper shaft blanket 2 and the lower shaft planner 1.

In the center of the reactor core between the upper shaft Planckels 1 to 2 and the lower shaft Planchers 1 to 3, an inner core 4 consisting of a nuclear fuel assembly with a low density of fissile material is formed. An outer core 5 consisting of a nuclear fuel assembly with a high density of fissile material is formed between the planks 1 and 1.

[Problems with Background Art J However, with this configuration, 1. = In a fast breeder reactor, the horizontal axis is the vertical distance Z from the core center shown in Figure 1, and the vertical axis is the relative power distribution. The relative output is distributed, and it cannot necessarily be said that the J5-U4fl vs. output (li) is sufficiently flattened in the Z-axis direction.

In general, d3C in the core design of fast breeder reactors is strongly considered because it is advantageous from the core economics to flatten the power distribution in the core as much as possible, reduce the C1 core diameter, or reduce the required suspension of fissile material. Although this is desired, as shown in FIG. 2, the conventional high-speed multiplication power 1(-) cannot be said to have flattened the output distribution to 1-min.

Therefore, in order to level out the axial output m of conventional fast breeder reactors, the plu-1-nium enrichment of the fuel belenium 1 accommodated in the fuel pin inserted into the reactor core was varied. , attempts were made to flatten the power distribution in the axial direction of the core.
(However, when this method is applied, the number of types of fuel will increase, leading to an increase in fuel production costs, and the management of fuel will become extremely complicated.) There's a problem.

1. Purpose of the invention] The present invention deals with such conventional circumstances and provides C.
By flattening the power distribution within the reactor core without increasing the types of fuel pellets with different levels of enrichment, the manufacturing cost of the burner 1 can be reduced, and the fuel pellets can be easily managed at high speed. There are many people who try to provide a furnace.

[Summary of the Invention 1 Rinawara] The present invention comprises an inner core made of nuclear fuel with a low fissile material trade density, and a nuclear fuel with a fissile material density higher than that of the inner core, which is surrounded by ( ). In a fast dusk reactor equipped with an outer core consisting of a core of There are fast breeder reactors.

"Embodiments of the Invention" The details of the present invention will be explained below with reference to the drawings and embodiments.

FIG. 3 shows the core of a fast breeder reactor according to an embodiment of the present invention. The core C' of this homogeneous reactor has a diameter plankera 1-0 formed at the outermost periphery, and this diameter 1 ranker 1-0. Upper glaze blankets 1 to 7 are placed on the inner upper part and σ-do part of 6, respectively.
J> and a lower axis planner 1-8 are formed. In the center of the reactor core between the lower shaft blanket 7 and the lower +lib planket 1-8, an inner core 9 consisting of a nuclear fuel assembly with a low density of fissile material is formed.
An outer core 1o is formed between the inner core 9 and the diameter blanket 6. The outer core 1o is made of a nuclear fuel assembly with a high density of fissile material.

The lower part of the inner core 9 and the lower IJ are regions [11
, 12 are formed.

Figure 4 shows the fuel pins 13 disposed in the inner core 9 of the Obisu breeder reactor configured as described above.
In this fuel pin 13, in order from the bottom, there is a fuel 31 bellet t-8a for the lower shaft blunt foot 8, and a fuel 1 bellet t-10a, which has the same brutonium enrichment as the outer core 10.
, 6 low-fissile fuel pellets forming the inner core 9 with 4IO ~ 9a, fuel pellets h 10 a J> with the same plutonium enrichment as the outer core 10 and 7 into the upper shaft planner 1. A fuel pellet 7a is provided.

FIG. 5 shows the fuel bottle 14 inserted into the outer core 10 of the fast increase reactor configured as described above. Fuel bellet for 8 1-88. Fuel pellets 10acl with high fissile material density for the outer core 10 and fuel pellets 7a for the upper shaft blanket 7 are provided, respectively.

In the fast breeder reactor configured as described above, the horizontal axis represents the distance from the center of the core in the 7@ direction, and the vertical axis represents the relative output.
Figure 6 shows a solid curve b (as shown in Figure 1, it is possible to flatten the C output distribution significantly compared to the conventional fast breeder reactor).

In other words, in a conventional fast breeder reactor, the broken line a is shown in Figure 6.
As you can see, the relative power in the distance 1llIo~, Ql rapidly decreased, but according to the high speed WJ breeder furnace shown in Fig. 3, iJ3 (lJ, lJ, d between it o ``□fl' +
3, the output can be increased, and the axial output distribution can be made even.

As a result, the maximum output value is the same as that of the fast breeder reactor shown in Figure 1. A core C that can be increased less than a conventional fast breeder reactor, and therefore has the same total power 1111, is a fast breeder reactor shown in FIG. As a result, it is possible to avoid reducing the volume of the reactor core, and the necessary pull 1~
It is possible to avoid reducing the total weight of aluminum loading.

FIG. 7 shows another embodiment of the present invention. In this fast breeder reactor, the upper part J3J of the inner core 9 and the outer core 10 formed in the σ soil part have the same pull 1 to nium enriched f marks. Regions M11a and 12a made of fuel on the right side are enlarged in the J5 CZ axis direction on the outer periphery of the inner core 9.

As shown in Figure 3, the fast breeder reactor C configured in this manner can obtain the same effects as the fast breeder, and at the same time,
Not shown in Figure 8 J: Sea urchin Same as Figure 3 High speed 14'l W4
Compared to a nuclear reactor, the power distribution in the radial direction of the core can be further flattened.

In Fig. 8, the horizontal axis shows the distance from the core center to the radial direction, and the vertical axis shows the phase output at a point other than t, and the curve C shown by the solid line C is shown in Fig. 7. The dashed line C represents the relative output of the fast breeder reactor shown in FIG. 3, and the curve d represents the relative output of the fast breeder reactor shown in FIG.

Effects of the Invention As stated above, if the fast breeder reactor of Komei is used, it will be possible to enrich the fast breeder reactor without increasing the number of different types of fuel. The output distribution can be flattened. Therefore, it is possible to completely eliminate the increase in production cost of fuel pellets 1~ caused by an increase in the number of fuel pellets 1~ of different types of plu 1~nium enrichment and the associated complexity of fuel pellet management. can.

Note that the present invention can be applied to, for example, a so-called three-zone core in which an intermediate core P4 is located between the outer core and the inner core. Area 11.124 is either the outer core or the intermediate core.
Nuclear fuel will be placed.

[Brief explanation of the drawing]

! Figure 11 shows a conventional fast breeder reactor; Figure 2 is a vertical sectional view of a conventional fast breeder reactor; FIG. 4 is a vertical sectional view showing the fast breeder reactor of the example (71 longitudinal sectional view showing the fuel pins arranged in the inner core of FIG. Figure 6 is a vertical sectional view showing the fuel pins installed in the flannel, Figure 6 is a diagram showing the relative power distribution in the axial direction of the fast breeder reactor as shown in Figure 3; Figure 7 shows the W1 reactor, and Figure 8 shows the radial power distribution of the fast breeder reactor.・・・・・・・・・Outer core 13.14...
・Fuel pin Fig. 1 Fig. 2 Fig. 3 Fig. 7 Fig. 8

Claims (1)

[Claims] (1) An inner reactor core made of nuclear fuel with a low density of fissile material, and a 'Ci! li! and an outer core made of nuclear fuel having a higher density of fissile material than the inner core, the upper and lower parts of the inner core being made of nuclear fuel having the same density of fissile material as the outer core. A fast breeder reactor characterized in that a region is formed.