JPS5839987A - Fuel assembly - 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] The present invention relates to a fuel assembly κ for a boiling water nuclear reactor.

The fuel assembly of a general κ boiling water expansion reactor consists of fuel rods arranged in a lattice shape with a predetermined O spacing to form a fuel pandle.
This is housed in the channel I box. The coolant (@water) is configured to flow between these fuel rods from below to above 7JK. and,
This coolant is heated as it flows between the fuel rods and becomes a two-phase flow of water and steam), and its steam content, or quality, increases as it moves upward.

As the quality of the coolant ζ increases, the heat removal ability of the coolant decreases, eventually causing overheating of the fuel, that is, Δ-ν out. When operating the reactor, a sufficient margin is estimated and the reactor is operated within thermal limits that do not cause ζ burnout. Therefore, the output of the fuel assembly is increased and the thermal margin is also increased.・
There was a demand for ζ that would increase the limit of d-in-out.

This work has been made based on circumstances κ that are more than inventive, and its I objective is to obtain a fuel collection body that increases the ability to remove heat from the Hiro fuel rods and increases the limit of pan-out. be.

The present invention will be explained below with reference to an embodiment shown in FIG.

In the figure, there are 11 fuel rods 9, and these fuel rods 1 are arranged in a grid of 8 rows and 8° columns with a predetermined gap between them.
It constitutes a fuel bundle L. This fuel bundle L has a channel having a square cross section accommodated in the cylinder 1. The fuel bundle 1 is provided with spacers 4-9 at predetermined intervals, and these spacers 4- maintain the fuel rods 1-O at a predetermined interval. t, 5 is a lower tie rate, and the coolant flows through the lower tie rate 5 with the coolant hole into the channel &9F Cusco, flows upward between the fuel rods 1... and flows into the channel -! It is configured to flow out from the upper end of the gas 3. Coolant deflecting bodies L.- are provided at predetermined intervals between the above-mentioned spaces (-4-.).These coolant deflecting bodies 1-.-. These metal wires F--...
It is perpendicular to the axial direction, that is, the flow direction of the coolant, and is arranged at the center of the gap between the fuel rods 1 and 1.

As described above (one embodiment of the present invention configured f11 company, channel I passing through the lower tie plate 5 of the cooling line,
and flows upward through the gaps between the fuel rods 1.

This coolant is heated while flowing between the fuel rods 1 and becomes a two-phase flow of water and steam. When this coolant passes through the coolant deflection body L..., the flow of the coolant is deflected by the metal wire y- toward both sides, that is, the surface of the fuel rod 1... . Since a low-pressure part is generated on the downstream side of these metal wires 7, the flow of the coolant deflected to both sides is repeated on the downstream side of these metal wires 1. ...is deflected toward the center of the gap between. By the way, this coolant contains steam, but this steam has a low specific gravity and low inertia, so the metal wire 1...
After passing through both sides of the fuel rod, it is immediately deflected toward the center of the fuel rod 1 and 0, as shown by the broken line in FIG.

On the other hand, since the coolant in the liquid phase of water has a large specific gravity and a large inertia, it passes through the metal wire 1... and the friend K is not deflected toward the center of the gap. , the predetermined section flows along the fuel rod J-O51 plane. Therefore, on the downstream side of the coolant deflector L..., near the surfaces of the fuel rods 1..., the liquid phase coolant 0 ratio is high, that is, the quality is low. Therefore, the ability to remove O heat from the fuel rods 1 . . . increases on the downstream side of the lever coolant deflection body L. Therefore, the limit of OΔ-siaaud of the entire fuel assembly is high, the fuel output is increased, and the thermal margin is increased. Note that the metal wire 1 above has a large spreading effect, which increases the lifting and removal capacity, but it also increases the flow resistance of the coolant. It is necessary to set it within a range that does not increase FtK excessively.

It should be noted that the present invention is not limited to the above-mentioned one embodiment, and the nine parables are the fourth embodiment.
As in the modification shown in the figure, the metal wires 2 may be woven into a complete rope shape, and by doing so, the strength of the coolant deflection body is increased.

Further, the coolant deflecting body is not limited to the one in the above embodiment, but may be any type as long as it deflects the coolant O flow toward *lfK of the fuel rod.

As described above, the present invention allows the flow of coolant between the fuel rods to
There are nine coolant deflectors that deflect the coolant toward the surface. Therefore, the coolant flowing between these fuel rods hits this coolant deflection body and is deflected toward the surface of the fuel rod 0.
Even after the liquid-phase coolant with large inertia passes through this coolant deflector, it does not immediately return to the center between the fuel rods, but instead flows along the surfaces of the fuel rods in a predetermined section. Therefore, on the downstream side of the coolant deflector, the steam content near the surface of the fuel rod, that is, the quality, is small, and the ability to remove heat from the fuel rod is increased.

In this way, the temperature-out limit of the fuel is increased, the output of the fuel assembly can be increased, and the thermal margin can be increased, etc., and the effects are great.

[Brief explanation of drawings]

The figure shows one embodiment of the present invention, and FIG. 1 is a secondary sectional view,
Figure 2 is a cross-sectional view taken along the line ■-■ of Figure 1, Figure 3 is a vertical cross-sectional view showing an enlarged layer portion of Figure 1, and Figure 4 is a cross-sectional view showing a modified example of the coolant deflector. It is a vertical WItllI diagram that is similar to the figure. 1... fuel rod, 1- fuel bundle, 3... channel! Kusu, Sumeragi...coolant deflector, 1...metal wire. Applicant's attorney Takehiko Suzue Figure 1 Figure 2

Claims (2)

[Claims] (1) A plurality of nine fuel rods arranged at predetermined intervals within the channel ZV tas, and a coolant deflection body provided between these fuel rods to deflect the flow of coolant toward the front surface of the fuel rods. A fuel assembly characterized by: (2) A patent characterized in that the coolant deflector has nine metal wires arranged in a lattice shape between fuel rods.