A fuel assembly of a nuclear reactor

 

(57) Abstract:

The essence: a fuel Assembly of a nuclear reactor contains a hexagonal bundle of fuel elements placed along the height of the Assembly spacer grids, head and tail of the parts connected support elements. The supporting elements mounted on the height from the tail to the top spacer grid and have the form stamped angular plates of zirconium alloy, and are welded to the spacer bars and screws with a tail part. 4 Il.

The invention relates to the field of nuclear energy, in particular for fuel assemblies of nuclear power reactors.

The famous design of the fuel assemblies of a nuclear power reactor [1] contains a hexagonal bundle of fuel elements placed along the length of the Assembly spacer grids of the head and the tail part, the United hexagonal outer case.

The presence of the cover provides the necessary strength and rigidity of the fuel Assembly, but it introduces spurious metal in the active zone and increases linear heat load of anise fuel elements per unit volume of the active zone), and increases the non-uniformity of energy deposition in the fuel Assembly.

The famous design of the fuel assemblies [2] in which the outer cover has openings spaced throughout the height and width of the face of the cover or window height facets of the case.

The presence of holes or Windows in the sides of the cover reduces the amount of parasitic metal in the core, however, does not reduce the linear heat load of the fuel element, and the non-uniformity of energy deposition in the fuel Assembly to be even bigger.

Known design fuel Assembly of a nuclear reactor [3] contains a hexagonal bundle of fuel elements placed along the length of the Assembly spacer grids of the head and the tail part, the United guiding channels passing through the spacer grid. The outer cover is missing. In the guide channels move the rods-absorbers. The spacing between fuel assemblies is reduced, the uniformity of the heat dissipation Assembly and a linear load, the fuel rod is reduced.

The referenced Assembly is more economical, however, the application of similar assemblies on the power units with VVER-1000 showed that on the third goleada, that a fuel Assembly loaded mechanically from the head part to prevent it from floating in the stream moving upward coolant. In addition, during operation of the reactor also appears thermomechanical loading design of the fuel Assembly from the fuel rod and guide channels through the spacer grid. Therefore, the rigidity of the specified design fuel Assembly was insufficient, which reduces the safety of nuclear reactor.

Known fuel Assembly of a nuclear reactor [4] contains a hexagonal bundle of fuel elements placed along the height of the Assembly spacer grids, head and tail of the parts connected support elements placed in the corners of the Assembly.

The disadvantage of the design is reduced efficiency because of the massive support elements on the periphery of the Assembly result in the need to remove a portion of the peripheral fuel elements. This increase also the non-uniformity of energy deposition in FA and increases linear heat load of the fuel element.

The objective of the invention is to improve the safety of nuclear reactor by ensuring the rigidity of the fuel Assembly the fuel element.

The solution provided by the fact that in the known fuel Assembly of a nuclear reactor containing a hexagonal bundle of fuel elements placed along the height of the Assembly spacer grids, head and tail of the parts connected support elements placed in the corners of the Assembly, the supporting elements made in the form established by the height of the Assembly from the tail to the top spacer grid stamped angular plates of zirconium alloy welded to the spacer bars and screws with a tail.

In Fig. 1 shows a section of the proposed fuel Assembly of a nuclear reactor;

in Fig. 2 section a-a in Fig. 1;

in Fig. 3 node I in Fig. 1;

in Fig. 4 site II in Fig. 1.

A fuel Assembly of a nuclear reactor contains a hexagonal bundle of fuel elements 1 placed along the height of the Assembly spacer grids 2 of zirconium alloy. Head 3 and the tail 4 parts, made of stainless steel, connected to the guide channels 5, made of zirconium alloy, and the head part 3 is spring-loaded relative to the channels 5. In the corners FA p is Tina 6 of zirconium alloy, with radiation resistance. Plate 6 are welded to the spacer grids 2 and 7 screws on the tail part 4. The screw 7 is now pin 8. The thickness of the rim spacer grid is reduced to accommodate the plate 6. Thus, the spacing between fuel assemblies remains the same.

The proposed fuel Assembly operates as follows.

When the reactor fuel Assembly is loaded mechanically from above in the axial direction by springs (not shown) to prevent its ascent in the stream moving upward coolant. In addition, when heating the entire structure to operating temperatures appears thermomechanical loading of a fuel Assembly from the fuel rod 1. Plate 6 together with the tail part 4 and the spacer grids 2 form a rigid frame, preventing deformation of the Assembly and, therefore, the guide channel 5. Absorbing rods (not shown) can move freely within the guide channel 5.

Thus, the increased safety of a nuclear reactor, the efficiency of the fuel cycle.

A fuel Assembly of a nuclear reactor containing a hexagonal bundle of fuel elements, various support elements, placed in the corners of the Assembly, characterized in that the supporting elements made in the form established by its height from the tail to the top spacer grid stamped angular plates of zirconium alloy welded to the spacer bars and screws with a tail part.

 

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