RU159364U1 - Spent Nuclear Fuel Storage Case - Google Patents

Abstract

The lattice of a spent nuclear fuel storage case, including vertical racks and cells for accommodating ampoules, made in several coaxial tiers, consisting of tubular sleeves connected to vertical racks and to each other by plates with the formation of round and triangular cells whose symmetry axes are located at the vertices of equilateral triangles moreover, the diameter of the inscribed circle of the triangular cells is equal to the inner diameter of the circular cells, and the peripheral cells located between the uprights from characterized in that the round and triangular cells are made with the possibility of installing ampoules in them with substandard bundles of fuel rods, and the peripheral cells with the possibility of installing ampoules with standard bundles of fuel rods in them.

Description

The utility model relates to nuclear engineering, in particular, to the management of spent nuclear fuel, and more particularly to the loading of ampoules with conditioned and substandard bundles of RBMK-1000 reactor fuel elements from a transport case into dry storage cases.

A known method of handling spent nuclear fuel (patent No. 2491665, CL. G21F 19/06), including placing at the nuclear power plant bundles of fuel elements (fuel rods) in ampoules, loading part of the ampoules with bundles of fuel rods into the lattice of canisters located in the nests of the transport case, and parts of ampoules - in the cells of the case, located between the nests. In a dry storage with a crane with a lifting capacity of 4000 kg, the grids loaded with ampoules are alternately removed from the nests of the transport case and installed in the cases, and the ampoules from the cells of the case are loaded into the case using an electromechanical manipulator with a carrying capacity of 500 kg.

After installing lattices with ampoules in the cases of the canisters and filling the lattice of the cans with ampoules from the cells of the transport case, the covers are installed on the cases of the canisters, they are connected to the cases by welding, vacuuming and filling of the canisters with excess pressure are carried out through the valve caps, after which the valves are sealed by welding. The transportation of loaded canisters to storage slots is carried out by a crane-manipulator with a lifting capacity of 4000 kg.

Known lattice sealed storage case for spent nuclear fuel of the RBMK-1000 reactor according to patent No. 2491665.

The grill is made with the possibility of extracting a pencil case from the housing and installing it in the socket of the transport cover. The grate is equipped with a base with vertical posts attached to it and a central pipe, and cells for accommodating ampoules with bundles of fuel rods. The cells are made in several coaxial tiers, consisting of tubular sleeves connected to the central pipe, vertical posts and between each other by plates with the formation of round and triangular cells. The axis of symmetry of the cells are located at the vertices of equilateral triangles, and the diameter of the inscribed circle of the triangular cells is equal to the inner diameter of the round cells. The ends of the plates located between the uprights are V-shaped. At the base, holes are made coaxial with the axis of symmetry of the cells.

Known lattice adopted by the applicant as a prototype.

Some parts of two-beam fuel assemblies, after being in a nuclear reactor and stored for a long time in the on-site storage, have significant deviations from the straightness and convexity of the zirconium fuel tubes between the spacer grids, increasing the outer diameter of the fuel rod bundle and not allowing them to be placed in ampoules installed in the cells of known grids. On this basis, the loading of such substandard bundles of fuel elements requires the use of ampoules with an increased inner diameter, which, in turn, will require an increase in both the diameter of the lattice cells and the pitch between them.

The internal diameter of the pencil case body, determined by the design of the nests of the already built dry storage, cannot be increased. Thus, in order to ensure placement of a lattice loaded in substandard bundles of fuel rods in the pencil case, an increase in the diameters of cells and ampoules is possible only by reducing their number in the lattice. Measurements of substandard fuel rod bundles performed at nuclear power plants showed that for their guaranteed placement in ampoules it is necessary to increase the internal diameter of the ampoules to 98 mm. When the wall thickness of the ampoule is 2 mm, it is necessary to carry out cells with an inner diameter of 104 mm, which provides the necessary gap between the cell and the ampoule for the free installation of ampoules in the cells.

Based on the ratio of conditioned and substandard bundles of fuel rods, the maximum load of the transport cover when implementing the method according to patent No. 2491665 is provided by placing ampoules with conditioned bundles of fuel rods in removable grids installed in the nests of the transport cover, and ampoules with substandard bundles of fuel rods in the cells of the cover located between the sockets . At the same time, ampoules with conditioned bundles of fuel rods are loaded into the cells of the case.

In a dry storage for separate storage of ampoules with substandard bundles of fuel rods, it is necessary to have gratings located in the cases of cases with an internal cell diameter of at least 104 mm, while the maximum capacity of such a grating will be only 19 ampoules.

The technical result that can be obtained by using the proposed lattice is to increase its capacity due to the mixed placement of ampoules in it with substandard and conditioned bundles of fuel rods.

The specified technical result is achieved by the fact that in the lattice, including vertical racks and cells for accommodating ampoules, made in several coaxial tiers, consisting of tubular sleeves connected to vertical racks and between each other by plates with the formation of round and triangular cells, the axis of symmetry of which are located in vertices of equilateral triangles, and the diameter of the inscribed circle of triangular cells is equal to the inner diameter of the circular cells and peripheral cells located between the vertical columns Ami, round and triangular cells are made with the possibility of installing ampoules with substandard bundles of fuel rods in them, and peripheral cells located between vertical racks, with the possibility of installing ampoules with standard bundles of fuel rods in them.

The implementation of round and triangular cells with the possibility of installing ampoules in them with substandard bundles of fuel rods, and peripheral cells with the possibility of installing ampoules with standard bundles of fuel rods, allows 25 cells to be placed along the cross-section of the grating and, thus, increasing the capacity of the grating.

The proposed utility model is illustrated by drawings, which depict:

in FIG. 1 - the proposed lattice in section, installed in the body of the pencil case;

in FIG. 2 is a view A in FIG. one.

The proposed lattice 1 (see Fig. 1 and 2) is installed in the housing of the pencil case 2 and contains vertical posts 3 connected in the lower part by a ring 4. In the upper part, radius plates 5 are attached to the vertical posts 3, by which the lattice 1 is fixed in the pencil case 2 on welding. The lattice 1 contains several coaxial tiers 6, consisting of tubular sleeves 7, interconnected by plates 8 with the formation of seven round 9 and six triangular 10 cells. The diameters of the inscribed circles of the triangular cells 10 and the inner diameters of the round cells 9 are made equal to 104 mm The outer tubular sleeves 7 are connected by welding to the uprights 3 by plates 11. The gaps 12 formed between the uprights 3 are separated by partitions 13 to form twelve cells 14 located between the pencil case 2, the radius plates 5, the partitions 13 and the outer tubular sleeves 7 with an inscribed diameter circumference 98 mm. The cross section of cells 8 and 9 of the lattice 1 allows you to place the ampoules 15 with substandard bundles of fuel rods in them, and the section of the cells 14 - ampoules 16 with standard bundles of fuel rods.

The proposed lattice 1 is operated as follows.

The case of the pencil case 2 with the grill 1 is installed in the loading slot of the camera picking case. Ampoules 15 or 16 with substandard and conditioned bundles of fuel rods are taken from the cells of the transport cover delivered from the NPP by the electromechanical manipulator (not shown in the drawings), respectively, and are installed in cells 9 and 10 or 14. After loading, the standard cover is installed on the canister body and the cover is welded to the case of the canister, filling the canister with a nitrogen-helium mixture through the valve, sealing the valve, checking the tightness of the welds, transporting and installing the canister in the nest of the dry storage.

Claims (1)

The lattice of a spent nuclear fuel storage case, including vertical racks and ampoule storage cells, made in several coaxial tiers, consisting of tubular sleeves connected to vertical racks and to each other by plates with the formation of round and triangular cells whose symmetry axes are located at the vertices of equilateral triangles moreover, the diameter of the inscribed circle of the triangular cells is equal to the inner diameter of the circular cells, and the peripheral cells located between the uprights from characterized in that the round and triangular cells are made with the possibility of installing ampoules in them with substandard bundles of fuel rods, and the peripheral cells with the possibility of installing ampoules with conditioned bundles of fuel rods in them.

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