RU2707504C1 - Transportation packaging container case for spent fuel assemblies - Google Patents

Abstract

FIELD: nuclear physics and equipment.

SUBSTANCE: invention relates to nuclear engineering, particularly, to transport packs (TP) for transportation and storage of spent fuel assemblies (SFA). TP jacket for SFA comprises base, central post fixed on the base, perforated steel discs and perforated discs made of separate segments and arranged on the rack, as well as pipes installed through disc perforation. Perforation of steel and aluminum disks coincides in axial direction. Between steel perforated discs there is at least two aluminum discs. Joints of each next aluminum disc segments are shifted relative to joints of previous aluminum disc segments. Perforation of segments of one disc is shifted by angle of offset of joints of segments of another disc, bulges are made along outer perimeter of disc segments. Discs adjoin each other with bulges. Cover is additionally equipped with couplers. External perimeter of the discs has holes.

EFFECT: invention allows maintaining integrity of geometrical shape of TP cover in normal and emergency conditions of transportation to maintain control over critical mass of nuclear material during transportation.

1 cl, 5 dwg

Description

The invention relates to nuclear engineering, in particular to covers of transport packaging sets (TUKs) for transporting and storing spent fuel assemblies (SFA) of VVER-1000/1200/1300 power units and can be used in transport packaging sets for placement during transportation and / or storage SFA.

A TUK cover for spent nuclear fuel is known, comprising a base fixed to a base of a central strut with spacing elements located thereon made of plates with high thermal conductivity and provided with openings that form channels for accommodating spent fuel assemblies and heat-separating inserts mounted on a central strut between spacing elements and rigidly connecting them in the axial direction (patent for utility model RU No. 78979, publ. 10.12.2008) .

A disadvantage of the known cover is the restriction on permissible mechanical loads on the cover due to the insignificant strength characteristics of the plates made of materials with high thermal conductivity, for example, aluminum.

The closest technical solution to the claimed invention is a cover of a transport and packaging set for spent fuel assemblies, comprising a base, a central rack fixed to the base, perforated steel disks located on a height stand and perforated aluminum disks of variable thickness made from separate segments, where the perforation of steel and axially aligned aluminum disks, as well as pipes installed in a case through disk perforation (patent for useful th RF №153580 Model, publ. 27.07.2015 city).

In the well-known case, aluminum and steel disks are arranged alternately along the height of the rack, segments of the aluminum disk are fastened together by locking protrusions-grooves along the inner and outer diameters.

A disadvantage of the known utility model is the low mechanical strength due to the likelihood of gaps between the groove and the protrusion when joining, for example, in case of a breakdown of the protrusion or inaccuracy of their joining, which will violate the integrity of the disk and heat removal from the SFA. In addition, the manufacture of segments with grooves and protrusions for their exact joining is accompanied by additional operations.

However, one of the main requirements for TUK covers is high mechanical strength, which ensures the preservation of the geometric shape integrity under normal and emergency transportation conditions, which ensures that control over the criticality of the mass of nuclear material during operation is maintained.

Thus, the technical problem of the invention is to maintain the integrity of the geometric shape of the TUK cover in normal and emergency transportation conditions, which will ensure, as a result, control over the criticality of the mass of nuclear material during transportation.

The technical result of the invention is to increase the mechanical strength of the cover TUK.

The technical result is achieved by the fact that the cover of the transport-packaging set for spent fuel assemblies, comprising a base, a central rack mounted on the base, perforated steel disks mounted on the rack in height and perforated aluminum disks of variable thickness made from separate segments, where the perforation of steel and aluminum disks coincides in the axial direction, as well as pipes installed through the perforation of the disks, between the perforated steel disks are located on e less than two aluminum disks, the joints of the segments of each subsequent aluminum disk are offset relative to the joints of the segments of the previous aluminum disk, while the perforation of the segments of one disk is shifted by the angle of displacement of the joints of the segments of the other disk, the thickenings are made along the outer diameter of the disk segments, the disks are adjacent to each other with thickenings, the cover is additionally equipped with couplers, holes are made along the outer perimeter of the disks, couplers are passed through the holes.

In addition, every third aluminum disc is stacked upside down.

The increase in the mechanical strength of the cover compared to the prototype is achieved by tightly pressing the disks against each other while displacing the joints of the disk segments located one on top of the other.

The displacement of the perforation of each subsequent disk by the angle of displacement of the disks ensures the coincidence of perforation for installing channels under the SFA in the disks.

The thickening of the segments of the aluminum disks in the outer diameter ensures that they are pressed against each other in height from the outside and the joints of the segments are fixed in the radial direction to form a single disk while maintaining a gap for heat removal between the central parts of the segments. The presence of couplers passing through the disks along the entire height fixes the design of the cover as a whole due to the vertical compression force.

The pressing of the segments to each other in the radial direction is an alternative to the protrusion-groove connection, thereby simplifying the manufacture of the segments and eliminating the breakage of the protrusions.

In addition, tight docking in the axial direction of the disks along the outer diameter is additionally protected against gamma radiation coming from the SFA in the radial direction.

Every third disk, installed upside down, allows you to more evenly distribute the loads acting on the segments, which further increases the mechanical strength of the cover.

Thus, the claimed design of the cover has mechanical strength, ensuring the integrity of the geometric shape in normal and emergency transportation conditions, which retains control over the criticality of the mass of nuclear material at any time.

The design of the cover is illustrated by drawings, where in FIG. 1 shows a longitudinal section through a case; FIG. 2 - type “A” segment, in FIG. 3 - type “B” segment, in FIG. 4 is a cross-sectional view of the cover through a series of “A” type segments, in FIG. 5 is a transverse section through the cover through a series of segments of type "A".

The cover is a metal structure, consisting of aluminum disks 1 and steel disks located closely above each other in height. Aluminum disks 1 consist of segments of type “A” and type “B”, which have a thickening in outer diameter. Disks 1 and disks 2 have a perforation 3 in the form of hexagonal holes. Perforation of the disks 1 and 2 located one above the other coincides. Through the perforation of the disks, eighteen hexagonal pipes 3 are installed. Hexagonal pipes 3 are installed in the supporting disk 4 and are fixed from above by the upper disk 5, made of high-strength corrosion-resistant steel.

The segments are made of two types: a segment of type "A" 8 (Fig. 4) and a segment of type "B" 9 (Fig. 5). Six segments of the same type, stacked in a row close to each other, form a perforated disk 1. Each subsequent disk 1 (row of segments) is shifted relative to the previous disk 1 (row of segments) so that the joints between the segments of one disk 1 overlap the next disk 1 in the form brickwork. In this case, the disks 1 are supported by thickenings of the outer diameter of the segments.

In order to match the perforation of the disks 1 located above each other, the perforation of the segments is shifted by the angle of displacement of the joints.

The alternation of aluminum disks 1 by types of segments can be as follows: disk 1 from segments of type “A”, disk 1 from segments of type “B”, disk 1 from segments of type “A”, disk 1 from inverted segments of type “B”, after which disc rotation cycle 1 is repeated.

This design condition for the shift of joints between segments allows you to provide the required strength characteristics of the cover during operation and in emergency situations.

The connection of aluminum disks 1 with steel disks 2, with the upper disk 5 and with the supporting disk 4 is carried out by bushings 6.

A central rack 7 is welded to the supporting disk 4, which performs the function of the bearing element of the cover, on which all the other components are located.

The rack 7 in the upper part is equipped with a socket 8 for gripping, with which an empty cover is installed and removed from the container body.

The fastening of the segments on the central rack 7 of the adjacent disks 1, as well as with the supporting 5, with the top 5 and with the steel intermediate disks 2, provides the inserts 9 installed between them in the annular grooves.

The connection of all parts of the cover in a single design is provided by eighteen couplers 10 located around the perimeter of the cover, by fixing with nuts 11 and washers 12. Couplers 10 are passed through holes 13 made in the thickening of the segments.

The assembly of the case and an example of a specific implementation are shown in the following example.

To the supporting disk 4, a stand 7 is welded from above with a socket 8. The eight supporting couplers are screwed into the threaded holes with equal angular pitch along the perimeter of the supporting 4 disk, with equal angular pitch 10, a sleeve 6 is put on each tie 10 and installed in the groove of the supporting disk 4, insert 9 is put on the rack 7. Then, passing through the holes 13 through the couplers 10 on the bushings 6, the first disk 1 consisting of six “A” type segments is installed on the insert 9 (Fig. 2). The perforation of the inner surface of the segments should coincide with the perforation of the supporting disk 4. Then, sleeve 6 is put on again for each screed 10 and installed in the groove of the segment, insert 9 is put on again. Then on bushings 6, passing through holes 13 through the ties 10 and onto the insert 9, a second disk 1 is installed, consisting of six type “B” segments (Fig. 3), the joints in this disk 1 between the segments are offset relative to the joints of the first disk (brickwork), while the perforation of the inner surface of the segments of the second disk must coincide with the perforation of the segments of the first disk 1. Then, on each screed 10, the sleeve 6 is put on again and installed in the groove of the segment, the insert 9 is put on again. Then on the bush 6, passing through the holes 13 through the ties 10 and the third disk is installed on the insert 9 1, consisting of six segments of type "A" (Fig. 2). The joints in this disk 1 between the segments are offset relative to the joints of the second disk 1, while the perforation of the inner surface of the segments of the third disk should coincide with the perforation of the segments of the second disk. Then, sleeve 6 is put on again for each screed 10 and installed in the groove of the segment, insert 9 is put on again. Then insert 6 is put on the bushings 6 through the ties 10 and the fourth disk 1 is installed on insert 9, which consists of six inverted "Type" B "segments (Fig. 3). The joints in this disk 1 between the segments are also offset relative to the joints of the third disk 1, while the perforation of the inner surface of the segments of the fourth disk 1 should coincide with the perforation of the segments of the third disk 1. The disks are stacked closely. Similarly, ten more disks 1 are stacked, forming a tier of the cover.

Then, on each screed 10, sleeve 6 is again put on and installed in the groove of the last disk 1, and insert 9 is put on the rack 7 and the intermediate steel disk 2 is installed close to the disk 1, the perforation profile of which must coincide with the segments. Similarly, six more tiers of the cover and five intermediate steel discs 2 are stacked.

The first and second tier of the cover are formed of fourteen disks 1 each, the third tier of the cover of twelve disks, the fourth, fifth, sixth tier of the cover of eleven disks each and the seventh tier consists of one disk.

Then, eighteen hexagonal pipes are installed in the hexagonal holes of the disks 1 and 2, at the bottom they abut the recesses of the support disk 4, and at the top they abut the recesses of the upper disk 5, which are installed with holes on the couplers 10 and fixed with nuts 11 with washers 12.

The claimed design of the cover allows for the safe transportation of spent nuclear fuel from nuclear reactors of the WWER-1000/1200 type.

Claims (2)

1. The cover of the transport packaging for spent fuel assemblies, comprising a base fixed to the base of the central pillar, perforated steel discs and perforated aluminum discs of varying thickness made from individual segments located on the pillar in height, while the perforation of steel and aluminum discs coincides in axial direction, as well as pipes installed through the perforation of the discs, characterized in that at least two are located between the steel perforated discs aluminum disks, the joints of the segments of each subsequent aluminum disk are offset relative to the joints of the segments of the previous aluminum disk, while the perforation of the segments of one disk is shifted by the angle of displacement of the joints of the segments of the other disk, thickenings are made along the outer perimeter of the disk segments, the disks are adjacent to each other with thickenings, the case is additionally equipped with screeds, holes are made along the outer perimeter of the disks, screeds are passed through the holes. 2. A case according to claim 1, characterized in that every third disk is laid upside down.

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