Patent Number: 044977700
Section: description

DESCRIPTION OF PREFERRED EMBODIMENT The support structure 1 is formed by a plurality of tubes 2 which may be square or rectangular in cross-section. Tubes 2 may be used to receive the nuclear waste. As an alternative, tubes 2 may be subdivided into several chambers 3 for receiving nuclear waste. The cross-section of these chambers depends upon the size of the radioactive material intended to be stored therein. Each storage tube 2 is closed at its lower end by a plate 4. Plates 4 are perforated as indicated at 5 to admit a cooling medium, such as water, to the fuel elements in tubes 2, or chambers 3, respectively. A plurality of bolts 6 is affixed to each tube 2 below plate 4. The number of bolts 6 should be at least three, and is preferably four, as shown in FIGS. 1 and 2. The longitudinal axes of bolts 6 intersect at a common point. To obtain as large a resistance as possible against tripping or tilting forces which may occur when storage tubes 2 are subjected to horizontal forces, bolts 6 are arranged in diagonal directions of storage tubes 2 near the edges of the latter. As shown in FIGS. 1 and 2, four support plates 7 are provided for supporting one storage tube 2, i.e. one plate 7 at each corner of one square or rectangular tube 2. Each of bolts 6 cooperates with one of support plates 7. Support plates 7 have upstanding portions 8. To be more specific, each supporting plate 7 has four upstanding portions 8 so that the entire structure 7,8 has the shape of a box having four side walls and being open at the top. Each upstanding portion 8--comparable to the side wall of a box open at the top thereof--is provided with a recess 9. Recesses 9 are open at the top and closed at the bottom thereof. The top ends, or open ends, of recesses 9 are slanting in opposite directions. Referring to FIG. 2, the open ends of recess 9 are both slanting, the left edge 10 bounding recess 9 slanting downwardly from left to right and the right edge 11 bounding recess 9 slanting downwardly from right to left. The surfaces 10,11 form guides for pins 6. Recess 9 has lower substantially circular bolt-bearing surfaces of which each is coaxially arranged to one of bolts 6. The diameter of these bolt-bearing surfaces is substantially equal to the diameter of bolts 6 to allow an easy engagement of bolt 6 with said bolt-bearing surfaces and at the same time allow a support of bolts 6 without play, or with a minimum of play. When assembling the structure shown in FIGS. 1 and 2, a crane lowers each storage tube 2 into position. Each bolt 6 engages one of recesses 9 and is guided by slanting surfaces 10,11 toward the closed ends of recesses 9 which are adapted to ultimately receive and support bolts 6. The upstanding portions 8 of base plates 7 have a nose-like projection 12 that projects at least to the vertical median plane of the bolt 6 which is lowered into the particular recess 9. These nose-like projections lock bolts 6 in position against the action of upward directed forces. The lateral or upstanding walls 8 are not necessarily planar as clearly shown in FIG. 1 of the drawings. When a tube is lowered into the position shown in FIG. 1, its weight is initially supported by surfaces 10,11, and thereafter the bolts 6 engage the circular or cylindrical portion of recesses 9. During this process of insertion of storage tubes 2 into recesses 9 the former are caused to perform a slight rotary motion that ends when bolts 6 are fixedly supported by walls 8. As shown in FIGS. 1 and 2, the four upstanding portions 8 of each base plate 7 each support one pin 6 forming part of, or affixed to, a different tube 2. All vertical forces resulting from the weight of tubes 2 and that of their content, as well as all horizontal impact forces are transmitted by way of bolts 6 to base plates 7. As shown in FIGS. 1 and 2, each storage tube 2 is held in position by four bolts each engaging one of four base plates 7, and each base plate 7 is adapted to lock in position four storage tubes 2. In FIGS. 3 and 4 the same reference numerals as in FIGS. 1 and 2 have been applied to indicate like parts. Thus FIGS. 3 and 4 require a description only to the extent that the structure shown therein differs from that shown in FIGS. 1 and 2. FIGS. 3 and 4 show one single storage tube 2 for receiving nuclear material. It may be subdivided into a plurality of compartments 3. The tubular member 2 is provided near the bottom thereof with a plurality of horizontal bolts or, to be more specific, four horizontal bolts. Their longitudinal axes intersect at one point designated by the reference letter M. Tubular storage member 2 is supported by a first circular plate 13 having a plurality of upstanding portions 8 which are angularly displaced, e.g. 90 deg. Each upstanding portion 8 of plate 13 supports one of bolts 6. Each upstanding portion 8 is provided at the upper edge thereof with an open recess 9 for the insertion of bolts 6. The details of this recess 9 are the same as shown in FIGS. 1 and 2. They include a relatively wide slanting entrance defined by surfaces or planes 10, 11 for inserting one of said plurality of bolts 6. Recesses 9 further include a substantially circular relatively narrow bottom portion coaxial with one of said plurality of bolts 6. The first circular plate 13 and a second circular plate 4 are arranged parallel to each other. The latter is perforated to allow admission of a cooling medium to the chambers inside of storage tube 2. A spacer to which reference numeral 14 has been applied spaces plates 4 and 13. The structure shown in FIGS. 1 to 4 is not limited to store fuel elements of a nuclear reactor. It may be used to store fuel elements which are still too highly radioactive and require an additional storage time before they can be shipped to a processing plant. The structure of FIGS. 1-4 may also be used for storing new radioactive fuel elements before they are used in a nuclear plant.