Patent Number: 
Section: claims

1. A debris filter for a nuclear reactor installation, the debris filter being in the shape of a screen having a lower inlet face and an upper outlet face, the debris filter comprising:a plurality of plates arranged side-by-side in a spaced relationship and delimiting between them flow passages extending through the debris filter from the lower inlet face to the upper outlet face, each passage having an intermediate section offset with respect to an inlet section and an outlet section, each plate having a lower portion extending from the inlet face, an upper portion extending from the outlet face and a waved intermediate portion extending between the lower portion and the upper portion and delimiting an intermediate section with the intermediate portion of each adjacent plate, at least one of the plates being formed with debris catching features distributed along the lower portion of the plate and protruding into at least one passage delimited by the plate,each debris catching feature being delimited in the plate by at least one notch or slot formed in the plate,each debris catching feature extending downwardly from the plate and delimiting at least one upwardly tapering debris catching space. 2. The filter according to claim 1, wherein the debris catching features are arranged as pairs of adjacent debris catching features and each pair of adjacent debris catching features of the plate define a debris catching space tapering upwardly. 3. The filter according to claim 1, wherein the plate is formed with debris catching features provided as vanes, each vane being cut in the plate and bent or twisted. 4. The filter according to claim 3, wherein the vanes are cut in a lower edge of the plate. 5. The filter according to claim 3, wherein the vanes are adjacent and twisted in the same direction. 6. The filter according to claim 3, wherein the vanes include vanes bent in one direction or twisted in one direction alternating with vanes bent in the opposite direction, respectively twisted in the opposite direction. 7. The filter according to claim 1, wherein the plate is formed with debris catching features provided as teeth cut in the plate, each tooth protruding obliquely inside a passage delimited by the plate and downwardly. 8. The filter according to claim 7 wherein the plates include teeth protruding from one face of the plate that alternate with teeth protruding the opposite face of the plate. 9. The filter according to claim 1 further comprising connection strips intersecting the plates for maintaining the spacing between the plates. 10. The filter according to claim 9, wherein each plate comprises connection slots extending from the upper edge of the plate, each slot receiving a corresponding one of the connection strips intersecting the plate. 11. The filter according to claim 9, wherein each connection strip is formed with spacing means for maintaining spacing between the upper portions of said plates. 12. The filter according to claim 9, wherein each connection strip is formed with spacing tabs cut in the upper edge of the connection strip, each spacing tab being twisted. 13. The filter according to claim 9, wherein the lower edge of each connection strip is formed with interlocking slits, each for engaging the lower closed end of a slot of the plate in which the connection strip is received. 14. A nuclear fuel assembly comprising:a bundle of fuel rods; anda debris filter according to claim 1. 15. The filter according to claim 9, wherein each connection strip includes guide dimples provided on the intersecting strips for maintaining the spacing between the plates. 16. The filter according to claim 1, wherein the plate comprises a plurality debris catching features provided as vanes cut in a lower edge of the plate and separated by the notches defining the debris catching spaces. 17. The filter according to claim 16, wherein each notch exhibits a V-shape converging upwardly. 18. The filter according to claim 16, wherein at least one of the vanes protrudes on both faces of the plate, the at least one vane having one edge protruding from one of the faces of the plate and another edge protruding from the other of the faces of the plate. 19. The filter according to claim 16, wherein at least one of the vanes protrudes on one face of the plate, both edges of the at least one vane protruding from the same face of the plate. 20. The filter according to claim 16, wherein adjacent side edges of vanes of a pair of adjacent vanes separated by a notch protrude from a same face of the plate. 21. The filter according to claim 7, wherein each tooth defines an upwardly tapering debris catching space with the lower portion of the plate. 22. A debris filter for a nuclear reactor installation, the debris filter being in the shape of a screen having a lower inlet face and an upper outlet face, the debris filter comprising:a plurality of plates arranged side-by-side in a spaced relationship and delimiting between them flow passages extending through the debris filter from the lower inlet face to the upper outlet face, each passage having an intermediate section offset with respect to an inlet section and an outlet section, each plate having a lower portion extending from the inlet face, an upper portion extending from the outlet face and a waved intermediate portion extending between the lower portion and the upper portion and delimiting an intermediate section with the intermediate portion of each adjacent plate, at least one of the plates being formed with debris catching features distributed along the lower portion of the plate and protruding into at least one passage delimited by the plate,the debris catching features being provided as vanes cut in a lower edge of the plate and separated by notches,the vanes extending downwardly with being twisted such that edges of the vanes protrude on opposed faces of the plate, the vanes each having one of the edges protruding from one of the faces of the plate and another of the edges protruding from the other of the faces of the plate, or bent to protrude on one of the faces of the plate, both edges of the respective vane protruding from the same face of the plate,one of the edges of each vane delimiting with an adjacent one of the edges of an adjacent one of the vanes a debris catching space tapering upwardly. 23. A debris filter for a nuclear reactor installation, the debris filter being in the shape of a screen having a lower inlet face and an upper outlet face, the debris filter comprising:a plurality of plates arranged side-by-side in a spaced relationship and delimiting between them flow passages extending through the debris filter from the lower inlet face to the upper outlet face, each passage having an intermediate section offset with respect to an inlet section and an outlet section, each plate having a lower portion extending from the inlet face, an upper portion extending from the outlet face and a waved intermediate portion extending between the lower portion and the upper portion and delimiting an intermediate section with the intermediate portion of each adjacent plate, at least one of the plates being formed with debris catching features distributed along the lower portion of the plate and protruding into at least one passage delimited by the plate,the plate being formed with the debris catching features provided as teeth cut in the plate, each tooth protruding obliquely inside a passage delimited by the plate and downwardly,each tooth defining an upwardly tapering debris catching space with the lower portion of the plate.