Patent Number: 
Section: claims

1. A module for forming a nuclear fuel assembly comprising:a casing extending in a longitudinal direction,a bundle of fuel rods encased in and supported by the casing anda connector provided on the casing for removably connecting the casing side-by-side to an other casing of at least one other module to obtain, when assembled, a nuclear fuel assembly having a channel box defined by the casing of the assembled module and the other casing of the at least one other module, the channel box being of a larger cross-section than that of the casing of each of the assembled modules and the other modules and a bundle of fuel rods of larger cross-section than that of each of the assembled modules and other modules, each module being movable as a single individual unit independent of the other modules. 2. The module according to claim 1 wherein the casing has a cross-section of polygonal shape with one bevelled corner for delimiting a space for a water channel between the casings of assembled modules. 3. The module according to claim 1 wherein the casing has a cross-section of a regular polygonal shape with the exception of one bevelled corner. 4. The module according to claim 2 wherein the bevelled corner is opened or is closed by a bevel wall of the casing. 5. The module according to claim 2 wherein the connector is provided on longitudinal edges of the casing edging the bevelled corner. 6. The module according to claim 2 wherein the connector comprises at least one sleeve aligned in the longitudinal direction with a missing edge of the polygonal cross-section of the casing. 7. The module according to claim 1 wherein the casing comprises at least one first side wall adapted to separate two sub-channels in the channel box defined by the casings of assembled modules. 8. The module according to claim 7 wherein each first side wall comprises at least one groove on an outer face of the first side wall. 9. The module according to claim 7 wherein each first side wall is adapted to define with first side walls of other modules assembled to the module a cross-shaped partition in the channel box defined by the casings of the assembled modules. 10. A nuclear fuel assembly comprising the module according to claim 1 assembled together side-by-side with the at least one other module. 11. The nuclear fuel assembly according to claim 10 comprising a water channel delimited by bevel walls of casings of the modules each closing a bevelled corner of a respective casing exhibiting a polygonal cross-section with the bevelled corner. 12. The nuclear fuel assembly according to claim 11 comprising the water channel delimited by a tube inserted in a spaced formed by the bevelled corners of the casings of the modules exhibiting a polygonal cross-section with the bevelled corner. 13. The nuclear fuel assembly according to claim 10 comprising a channel box defined by the casings of the assembled modules and a partition of cross-shaped cross-section dividing the channel box in sub-channels receiving a sub-bundle of fuel rods. 14. The nuclear fuel assembly according to claim 10 comprising an outer tubular housing having a section corresponding to that of the channel box defined by the modules assembled side-by-side. 15. The module as recited in claim 3 wherein the casing has a cross-section of the beveled corner and four other sides.