Patent Number: 
Section: claims

1. A fuel assembly for a boiling water reactor, comprising:inner webs disposed in a crosswise fashion;outer webs each having an inner side and surrounding said inner webs in a form of a frame, said inner webs and said outer webs together defining and forming a number of spacers having cells for receiving fuel rods, each of said spacers containing at least one guide device disposed in a respective outer web, said guide device having a flow opening formed therein and a guide element, said guide element as viewed in a flow direction of a coolant, being disposed upstream of said flow opening, and projecting from said inner side of said respective outer web, said guide element constricting a flow channel formed by a surface of a respective fuel rod and said inner and outer webs surrounding the respective fuel rod; andinwardly projecting clamping springs each for cooperating with a respective one of the fuel rods and attached to said outer webs;said guide device disposed laterally offset from a respective inwardly projecting clamping spring at a region of said respective outer web extending between said respective inwardly projecting clamping spring and a respective inner web, said guide device disposed completely in said region. 2. The spacer according to claim 1, wherein said guide element is a flow vane integrally formed on said respective outer web and forms an acute angle α, opening in the flow direction, with a flat plane of said respective outer web. 3. The spacer according to claim 2, wherein:said flow opening has a lower edge; andsaid flow vane is a wall region of said respective outer web, said wall region having two cutouts formed therein defining said flow vane, said two cutouts extending from said lower edge opening into said outer web in an upstream direction, said two cutouts laterally delimiting said flow vane. 4. The spacer according to claim 2, wherein said flow vane is formed by a deep-drawn wall region of said respective outer web that adjoins a lower edge of said flow opening. 5. The spacer according to claim 1, wherein each of said cells adjoining one of said outer webs is assigned at least one said guide device. 6. The spacer according to claim 1, wherein said flow opening has a greater width than said guide element. 7. The spacer according to claim 1, wherein said flow opening is formed as an elongated hole and disposed obliquely to the flow direction. 8. The spacer according to claim 7, wherein said flow opening is one of two adjacently disposed flow openings that are positioned obliquely in opposite senses and enclose an acute angle β opening against the flow direction. 9. The spacer according to claim 8, wherein said two flow openings are assigned to neighboring ones of said cells. 10. The spacer according to claim 1, wherein an upper edge of said flow opening and a wall region of said respective outer web subsequent thereto in the flow direction are cambered convexly outward.