| 摘要 |
A fuel assembly for a boiling water reactor has at least one fuel rod which has a lower column (6) of fuel pellets with a relatively larger diameter and an upper column of fuel pellets (7) with a relatively smaller diameter, and a cladding tube (5) with a lower coarser part (5a) which surrounds the lower column of fuel pellets, an upper narrower part (5b) which surrounds the upper column of fuel pellets, and a transition portion (13) between the lower and upper parts. A spacing member (12), which is movable in the longitudinal direction of the tube, is arranged between the lower and upper columns. The upper end of the spacing member is arranged above or in the transition portion and the lower end of the spacing member is arranged below and at a distance from the transition portion. A spring (11) arranged in the upper end of the fuel rod exerts a compressive force on the upper column and, via the spacing member, on the lower column. |
