| 摘要 |
1. Nuclear reactor comprising : a core consisting of fuel assemblies located side-by-side and cooled by an upward flow of a cooling fluid ; clusters for controlling the nuclear reactor each formed of a plurality of absorbing rods (8) vertically movable and connected together by a spider having radially directed arms to a common axial drive shaft, the rods having such a distribution that some of them are located as pairs of two rods radially aligned with respect to the axis of the cluster ; and devices for guiding the control clusters during their movements above the core, each having a guide casing within which horizontal plates achieve discontinuous guiding of the absorbing rods of the control cluster in the upper part of the casing (11), characterized in that, in the lower portion of each casing (11), those absorbing rods (8) which are arranged in pairs are mechanically guided on their periphery by the horizontal plates (14) only and in that each pair is surrounded by an envelope (22) each connecting two plates, defining a cooling fluid steadying space around said absorbing rods and decreasing the hydraulic actions onto the rods. |
