摘要 |
A boiling water nuclear power reactor includes an improved control rod associated with each of its clusters of fuel assemblies. The control rod has an elongated central stem defining a longitudinally extending internal central gas plenum and a plurality of blades orthogonally arranged in pairs to provide a cruciform configuration in which the blades connect to and extend radially outward from the central stem. Each blade incorporates a series of internal cavities arranged in columns and rows across the length and width of the blade, and a neutron absorbing pellet is disposed in each cavity. The cavities communicate with the central plenum so that any gases generated by irradiation of the pellets can expand into the plenum. The cavities and pellets are arranged to form a longer, constant worth section in a body portion of each blade and a shorter, reduced worth section in an end tip portion of each blade. The end tip portion leads insertion of the blade body within the space between adjacent fuel assemblies when the control rod is moved into the fuel assemblies to control the reactive power thereof. |