| 摘要 |
<p>915,190. Reactors. BABCOCK & WILCOX CO. March 9, 1960 [March 9, 1959], No. 8396/60. Drawings to Specification. Class 39 (4). In a nuclear reactor, the fall in reactivity due to burn-out and poisoning is compensated by means of movable control rods; after a given change in reactivity, a number of fixed control rods are removed from the core, subsequent adjustment again being effected by the movable rods. To maintain the distribution of coolant throughout the core, the positions left empty by the removal of the fixed rods are re-filled by flow control rods of low neutron absorption crosssection. Flux depressor plates of neutron absorbent material are placed at the circumference of the core to reduce the reactivity and temperature gradient there. The fuel is arranged in three concentric zones, which have different fissile to fertile material weight ratios, thereby to flatten the neutron flux gradient across the core. The control rods may be of hafnium, cadmium or boron-steel, and the flow rods of zircaloy 2. Upward displacement of the core by coolant flow is prevented by members round the core circumference. Specification 913,653 is referred to.</p> |
