摘要 |
<p>A spectral shift pressurized water reactor comprising apparatus (38) for inserting and withdrawing water displacer elements (40, 82) having differing neutron absorbing capabilities for selectively changing the watermoderator volume in the core (34) thereby changing the reactivity of the core. The displacer elements (40, 82) comprise substantially hollow cylindrical low neutron absorbing rods (40) and substantially hollow cylindrical- thick walled stainless rods (82). Since the stainless steel displacer rods have greater neutron absorbing capability, they can effect greater reactivity change per rod. However, by arranging fewer stainless steel displacer rods (82) in a cluster, the reactivity worth of the stainless steel displacer rod cluster can be less than a low neutron absorbing displacer rod cluster.</p> |