Reactivity worth of control rods in the beryllium oxide moderated pebble bed reactor

Abstract

Preliminary and final studies are reported for the worth of tubular control rods in a beryllium oxide moderated pebble bed reactor system. In the preliminary study the consideration of ball flow forces the investigation of a number of control rod arrangements. In addition, a range of rod sizes is considered. In the final study a particular rod size and pattern is chosen for more detailed investigation. For the intermediate reactor cores under consideration the control rods must absorb appreciably in the KeV region. A feature of the final study is the accurate way the epithermal absorption can be taken into account while using a three group model in the reflected reactor. The preliminary study is not so accurate but is useful for comparative purposes.