Discussion of options to increase the control drum worth in fast reactor

Abstract The control drum is usually placed in the periphery of the active zone of the reactor core, and the control drum worth is generally small. This paper discusses different schemes to improve the control drum worth by the combination of neutron reflectors and absorbers, and the design optimization of the drums under the condition that external dimensions of the drums and positions of the drums relative to the core are fixed. The results show that BeO as the reflector, B4C and Gadolinium as the neutron absorber can obtain relatively higher drum worth. In addition, the control drum worth can also be appropriately improved by using a double-layer combination of moderator material and neutron absorber material, but it cannot be effectively improved by enlarging the central angle of the neutron absorber sector.