Neutronic analysis of a gaseous control system for the HTR-10 reactor

Highlights: ► Implementation of gaseous control system in HTR-10 reactor. ► Modeling of the reactor core and gaseous control system. ► Investigation of the B10 enrichment percentage effect on reactivity worth and differential reactivity. ► Comparative study of the solid rod and gaseous control systems in terms of total and differential reactivity. ► Comparative study of the solid rod and gaseous control systems in terms of axial thermal neutron distribution. - Abstract: Solid rod control systems are based on the movement of the rod inside the reactor core. Thus they require an electromechanical system in order to operate. The systems dependence on such a system could decrease its reliability. As shown by our calculations, these systems have very high differential reactivity and therefore require very precise electromechanical systems. The up and down moving rods will also deform and sharpen the peak of the already non-uniform axial neutron flux distribution inside the core. As is shown in this paper, by means of comparison of flux distribution and total and differential reactivity, the proposed gaseous control system perform better in these areas.