(The) reactivity worth of control rods in PWR

Abstract

In nuclear reactors, control rods are very important in controlling core reactivity. Thus, in this paper, it is proposed for an analytic method to calculate the control rod worth in a cylindrical geometry with control rods formed by two rings. For multi-ring problems, existing methods assume that irregular solutions due to the control rod are not depend on angle over the control rod. But this method gives an exact solution because the angular dependency over the control rod is not neglected. And more natural boundary condition for a control rod is used. This method gives n x n matrix equation. As n approaches to infinite, an exact solution can be obtained. But this is impossible, so we restricted numerical results up to first order. In order to obtain the numerical results, a Fortran program is developed. The mumerical results for the Zeroth and First Order Approximations will be shown. Finally, the control rod worth for the control banks of Kori Unit 5 will be obtained and discussed.