Applications of the Upper Bound Estimation Method in Reactor Theory

The upper bound estimation method is applied for estimating perturbations in reactor theory calculations. The results of this method are numerically compared with the regular first-order perturbation theory. It is concluded from the comparison that first-order perturbation in the integral formalism gives the best estimate for the changes in eigen-values. For those cases in which first-order perturbation yields low estimates, it is possible to obtain lower and upper bounds by applying both methods. A discussion of the possibility of obtaining a rough estimation to a perturbation without knowing the unperturbed regular and adjoint fluxes is presented and demonstrated with a numerical example.