A neutronic evaluation of the (Pu–U) and (Am–Pu–U) insertion in a typical fuel of Angra-I

Abstract

The goal is to evaluate the neutronic behavior when (Pu–U) and (Am–Pu–U) mixed oxide are inserted in a typical cell of a Pressurized Water Reactor (PWR) such as Angra-I. Four types of fuels were studied: (1) MOX fuel enriched at 3.1% and V m/ V f = 1.15; (2) MOX fuel enriched at 4.5% and V m/ V f = 1.15; (3) MOX fuel enriched at 4.5% and V m/ V f = 2.0 and (4) MOX fuel enriched at 4.5%, with 1% of Americium insertion in its composition (62.8% of Am 241, 0.1% of Am 242m and 37.1% of Am 243) and with V m/ V f = 2.0. The first case represents the standard state of Angra I, but with Pu. The second case is similar to the first but the enrichment is increased. To evaluate the Americium insertion, a study of the V m/ V f was made and better results were obtained with V m/ V f = 2.0 and to compare, this case was too evaluated to (Pu–U) in the third and fourth cases. The idea is to verify the possibility of using these fuels in Angra-I analyzing neutronic parameters such as infinite multiplication factor, hardening spectrum, Boron worth and reactivity temperature coefficients. The results show that it is possible to use all the studied fuels in Angra-I as well as to burn Am inserted in the MOX fuel by a considerable quantity during PWR operation. The WIMS-D5 code was used to perform a simplified neutronic and burnup simulations to evaluate this possibility.