Pergamon Ann. Nucl. Energy, Vol. 24, No. 10, pp. 829 834, 1997 Copyright © 1997 Elsevier Science Ltd. All rights reserved PII:S0306-4549(96)0005 I-5 Printed in Great Britain 0306-4549/97 $17.00 + 0.00 TECHNICAL NOTE NEUTRONIC EVALUATION OF THE NON-PROLIFERATING REPROCESSED NUCLEAR FUELS IN PRESSURIZED WATER REACTORS STELA COTA and CLAUBIA PEREIRA Departamento de Engenharia Nuclear, Universidade Federal de Minas Gerais, Av. Contorno, 842/9° andar, Centro, 30110-060 Belo Horizonte, MG, Brasil (Received 26 April 1996) Abstract--Alternative reprocessing methods with low grade decontamination and uranium-plutonium coextraction characteristics are proposed for increas- ing proliferation resistance and permitting recovered fissile materials utiliza- tion in LWR reactors. This work brings out a preliminary neutronic study of fuels reprocessed by Coprocessing and AIROX techniques. © 1997 Elsevier Science Ltd. 1. INTRODUCTION Despite the agreement among experts that plutonium reaches its best neutronic perfor- mance in fast breeder reactors (FBR), it has been used in LWR reactors since the 1960s (Dievoet et al., 1990). Originally, the plutonium recycling in LWR was conceived as a way of increasing the amount of plutonium produced in commercial reactors, and recovered by the PUREX reprocessing method, until the FBRs could operate in large scale. Nowa- days, some European plants have accumulated 30 years of experience in LWR plutonium utilization. Besides the delay in FBR development, today other factors are contributing to increase the number of options of recycling. First, the minimization of the high level waste (HLW) in the nuclear fuel cycle has been considered the main way to reduce the envir- onmental impact of final fuel disposal. Moreover, the exhaustion of natural uranium resources, estimated to the next century (Wichers and Heijboer, 1993), has increased the need of optimizing fissile material use by taking advantage of fissile isotopes in irradiated fuels. Nevertheless, the closed fuel cycle has been related to risks of nuclear weapon prolif- eration, due to the high purity of the plutonium produced by the PUREX method. Because of this characteristic, in 1977, the U.S. government instituted a non-proliferation policy and made the option for direct disposal of its spent fuel. To bypass this problem, the alternative fuel concept was developed, based on low-decontamination reprocessing 829