Multi-objective optimization of a compact pressurized water nuclear reactor computational model for biological shielding design using innovative materials M. A. Tunes a , C. R. E. de Oliveira b , C. G. Sch¨ on a,* a Department of Metallurgical and Materials Engineering, Escola Polit´ ecnica da Universidade de S˜ ao Paulo, Av. Prof. Mello Moraes, 2463 – CEP 05508 – 030 S˜ao Paulo, Brazil. b Department of Nuclear Engineering, The University of New Mexico, Farris Engineering Center, 221, Albuquerque-NM, USA - 87131-1070. Abstract The aim of the present work is to develop a computational model of a compact pressurized water nuclear reactor (PWR) to investigate the use of innovative materials to enhance the biological shielding effectiveness. Two radiation transport codes were used: the first one – MCNP – for the PWR design and the GEM/EVENT to simulate (in a 1D slab) the behavior of several mate- rials and shielding thickness on gamma and neutron radiation. Additionally MATLAB Optimization Toolbox was used to provide new geometric config- urations of the slab aiming at reducing the volume and weight of the walls by means of a cost/objective function. It is demonstrated in the reactor model that the dose rate outside biological shielding has been reduced by one order of magnitude for the optimized model compared with the initial configura- tion. Volume and weight of the shielding walls were also reduced. The results * Corresponding author: Tel. +55-11-3091-5726 Fax: +55-11-3091-5243. Email addresses: matheus.tunes@usp.br (M. A. Tunes), cassiano@unm.edu (C. R. E. de Oliveira), schoen@usp.br (C. G. Sch¨ on) Preprint submitted to Nuclear Engineering and Design November 23, 2016