FAST-NEUTRON SHIELDLNG AND NEUTRON-TRANSPORT STUDIES AT YAYOI

The fast neutron shielding experiments at the fast neutron source reac tor YAYOI of the University of Tokyo were summarized. The experiments were grouped into the following four types; (1) experiments for shield design of fast breeder reactor, (2) fast neutron transmission experim ents, (3) fast neutron streaming experiments, (4) neutron skyshine exp eriment. The experimental data are useful for shield design and assess ing the accuracy of the calculational methods. The accuracy of numeric al solution of the neutron transport equation by die discrete ordinate s method were analysed. The effect of the uncertainty of the neutron c ross sections and approximations in the computational method on the er rors were assessed. The errors of multigroup approximation was dominan t in the iron shield calculation. (C) 1997 Elsevier Science Ltd.