Development of advanced neutronics design system of next generation, AEGIS

Very rigorous and advanced neutronics design system of next generation, AEGIS, which is based on the deterministic method, is being developed using advanced technology of computer science. The method of characteristics, which has a merit to treat the heterogeneous geometry explicitly, is utilized in AEGIS as a neutron transport solver. Therefore, AEGIS can explicitly model many types of fuel lattices in both commercial LWRs and advanced reactors such as Generation-IV reactors. AEGIS can also treat the higher order anisotropic scattering accurately based on the spherical harmonics expansion. The transport solution of AEGIS has been verified through various benchmark problems. It was found that AEGIS can explicitly treat the complicated geometry and efficiently perform the large-scale problem. The results considering the anisotropic scattering by AEGIS also agreed well with those by the reference solution and very excellent accuracy of AEGIS transport solver was shown in the 2-D C5G7 MOX benchmark problem. In order to calculate effective microscopic cross sections in the resonance energy region accurately, resonance calculation using ultrafine energy group structure was tried with coupling with neutron transport calculation by the method of characteristics. It was found that the effective microscopic cross sections by AEGIS agreed well with those by the continuous-energy Monte Carlo code, MVP. These results show that flexibility in geometry handling and very rigorous neutronics calculation models of AEGIS will contribute to predict the neutronics characteristics accurately for not only commercial LWRs but also advanced reactors. (authors)