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The focus of this work is to analyse the suitability of two-group diffusion coefficients and macro constants generated from SERPENT using out-scattering approximation (OSA), transport correction (TRC) and cumulative migration methods (CMM) for fuel and non-fuel materials. For this purpose, various assembly and core models of ACP-100 SMR were designed. Assessment of these constants was conducted using COMSOL Multiphysics. For six distinct fuels, the best models were proposed with the least error margin in k eff . Fuel material affects the group constants of non-fuel components except for radial reflectors. The sufficiency of two-group calculation was justified through spectrum analysis. Additional analysis revealed that MOX-RG has the hardest spectrum among all the fuels. Moreover, the effectiveness of boric acid to control excess reactivity was observed. Subcriticality was achieved for all fuel types except MOX-RG at a boric acid concentration of 4500 ppm. The influence of variation of boric acid concentrations on group constants was investigated using TRC and OSA. The reactivity difference between SERPENT and COMSOL was determined. It was found that OSA generates the most accurate results for MOX-RG with maximum 863 pcm error, while TRC produces higher accuracy with maximum error of approximately 250 pcm for other fuels.

Host heterogeneity can be modeled by using multi-group structures in the population. In this paper we investigate the existence and nonexistence of traveling waves of a two-group SIR epidemic model with time delay and constant recruitment and show that the existence of traveling waves is determined by the basic reproduction number \\[R_0.\\] More specifically, we prove that (i) when the basic reproduction number \\[R_0>1,\\] there exists a minimal wave speed \\[c^*>0,\\] such that for each \\[c c^*\\] the system admits a nontrivial traveling wave solution with wave speed c and for \\[c

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