Development and verification of three-dimensional Hex-Z burnup sensitivity solver based on generalized perturbation theory

A burnup sensitivity analysis solver based on generalized perturbation theory has been developed in a multi-purpose analysis framework MARBLE. The new solver has capability to calculate sensitivity coefficients of transmuted nuclear fuel composition after burnup, i.e. atomic number density, with respect to nuclear data. Based on the diffusion theory, the new solver calculates the burnup sensitivity coefficients not only in 2-dimensional R-Z model but also in 3-dimensional Hexagonal-Z model, that is not supported in a existing code system in JAEA. The new solver has been verified by comparing with results of so-called direct calculation. According to the generalized perturbation theory, it is possible to calculate a breakdown of the burnup sensitivity coefficient by using five terms which appear in the formulation. In the present paper, a new numerical verification method named component-wise direct calculation is proposed to check the results of each term. A numerical experiment of the new verification method was performed, and it shows that the new verification method is valid. In addition, a sample application result is shown in order to evaluate calculation model effects due to difference between 2- and 3-dimensional models. The sample application result suggests that 3-dimensional calculation model is necessary for some heterogeneous core configuration. (author)