Prompt alpha eigenvalue calculations with TRIPOLI-4

CEA/Saclay, DEN/DM2S/SERMA, 91191 Gif-sur-Yvette Cedex, France

Abstract

Monte Carlo criticality analyses aimed at determining reactor parameters have been historically based on iterative algorithms whose outcome is the effective multiplication coefficient (k_eff), i.e., the fundamental eigenvalue of the transport equation. Less attention has been comparatively paid to Monte Carlo algorithms for the estimation of the so-called (prompt) α eigenvalues, which provide information about the (prompt) time evolution of the system. In recent years, this issue has witnessed a renewed interest, mostly due to increased computer power, allowing for reliable and stable search strategies for assessing the fundamental α eigenvalue. In this work, we revisit the theory behind α eigenvalues and propose a Monte Carlo iterative algorithm for the development version of Tripoli-4. In order toillustrate the algorithm, some significant examples are finally discussed.