Calculation of the Effective Delayed Neutron Fraction by Deterministic and Monte Carlo Methods. (22nd August 2011)

• Record Type: Journal Article
• Authors: Carta, M.; Dulla, S.; Peluso, V.; Ravetto, P.; Bianchini, G.
• Other Names: Alvim Antonio Academic Editor.
• Is Part Of: Science and technology of nuclear installations. Volume 2011(2011)
• Publication Date: 2011-08-22
• Subjects: Nuclear engineering -- Periodicals; Nuclear facilities -- Periodicals; Nuclear engineering; Nuclear facilities; Electronic journals; Periodicals; 621.48
• DOI: 10.1155/2011/584256
• Languages: English
• ISSNs: 1687-6075

Abstract

Abstract : The studies on Accelerator-Driven Systems (ADSs) have renewed the interest in the theoretical and computational evaluation of the main integral parameters characterizing subcritical systems (e.g., reactivity, effective delayed neutron fractionβ e f f, and mean prompt neutron generation time). In particular, some kinetic parameters, as the effective delayed neutron fraction, are evaluated in Monte Carlo codes by formulations which do not require the calculation of the adjoint flux. This paper is focused on a theoretical and computational analysis about how the differentβ e f f definitions are connected and which are the approximations inherent to the Monte Carlo definition with respect to the standard definition involving weighted integrals. By means of a refined transport computational analysis carried out in a coherent and consistent way, that is, using the same deterministic code and neutron data library for theβ e f f evaluation in different ways, the theoretical analysis is numerically confirmed. Both theoretical and numerical results confirm the effectiveness of the Monte Carloβ e f f evaluation, at least in cases where spectral differences between total and prompt fluxes are negligible with respect to the value of the functionals entering the classicalβ e f f formulation.