Neutron transport in anisotropic random media

Alessandro Marinosci (1, 2) , Coline Larmier (1) , Andrea Zoia (1)

1 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
2 Polito - Politecnico di Torino = Polytechnic of Turin

Assessing the impact of random media for eigenvalue problems plays a centralrole in nuclear reactor physics and criticality safety. In a recent work (Larmieret al., 2018a), we have applied a probabilistic model based on stochastic tessellationsin order to describe fuel degradation following severe accidents withpartial melting and re-arrangement of the resulting debris. The distribution ofthe multiplication factor and of the kinetics parameters as a function of the mixingstatistics model and of the typical correlation length of the tessellation wereexamined in detail for a benchmark configuration consisting in a fuel assemblywith UOX or MOX fuel pins. In this paper, we extend our previous findingsby including in the stochastic tessellation model the effects of anisotropy thatmight result from gravity and material stratification for this purpose, we adoptthe broad class of anisotropic Poisson geometries. We examine the evolution ofthe statistical properties of the tessellations, including the volume, surface andchord length of the cells for various anisotropy laws, and compare them to thecase of isotropic Poisson geometries. Then, we discuss the behaviour of the keyobservables of interest for eigenvalue problems in anisotropic tessellations byrevisiting the fuel assembly benchmark calculations proposed in (Larmier et al.,2018a). The effects of anisotropic random media on the multiplication factor andon the kinetics parameters will be carefully examined.

Keywords: Monte Carlo; tessellations; eigenvalues; Poisson; Markov; anisotropic; Random media; Markov tessellations; Anisotropy; TRIPOLI-4$^R$; Kinetics parameters * Corresponding author

Domains: Physics [physics]; Nuclear Experiment [nucl-ex]; Physics [physics]; Nuclear Theory [nucl-th]

Alessandro Marinosci, Coline Larmier, Andrea Zoia. Neutron transport in anisotropic random media. Annals of Nuclear Energy, 2018, 118, pp.406-413. ⟨10.1016/j.anucene.2018.04.031⟩. ⟨cea-02339792⟩