Study on double heterogeneity effect of Pu-rich agglomerates in mixed oxide fuel using cross section homogenization method for particle-dispersed media

Yamamoto, Toshihiro

doi:10.1016/j.anucene.2009.11.016

Cited by 11 publications

(8 citation statements)

References 11 publications

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“…Neutron multiplication in stochastic media has attracted intense research efforts, in view of many relevant applications emerging in reactor physics and criticality safety, such as the design of prismatic and pebble-bed reactors with double heterogeneity fuel (Murata et al, 1996;Liang et al, 2013;Brown and Martin, 2004), the analysis of neutron absorbers with dispersed poison grains (Doub, 1961) or MOX fuels with Pu-rich agglomerates (Yamamoto, 2010), optimal radioactive waste storage (Williams, 2003), and the assessment of the safety margins due to the multiplication factor distribution (Pomraning, 1999;Williams, 2000;Williams and Larsen, 2001), only to name a few.…”

Section: Introductionmentioning

confidence: 99%

Neutron multiplication in random media: Reactivity and kinetics parameters

Larmier

Zoia

Malvagi

et al. 2018

Annals of Nuclear Energy

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Eigenvalue problems for neutron transport in random geometries are key for many applications, ranging from reactor design to criticality safety. In this work we examine the behaviour of the reactivity and of the kinetics parameters (the effective delayed neutron fraction and the effective neutron generation time) for three-dimensional UOX and MOX assembly configurations where a portion of the fuel pins has been randomly fragmented by using various mixing statistics. For this purpose, we have selected stochastic tessellations of the Poisson, Voronoi and Box type, which provide convenient models for the random partitioning of space, and we have generated an ensemble of assembly realizations; for each geometry realization, criticality calculations have been performed by using the Monte Carlo code TRIPOLI-4 R , developed at CEA. We have then examined the evolution of the ensemble-averaged observables of interest as a function of the average chord length of the random geometries, which is roughly proportional to the correlation length of the fuel fragmentation. The methodology proposed in this work is fairly general and could be applied, e.g., to the assessment of re-criticality probability following severe accidents.

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Section: Introductionmentioning

confidence: 99%

Neutron multiplication in random media: Reactivity and kinetics parameters

Larmier

Zoia

Malvagi

et al. 2018

Annals of Nuclear Energy

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“…For more details, see the references [1][2][3][4]. Suppose that spherical particles with the diameter of D are dispersed uniformly in a slab with the thickness of L (>D).…”

Section: Theory Of the Sld Methodsmentioning

confidence: 99%

“…Suppose that spherical particles with the diameter of D are dispersed uniformly in a slab with the thickness of L (>D). The effective homogenized macroscopic total cross section of the particle-dispersed slab is given by [1][2][3][4] [ ]…”

Section: Theory Of the Sld Methodsmentioning

confidence: 99%

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Heterogeneity effect on neutron shielding in borated concrete and Monte Carlo-based cross section homogenization method for particle dispersed media

Yamamoto

2014

Progress in Nuclear Science and Technology

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A Monte Carlo-based radiation transport calculation method to treat media containing randomly and uniformly dispersed spherical particles was developed by Shmakov et al. The method (hereinafter referred to as "SLD method") formulates effective homogenized cross sections for particle dispersed media. This paper discusses the applicability of the SLD method to neutron shielding in an ordinary concrete and a low-activation concrete containing small B 4 C particles. If the absorber particles are not small enough, the heterogeneity effect needs to be treated for accurate dose or activation estimations. The direct heterogeneous representation of the small particles requires long computing time. The use of the SLD method could considerably reduce the computational burdens without reducing its accuracy. The heterogeneity effect on neutron shielding is significant below 10 eV. The homogeneous calculation underestimates the neutron absorption rate of 23 Na by 11 % in the ordinary concrete and of 151Eu by 14% in the low-activation concrete containing 14-μm-diameter B 4 C particles. MCNP 4C calculations with the SLD method agree very well with the direct heterogeneous calculations. The SLD method improves the figure of merit by a factor of 100 with respect to the direct heterogeneous calculation.

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“…Linear particle transport through random media is key to several applications in nuclear science (1), such as pebble-bed reactors (2), fluid-vapour mixtures in boiling water reactors (3), radiation shielding by concrete structures (4), hydrodynamical instabilities in fusion pellets (5; 6; 7), the assessment of recriticality probability following core degradation (8; 9) and the impact of irregular aggregates in neutron absorbers (10) and MOX fuels (11). Moreover, random media concern also light propagation through turbid materials (12; 14; 15) and tracer diffusion in biological tissues (16).…”

Section: Introductionmentioning

confidence: 99%

Chord length distribution in d-dimensional anisotropic Markov media

Larmier

Marinosci

Zoia

2019

Journal of Quantitative Spectroscopy and Radiative Transfer

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Markov media are often used as a prototype model in the analysis of linear particle transport in disordered materials. For this class of stochastic geometries, it is assumed that the chord lengths must follow an exponential distribution, with a direction-dependent average if anisotropy effects are to be taken into account. The practical realizability of Markov media in arbitrary dimension has been a long-standing open question. In this work we show that Poisson hyperplane tessellations provide an explicit construction for random media satisfying the Markov property and easily including anisotropy. The average chord length can be computed explicitly and is be shown to be intimately related to the statistical properties of the tessellation cells and in particular to their surface-to-volume ratio. A computer code that is able to generate anisotropic Poisson tessellations in arbitrary dimension restricted to a given finite domain is developed, and the convergence to exact asymptotic formulas for the chord length distribution and the polyhedral features of the tessellation cells is established by extensive Monte Carlo simulations in the limit of domains having an infinite size.

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Study on double heterogeneity effect of Pu-rich agglomerates in mixed oxide fuel using cross section homogenization method for particle-dispersed media

Cited by 11 publications

References 11 publications

Neutron multiplication in random media: Reactivity and kinetics parameters

Neutron multiplication in random media: Reactivity and kinetics parameters

Heterogeneity effect on neutron shielding in borated concrete and Monte Carlo-based cross section homogenization method for particle dispersed media

Chord length distribution in d-dimensional anisotropic Markov media

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