Particle clustering in Monte Carlo criticality simulations

Dumonteil, Éric; Malvagi, Fausto; Zoia, Andrea; Mazzolo, Alain; Artusio, Davide; Dieudonné, Cyril; Mulatier, Clélia de

doi:10.1016/j.anucene.2013.09.008

Cited by 42 publications

(38 citation statements)

References 16 publications

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“…The full spatial-dependent behaviour of the neutron population in a nuclear reactor can be fully assessed only by resorting to numerical simulations including a realistic description of the heterogeneous geometry and of the compositions of the core components [29,31]. However, for the purposes of this work we will introduce a prototype model of a nuclear reactor that is simple enough in order for the relevant physical mechanisms to be singled out, and yet retains all the key ingredients of a real system.…”

Section: A Prototype Model Of Fission Chains In Nuclear Reactorsmentioning

confidence: 99%

“…Non-uniform neutron densities in the reactor fuel elements (which have been named 'neutron clustering') might lead to hot spots, and thus represent a most undesirable event with respect to the safe operation of nuclear power plants [29,30]. In view of the relevance of neutron clustering in the context of nuclear reactor physics, in this paper we will investigate the spatial and temporal behaviour of a collection of neutrons undergoing scattering (random displacements), fission (reproduction) and absorption (death).…”

Section: Introductionmentioning

confidence: 99%

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Neutron fluctuations: The importance of being delayed

et al. 2015

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The neutron population in a nuclear reactor is subject to fluctuations in time and in space due to the competition of diffusion by scattering, births by fission events, and deaths by absorptions. As such, fission chains provide a prototype model for the study of spatial clustering phenomena. In order for the reactor to be operated in stationary conditions at the critical point, the population of prompt neutrons instantaneously emitted at fission must be in equilibrium with the much smaller population of delayed neutrons, emitted after a Poissonian time by nuclear decay of the fissioned nuclei. In this work, we will show that the delayed neutrons, although representing a tiny fraction of the total number of neutrons in the reactor, have actually a key impact on the fluctuations, and their contribution is very effective in quenching the spatial clustering.

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Section: A Prototype Model Of Fission Chains In Nuclear Reactorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Neutron fluctuations: The importance of being delayed

et al. 2015

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“…The neutron flux solution no longer necessarily has the symmetry of the reactor core loading. For a detailed discussion of particle clustering please refer to Dumonteil et al (2014). Since the authors want to use Monte Carlo neutron transport to estimate the mean neutron flux obtainable with deterministic solutions, handling the tally asymmetry is crucial for large problems such as full PWR core even though it reflects a physical reality.…”

Section: Wielandt Shift Implementationmentioning

confidence: 99%

High-fidelity coupled Monte Carlo neutron transport and thermal-hydraulic simulations using Serpent 2/SUBCHANFLOW

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Sjenitzer

et al. 2015

Annals of Nuclear Energy

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“…is the per sequence mutation number. The stationary solution u k for large times of relations (7)(8)(9), which is a one term recurrence relation, is:…”

Section: Infinite Sequence Modelmentioning

confidence: 99%

“…It can be shown however [2][3][4][5]that diffusion is not enough to efficiently dilute the correlation creation at short distances for spatial dimensions d ≤ 3 and large system size extension. This phenomena is called neutral clustering (see [6] for a review); it has been demonstrated experimentally [7] and the main concept has been applied to other systems such as neutrons in nuclear reactors [8,9] and evolution of bimolecular networks [10].…”

Section: Introductionmentioning

confidence: 99%

Neutral aggregation in finite-length genotype space

Houchmandzadeh

2017

Phys. Rev. E

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The advent of modern genome sequencing techniques allows for a more stringent test of the neutrality hypothesis of Darwinian evolution, where all individuals have the same fitness. Using the individual based model of Wright and Fisher, we compute the amplitude of neutral aggregation in the genome space, i.e., the probability of finding two individuals at genetic (hamming) distance k as a function of genome size L, population size N and mutation probability per base ν. In well mixed populations, we show that for N ν < 1/L, neutral aggregation is the dominant force and most individuals are found at short genetic distances from each other. For N ν > 1 on the contrary, individuals are randomly dispersed in genome space. The results are extended to geographically dispersed population, where the controlling parameter is shown to be a combination of mutation and migration probability. The theory we develop can be used to test the neutrality hypothesis in various ecological and evolutionary systems.

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Particle clustering in Monte Carlo criticality simulations

Cited by 42 publications

References 16 publications

Neutron fluctuations: The importance of being delayed

Neutron fluctuations: The importance of being delayed

High-fidelity coupled Monte Carlo neutron transport and thermal-hydraulic simulations using Serpent 2/SUBCHANFLOW

Neutral aggregation in finite-length genotype space

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