Methodology, applications and performance of the CAD-based geometry type in the serpent 2 Monte Carlo code

Leppänen, Jaakko

doi:10.1016/j.anucene.2022.109259

Cited by 12 publications

(2 citation statements)

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“…Common errors in STL geometries are gaps between facets and degenerate facets, in which all three points are located on the same line. Serpent2 has features to tolerate these errors [15], but larger errors usually require fixing the STL model itself. In this work, simulations up to 1 × 10 −9 neutron histories were carried out without loss of neutrons using the converted STL meshes.…”

Section: Parametric Geometry Model and Simulation Toolmentioning

confidence: 99%

Proof-of-principle of parametric stellarator neutronics modeling using Serpent2

Lyytinen,

Snicker,

Virtanen

et al. 2024

Nucl. Fusion

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This contribution presents neutron transport studies for the 5-period HELIAS stellarator using the Serpent2 code. These studies utilize a parametric geometry model, enabling scans in neutronics modeling by varying the thickness of the reactor layers. For example, the tritium breeding ratio (TBR) can be determined by exploring various blanket material options and thicknesses to identify the threshold configuration that meets the TBR design criterion of 1.15. We found out that with the helium-cooled pebble ped (HCPB) candidate option, the TBR criterion is met with a breeding zone thickness of 26 cm, while with the dual-coolant lithium lead (DCLL) the threshold is exceeded at a thickness of 46 cm. Furthermore, the geometry includes non-planar field coils, allowing to study the fast neutron flux in these superconducting coils with a technological limit of 1e9 1/cm2s. It is shown that the neutron fast flux is not constant at the coils, necessitating a neutron transport simulation to determine the distribution of the fast-flux at the coils. We show that the peak flux can be more than a factor of 2 higher than the average flux, and that the peak flux location rotates helically.

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Section: Parametric Geometry Model and Simulation Toolmentioning

confidence: 99%

Proof-of-principle of parametric stellarator neutronics modeling using Serpent2

Lyytinen,

Snicker,

Virtanen

et al. 2024

Nucl. Fusion

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“…Fission reactors, on the other hand, are inherently simpler from a geometric standpoint-often with repeated arrays of fuel pins and assemblies-and thus can often be modeled using CSG without too much difficulty. However, there are many use cases for fission reactors whereby simulation on a CAD model would be advantageous, such as modeling research and test reactors (Shriwise et al, 2022), detailed or as-built experiments (Talamo et al, 2018), spent fuel installations (Leppänen, 2022), and advanced reactors. In all these cases, the ability to tie into an existing CAE workflow that starts with a CAD model can eliminate most of the redundant effort in constructing a model specifically for MC particle transport and simplify downstream analyses.…”

Section: Introductionmentioning

confidence: 99%

CAD and constructive solid geometry modeling of the Molten Salt Reactor Experiment with OpenMC

Yilmaz,

Romano,

Chierici

et al. 2024

Front. Nucl. Eng.

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In this study, we present a detailed comparison of two independently developed models of the Molten Salt Reactor Experiment (MSRE) for Monte Carlo particle transport simulations: the constructive solid geometry (CSG) model that was developed in support of the MSRE benchmark in the International Handbook of Evaluated Reactor Physics Benchmark Experiments, and a CAD model that was developed by Copenhagen Atomics. The original Serpent reference CSG model was first converted to OpenMC’s input format so that it could be systematically compared to the CAD model, which was already available as an OpenMC model, using the same Monte Carlo code. Results from simulations using the Serpent and OpenMC CSG models showed that keff agreed within 10 pcm while the flux distribution in space and energy generally agreed within 0.1%. Larger differences were observed between the OpenMC CAD and CSG models; notably, the keff computed for the CAD model was 1.00872, which is more than 1% lower than the value for the CSG model and much closer to experiment. Several areas of the reactor that were modeled differently in the CSG and CAD models were discussed and, in several cases, their impact on keff was quantified. Lastly, we compared the computational performance and memory usage between the CAD and CSG models. Simulation of the CSG model was found to be 1.4–2.3× faster than simulation of the CAD model based on the Embree ray tracer while using 4× less memory, highlighting the need for continued improvements in the CAD-based particle transport ecosystem. Finally, major performance degradation was observed for CAD-based simulations when using the MOAB ray tracer.

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