The Physical Models and Statistical Procedures Used in the RACER Monte Carlo Code

Sutton, Thomas M.; Brown, Forrest B.; Bischoff, Francisco; MacMillan, D. B.; Ellis, C.L.; Ward, J.T.; Ballinger, C.T.; Kelly, Daniel J.; Schindler, L.

doi:10.2172/767449

Cited by 8 publications

(6 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The energy hash table methods also provide simple means of speeding up simulations that can be relatively cheap from a memory perspective. However, as the speedup with respect to the global unionized 10 Speedup values are relative to the same optimization schemes run in serial. 11 Speedup values are relative to the single-nuclide energy grid binary search run with 8 threads.…”

Section: Discussionmentioning

confidence: 99%

“…The unionized energy grid treatment [9] is one method which has been shown to significantly cut down simulation runtime relative to the individual nuclide energy grid method just described. This algorithm, which can be traced at least as far back as its implementation in RACER [10] and RCP01 [11] and was recently reintroduced in the Serpent code [12], calls for the construction of a grid containing the union of all of the energy points from the individual grids of every nuclide in the problem. Then, the individual reaction cross sections for each nuclide are stored on this same grid.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Optimizations of the energy grid search algorithm in continuous-energy Monte Carlo particle transport codes

Walsh

Romano

Forget

et al. 2015

Computer Physics Communications

View full text Add to dashboard Cite

In this work we propose, implement, and test various optimizations of the typical energy grid-cross section pair lookup algorithm in Monte Carlo particle transport codes. The key feature common to all of the optimizations is a reduction in the length of the vector of energies that must be searched when locating the index of a particle's current energy. Other factors held constant, a reduction in energy vector length yields a reduction in CPU time. The computational methods we present here are physics-informed. That is, they are designed to utilize the physical information embedded in a simulation in order to reduce the length of the vector to be searched. More specifically, the optimizations take advantage of information about scattering kinematics, neutron cross section structure and data representation, and also the expected characteristics of a system's spatial flux distribution and energy spectrum. The methods that we present are implemented in the OpenMC Monte Carlo neutron transport code as part of this work. The gains in computational efficiency, as measured by overall code speedup, associated with each of the optimizations are demonstrated in both serial and multithreaded simulations of realistic systems. Depending on the system, simulation parameters, and optimization method employed, overall code speedup factors of 1.2 − 1.5, relative to the typical single-nuclide binary search algorithm, are routinely observed.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optimizations of the energy grid search algorithm in continuous-energy Monte Carlo particle transport codes

Walsh

Romano

Forget

et al. 2015

Computer Physics Communications

View full text Add to dashboard Cite

show abstract

“…Since each volume element allows for analytic sampling, all we need is a way to carry samples across its boundaries in case the sampled distance exceeds them. This method is known as regular tracking [SBB*99] or surface tracking [Lep10] and works as follows.…”

Section: Distance Samplingmentioning

confidence: 99%

Monte Carlo Methods for Volumetric Light Transport Simulation

Novák

Georgiev

Hanika

et al. 2018

Computer Graphics Forum

104

View full text Add to dashboard Cite

The wide adoption of path‐tracing algorithms in high‐end realistic rendering has stimulated many diverse research initiatives. In this paper we present a coherent survey of methods that utilize Monte Carlo integration for estimating light transport in scenes containing participating media. Our work complements the volume‐rendering state‐of‐the‐art report by Cerezo et al. [CPP*05]; we review publications accumulated since its publication over a decade ago, and include earlier methods that are key for building light transport paths in a stochastic manner. We begin by describing analog and non‐analog procedures for free‐path sampling and discuss various expected‐value, collision, and track‐length estimators for computing transmittance. We then review the various rendering algorithms that employ these as building blocks for path sampling. Special attention is devoted to null‐collision methods that utilize fictitious matter to handle spatially varying densities; we import two “next‐flight” estimators originally developed in nuclear sciences. Whenever possible, we draw connections between image‐synthesis techniques and methods from particle physics and neutron transport to provide the reader with a broader context.

show abstract

“…For LWR applications in particular this means that coolant temperature cannot be adjusted, even though the distribution is passed into the tracking routine. Various solutions successfully implemented in other Monte Carlo codes are currently being evaluated for compatibility with Serpent, including direct tabular interpolation (Sutton et al, 1999) and functional expansion (Pavlou and Ji, 2014) of temperature-dependent S(a; b) data. The incapability to model self-shielding effects in the unresolved resonance region becomes an issue in fast spectrum systems, and the extension of TMS to probability table sampling is currently being studied.…”

Section: Future Plansmentioning

confidence: 99%

The Numerical Multi-Physics project (NUMPS) at VTT Technical Research Centre of Finland

Leppänen

Hovi

Ikonen

et al. 2015

Annals of Nuclear Energy

View full text Add to dashboard Cite

The Physical Models and Statistical Procedures Used in the RACER Monte Carlo Code

Cited by 8 publications

References 9 publications

Optimizations of the energy grid search algorithm in continuous-energy Monte Carlo particle transport codes

Optimizations of the energy grid search algorithm in continuous-energy Monte Carlo particle transport codes

Monte Carlo Methods for Volumetric Light Transport Simulation

The Numerical Multi-Physics project (NUMPS) at VTT Technical Research Centre of Finland

Contact Info

Product

Resources

About