MC21 v.6.0 – A continuous-energy Monte Carlo particle transport code with integrated reactor feedback capabilities

Griesheimer, David P.; Gill, Daniel; Nease, Brian R.; Sutton, Thomas M.; Stedry, M. H.; Dobreff, P. S.; Carpenter, D.C.; Trumbull, Timothy; Caro, E.; Joo, H.; Millman, David L.

doi:10.1016/j.anucene.2014.08.020

Cited by 60 publications

(14 citation statements)

References 18 publications

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“…Isotopic depletion is now a routine component of many Monte Carlo codes (Leppänen et al, 2015;Griesheimer et al, 2015;Josey, 2017). These codes typically offer a large variety of options for coupling the transport and depletion solvers.…”

Section: Transport and Depletion Couplingmentioning

confidence: 99%

A simple implicit coupling scheme for Monte Carlo neutronics and isotopic depletion

Cosgrove

Shwageraus

Parks

2020

Annals of Nuclear Energy

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The stochastic implicit Euler scheme and its variants can be used to prevent non-physical behaviour that may emerge when coupling Monte Carlo neutron transport and isotopic depletion solvers for spatially-decoupled reactor problems. However, stochastic implicit methods tend to require many iterations to obtain a stable solution. This paper demonstrates that this is due to using a sub-optimal relaxation scheme: rather than using a variable relaxation factor, a fixed relaxation factor can give a more stable solution in fewer iterations. Furthermore, like stochastic implicit schemes, even though multiple transport solutions are required, using a fixed relaxation factor allows computational effort to be reduced by lowering the number of particles simulated during the corrector step while still providing stable results. This shows that using a fixed relaxation factor to stabilise Monte Carlo burn-up calculations can be more effective than applying the stochastic approximation.

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Section: Transport and Depletion Couplingmentioning

confidence: 99%

A simple implicit coupling scheme for Monte Carlo neutronics and isotopic depletion

Cosgrove

Shwageraus

Parks

2020

Annals of Nuclear Energy

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“…To validate the performance of ENDF light-water TSLs, PNDA simulations were conducted with the MC21 Monte Carlo transport code [59] at 22 °C and 227 °C (at saturation pressure) for eight spheres of water with radii ranging from 3.6 cm to 14.4 cm. (295.15 K and 500 K exactly were used.)…”

Section: Resultsmentioning

confidence: 99%

Validation of Thermal Scattering Laws for Light Water at Elevated Temperatures With Diffusion Experiments

2021

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Light water is the most important neutron moderator in many reactor applications. Thermal neutron scattering kernels for H bound in H2O are represented by ENDF-format thermal scattering laws (TSLs) evaluated at discrete temperatures T. Nuclear data evaluations are conventionally validated utilizing a combination of critical benchmarks and experimental cross section data. Existing public critical benchmarks may be inadequate for testing water TSLs over the full range of T of interest in reactor applications, and experimental thermal scattering cross section data for water is sparse at elevated T. In this work, MC21 is used to simulate the decay of the equilibrium thermal neutron flux in light-water spheres of several radii. The fundamental-mode time eigenvalue α is calculated at 22 °C and 227 °C (at saturation pressure) for each sphere using three different H-H2O TSLs. Fitting α to a polynomial function of geometric buckling allows calculation of the thermal neutron diffusion length L. Extrapolation lengths are treated as a function of the transport mean free path and geometry. Experimental L data from 25 publications at 49 temperatures (from 10 °C to 295 °C), computed by several different time-dependent and space-dependent decay methods, is used to develop an empirical fit of L vs. T. The MC21-calculated L for the TSLs tested are within ±1% of the predicted values at 22 °C and 227 °C. This validation approach, which may be repeated at arbitrary T, constitutes an integral benchmark specific to and characterizing the detailed physics of the thermal scattering kernel applied.

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“…The energy rebalance factor forces consistency between neutron energy release and deposition, as defined in Equation (5). Imposing this consistency on the master energy balance equation (Equation ( 2)) allows cancellation of the neutron energy production and birth terms, yielding:…”

Section: Quasistatic Energy Balancementioning

confidence: 99%

Self-Consistent Energy Normalization for Quasistatic Reactor Calculations

Griesheimer

Douglass

Stedry

2021

JNE

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Use of the quasistatic (keff) approximation for producing steady-state solutions for non-critical fission systems is known to result in an imbalance between energy release and deposition within the system. In this paper, we formally quantify this imbalance and present a self-consistent energy normalization technique that preserves nuclear energy release per reaction, as well as enforces energy balance between release and deposition mechanisms, regardless of the criticality state of the system. The proposed technique is straightforward to implement in any type of transport solver through the use of a simple energy rebalance factor. Theoretical and numerical results are presented that demonstrate the energy deposition bias for non-critical systems and the effectiveness of the proposed energy normalization technique.

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MC21 v.6.0 – A continuous-energy Monte Carlo particle transport code with integrated reactor feedback capabilities

Cited by 60 publications

References 18 publications

A simple implicit coupling scheme for Monte Carlo neutronics and isotopic depletion

A simple implicit coupling scheme for Monte Carlo neutronics and isotopic depletion

Validation of Thermal Scattering Laws for Light Water at Elevated Temperatures With Diffusion Experiments

Self-Consistent Energy Normalization for Quasistatic Reactor Calculations

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