APOLLO2 YEAR 2010

RICHARD SANCHEZ,IGOR ZMIJAREVIC,M. COSTE-DELCLAUX,EMILIANO MASIELLO,SIMONE SANTANDREA,EMANUELE MARTINOLLI,LAURENCE VILLATE,NADINE SCHWARTZ,NATHALIE GULER 한국원자력학회 2010 Nuclear Engineering and Technology Vol.42 No.5

This paper presents the most important developments implemented in the APOLLO2 spectral code since its last generalpresentation at the 1999 M&C conference in Madrid. APOLLO2 has been provided with new capabilities in the domain ofcross section self-shielding, including mixture effects and transfer matrix self-shielding, new or improved flux solvers (CPMfor RZ geometry, heterogeneous cells for short MOC and the linear-surface scheme for long MOC), improved accelerationtechniques (DP1), that are also applied to thermal and external iterations, and a number of sophisticated modules and tools tohelp user calculations. The method of characteristics, which took over the collision probability method as the main fluxsolver of the code, allows for whole core two-dimensional heterogeneous calculations. A flux reconstruction technique leadsto fast albeit accurate solutions used for industrial applications. The APOLLO2 code has been integrated (APOLLO2-A)within the ARCADIAreactor code system of AREVA as cross section generator for PWR and BWR fuel assemblies.APOLLO2 is also extensively used by Electricité de France within its reactor calculation chain. A number of numericalexamples are presented to illustrate APOLLO2 accuracy by comparison to Monte Carlo reference calculations. Results of thevalidation program are compared to the measured values on power plants and critical experiments.

DIFFUSION PIECEWISE HOMOGENIZATION VIA FLUX DISCONTINUITY RATIOS

Sanchez, Richard,Dante, Giorgio,Zmijarevic, Igor Korean Nuclear Society 2013 Nuclear Engineering and Technology Vol.45 No.6

We analyze piecewise homogenization with flux-weighted cross sections and preservation of averaged currents at the boundary of the homogenized domain. Introduction of a set of flux discontinuity ratios (FDR) that preserve reference interface currents leads to preservation of averaged region reaction rates and fluxes. We consider the class of numerical discretizations with one degree of freedom per volume and per surface and prove that when the homogenization and computing meshes are equal there is a unique solution for the FDRs which exactly preserve interface currents. For diffusion submeshing we introduce a Jacobian-Free Newton-Krylov method and for all cases considered obtain an 'exact' numerical solution (eight digits for the interface currents). The homogenization is completed by extending the familiar full assembly homogenization via flux discontinuity factors to the sides of regions laying on the boundary of the piecewise homogenized domain. Finally, for the familiar nodal discretization we numerically find that the FDRs obtained with no submesh (nearly at no cost) can be effectively used for whole-core diffusion calculations with submesh. This is not the case, however, for cell-centered finite differences.

PROSPECTS IN DETERMINISTIC THREE-DIMENSIONAL WHOLE-CORE TRANSPORT CALCULATIONS

Sanchez, Richard Korean Nuclear Society 2012 Nuclear Engineering and Technology Vol.44 No.2

The point we made in this paper is that, although detailed and precise three-dimensional (3D) whole-core transport calculations may be obtained in the future with massively parallel computers, they would have an application to only some of the problems of the nuclear industry, more precisely those regarding multiphysics or for methodology validation or nuclear safety calculations. On the other hand, typical design reactor cycle calculations comprising many one-point core calculations can have very strict constraints in computing time and will not directly benefit from the advances in computations in large scale computers. Consequently, in this paper we review some of the deterministic 3D transport methods which in the very near future may have potential for industrial applications and, even with low-order approximations such as a low resolution in energy, might represent an advantage as compared with present industrial methodology, for which one of the main approximations is due to power reconstruction. These methods comprise the response-matrix method and methods based on the two-dimensional (2D) method of characteristics, such as the fusion method.

APOLLO2 YEAR 2010

Sanchez, Richard,Zmijarevi, Igor,Coste-Delclaux, M.,Masiello, Emiliano,Santandrea, Simone,Martinolli, Emanuele,Villate, Laurence,Schwartz, Nadine,Guler, Nathalie Korean Nuclear Society 2010 Nuclear Engineering and Technology Vol.42 No.5

This paper presents the mostortant developments implemented in the APOLLO2 spectral code since its last general presentation at the 1999 M&C conference in Madrid. APOLLO2 has been provided with new capabilities in the domain of cross section self-shielding, including mixture effects and transfer matrix self-shielding, new or improved flux solvers (CPM for RZ geometry, heterogeneous cells for short MOC and the linear-surface scheme for long MOC), improved acceleration techniques ($DP_1$), that are also applied to thermal and external iterations, and a number of sophisticated modules and tools to help user calculations. The method of characteristics, which took over the collision probability method as the main flux solver of the code, allows for whole core two-dimensional heterogeneous calculations. A flux reconstruction technique leads to fast albeit accurate solutions used for industrial applications. The APOLLO2 code has been integrated (APOLLO2-A) within the $ARCADIA^{(R)}$ reactor code system of AREVA as cross section generator for PWR and BWR fuel assemblies. APOLLO2 is also extensively used by Electricite de France within its reactor calculation chain. A number of numerical examples are presented to illustrate APOLLO2 accuracy by comparison to Monte Carlo reference calculations. Results of the validation program are compared to the measured values on power plants and critical experiments.

PROSPECTS IN DETERMINISTIC THREE-DIMENSIONAL WHOLE-CORE TRANSPORT CALCULATIONS

RICHARD SANCHEZ 한국원자력학회 2012 Nuclear Engineering and Technology Vol.44 No.2

The point we made in this paper is that, although detailed and precise three-dimensional (3D) whole-core transport calculations may be obtained in the future with massively parallel computers, they would have an application to only some of the problems of the nuclear industry, more precisely those regarding multiphysics or for methodology validation or nuclear safety calculations. On the other hand, typical design reactor cycle calculations comprising many one-point core calculations can have very strict constraints in computing time and will not directly benefit from the advances in computations in large scale computers. Consequently, in this paper we review some of the deterministic 3D transport methods which in the very near future may have potential for industrial applications and, even with low-order approximations such as a low resolution in energy, might represent an advantage as compared with present industrial methodology, for which one of the main approximations is due to power reconstruction. These methods comprise the response-matrix method and methods based on the two-dimensional (2D) method of characteristics, such as the fusion method.

Diffusion Piecewise Homogenization Via Flux Discontinuity Ratios

RICHARD SANCHEZ,Giorgio Dante,IGOR ZMIJAREVIC 한국원자력학회 2013 Nuclear Engineering and Technology Vol.45 No.6

We analyze piecewise homogenization with flux-weighted cross sections and preservation of averaged currents at theboundary of the homogenized domain. Introduction of a set of flux discontinuity ratios (FDR) that preserve reference interfacecurrents leads to preservation of averaged region reaction rates and fluxes. We consider the class of numerical discretizationswith one degree of freedom per volume and per surface and prove that when the homogenization and computing meshes areequal there is a unique solution for the FDRs which exactly preserve interface currents. For diffusion submeshing we introducea Jacobian-Free Newton-Krylov method and for all cases considered obtain an ‘exact’ numerical solution (eight digits for theinterface currents). The homogenization is completed by extending the familiar full assembly homogenization via fluxdiscontinuity factors to the sides of regions laying on the boundary of the piecewise homogenized domain. Finally, for thefamiliar nodal discretization we numerically find that the FDRs obtained with no submesh (nearly at no cost) can beeffectively used for whole-core diffusion calculations with submesh. This is not the case, however, for cell-centered finitedifferences. We analyze piecewise homogenization with flux-weighted cross sections and preservation of averaged currents at the boundary of the homogenized domain. Introduction of a set of flux discontinuity ratios (FDR) that preserve reference interface currents leads to preservation of averaged region reaction rates and fluxes. We consider the class of numerical discretizations with one degree of freedom per volume and per surface and prove that when the homogenization and computing meshes are equal there is a unique solution for the FDRs which exactly preserve interface currents. For diffusion submeshing we introduce a Jacobian-Free Newton-Krylov method and for all cases considered obtain an ‘exact’ numerical solution (eight digits for the interface currents). The homogenization is completed by extending the familiar full assembly homogenization via flux discontinuity factors to the sides of regions laying on the boundary of the piecewise homogenized domain. Finally, for the familiar nodal discretization we numerically find that the FDRs obtained with no submesh (nearly at no cost) can be effectively used for whole-core diffusion calculations with submesh. This is not the case, however, for cell-centered finite differences.

Analysis of alpha modes in multigroup diffusion

Richard Sanchez,Daniele Tomatis,IGOR ZMIJAREVIC,주한규 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.6

The alpha eigenvalue problem in multigroup neutron diffusion is studied with particular attention to thetheoretical analysis of the model. Contrary to previous literature results, the existence of eigenvalue andeigenflux clustering is investigated here without the simplification of a unique fissile isotope or a singleemission spectrum. A discussion about the negative decay constants of the neutron precursors concentrationsas potential eigenvalues is provided. An in-hour equation is derived by a perturbationapproach recurring to the steady state adjoint and direct eigenvalue problems of the effective multiplicationfactor and is used to suggest proper detection criteria of flux clustering. In spite of the priorwork, the in-hour equation results give a necessary and sufficient condition for the existence of theeigenvalue-eigenvector pair. A simplified asymptotic analysis is used to predict bands of accumulation ofeigenvalues close to the negative decay constants of the precursors concentrations. The resolution of theproblem in one-dimensional heterogeneous problems shows numerical evidence of the predictedclustering occurrences and also confirms previous theoretical analysis and numerical results.

Perceptions About Alcohol Harm and Alcohol-control Strategies Among People With High Risk of Alcohol Consumption in Alberta, Canada and Queensland, Australia

Sanchez-Ramirez, Diana C.,Franklin, Richard C.,Voaklander, Donald The Korean Society for Preventive Medicine 2018 Journal of Preventive Medicine and Public Health Vol.51 No.1

Objectives: To explore alcohol perceptions and their association hazardous alcohol use in the populations of Alberta, Canada and Queensland, Australia. Methods: Data from 2500 participants of the 2013 Alberta Survey and the 2013 Queensland Social Survey was analyzed. Regression analyses were used to explore the association between alcohol perceptions and its association with hazardous alcohol use. Results: Greater hazardous alcohol use was found in Queenslanders than Albertans (p<0.001). Overall, people with hazardous alcohol were less likely to believe that alcohol use contributes to health problems (odds ratio [OR], 0.46; 95% confidence interval [CI], 0.27 to 0.78; p<0.01) and to a higher risk of injuries (OR, 0.54; 95% CI, 0.33 to 0.90; p<0.05). Albertans with hazardous alcohol use were less likely to believe that alcohol contributes to health problems (OR, 0.48; 95% CI, 0.26 to 0.92; p<0.05) and were also less likely to choose a highly effective strategy as the best way for the government to reduce alcohol problems (OR, 0.63; 95% CI, 0.43 to 0.91; p=0.01). Queenslanders with hazardous alcohol use were less likely to believe that alcohol was a major contributor to injury (OR, 0.39; 95% CI, 0.20 to 0.77; p<0.01). Conclusions: Our results suggest that people with hazardous alcohol use tend to underestimate the negative effect of alcohol consumption on health and its contribution to injuries. In addition, Albertans with hazardous alcohol use were less in favor of strategies considered highly effective to reduce alcohol harm, probably because they perceive them as a potential threat to their own alcohol consumption. These findings represent valuable sources of information for local health authorities and policymakers when designing suitable strategies to target alcohol-related problems.

Hazardous Alcohol Use in 2 Countries: A Comparison Between Alberta, Canada and Queensland, Australia

Sanchez-Ramirez, Diana C.,Franklin, Richard,Voaklander, Donald The Korean Society for Preventive Medicine 2017 Journal of Preventive Medicine and Public Health Vol.50 No.5

Objectives: This article aimed to compare alcohol consumption between the populations of Queensland in Australia and Alberta in Canada. Furthermore, the associations between greater alcohol consumption and socio-demographic characteristics were explored in each population. Methods: Data from 2500 participants of the 2013 Alberta Survey and the 2013 Queensland Social Survey were analyzed. Regression analyses were used to explore the associations between alcohol risk and socio-demographic characteristics. Results: A higher rate of hazardous alcohol use was found in Queenslanders than in Albertans. In both Albertans and Queenslanders, hazardous alcohol use was associated with being between 18 and 24 years of age. Higher income, having no religion, living alone, and being born in Canada were also associated with alcohol risk in Albertans; while in Queenslanders, hazardous alcohol use was also associated with common-law marital status. In addition, hazardous alcohol use was lower among respondents with a non-Catholic or Protestant religious affiliation. Conclusions: Younger age was associated with greater hazardous alcohol use in both populations. In addition, different socio-demographic factors were associated with hazardous alcohol use in each of the populations studied. Our results allowed us to identify the socio-demographic profiles associated with hazardous alcohol use in Alberta and Queensland. These profiles constitute valuable sources of information for local health authorities and policymakers when designing suitable preventive strategies targeting hazardous alcohol use. Overall, the present study highlights the importance of analyzing the socio-demographic factors associated with alcohol consumption in population-specific contexts.

Perceptions About Alcohol Harm and Alcohol-control Strategies Among People With High Risk of Alcohol Consumption in Alberta, Canada and Queensland, Australia

Diana C. Sanchez-Ramirez,Richard C. Franklin,Donald Voaklander 대한예방의학회 2018 Journal of Preventive Medicine and Public Health Vol.51 No.1

Objectives: To explore alcohol perceptions and their association hazardous alcohol use in the populations of Alberta, Canada and Queensland, Australia. Methods: Data from 2500 participants of the 2013 Alberta Survey and the 2013 Queensland Social Survey was analyzed. Regression analyses were used to explore the association between alcohol perceptions and its association with hazardous alcohol use. Results: Greater hazardous alcohol use was found in Queenslanders than Albertans (p<0.001). Overall, people with hazardous alcohol were less likely to believe that alcohol use contributes to health problems (odds ratio [OR], 0.46; 95% confidence interval [CI], 0.27 to 0.78; p<0.01) and to a higher risk of injuries (OR, 0.54; 95% CI, 0.33 to 0.90; p<0.05). Albertans with hazardous alcohol use were less likely to believe that alcohol contributes to health problems (OR, 0.48; 95% CI, 0.26 to 0.92; p<0.05) and were also less likely to choose a highly effective strategy as the best way for the government to reduce alcohol problems (OR, 0.63; 95% CI, 0.43 to 0.91; p=0.01). Queenslanders with hazardous alcohol use were less likely to believe that alcohol was a major contributor to injury (OR, 0.39; 95% CI, 0.20 to 0.77; p<0.01). Conclusions: Our results suggest that people with hazardous alcohol use tend to underestimate the negative effect of alcohol consumption on health and its contribution to injuries. In addition, Albertans with hazardous alcohol use were less in favor of strategies considered highly effective to reduce alcohol harm, probably because they perceive them as a potential threat to their own alcohol consumption. These findings represent valuable sources of information for local health authorities and policymakers when designing suitable strategies to target alcohol-related problems.