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AREVA NP – a joint's subsidiary of AREVA and Siemens– decided to develop a new calculation scheme based on the multigroup neutron transport code APOLLO2, developed at CEA, for industrial application to Boiling Water Reactors. This scheme is based on the CEA93 library with the XMAS-172 energy mesh and the JEF2.2 evaluation. Microscopic cross-section...
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Context 1
... is a 10x10 rods assembly including a central 3x3 moderating water hole. It has a channel box with squared corners (Fig. 1a.) in the NEA benchmark description [5], and a channel box with rounded corners in the industrial application (Fig. 1b.). In both descriptions, the assembly is loaded with 6 types of MOX fuel with a total plutonium content of 2.69, 3.86, 5.2, 6.71, 7.55, 10.57 wt% and 6 UO 2 -Gd 2 O 3 rods with 1.5 wt% of gadolinium and 3.95 wt% of 235 ...
Context 2
... is a 10x10 rods assembly including a central 3x3 moderating water hole. It has a channel box with squared corners (Fig. 1a.) in the NEA benchmark description [5], and a channel box with rounded corners in the industrial application (Fig. 1b.). In both descriptions, the assembly is loaded with 6 types of MOX fuel with a total plutonium content of 2.69, 3.86, 5.2, 6.71, 7.55, 10.57 wt% and 6 UO 2 -Gd 2 O 3 rods with 1.5 wt% of gadolinium and 3.95 wt% of 235 U. ...
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... presented on Fig. 10 for reactivity and pin-by-pin fission rates at 0, 40 and 80% void and on Fig.11 for isotopic content during depletion at 40% void. The discrepancy remains smaller ...
Context 4
... presented on Fig. 10 for reactivity and pin-by-pin fission rates at 0, 40 and 80% void and on Fig.11 for isotopic content during depletion at 40% void. ...
Context 5
... calculations performed for the ATRIUM10 MOX were also run for the ATRIUM10UGD5. As an example, Fig. 12 shows the discrepancy on reactivity to MCNP versus the void fraction for the uncontrolled and controlled assembly. Industrial ...
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Citations
... Target-accuracies are steadily decreasing for LWR calculations; moreover, fast and accurate BWR assembly calculations are requested by AREVA-NP for their industrial applications [1]. Therefore, a new version APOLLO2.8 based on the Method Of Characteristics was developed to allow enhanced LWR calculations in 2D-exact geometry [2]. ...
This paper summarizes the Validation work performed to demonstrate the accuracy of the new APOLLO2.8/SHEM-MOC package based on JEFF3.1.1 nuclear data file for the prediction of BWR neutronics parameters. The Uncertainty Quantification derived from the experimental validation points out that design target-accuracies are met.
... Cross section models used in core calculations adopt generally only one depletion history in PWRs, thus fixing the evolution of the isotopic content in the assembly [9]. This issue is still present with simulations in BWRs, even if the corresponding models use more depletion evolutions for considering the coolant void history as additional state parameter [10]. Hence, depletion modules have to track important isotopes and perform a history correction to the nodal cross sections. ...
Few-group cross sections used in nodal calculations derive from standard energy collapsing and spatial homogenization performed during preliminary lattice transport calculations, that implicitly assume an infinite array of identical fuel-assemblies. The infinite-medium neutron flux used for cross section weighting does not account for environmental effects arising in case of heterogeneous configurations, which can lead to considerable leakages out of or into the assembly and thus invalidate the reflective boundary conditions used for the lattice simulation. Core-environment effects can also cause variations, with respect to the infinite-lattice calculation, in the reference cross section distribution used for few-group constant collapsing. These sources of inaccuracy prevent from reproducing with high fidelity the best estimate of the reaction rates and multiplication factor coming from the reference transport global solution. Rehomogenization techniques are therefore needed. The purpose of the present paper, which builds upon previous work done at AREVA in the area of rehomogenization, is to formalize a mathematical model that encompasses the different kinds of homogenization errors. In order to investigate the accuracy of the corresponding cross section corrections, numerical tests of an assembly-configuration sample are presented.
... The product is now extensively qualified against integral experiments of every relevant PWR design parameters (Santamarina, 2002). However, as required target accuracies are evolving for PWRs, faster and more accurate calculations for BWR are requested by AREVA-NP for its industrial applications (Marotte et al., 2006). ...
The interpretation of the VIP-BWR program conducted in the CEN·SCK Mol VENUS critical facility (Belgium), has been performed with the new APOLLO2.8 product and its CEA2005V4.1 library based on the JEFF3.1.1 file. Both reference SHEM-MOC (281groups without equivalence) and Optimized BWR 26G (26 groups with equivalence) schemes are used for UO2 and MOX BWR assembly calculations. The VIP-BWR program was aimed to provide an experimental database for BWR neutronics tools in mixed Gd poisoned configurations with 8 × 8 UO2 and MOX assemblies. The experimental conditions are relatively representative of actual industrial BWR core characteristics, at least in terms of void fraction. Measured pin-by-pin power distributions enable to exact valuable information at various interfaces. For fresh (UO2/UO2–Gd) and recycled UO2 (UO2 only) cores loadings, the information is given through the “UO2” core. In the case of partial MOX loadings (UO2/MOX interface), the power distributions are available through the “T-MOX” core. All critical sizes are predicted within 1 with SHEM-MOC reference calculation scheme. For UO2 core, the (C–E) on keff are (95 ± 266) pcm and (203 ± 266) pcm for SHEM-MOC and Optimized scheme respectively. For MOX core, the results are (87 ± 214) pcm and (283 ± 214) pcm. The uncertainties take into account both measurement uncertainties and technological uncertainties such as enrichment, clad thicknesses, grid pitch or fuel densities.
... AREVA has adapted CEA's APOLLO2 (V2.8) to its industrial needs as a stand-alone neutron transport code as well as cross section generator code. This industrial version, named APOLLO2-A, [81][82][83] is designed for PWR and BWR lattice physics calculations as part of the new ARCADIA Reactor Code System. [9] The industrial adaptation consists of a layered computational methodology (multi-level scheme) and a flexible input/output software layer. ...
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 (), 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 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.
... As required target accuracies are decreasing on PWRs, in parallel, faster and more accurate calculations for BWR are now requested by CEA industrial partners. The recent advances in LWR calculationsmainly PWR for historical reasons in France -allowed the definition of a complete work program focused on BWR qualification with the APOLLO2.8 lattice code and its associated CEA2005V4 multigroup nuclear data library (Marotte et al., 2006). The VVQ methodology (Verification/Validation/Qualification), already implemented successfully in PWR applications definition of a particular ''BWR qualification Plan". ...
Within the frame of several extensive experimental core physics programs led between 1996 and 2008 between CEA and Japan Nuclear Energy Safety Organization (JNES), the FUBILA experiment has been conducted in the French EOLE Facility between 2005 and 2006 to obtain valuable data for the validation of core analysis methods related to full MOX advanced BWR and high-burn up BWR cores. During this experimental campaign, a particular FUBILA 10 × 10 Advanced BWR configuration devoted to the validation of high-burn up 100%MOX BWR bundles was built. It is characterized by an assembly average total Pu enrichment of 10.6 wt.% and in-channel void of 40%, representative of hot full power conditions at core mid-plane and average discharge burnup of 65 GWd/t. This paper details the validation work led on the TRIPOLI-4.5 Continuous Energy Monte Carlo code and APOLLO2.8/CEA2005V4 deterministic code package for the interpretation of this 10 × 10 high-burn up configuration. The APOLLO2.8/CEA2005V4 package relies on the deterministic lattice transport code APOLLO2.8 based on the Method of Characteristics (MOC), and its new CEA2005v4 multigroup library based on the latest JEFF-3.1.1 nuclear data file, processed also for the TRIPOLI-4.5 code. The results obtained on critical mass and radial pin-by-pin power distributions are presented. For critical mass, the calculation-to-experiment C–E on the keff spreads from 300 pcm for TRIPOLI to 600 pcm for APOLLO2.8 in its Optimized BWR Scheme (OBS) in 26 groups. For pin-by-pin radial power distributions, all codes give acceptable results, with maximum discrepancies on C/E − 1 of the order of 3–4% for very heterogeneous bundles where Pmax/Pmin reaches 4, 2. These values are within 2 standard deviations of the experimental uncertainty. Those results demonstrate the capability of both codes and schemes to accurately predict Advanced High burnup 100%-MOX BWR key-neutron parameters.
... AREVA has developed the deterministic neutron transport code APOLLO2-A [1,2] designed for lattice physics calculations as part of the new ARCADIA ® [3] reactor code system. It is based on APOLLO2 kernel [4,5] developed by the French Commissariat à l'Energie Atomique (CEA) with the support of AREVA and Electricité de France (EdF). ...
AREVA has developed the ARCADIAR reactor code system including the lattice physics transport code APOLLO2-A. Based on the APOLLO2 kernel developed by CEA, APOLLO2-A features a state-of-the-art methodology designed by AREVA for Light Water Reactor industrial applications. The validation of the code is achieved through comparisons with a comprehensive experimental database and with Monte-Carlo reference codes. In this paper, the main features of APOLLO2-A, the methodology and results from the validation base are presented.
... As required target accuracies are decreasing on PWRs, in parallel, faster and more accurate calculations for BWR are now requested by AREVA-NP for its industrial applications [11]. The recent advances in LWR calculations -mainly PWR for historical reasons in France -allowed the definition of a complete work program focused on BWR qualification with the APOLLO2.8/CEA2005V4 ...
This paper details the validation work led on the REL2005 code package, applied to the modeling of 100%MOX 9×9 Advanced BWR assemblies with increasing void fraction (0 to 70%). The REL2005 package relies on the deterministic lattice transport code APOLLO2.8 based on the Method of Characteristics (MOC), and its new CEA2005 multigroup library based on the latest JEFF-3.1.1 nuclear data file. We describe the overall results obtained on 3 critical cores of the FUBILA experimental program that took place in the EOLE facility between 2005 and 2006: FUBILA/REF (0% void), NORM (40% void) and 70%VOID, for critical masses, void reactivity coefficients and pinby-pin power distributions by using the REL2005-BWR optimized scheme (26 energy groups coupled with unstructured 2D geometry). For critical masses, the calculation-to-experimentratio C/E on the keff increases with the void fraction from 200 pcm for the REF core to 500 pcm at 70%void. A reference full 3D calculation made with TRIPOLI-4.5 Monte Carlo confirms this trend, as for the void coefficient. For pin-by-pin radial power distributions REL2005 gives acceptable results, with maximum discrepancies of the order of 3 to 4%, as void fraction increases. These values are within 2 standard deviations of the experimental uncertainty. Those results lead us to be confident in the capability of the REL2005 code package to accurately predict 100%MOX BWR key-neutron parameters.
... However, target-accuracies are steadily decreasing for PWR calculations; moreover, fast and accurate BWR assembly calculations are now requested by AREVA NP for their industrial applications (Marotte et al., 2006). Therefore, a new version APOLLO2.8 based on the Method of Characteristics was developed to allow enhanced LWR calculations in heterogeneous and 2D-exact geometry (Santandrea and Sanchez, 2005). ...
This paper summarizes the developments implemented in the new APOLLO2.8 neutronics tool to meet the required target accuracy in LWR applications, particularly void effects and pin-by-pin power map in BWRs. The Method of Characteristics was developed to allow efficient LWR assembly calculations in 2D-exact heterogeneous geometry; resonant reaction calculation was improved by the optimized SHEM-281 group mesh, which avoids resonance self-shielding approximation below 23 eV, and the new space-dependent method for resonant mixture that accounts for resonance overlapping. Furthermore, a new library CEA2005, processed from JEFF3.1 evaluations involving feedback from Critical Experiments and LWR P.I.E, is used. The specific “2005–2007 BWR Plan” settled to demonstrate the validation/qualification of this neutronics tool is described. Some results from the validation process are presented: the comparison of APOLLO2.8 results to reference Monte Carlo TRIPOLI4 results on specific BWR benchmarks emphasizes the ability of the deterministic tool to calculate BWR assembly multiplication factor within 200 pcm accuracy for void fraction varying from 0 to 100%. The qualification process against the BASALA mock-up experiment stresses APOLLO2.8/CEA2005 performances: pin-by-pin power is always predicted within 2% accuracy, reactivity worth of B4C or Hf cruciform control blade, as well as Gd pins, is predicted within 1.2% accuracy.
