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[en] Recent advances in parallel software development for solving three-dimensional (3-D) neutron transport problems using the characteristics method are presented. The characteristics method solves the transport equation by collecting local angular fluxes along neutron paths. In order to be able to solve large 3-D transport problems in a reasonable time frame, the characteristics solver needs to be accelerated. After applying adequate numerical acceleration techniques, the only issue is to parallelize the solver. The parallelization of this solver is based on distributing a group of tracks, generated by a ray-tracing procedure, on several processors. Different distributing schemes and load-balancing techniques based on a calculation load model are presented. A message-passing model is used to communicate the local solutions between processes participating in solving a problem. Both analytical models of this parallel algorithm and performance analysis are presented and illustrated by several examples
[en] Highlights: • Utilization of FUGEN data for physics design verification of ACR-1000 is presented. • Results from flux distribution benchmark calculations are presented. • Five FUGEN operating cycles were evaluated. • The physics toolsets produce reasonable flux distributions compared to the measurement data. - Abstract: As for any new reactor design, the ACR-1000® design has to go through a comprehensive design verification process. One of the activities for supporting the ACR physics design calculations using the ACR physics code toolset, namely WIMS-AECL/DRAGON/RFSP, is to compare the flux distributions resulting from the calculation using this toolset at various power calibration monitor (PCM) detector locations against the flux measurement data from the Japanese Advanced Thermal Reactor (ATR) FUGEN. The discussion of this particular design verification exercise will be presented in a two-part paper. The usage of data from the FUGEN reactor qualifies this exercise as design verification by alternate analysis. In order to have meaningful results at the end of the design verification process, the similarity between the ACR-1000 and FUGEN reactors has to be demonstrated. It is accomplished through the sensitivity and uncertainty analysis using the TSUNAMI (Tools for Sensitivity and Uncertainty Analysis Methodology Implementation) methodology. The results from the similarity comparison have been presented in Part I of the paper. In Part II, results from flux distribution comparison will be presented. Favourable results from this design verification exercise give a high level of confidence that using the same physics toolset in calculating the flux distribution for ACR-1000 reactor will produce results with acceptable fidelity. In addition, the results will also give an indication of expected margins in the design calculations, not only at the locations of the PCM detectors but also at the derived bundle and channel powers obtained through the flux mapping calculation.
[en] Highlights: • A flux reconstruction method is presented that uses a 3D transport theory form factor. • 3D form factor is a 2D xy-plane component times an approximate 1D z-axis component. • Method is used to simulate travelling flux detector scan (TFD scan) readings. - Abstract: Even with current computing capabilities, detailed full core three-dimensional (3-D) transport calculations are still not practical. However, if we are satisfied with knowing only the average values of spatial flux distributions, the 3-D diffusion solution will constitute the final solution. On the other hand, in reactor design and safety analysis, direct information about the local flux distribution for the heterogeneous assemblies is required to assess the design and determine the safety margins. For this reason, after having solved the full-reactor-core problem, we have to look into the possibilities of recovering in a second step the information on local properties of single heterogeneous assemblies. In particular, the detector readings at detector locations are derived using these global homogenized parameters by applying appropriate numerical methods such as advanced interpolations. In this paper, we propose a method based on flux reconstruction to calculate the simulated detector readings in three-dimensions with high fidelity. Data from detector readings are very important in ensuring optimal reactor operations as well as in detecting any deviations from normal operations. Thus, calculating the detector readings with high fidelity will allow improvements to operating and safety margins. To validate this method, comparisons between detector reading simulation results and measurements from an operating CANDU reactor will be conducted and results will be presented.