A Validation Study of Existing Neutronics Tools against ZPPR-21 and ZPPR-15 Critical Experiments

Yang, Won Sik; Kim, S.J.

doi:10.2172/1031456

Cited by 1 publication

(1 citation statement)

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“…The first test considered the impact of smearing the plate masses guided by previous experience [26][27]. In the first approach, termed Model A, the plate dimensions and heavy metal compositions in the X direction are preserved with the extra (Y & Z directional) structural material added to the non-heavy metal plates according to their respective thicknesses.…”

Section: Slab Geometry Scoping Studiesmentioning

confidence: 99%

FY2010 status report on advanced neutronics modeling and validation.

Smith¹,

Mohamed²,

Marin-Lafleche³

et al. 2011

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SUMMARYUNIC is the neutronics component of the massively parallel, multi-physics SHARP (Simulation for High-efficiency Advanced Reactor Prototyping) framework under development at Argonne National Laboratory. During this fiscal year, the SN2ND solver, MOCFE solver, and NODAL solver received significant development to meet the needs of the SHARP project. Additional follow-on analysis of the ZPR-6/6A from the previous year was performed in addition to new analysis of the ZPR-6/7 experiments where UNIC predictions of ZPR foil activation were made against experimentally measured values.The SN2ND solver was applied to a plate-by-plate model of ZPR-6/6A using 294,912 cores of BlueGene/P and 222,912 cores of XT5, the two largest open-science high performance computing machines. The calculations proved that the SN2ND solver could be applied to heterogeneous reactor modeling problems, but more solver development (e.g., multigrid preconditioner) and computing power are required before such calculations are routine. As a consequence, the SN2ND solver was revised to incorporate a new multigrid preconditioner concept in addition to removing the remaining inappropriate spherical harmonics related quantities left over from its beginning (i.e. PN2ND). At the time of this report, the new version of SN2ND has not been completed, and the follow on work for SN2ND will continue to focus on updating the preconditioner as outlined in this report.The MOCFE solver was rebuilt into UNIC in the previous year such that it obeyed the basic concepts of parallelism (scalable memory and communication). The MOCFE parallel algorithm was fully debugged this year and initial scalability tests on over 2048 processors were carried out such that the parallel algorithm could be assessed. That work indicated that a significant load imbalance in the coefficient matrix-vector application exists. A possible solution was formulated, but it has not been fully tested at the time of this report. Various setbacks caused by numerous ray tracing problems and a mistake in the implementation were unanticipated thus delaying progress on the MOCFE solver and the targeted development tasks for MOCFE were not completed this year.In addition to the high fidelity solvers SN2ND and MOCFE, some time was spent implementing the NODAL solver. NODAL is similar to an existing legacy tool, but employs parallelism for enhanced performance and a capability to map a heterogeneous geometry into the homogenized geometry. This solver would provide a path to improve upon the existing homogenization approaches used for fuel cycle analysis, transient analysis, and perturbation theory calculations. An appropriate preconditioner was identified for NODAL this year and the solver algorithm was partially completed in UNIC. To facilitate the validation tests of UNIC using the ZPR-6 critical experiments, the BuildZPRmodel tool was also updated and a mesh merging algorithm was created. In addition to the newly implemented "solution along a line" analysis capability, these tools proved crucial t...

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Section: Slab Geometry Scoping Studiesmentioning

confidence: 99%