FY2010 status report on advanced neutronics modeling and validation.

Smith, M. A.; Mohamed, A.; Marin-Lafleche, A.; Lewis, E.E.; Derstine, K.L.; Lee, C.H.; Wollaber, Allan B.; Yang, Won-Sik

doi:10.2172/1054061

Cited by 4 publications

(11 citation statements)

References 9 publications

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“…The primary focus of the SN2ND derivation is to recast these two first-order equations into a second-order equation for the even-parity flux with the form [2]: …”

Section: Sn2nd Transport Discretization Reviewmentioning

confidence: 99%

“…A that is solvable using the efficient conjugate gradient (CG) algorithm as discussed previously [2].…”

Section: Sn2nd Transport Discretization Reviewmentioning

confidence: 99%

“…In FY2010, significant time was spent setting up the ZPR-6 Assembly 7 benchmark [15][16][17][18] using the BuildZPRmodel [2] to reduce input errors. The intent of that work was to define September 30, 2011 ANL/NE-11-40 a clear procedure for validating the heterogeneous modeling capability available with SN2ND+MC 2 -3 using ZPR benchmarks.…”

Section: Homogenized Drawer Modeling Of Zpr-6 Assembly 7 Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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FY2011 Status Report on SN2ND neutronics solver development.

Smith¹,

Mohamed²,

Marin-Lafleche³

et al. 2011

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SUMMARYA change in focus of NEAMS to a broader set of reactor types necessitated significant effort being diverted away from SN2ND development in FY2011. Nevertheless, significant gains were made with regard to building the new preconditioner and meeting the objectives of 1) parallelism in energy, 2) a spatial multigrid concept, 3) using S N vector spaces to accommodate the adjoint and time dependent functionalities needed for NEAMS work, and 4) complete manuals and documentation. While the desired goal of an exportable SN2ND solver usable within the NEAMS community for neutronics analysis was not completed, we can be confident that this year's work puts the SN2ND solver well on its way to meeting that objective. It is important to note that SN2ND is just as capable as any other methodology for doing thermal reactor analysis, but the motivation to execute on smaller scale machines has initiated focused development on simplified treatments such as those proposed in the MOCARV tool.All of the cited coding tasks were completed but not all are fully working (i.e. debugged). The spatial multigrid technique was by far the most time consuming part of the SN2ND development process. It required multiple new data structure concepts along with identifying the necessary changes in the vectors and their associated functions. Combining the spatial multigrid as part of a GMRES preconditioner operating on the full vector space, necessary for parallelization in energy, increased the complexity of that development. Research into spatial multigrid techniques for unstructured meshes, void treatments, and code optimization and acceleration are key development needs for SN2ND.Similar to previous years, a considerable amount of effort was spent on validation work. Again we focused on fast reactor problems such as ZPR experiments and the MONJU reactor in Japan. Conventional drawer homogenized models and partially heterogeneous models were used on the ZPR calculations. The drawer homogenized models produced excellent results for both eigenvalue and foil measurements on four loadings of ZPR-6/7. The partially heterogeneous models of ZPR-6/7 also produced good results, but additional work is necessary to generate consistent effective cross section data. Calculations for MONJU were homogeneous and also gave excellent results.Finally, mock-up heterogeneous calculations were setup and attempted to scope out the performance limitations of SN2ND on whole core heterogeneous calculations. Specifically, heterogeneous models of a PWR, a VHTR, and the MONJU reactor were created using anywhere from 2 group to 33 group cross section data. Meshes with greater than 100,000,000 vertices are necessary for accuracy and a specific non-scaling memory issue in PETSc restricted the SN2ND modeling (VHTR and PWR could not be solved). All of the calculations performed this year indicate that significant computational resources beyond those available today are required to obtain a high fidelity solution possible with SN2ND.The future goals for SN2ND are to get th...

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“…The primary focus of the SN2ND derivation is to recast these two first-order equations into a second-order equation for the even-parity flux with the form [2]: …”

Section: Sn2nd Transport Discretization Reviewmentioning

confidence: 99%

“…A that is solvable using the efficient conjugate gradient (CG) algorithm as discussed previously [2].…”

Section: Sn2nd Transport Discretization Reviewmentioning

confidence: 99%

Section: Homogenized Drawer Modeling Of Zpr-6 Assembly 7 Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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FY2011 Status Report on SN2ND neutronics solver development.

Smith¹,

Mohamed²,

Marin-Lafleche³

et al. 2011

Self Cite

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“…The basic goal is to reduce the uncertainties and biases in various areas of reactor design activities by providing enhanced prediction capabilities. For the fast reactor component, a high-fidelity deterministic neutron transport code named UNIC [2][3] was developed, now termed PROTEUS-SN2ND or SN2ND. The application scope of PROTEUS-SN2ND ranges from conventional homogenized assembly approaches to explicit geometry, time dependent transport calculations coupled to thermal-hydraulics and structural mechanics calculations for reactor accident simulations.…”

Section: Introductionmentioning

confidence: 99%

FY2012 status report on subgroup library development

Smith¹,

Lee²,

Yesilyurt³

2012

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SUMMARYThe goal of SHARP is to develop a suite of modern simulation tools for use on all reactor types of interest. Part of that desire is to build a heterogeneous neutron transport capability which gives accurate, detailed power distributions throughout the entire reactor core, of which we have focused our efforts on deterministic methodologies. The existing SHARP neutronics tool has demonstrated good accuracy when using conventional homogeneous modeling, but when applied on fully heterogeneous problems such as the Advanced Test Reactor (ATR) and Zero Power Reactors (ZPR), the results were not acceptable. These errors are primary attributable to the use of a three step cross section generation procedure (unit cell, lattice, and whole core). Given the success of the DeCART tool on thermal spectrum systems such as PWR, BWR, and VHTR, the subgroup methodology was identified as a potential means by which to resolve the cross section related problems in the NEAMS tools. The subgroup project in NEAMS is thus focused on creating a general purpose cross section methodology that is usable on both thermal and fast spectrum systems.The subgroup methodology is a well studied scheme appearing very early in the nuclear engineering literature. We investigated using the subgroup methodology as a potential means to handle fast reactor problems. A considerable amount of work was performed on the subgroup library software for NEAMS where several subgroup formulations were investigated. Further, while the subgroup method has been demonstrated to be accurate enough on several problems via our own experiences with DeCART, it is not clear what its accuracy will be on more complicated problems such as the ATR.In any case, one must have a capability to generate a library in which subgroup parameters can cover neutron spectrum characteristics of the reactor of interest. For better accuracy, we propose to use MCNP as an alternative pin-cell calculation means of generating the subgroup data and have developed a prototype code package to demonstrate the capability.With regard to fast spectrum systems, there are numerous concerns with the subgroup methodology in which the conventional Bondarenko iteration approach often used would not accurately handle the resonance interference effect that becomes more complex and important in a fast reactor. An alternative methodology involving the local escape cross section looks promising, but substantial research needs to be completed and a basic algorithm tested before success can be confirmed.Overall, the creation of a subgroup library application was not finished, primarily due to the fact that a bulk of the funding was moved into the next fiscal year. A better understanding of the underlying methodology was gained and a means by which to generate subgroup data was created. The work on the subgroup method for an Application Program Interface (API) is thus not complete and can be expected to continue into the next year.

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