IFDF acceleration method with adaptive diffusion coefficients for SN nodal calculation in SARAX code system. (February 2020)

• Record Type: Journal Article
• Authors: Xu, Zhitao; Zheng, Youqi; Wang, Yongping; Wu, Hongchun
• Is Part Of: Annals of nuclear energy. Volume 136(2020)
• Publication Date: 2020-02
• Subjects: IFDF -- CMFD -- SN nodal method -- Fast reactor; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 621.4805
• DOI: 10.1016/j.anucene.2019.107056
• Languages: English
• ISSNs: 0306-4549

Abstract

Highlights: Stability of IFDF acceleration was improved by adaptive diffusion coefficients. The improved IFDF was implemented in SN nodal calculation. Hexagonal prism meshes and external-source multiplication problem were considered. Results showed that good stability and acceleration effect were achieved. Abstract: SN nodal method has been successfully applied to fast reactor core neutronics analysis. The computational efficiency can be enhanced efficiently by the popular coarse-mesh finite difference (CMFD) method. However, the CMFD method suffers from the problem of instability, especially for optically thick problems. In this paper, another efficient nonlinear acceleration method, named interface flux discontinuity factor (IFDF) acceleration, was studied and improved for the SN nodal calculation in hexagonal prism and cuboid meshes. With adaptive diffusion coefficients, the IFDF is guaranteed to be positive and within a reasonable region, which makes the acceleration stable. It was found that the IFDF and CMFD methods obtained similar speedups for the tested fast reactor problems. However, the stability of the IFDF method was much better than the CMFD method even with artificial diffusion improvement. Additionally, the rebalance accelerated IFDF method was applied to the external-source multiplication problem besides the common eigenvalue problem.