Variational nodal method for three-dimensional multigroup neutron diffusion equation based on arbitrary triangular prism. (August 2021)

• Record Type: Journal Article
• Authors: Zhuang, Kun; Shang, Wen; Li, Ting; Yan, Jiangtao; Wang, Sipeng; Tang, Xiaobin; Li, Yunzhao
• Is Part Of: Annals of nuclear energy. Volume 158(2021)
• Publication Date: 2021-08
• Subjects: Variational nodal method -- Neutron diffusion -- Arbitrary triangular mesh; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 621.4805
• DOI: 10.1016/j.anucene.2021.108285
• Languages: English
• ISSNs: 0306-4549

Abstract

Highlights: Variational nodal method of 3D multigroup neutron diffusion theory based on arbitrary triangular prism nodal was developed. 4 types of typical benchmarks with different assembly geometry were employed to verify TriVNM code. TriVNM can be applicable for modeling of complex geometry reactor core in a good accuracy. Abstract: With the development of nuclear technology, new concepts of reactor core have been continuously proposed, and new types of geometric assembly and reactor core configuration would be adopted to achieve better characteristics. Traditional nodal method based on rectangle or hexagonal nodal is no longer applicable for complex geometry modeling. Given that triangles have the advantage of constructing arbitrarily complex geometry, in this study, variational nodal method of three-dimensional multigroup neutron diffusion theory based on arbitrary triangular prism was developed. ANSYS code is used to divide calculation region into arbitrary triangle mesh, which is then transformed into regular triangle mesh by coordinate transformation, and a set of orthogonal polynomial basis function is built. Variables such as nodal neutron scalar flux and neutron current on nodal surface are expanded based on those polynomial basis functions. The response relationship between neutron partial neutron current and neutron flux can be obtained by variational principle, and traditional power method is employed to solve those response matrix system. Based on above, TriVNM code was developed, and 4 types of typical benchmarks including rectangle, hexagonal assembly reactor and reactor with curved boundary were employed to verify TriVNM. Both power distributions and keff calculated by TriVNM code agree well with reference results, and the maximum relative error of all the benchmarks' power doesn't exceed 1% and error of keff doesn't exceed 50 pcm. TriVNM code achieves the same or higher level of calculation accuracy compared with other diffusion codes. Mesh sensitivity analysis shows that for large mesh size TriVNM code still has good accuracy.