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Nodal method for handling irregularly deformed geometries in hexagonal lattice cores

  • Seongchan Kim (School of Mechanical Engineering, Pusan National University) ;
  • Han Gyu Joo (Department of Nuclear Engineering, Seoul National University) ;
  • Hyun Chul Lee (School of Mechanical Engineering, Pusan National University)
  • Received : 2023.05.09
  • Accepted : 2023.07.18
  • Published : 2024.03.25

Abstract

The hexagonal nodal code RENUS has been enhanced to handle irregularly deformed hexagonal assemblies. The underlying RENUS methods involving triangle-based polynomial expansion nodal (T-PEN) and corner point balance (CPB) were extended in a way to use line and surface integrals of polynomials in a deformed hexagonal geometry. The nodal calculation is accelerated by the coarse mesh finite difference (CMFD) formulation extended to unstructured geometry. The accuracy of the unstructured nodal solution was evaluated for a group of 2D SFR core problems in which the assembly corner points are arbitrarily displaced. The RENUS results for the change in nuclear characteristics resulting from fuel deformation were compared with those of the reference McCARD Monte Carlo code. It turned out that the two solutions agree within 18 pcm in reactivity change and 0.46% in assembly power distribution change. These results demonstrate that the proposed unstructured nodal method can accurately model heterogeneous thermal expansion in hexagonal fueled cores.

Keywords

Acknowledgement

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2019R1A2C2089962).

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