Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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Calculation of Degenerated Eigenmodes with Modified Power Method

  • Zhang, Peng (School of Power and Mechanical Engineering, Wuhan University) ;
  • Lee, Hyunsuk (School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology) ;
  • Lee, Deokjung (School of Mechanical and Nuclear Engineering, Ulsan National Institute of Science and Technology)
  • Received : 2016.06.07
  • Accepted : 2016.08.08
  • Published : 2017.02.25
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Abstract

The modified power method has been studied by many researchers to calculate the higher eigenmodes and accelerate the convergence of the fundamental mode. Its application to multidimensional problems may be unstable due to degenerated or near-degenerated eigenmodes. Complex eigenmode solutions are occasionally encountered in such cases, and the shapes of the corresponding eigenvectors may change during the simulation. These issues must be addressed for the successful implementation of the modified power method. Complex components are examined and an approximation method to eliminate the usage of the complex numbers is provided. A technique to fix the eigenvector shapes is also provided. The performance of the methods for dealing with those aforementioned problems is demonstrated with two dimensional one group and three dimensional one group homogeneous diffusion problems.

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References

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