NE Seminars

Thursday, April 3, 2003

• Hikaru Hiruta, PhD Student, NCSU, Department of Nuclear Engineering
• "Splitting Method For Solving The Coarse-Mesh
  Discretized Low-Order Quasidiffusion Equations"
• Abstract:
  
  The current generation of reactor physics methodology for full reactor-core calculations is based on the diffusion equation. To obtain highly
  accurate results using such methodology, it is necessary to address the limitations of diffusion theory. A series of significant improvements have
  been developed over the years by means of sophisticated methods of preparation of group cross section data, effective transport corrections at the interface of assemblies, etc. An alternative approach is to create a general methodology that is based on equations that can take into account the transport effects exactly. The low-order equations of the quasidiffusion (QD) method meet this criterion. In this talk, we present a methodology for reactor physics calculations based on the ideas of the QD method.

  A methodology that accounts for transport effects in reactor core calculations requires extra computational effort compared with solving the
  diffusion equation. It is highly desirable to minimize these extra costs. We propose a splitting method that formulates two problems instead of one original low-order QD problem. The first problem is a tensor diffusion equation, and hence existing advanced methods for diffusion problems can be used to solve it efficiently. The solution of the second problem is basically a transport correction to the first solution. We study ways to minimize costs for solving the second problem to optimize the solution of the overall low-order QD problem. The developed methodology can be directly used in existing production reactor-physics codes for full-core calculations.

  This work was done in cooperation with D. Anistratov (NC State) and M. Adams (Texas A&M).

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