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Reconstruction of neutron flux distribution by nodal synthesis method using online in-core neutron detector readings

Ramezani, I ; Sharif University of Technology | 2020

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  1. Type of Document: Article
  2. DOI: 10.1016/j.pnucene.2020.103574
  3. Publisher: Elsevier Ltd , 2020
  4. Abstract:
  5. The safety and optimal performance of nuclear reactors require online monitoring in the core. The present paper describes a method that avoids the solution of the time-dependent neutron diffusion equation, and it uses online readings of the fixed in-core neutron detectors to reconstruct the three-dimensional (3D) neutron flux distribution. The essential idea of the nodal synthesis method is the separation of time and space-dependence of the neutron flux distribution. The time-dependent section of the flux distribution is determined by in-core neutron detector readings, and the space-dependent section is obtained from pre-computed harmonics of the neutron diffusion equation. In online computation, time-dependent coefficients are only computed, and flux distribution is reconstructed by pre-computed harmonics. To calculate the diffusion equation harmonics, the nodal expansion method and the Gram-Schmidt process are used. Online reconstruction of neutron flux distribution in the Bushehr Nuclear Power Plant with VVER-1000/446 reactor type is simulated, and the results are benchmarked by valid results. The maximum relative percent error between reconstructed results and the valid results is about 5%, and the computing time is about 0.5 s. © 2020 Elsevier Ltd
  6. Keywords:
  7. Bushehr nuclear power plant ; Gram–schmidt process ; Neutron flux reconstruction ; Nodal expansion method ; Time-synthesis ; Diffusion ; Harmonic analysis ; Neutron detectors ; Neutron flux ; Nuclear fuels ; Nuclear reactors ; Partial differential equations ; Neutron diffusion equations ; Neutron flux distributions ; Nodal expansion method ; Online reconstruction ; Optimal performance ; Threedimensional (3-d) ; Time dependent neutron diffusion equations ; Time-dependent coefficients ; Nuclear power plants
  8. Source: Progress in Nuclear Energy ; 2020
  9. URL: https://www.sciencedirect.com/science/article/abs/pii/S0149197020303218