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Online Reconstruction of Neutron Flux Distribution using BNPP Operating Data

Ramezani, Iman | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50312 (46)
  4. University: Sharif University of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Ghofrani, Mohammad Bagher; Raji, Mohammad Hossein
  7. Abstract:
  8. The safety and optimal performance of nuclear reactors require online monitoring in the core. One of the most important requirements of core monitoring is the knowledge at all time of the neutron flux distribution in the core. The present M.Sc thesis describes a method which avoids the solution of time dependent neutron diffusion equation and uses online readings of the fixed in-core neutron detectors to reconstruct the three-dimensional (3D) neutron flux distribution. The essential idea of nodal synthesis method is separation of time and space dependence of the neutron flux distribution. The time dependent section of the flux distribution is determined by neutron detector readings and space dependent section is obtained from pre-computed harmonics of the neutron diffusion equation. In online computation, only time dependent coefficients are computed and flux distribution is reconstructed by pre-computed harmonics. This procedure reduces computing time and provides online calculations. To calculate diffusion equation harmonics, nodal expansion method and Gram-Schmidt process are used. The Unit 1 reactor of Bushehr Nuclear Power Plant (BNPP) in Iran is considered for verification. Online reconstruction of neutron flux distribution in this reactor is simulated and the results are benchmarked against the 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 seconds. Therefore this method is suitable for the online reconstruction of 3D neutron flux distribution in BNPP reactor
  9. Keywords:
  10. Neutron Flux ; Neutron Detection ; Online Monitoring ; Nodal Expansion Method ; Bushehr Nuclear Power Plant ; Harmonics Expansion

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