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Article Dans Une Revue Journal of Nuclear Engineering Année : 2021

Comparison of Direct and Adjoint k and α-Eigenfunctions

Vito Vitali
  • Fonction : Auteur
Florent Chevallier
  • Fonction : Auteur
Andrea Zoia

Résumé

Modal expansions based on k-eigenvalues and α-eigenvalues are commonly used in order to investigate the reactor behaviour, each with a distinct point of view: the former is related to fission generations, whereas the latter is related to time. Well-known Monte Carlo methods exist to compute the direct k or α fundamental eigenmodes, based on variants of the power iteration. The possibility of computing adjoint eigenfunctions in continuous-energy transport has been recently implemented and tested in the development version of TRIPOLI-4®, using a modified version of the Iterated Fission Probability (IFP) method for the adjoint α calculation. In this work we present a preliminary comparison of direct and adjoint k and α eigenmodes by Monte Carlo methods, for small deviations from criticality. When the reactor is exactly critical, i.e., for k0 = 1 or equivalently α0 = 0, the fundamental modes of both eigenfunction bases coincide, as expected on physical grounds. However, for non-critical systems the fundamental k and α eigenmodes show significant discrepancies.

Dates et versions

hal-04427819 , version 1 (31-01-2024)

Identifiants

Citer

Vito Vitali, Florent Chevallier, Alexis Jinaphanh, Andrea Zoia, Patrick Blaise. Comparison of Direct and Adjoint k and α-Eigenfunctions. Journal of Nuclear Engineering, 2021, 2 (2), pp.132-151. ⟨10.3390/jne2020014⟩. ⟨hal-04427819⟩
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