Neutronic Simulation of Fuel Assembly Vibrations in a Nuclear Reactor
Journal article, 2020

The mechanical vibrations of core internals such as fuel assemblies (FAs) cause oscillations in the neutron flux that require in some circumstances nuclear power plants to operate at a reduced power level. This work simulates and analyzes the changes of the neutron flux throughout a nuclear core due to the oscillation of a single FA without considering thermal-hydraulic feedback. The amplitude of the FA vibration is bounded to a few millimeters, and this implies the use of fine meshes and accurate numerical solvers due to the different scales of the problem. The results of the simulations show a main oscillation of the neutron flux with the same frequency as the FA vibration along with other harmonics at multiples of the vibration frequency much smaller in amplitude. Also, this work compares time domain analysis and frequency domain analysis of the mechanical vibrations. Numerical results show a close match between these two approaches for the fundamental frequency.

fuel assembly vibrations

Neutron noise

neutron diffusion approximation

frequency domain modeling

time domain modeling


A. Vidal-Ferrandiz

Polytechnic University of Valencia (UPV)

A. Carreno

Polytechnic University of Valencia (UPV)

D. Ginestar

Polytechnic University of Valencia (UPV)

Christophe Demaziere

Subatomic, High Energy and Plasma Physics

G. Verdu

Polytechnic University of Valencia (UPV)

Nuclear Science and Engineering

0029-5639 (ISSN)

Vol. In Press

Core monitoring techniques and experimental validation and demonstration (CORTEX)

European Commission (Horizon 2020), 2017-09-01 -- 2021-08-31.

Subject Categories

Applied Mechanics

Energy Engineering

Areas of Advance




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7/3/2020 7