Assessment of the neutron noise induced by stationary fuel assembly vibrations in a light water reactor
Paper in proceedings, 2019

A systematic increase of the neutron noise levels over time has been observed in some of the pre-KONVOI PWRs operating in Europe. A possible reason for this anomaly was identified as increased mechanical vibrations of reactor internals, specifically of fuel assemblies. To verify this conjecture, the modeling of stationary vibrations of fuel assemblies and of the corresponding neutron noise is essential. In this paper, using the epsilon/d model basis, we illustrate the modeling of the neutron noise sources for fuel assembly vibrationsand study the effect of homogenization of cross sections on such stationary perturbations. A comparative analysis between the classical nodal approach (both localized at the boundaries of the vibrating fuel assembly or involving the entire neighboring fuel assemblies) and a pin-wise approach shows that the ‘boundary-localized’ nodal approach seems to capture local noise information, as a pin-wise approach would do, without the need of a complex pin-by-pin model when the detectors are placed close to the perturbation. However, when considering region of the active core away from the perturbation, all three approaches lead to comparable results.

fuel assembly vibration

noise analysis

Neutron noise

CORE SIM

frequency domain

Author

Vasudha Verma

Paul Scherrer Institut

Christophe Demaziere

Chalmers, Physics, Subatomic and Plasma Physics

Paolo Vinai

Chalmers, Physics, Subatomic and Plasma Physics

Guillaume Ricciardi

The French Alternative Energies and Atomic Energy Commission (CEA)

Robert Jacqmin

The French Alternative Energies and Atomic Energy Commission (CEA)

International Conference on Mathematics and Computational Methods applied to Nuclear Science and Engineering - M&C 2019

Vol. 2019 1124-1133

International Conference on Mathematics and Computational Methods applied to Nuclear Science and Engineering - M&C 2019
Portland, USA,

Subject Categories

Other Engineering and Technologies not elsewhere specified

Other Physics Topics

Areas of Advance

Energy

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7/17/2020