Neutron noise patterns from coupled fuel-assembly vibrations
Publikation: Beitrag zu Konferenzen › Paper › Beigetragen › Begutachtung
Beitragende
Abstract
The neutron flux fluctuation magnitude of KWU-built PWRs shows a hitherto unexplained correlation with the types of loaded fuel assemblies. Also, certain measured long-range neutron flux fluctuation patterns in neighboring core quadrants still lack a closed understanding of their origin. The explanation of these phenomena has recently revived a new interest in neutron noise research. The contribution at hand investigates the idea that a synchronized coolant-driven vibration of major parts of the fuel-assembly ensemble leads to these phenomena. Starting with an assumed mode of such collective vibration, the resulting effects on the time-dependent neutron-flux distribution are analyzed via a DYN3D simulation. A three-dimensional representation of the time-dependent bow of all fuel assemblies is taken into account as a nodal DYN3D feedback parameter by time-dependent variations of the fuel-assembly pitch. The impact of its variation on the cross sections is quantified using a cross-section library that is generated from the output of corresponding CASMO5 calculations. The DYN3D simulation qualitatively reproduces the measured neutron-flux fluctuation patterns. The magnitude of the fluctuations and its radial dependence are comparable to the measured details. The results imply that collective fuel-assembly vibrations are a promising candidate for being the key to understand long-known fluctuation patterns in KWU built PWRs. Further research should elaborate on possible excitation mechanisms of the assumed vibration modes.
Details
Originalsprache | Englisch |
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Seiten | 227-234 |
Seitenumfang | 8 |
Publikationsstatus | Veröffentlicht - 2020 |
Peer-Review-Status | Ja |
Konferenz
Titel | 2020 International Conference on Physics of Reactors: Transition to a Scalable Nuclear Future, PHYSOR 2020 |
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Dauer | 28 März - 2 April 2020 |
Stadt | Cambridge |
Land | Großbritannien/Vereinigtes Königreich |
Schlagworte
ASJC Scopus Sachgebiete
Schlagwörter
- KWU, Neutron noise, PWR