EPJ Nuclear Sci. Technol.
Volume 7, 2021
|Number of page(s)||26|
|Published online||22 October 2021|
A hybrid approach for neutronics calculations in the neutron shielding of sodium fast reactors
CEA Cadarache, DES/IRESNE/DER/SPRC/LE2C, 13108 Saint Paul Lez Durance, France
2 CEA Cadarache, DES/IRESNE/DER/SPESI, 13108 Saint Paul Lez Durance, France
3 CEA Saclay, DES/Scientific Division Energies, 91191 Gif-sur-Yvette, France
* e-mail: email@example.com
Received in final form: 18 March 2021
Accepted: 27 September 2021
Published online: 22 October 2021
Neutron calculations in the neutron shielding of fast neutron reactors are a complex problem as deterministic schemes are usually not suited for such calculations while Monte-Carlo codes have poor computational performance due to the very low flux levels in neutron shields. In this article, both methods are studied, as well as a hybrid scheme on the neutron shielding of the ASTRID fast reactor benchmark. This hybrid scheme uses a fission source calculated by a deterministic code in order to precisely calculate neutron fluxes in the shielding with a Monte-Carlo code using variance reduction techniques. This provides reference results in order to validate deterministic calculations. Comparisons between deterministic codes and this hybrid reference show that large biases are obtained, up to 50%. Further studies are made to reduce the biases, showing that many physical phenomena should be treated, including anisotropy of the scattering law at high energies and spatial self-shielding inside the boron carbide shielding. These improvements reduce the biases to less than 10%. Finally, some applications to designing criteria for the neutron shielding are presented, such as gas production in the neutron shielding and activation of secondary sodium at the intermediate heat exchanger (IHX).
© A. Hajji et al., published by EDP Sciences, 2021
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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