Reassessment of gadolinium odd isotopes neutron cross sections: scientific motivations and sensitivity-uncertainty analysis on LWR fuel assembly criticality calculations
ENEA, Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Centro Ricerche “E. Clementel”,
Via Martiri di Monte Sole, 4,
2 Department of Physics and Astronomy, University of Bologna, Via Irnerio, 46, 40126 Bologna, Italy
3 INFN, Via Irnerio, 46, 40126 Bologna, Italy
* e-mail: email@example.com
Received in final form: 11 May 2017
Accepted: 2 June 2017
Published online: 30 June 2017
Gadolinium odd isotopes cross sections are crucial in assessing the neutronic performance and safety features of a light water reactor (LWR) core. Accurate evaluations of the neutron capture behavior of gadolinium burnable poisons are necessary for a precise estimation of the economic gain due to the extension of fuel life, the residual reactivity penalty at the end of life, and the reactivity peak for partially spent fuel for the criticality safety analysis of Spent Fuel Pools. Nevertheless, present gadolinium odd isotopes neutron cross sections are somehow dated and poorly investigated in the high sensitivity thermal energy region and are available with an uncertainty which is too high in comparison to the present day typical industrial standards and needs. This article shows how the most recent gadolinium cross sections evaluations appear inadequate to provide accurate criticality calculations for a system with gadolinium fuel pins. In this article, a sensitivity and uncertainty analysis (S/U) has been performed to investigate the effect of gadolinium odd isotopes nuclear cross sections data on the multiplication factor of some LWR fuel assemblies. The results have shown the importance of gadolinium odd isotopes in the criticality evaluation, and they confirmed the need of a re-evaluation of the neutron capture cross sections by means of new experimental measurements to be carried out at the n_TOF facility at CERN.
© F. Rocchi et al., published by EDP Sciences, 2017
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