Abstract
We propose a model describing the HBS formation and the progressive intra-granular xenon depletion in UO2. The HBS formation is modeled employing the Kolmogorov-Johnson-Mehl-Avrami (KJMA) formalism for phase transformations, which has been fitted to experimental data on the restructured volumetric fraction as a function of the local effective burnup. To this end, we employed available experimental data and novel data extracted in this work. The HBS formation model is coupled to a description of the intra-granular fission gas behavior, allowing to estimate the evolution of the retained xenon in order to consistently compute fission gas retention and its effect on the fuel matrix swelling. The satisfactory agreement of the model predictions to experimental data and state-of-the-art models’ results, in terms of both xenon depletion and fuel matrix swelling as a function of the local burnup, paves the way to the inclusion of the model in fuel performance codes.
Highlights
In nuclear fuels, where substantial irradiation damage is accompanied by a limited possibility of recovering the damage, a dramatic change occurs to the as-fabricated microstructure
We implemented the model in the SCIANTIX code [58], a stand-alone, open-source, meso-scale computer code developed at Politecnico di Milano, aimed at simulating fission gas behavior in nuclear fuel and conceived for coupling/inclusion in fuel performance codes
We present the results of the presented model, comparing the predictions, in terms of local xenon retention as a function of effective burnup, to available experimental data and to several models available in the open literature and conceived for application to fuel performance codes (FPC)
Summary
In nuclear fuels, where substantial irradiation damage (e.g., local burnups above 45/50 MWd kgUÀ1) is accompanied by a limited possibility of recovering the damage (i.e., local temperatures below 1000 C), a dramatic change occurs to the as-fabricated microstructure. Lassmann et al [41] developed a pragmatic, empirical model to account for intra-granular xenon depletion, decreasing its concentration with an exponential law as a function of burnup (not considering the effect of temperature) and needing as an input parameter the HBS formation threshold This approach represents the legacy treatment of HBS in the TRANSURANUS FPC code [42]. The consistent description of the kinetics of intra-granular fission gas behavior and fuel gaseous swelling, together with the formulation grounded on a physical basis e for both formation and fission gas depletion e results in a model which founds a wider applicability, in terms of operating conditions and fuel types, than state-of-the-art models available in fuel performance codes.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
