Molybdenum release from high burnup spent nuclear fuel at alkaline and hyperalkaline pH

This work presents experimental data and modelling of the release of Mo from high-burnup spent nuclear fuel (63 MWd/kgU) at two different pH values, 8.4 and 13.2 in air. The release of Mo from SF to the solution is around two orders of magnitude higher at pH = 13.2 than at pH = 8.4. The high Mo release at high pH would indicate that Mo would not be congruently released with uranium and would have an important contribution to the Instant Release Fraction, with a value of 5.3%. Parallel experiments with pure non irradiated Mo(s) and XPS determinations indicated that the faster dissolution at pH = 13.2 could be the consequence of the higher releases from metallic Mo in the fuel through a surface complexation mechanism promoted by the OH- and the oxidation of the metal to Mo(VI) via the formation of intermediate Mo(IV) and Mo(V) species.

GARCÍA GÓMEZ Sonia;  GIMÉNEZ Javier;  CASAS Ignasi;  LLORCA Jordi;  DE PABLO Joan;  MARTÍNEZ TORRENTS Albert;  CLARENS Frederic;  KOKINDA Jakub;  IGLESIAS Luis;  SERRANO PURROY Daniel; 

2024-01-31

KOREAN NUCLEAR SOC

JRC136213

1738-5733 (online),   

https://www.sciencedirect.com/science/article/pii/S1738573323003868?via%3Dihub,    https://publications.jrc.ec.europa.eu/repository/handle/JRC136213,   

10.1016/j.net.2023.08.024 (online),