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Euratom Project Award for Dr. Philip Kegler et al.

for the high scientific level and orginality of the contribution in the EURATOM Project Poster Session

The poster entitled

Chromium doped UO2-based model systems: The model materials for the study of the matrix corrossion of modern spent nuclear fuels.

by Dr. Kegler, P. (1); Dr. Klinkenberg, M. (1); Dr. Bukaemskiy, A. (1); Dr. Deissmann, G. (1); Prof. Bosbach, D. (1); Prof. Alekseev, E. (1); Dr. Delville, R. (2); Dr. Cachoir, C. (2); Dr. Mennecart, T. (2); Dr. Lemmens, K. (2); Prof. Verwerft, M. (2)

(1) Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research -Nuclear Waste Management and Reactor Safety, Germany;
(2) Belgian Nuclear Research Centre, BE-2400 Mol, Belgium

received the Euratom Project's Poster Award at the EURADWASTE ’19 conference, held from June 4 to 7 in Pitesti, Romania.

C o n g r a t u l a t i o n s !

Abstract: The current efforts to improve fuel performance in nuclear power generation resulted in an increased utilization of a variety of new types of light-water reactor (LWR) fuels such as Cr-, Al-, and Si-doped fuels. The corrosion behaviour of these types of fuels in the systems relevant to deep geological waste repository has hardly been studied so far. Experiments with spent nuclear fuel (SNF) cannot entirely unravel all of the various concurring dissolution mechanisms due to the chemical and structural complexity of spent nuclear fuel and its high beta-and gamma radiation field and technical restrictions allowing only for a very limited number of experiments. Therefore, within the EU-DISCO project ( experiments on irradiated Cr-doped fuels are complemented with systematic dissolution studies carried out with carefully prepared and characterized, simplified UO2-based model materials. A bottom-up approach is followed to understand how the addition of Cr-oxide into the fuel matrix affects SNF dissolution behaviour under repository relevant conditions.Here, we present recent results on the development and optimization of the process steps for a wet-chemical route to produce pure reference UO2, Cr-doped UO2 as well as Cr-and alpha doped (238Pu) pellets. A wet chemical route was favoureddue to the very low doping levels of 238Pu required to mimic fuel ages between 1,000 and 10,000 a later in DISCO. Process optimisation was achieved by a systematic investigation of various process parameters such as calcination temperature and pelletisation pressure. Syntheses were performed by co-precipitation and wet-coating methods and had to be free of any grinding steps to be applicable in a dedicated glove box. In order to provide insights into the effects of the material's micro-structure on the dissolution behaviour (e.g. regarding the larger grain size in doped fuels and contributions of grain boundaries) the model materials are produced in form of sintered pellets. The microstructure (grain size, grain orientation) of and dopant distribution (i.e. either in solid solution within the UO2matrix or segregated on grain boundaries) in the model materials were characterised using various methods (e.g. SEM, EBSD, EMPA, ToF-SIMS, XRD).