AGR fuel corrosion: SIMFUEL-based method development in preparation for electrochemical studies of real spent AGR nuclear fuel electrode

Electrochemical corrosion of lower-activity spent fuel simulants, SIMFUELs, has been investigated in support of on-going analogous studies of a real AGR spent nuclear fuel electrode. Two electrode coupling methods have been investigated, to study the coupling of a sample of 25 GWd/tU SIMFUEL pellet to a sample of 20/25/Nb AGR cladding to replicate the real AGR fuel electrode setup. Method-1 involves coupling of individual standalone electrodes, while Method-2 involves coupling of the cladding and SIMFUEL within the same electrode. For both coupling methods, open circuit potentials and linear sweep voltammetry measurements were conducted in electrolyte solutions containing 30 μmol/m 3 NaCl, dosed with NaOH to pH 8, 11.4 and 12.5. Resultant data were compared with single-component studies of SIMFUEL and cladding electrodes. Method-1 presents inconsistent electrochemical behaviour which we attribute to pitting/crevice corrosion effects on the cladding, whereas Method-2 shows a consistent behaviour that most resembles that of the SIMFUEL component. Graphical abstract