Determination of oxygen/uranium ratio in irradiated uranium dioxide based on dissolution with strong phosphoric acid

Oxygen stoichiometry shift of irradiated LWR-fuels at high burn-ups: Review of data and alternative interpretation of recently published results

“…In this respect, the modified spectrophotometric method by Kihara et al [19], which has been frequently utilized for U-Me-O systems [18], and other chemical methods likewise based in the determination of the U 4+ /U 6+ ratio in solution (e.g. flow coulometry, polarography), as those early used for UO 2+x [62] and already put in practice for low burn-up irradiated LWRfuels [20,21], may be worthwhile to be explored for the high burn-up fuels.…”

“…Also, determinations of the oxygen stoichiometry via chemical methods (e.g. spectrophotometry, coulometry) in spent LWR-fuels had been up to now rare, with only two known cases in the open literature at burn-ups of 2.5 [20] and 34 GWd/tM [21]. For this reason, a reasonable way to estimate the oxygen stoichiometry of the irradiated fuel remains the comparison of the measured oxygen potential, e.g.…”

Development of an electrochemistry apparatus for the heaviest elements

“…The electrochemistry apparatus developed is based on the flow electrolytic cell [13][14][15]. A cross sectional view of the apparatus is illustrated in Fig.…”

“…The apparatus is based on a flow electrolytic cell [13][14][15] equipped with a chemically modified electrode [16][17][18][19] that is quite suitable for rapid and efficient chemical experiments of the heaviest elements. A chemically modified method was applied to separate ions of interest in different oxidation states on the electrode.…”

Development of gamma spectrometric method for the determination of thorium in phosphoric acid solution

“…Since 232 Th is a long lived isotope, alpha spectrometric determination gives erroneous results due to self-absorption effects of thick alpha sources and suffers [5][6][7][8][9]. Irradiated uranium dioxide fuel dissolution in strong phosphoric acid [10] and determination of uranium in phosphoric acid using neutron activation analysis [11] were reported. Therefore, dissolution of sintered ThO 2 using strong H 3 PO 4 was studied by autoclave and microwave energy heating.…”