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Description
An important characteristic of spent nuclear fuel is its burnup, which is a measure of fissionable material consumption prior to fuel replacement. Isolation of lanthanides, most importantly neodymium, from spent nuclear fuel is necessary to determine the burnup experimentally. As an introduction, various ion chromatographic strategies for lanthanide isolation described in literature will be discussed briefly. In one approach, lanthanides are bound to a mixed-bed ion-exchange column and are eluted, with oxalic acid, as negatively charged oxalate complexes (e.g.[1]). The lanthanides elute sequentially in order of decreasing ionic radius, from La to Lu. In a second approach, a cation-exchange column containing sulfonic acid functional groups as active sites on the stationary phase, and a hydroxy carboxylic acid as mobile phase can achieve lanthanide separation (e.g.[2]). Lanthanides then elute in the opposite order to the first approach. Finally, reverse phase monolithic C-18 columns are a third type of chromatographic columns that can be used to separate lanthanides, provided these columns are first modified to dynamic ion-exchangers, by using e.g. camphor-10-sulfonic acid (e.g.[3]).
Secondly, an analytical method to isolate pure and complete fractions of neodymium, samarium, europium, gadolinium and dysprosium by means of high performance ion chromatography (HPIC) using a cation-exchange column and gradient elution with alpha-hydroxyisobutyric acid solutions of different concentrations and pH will be presented. Evaluation of intermediate precision and robustness against changes in pH of the eluent, lanthanide concentration and uranium matrix concentration indicated that the method proposed was reproducible. Eluent pH was identified as the most important parameter affecting the elution of the lanthanides. In addition, investigation of the elution behaviour of the most important fission and activation products and actinides indicated that in order to prevent the accumulation of cesium on the cation-exchange column, isocratic elution with a 1.0 M α-HIBA solution after elution of the lanthanides was required. Characteristics of the method presented will be discussed in relation to other studies dealing with the subject. Finally, sample preparation methods for removal of organic carbon prior to mass spectrometric analysis optimized by using acid digestion followed by UV photo-oxidation will be discussed. This presentation summarizes a recently published article [4].
References:
1. Perna L, Bocci F, Aldave de las Heras L, De Pablo J, Betti M (2002) Journal of Analytical Atomic Spectrometry 17 (9):1166-1171.
2. Goutelard F, Caussignac C, Brennetot R, Stadelmann G, Gautier C (2009) Journal of Radioanalytical and Nuclear Chemistry 282 (2):669-675.
3. Raut NM, Jaison PG, Aggarwal SK (2004) Journal of chromatography A 1052 (1-2):131-136.
4. Van Hoecke K, Bussé J, Gysemans M, Adriaensen L, Dobney A, Cardinaels T (2017) Journal of Radioanalytical and Nuclear Chemistry 314 (3):1727-1739.
