Optimization of a simplified radiochemical method based on Sr®-resin for measurement of 90-Sr in nuclear waste
Résumé
As a caracteristic fission product with a half-life of 28.8 years, Sr-90 must be quantified in nuclear waste. Prior to its nuclear measurement, it is necessary to separate it from its matrix and interferents with radiochemical method. The extraction chromatographic resin, Sr-resin®, developed by Eichrom in the 1990s is widely applied. Its efficiency has been demonstrated for a wide range of samples even if pre-treatments are necessary depending on the nature of the sample. For nuclear waste, difficulties can be encountered especially with samples with high Pu content. A precipitation with ammonia can be used but this can lead to a Sr loss depending on the experimental conditions (ex: digestion step with HF acid or not) and interferents present. In this presentation, the robustness of an alternative pre-treatment using TRU-resin® will be highlighted. It has been proven to be efficient on all the nuclear waste samples investigated in the study, such as effluent, sludge, resin and concrete, even if they contain high Pu amount. Moreover, in this method, a plastic scintillation resin for Sr-90, PS-resin, developed by Bàgan et al., has been tested for nuclear waste samples. The advantages of this new resin is to reduce time of separation by eliminating elution step but mainly to avoid the use of scintillation cocktails. Due to their high toxicity, they are concerned by the REACH regulation and their implementation will become complicated in a near future. The PS-resin could be a suitable alternative for Sr-90 measurement by scintillation counting.