RESUMO
Determining long-lived radionuclide concentrations in radioactive waste has fundamental implications for the long-term management of storage sites. This paper focuses on the measurement of low (129)I contents in ion exchange resins used for primary fluid purification in Pressurised Water Reactors (PWR). Iodine-129 concentrations were successfully determined using Accelerator Mass Spectrometry (AMS) following a chemical procedure which included (1) acid digestion of resin samples in HNO3/HClO4, (2) radioactive decontamination by selective iodine extraction using a new chromatographic resin (CL Resin), and (3) AgI precipitation. Measured (129)I concentrations ranged from 4 to 12 ng/g, i.e. from 0.03 to 0.08 Bq/g. The calculation of (129)I/(137)Cs activity ratios used for routine waste management produced values in agreement with the few available data for PWR resin samples.
Assuntos
Radioisótopos de Césio/análise , Radioisótopos do Iodo/análise , Resinas de Troca Iônica/análise , Resíduos Radioativos/análise , Descontaminação , Espectrometria de Massas/métodosRESUMO
The radiological characterisation of nuclear waste is essential for managing storage sites. Determining the concentration of Long-Lived RadioNuclides (LLRN) is fundamental for their long-term management. This paper focuses on the measurement of low (41)Ca concentrations in ions exchange resins used for primary fluid purification in Pressurised Water Reactors (PWR). (41)Ca concentrations were successfully measured by Accelerator Mass Spectrometry (AMS) after the acid digestion of resin samples, followed by radioactive decontamination and isobaric suppression through successive hydroxide, carbonate, nitrate and final CaF2 precipitations. Measured (41)Ca concentrations ranged from 0.02 to 0.03 ng/g, i.e. from 0.06 to 0.09 Bq/g. The (41)Ca/(60)Co activity ratios obtained were remarkably reproducible and in good agreement with the current ratio used for resins management.
Assuntos
Radioisótopos de Cálcio/análise , Espectrometria de Massas/métodos , Resíduos Radioativos/análise , Precipitação Química , Radioisótopos de Cobalto/análise , Descontaminação , Resinas de Troca Iônica , Espectrometria de Massas/estatística & dados numéricos , Centrais Nucleares , Radioisótopos de Potássio/isolamento & purificação , Reprodutibilidade dos TestesRESUMO
A new value of (79)Se half-life was determined by the means of inductively coupled plasma mass spectrometry (ICP-MS) and liquid scintillation counting (LSC) on a sample source isolated from a nuclear reprocessing solution. The procedure used to extract Se from the complex sample solution consisted in liquid-liquid extraction and ion exchange chromatographic methods. The concentration of (79)Se was measured using ICP-MS coupled with electro-thermal vaporisation to eliminate potential isobaric interferences. The activity was measured using LSC after gamma-ray spectrometry to check the contribution of residual radioactive contaminants. From these results, the half-life of (79)Se was found to be 3.77 (19) x 10(5) a.