Complete dissolution of solid matrices using automated borate fusion in support of nuclear decommissioning and production of reference materials

Abstract

Accurate measurement of natural and anthropogenic radionuclide concentrations is of critical importance to end users in the nuclear sector to ensure correct classification prior to storage, recycling, reprocessing or disposal. Uncertainties in the characterisation of solid matrices and materials could lead to safety, quality and financial implications. Robust sample preparation methods are vital, in particular effective sample digestion, as under-estimated chemical yield recovery results in a corresponding under-estimation of activity levels. Borate fusion has been proven to effectively digest a range of complex sample matrices in the geosciences but is not used routinely elsewhere. In this study, we describe an automated procedure for borate fusion of multiple matrices encountered in nuclear decommissioning, containing diverse radionuclides over a range of activity concentrations. The impact of digestion flux, sample mass and sample to flux ratios are described, as well as the subsequent separation and measurement techniques. The results contribute to accurate and precise measurement of radionuclides in various matrices, as well as to characterisation of reference materials, providing greater confidence in nuclear industry programmes worldwide.

Capture and electrochemical conversion of CO2 in molten alkali metal borate–carbonate blends

“…[35][36][37] The viscosity of molten lithium borates under temperature gradients is determined by the ratio of optically opaque crystalline matrices and amorphous phases, both with the chemical formula of Li 2 B 5 O 9 . [35][36][37][38][39][40][41] The amorphous motif can have the structural form of a single tetrahedral boron connected to four oxygen atoms. The oxygen atoms are connected to the trigonal boron species to form a ring with the chemical formula of B 3 O 3 .…”

“…Alkali (e.g., primarily Li) meta-and tetraborates have been used extensively in a number of applications, primarily as fluxing components for X-ray fluorescence (XRF), atomic emission spectrometry and related analytical techniques. 34,35 Molten lithium Please do not adjust margins Please do not adjust margins tetraborate generally possesses a high viscosity and tends to solidify as a glass under small temperature gradients. [35][36][37] The viscosity of molten lithium borates under temperature gradients is determined by the ratio of optically opaque crystalline matrices and amorphous phases, both with the chemical formula of Li2B5O9.…”

“…34,35 Molten lithium Please do not adjust margins Please do not adjust margins tetraborate generally possesses a high viscosity and tends to solidify as a glass under small temperature gradients. [35][36][37] The viscosity of molten lithium borates under temperature gradients is determined by the ratio of optically opaque crystalline matrices and amorphous phases, both with the chemical formula of Li2B5O9. [35][36][37][38][39][40][41] The amorphous motif can have the structural form of a single tetrahedral boron connected to four oxygen atoms.…”

Development of 3H, 14C, 41Ca, 55Fe, 63Ni radiochemical analysis methods in activated concrete samples

“…A variety of alkaline fusion methods exist for a complete dissolution of, e.g., geological, environmental and nuclear decommissioning samples. These methods utilise sodium hydroxide [6,7], lithium borate [8,9], sodium peroxide [10,11] and similar alkaline compounds in different mixtures together with high temperature (most often over 600 °C) for complete destruction of even resistant silica minerals. In traditional methods, alkaline fusion is carried out in crucibles which are manually placed in and out of the oven.…”

“…However, sophisticated and safe instruments have been developed for this purpose during the last decades, which minimise the safety hazards of sample treatment. Modern fusion techniques also enable automated fusion processes [9]. In this study, preliminary tests were carried out according to Ref.…”