Development and comparison of two high accuracy methods for uranium concentration in nuclear fuel: ID-TIMS and K-edge densitometry

Abstract

This study compares the two analytical methods for uranium concentration determination with high accuracy in uranium pellet: K-edge densitometer (KED) and the isotope dilution with Thermal Ionisation Mass Spectrometry measurements (ID-TIMS). Both techniques are compared in terms of time, generated radioactive effluent, simplicity, uncertainty estimation and detection limit. ID-TIMS shows lower detection limit and uncertainties than KED. However, the KED analysis time is shorter and generates less effluent. Both techniques were used for metrological analysis of uranium concentration in nuclear materials. The optimization of sample spike mixture isotope ratio for ID-TIMS to decrease uncertainties is also discussed.

A combined TIMS and ICP-MS study for Th0.5Np0.5O2 thorium neptunium mixed oxide analysis

“…The uncertainty calculation of Th mass fraction, determined by ID-TIMS, was detailed previously for uranium [10] and used here for Th. It was estimated by combining the uncertainties from each term of the isotope dilution equation (Eq.…”

“…TIMS measurements coupled to Isotope Dilution (ID-TIMS) is a powerful methodology for a highly accurate determination of actinides mass fraction (i.e. measurement trueness and precision) [6,10,11]. The principle of ID is adding to the sample a known amount of spike with a known mass fraction and a known isotopic composition (that must be different than that of the sample analyzed) [12,13].…”

Optimization of double isotope dilution

“…the minimum mass fraction uncertainty), the mixture between the sample and the spike must be prepared carefully. The ID-TIMS require an optimal mixture isotope ratio which can be determined theoretically [15].…”

“…Isotope dilution (ID) is the main methodology used in mass spectrometry to determine accurately the mass fraction determination of an analyte in a sample, as it is a reference calibration method. 14–17 The ID principle is to mix a known amount of a sample, with a known isotope composition, with a spike solution containing the same analyte as the sample but with a different isotope composition. This solution is called the (sample–spike) mixture and its isotope ratio reflects the sample analyte mass fraction.…”

“…The ID-TIMS requires an optimal mixture isotope ratio which can be determined theoretically. 15 The mixture is then prepared to obtain a mixture isotope ratio as close as possible to the theoretical one. The ratio between two isotopes of two elements is then calculated using the mass fraction of the two elements determined with the ID methodology, the isotope abundances and the molar masses.…”