Within the nuclear community, the benchmark for isotope ratio measurements is still TIMS (Thermal Ionization Mass Spectrometry).[i] RCA performs isotope ratio measurements by means of TIMS as a valuable part of fuel qualification and post-irradiation examination (PIE). TIMS is therefore a crucial technique for destructive radiochemical analysis and used for, amongst others, burn-up determinations, spent fuel characterization programmes, and research into new/alternative fuel types (e.g. thorium based fuels, reprocessed uranium containing fuels). The advantage of TIMS is its high precision, giving relative measurement uncertainties for Pu and U assays (using isotope dilution, IDMS) of 0.25 – 0.35 % (k = 2).
Description
The two objectives of the project will be to develop analytical methods:
1.
to measure isotopic ratios of the lanthanides Nd, Sm, Eu, Gd, Dy by single-collector ICP‑SF‑MS
Recently published improvements in measurements of the isotopic abundances of certain lanthanides (e.g. Nd, Dy) has reduced the uncertainties of some of the natural lanthanide materials we use as spikes in IDMS. Their contributions to the final uncertainties on the lanthanide assays were always large. By taking advantage of these now smaller contributions, we aim to offset the inferior precision (compared to TIMS) of ICP SF MS isotope ratios, with the goal of obtaining fit-for-purpose measurement results more rapidly than has been the case with TIMS analyses. The focus here is on optimizing the measurement conditions and requires a comprehensive understanding of isotope ratio measurements. Method development can be done on inactive single lanthanides, but real samples will also be analysed as the final proof of how well the analytical methods perform. The samples used will be lanthanide fractions separated off-line (as is done for TIMS) followed by batch analysis.
2.
to measure radionuclides (including, but not limited to) Ra-226, Th-229, Th-230 by single-collector ICP-SF-MS, including the development of separation schemes for analytical size quantities
The determination of Ra-226 in solid environmental samples and natural waters , including by ICP‑MS, has been discussed by Larivière et al [i]. Various commercial resins (Ln-Spec, DGA, MnO2) are available for precipitation and/or separation , for example Triskem [ii] and Eichrom, [iii] some of which are already used in RCA for other purposes. TEVA resin can be used to preconcentrate thorium in nitric acid media before elution in dilute HCl media. TEVA is also relevant for Np-237. However, the applications of these resins and measurement techniques have been mainly towards low activity level samples, where often the challenge is in reaching an extremely low detection limit, since the samples contain essentially none of these radionuclides. The UTEVA resin has been used to separate uranium, even at concentrations much higher than found in environmental samples. But, in general, the activities being dealt with are rather low. The aim of this work is to expand upon and develop the use of this wide range of commercially available chromatographic resins towards samples containing considerably higher activities of these radionuclides, as might be potentially encountered in irradiated fuels, alternative fuel cycle fuels. The study of these different resins to identify and develop the separation strategies will be performed in partnership with the radioanalytical experts within RCA to ensure optimal applicability.
Nr of positions available : 1
Research Fields
Engineering
Career Stage
Early stage researcher or 0-4 yrs (Post graduate)
Research Profiles
First Stage Researcher (R1)