Determination of traces of neptunium-237 in enriched uranium solutions using inductively coupled plasma mass spectrometry

Abstract

A procedure using inductively coupled plasma mass spectrometry (ICP-MS) has been developed for determining traces of 237Np in isotopically enriched solutions of U. The chemical treatment of the samples consists of: extracting 237Np in a 1 mol dm-3 solutions of nitric acid using 0.5 mol dm-3 thenoyltrifluoroacetone in xylene, leaving 99% of the U matrix in the aqueous phase; re-extracting 237Np in 10 mol dm-3 nitric acid; heating the extracted solution to white fumes in order to remove the excess of acid; and diluting the resulting solution with 2% HN03. Optimization of the analytical parameters involved suppressing the spectral overlap between 237Np and 238U. By applying an additive continuous tension to the quadrupole on m/z 237 only, the interfering part of the 238U peak is eliminated and good resolution can be achieved between m/z 237 and 238, if the concentration of U is less than 100 mg dm-3. The operating conditions adopted result from a compromise between resolution and sensitivity. The suppression of the analyte signal, arising from U at a high concentration, is corrected for by adding an internal standard to the calibration and measuring solutions. The detection limit is about 0.005 pg of Np per gram of U, for an initial sample of 1 g of U and an additive continuous tension of 7.5 V. The analytical performance of ICP-MS is compared with that of a-spectrometry. The radiochemical determination of 237Np involves a tedious pre-treatment and measurement procedure. In contrast, ICP-MS appears to be a good alternative to a-spectrometry (for the determination of long-lived radionuclides) because of its simplicity, accuracy, excellent detection limits and rapidity of analysis.

Determination of Transuranium Isotopes (Pu, Np, Am) by Radiometric Techniques: A Review of Analytical Methodology

“…TTA was used as early as 1947 by Magnusson. 102 Neptunium was reduced with ferrous sulfamate and hydroxylamine in 1 M HCl, 103 ferrous sulfamate in 1 M HNO 3 , 104 hydroxylamine in 1 M HNO 3 , 105 or ferrous ions and hydroxylamine in 1 M HNO 3 . 106 Neptunium retained from 1 M HNO 3 or HCl on about 0.5 M TTA in xylene was later stripped with 8 to 10 M HNO 3 .…”

“…Several papers have been published on the comparative evaluation of radiometric and ICPMS techniques. 20,27,39,42,73,105,112,120,147,193,197,225 Although mass spectrometric techniques have generally low sensitivity for the "short-lived" 241 Am, recently high sensitivity SF-ICPMS has become available for 241 Am analysis and a few papers have been published on the comparative evaluation of R spectrometry and ICPMS. 50,87,161 The detection limit of the SF-ICPMS, about 1 fg/mL, 100 equals about 0.1 mBq/mL 241 Am, which is in the range of the sensitivity of R spectrometry for 241 Am if 0.1 mBq Am is concentrated in 1 mL of sample solution.…”

Plasma source mass spectrometry for radioactive waste characterisation in support of nuclear decommissioning: a review

“…In essence, ions are systematically transferred from the plasma to the detector in a highly controlled electrostatic eld within a dynamically increasing vacuum which was followed several years later by early measurements of radionuclides. [22][23][24][25][26][27] The rapidity of ICP-QMS and ability to simultaneously measure multiple radionuclides were established as major advantages compared to alpha and beta counting techniques, [28][29][30] whilst the robustness of the technique better-suited to routine analysis compared to alternative mass spectrometric techniques, specically thermal ionization mass spectrometry (TIMS). 30,31 Additionally, sample introduction into ICP-QMS could be achieved from a solid, liquid or gas.…”

“…32 Early studies were critical in establishing the uncertainties associated with radionuclide detection by ICP-QMS and considerations for instrumental setup. This included sample pre-treatment prior to sample introduction to improve detection limits, 23 the impact of sample introduction on sensitivity and interference removal, 27,29,[33][34][35] the importance of abundance sensitivity in removing peak tailing, 26 and the use of internal standardization to account for matrix effects. 36 As well as advances in quadrupole instrument design, the development of other ICP-MS setups including sector eld (ICP-SFMS), collision/reaction cell instruments and multiple detector systems (MC-ICP-MS) has increased the sensitivity, interference-removal capability, and the number of nuclides measurable (Fig.…”

Characterization of nuclear fuels by ICP mass-spectrometric techniques

“…Advantages are the low detection limits for a large number of elements combined with the ability to analyze the isotopic composition of the elements and the applicability of the techniques for measuring stable as well as radioactive nuclides with similar sensitivity. Among these techniques, ICP-MS and thermal ionization mass spectrometry (TIMS) are the most frequently applied methods and are also used for routine measurements in the nuclear industry [2][3][4][5][6][7]. For example, the American Society for Testing and Materials (ASTM) has developed and published ICP-MS atom counting standard methods for the determination of many long-lived actinides and their daughter products [8][9][10][11].…”