Mass-spectrometric determination of iodine-129 using O2–CO2 mixed-gas reaction in inductively coupled plasma tandem quadrupole mass spectrometry

Development of an optimised method for measurement of iodine-129 in decommissioning wastes using ICP-MS/MS

“…In a study by Matsueda et al , a combination of O 2 and CO 2 was used for 129 Xe and 127 I 1 H 2 removal, achieving a ratio of ( m / z 129 background/ 127 I of 4.6 × 10 −10 (ref. 16)). The tandem ICP-MS/MS setup has been effectively used in the measurement of 129 I/ 127 I in rainwater, and Fukushima-contaminated soil samples following pyrohydrolysis and solvent extraction sample preparation.…”

“…One radionuclide of interest is the long-lived ssion product 129 I (half-life 16.1(7) × 10 6 years), which is produced by thermal neutron induced ssion of 235 U (0.706% yield), spontaneous ssion of 238 U, and neutron activation of 128 Te. 2 Iodine-129 is also produced naturally by cosmic-ray spallation of Xe isotopes in the atmosphere.…”

“…Free release of waste requires conrmation that 129 I activities are below the out-of-scope limit of 0.01 Bq g −1 (1.57 ng g −1 ). 10 This has been achieved in previous studies focused on environmental matrices including water, soil, plants, milk and in ambient air as particulate and gaseous 129 I, [11][12][13][14][15][16][17] with relatively limited measurement of decommissioning wastes.…”

“…Accelerator mass spectrometry (AMS) has been the most sensitive technique applied to date, with measurement of 129 I/ 127 I ratios in the 10 −13 -10 −10 range. 2,12,16,17,[20][21][22][23][24] Limitations to AMS for routine nuclear waste characterisation are the relatively high cost, limited availability and analytical exibility.…”

“…Accurate measurement of 129 I by ICP-MS is complicated by isobaric interferences from 129 Xe (26.40% abundance) present as an impurity in the argon plasma gas, multiple plasma and reaction cell-derived polyatomic interferences including 127 I 1 H 2 , 97 Mo 16 O 2 , 113 Cd 16 O, 115 In 14 N and 89 Y 40 Ar, and tailing from high concentrations of stable 127 I (100% abundance), which cannot be chemically separated. 15,27,28,30,31,40 Isobaric 129 Xe has been corrected by monitoring 131 Xe (4.07% abundance) and using the known 129 Xe/ 131 Xe isotopic ratio, 26,27,31 or suppressing the signal using a combination of collision and reaction gases…”