Determination of 63Ni and 55Fe in nuclear waste samples using radiochemical separation and liquid scintillation counting

Critical comparison of radiometric and mass spectrometric methods for the determination of radionuclides in environmental, biological and nuclear waste samples

“…However, due to the low energy of the Auger electrons (< 20 keV), the counting efficiency of LSC for radionuclides decaying by these processes is low (< 30%) [18][19]. Comparing with the GM counter, the background count rate is higher in LSC, the lowest count rate measured using the commercial Quantulus Ultra low-level LSC produced by Wallac, PerkinElmer is around 0.5 counts per minute (CPM) for the 3 H window and 1.5 CPM for the 99 Tc window while the background for the anticoincidence shielded GM counter may be as low as 0.1-0.2 CPM, this makes the detection limit of LSC is worse than using low level GM counters (Table 4).…”

“…The interest in the determination of 63 Ni and 59 Ni results from the characterization of radioactive wastes for the decommissioning and disposal of nuclear waste, and the use in a number of applications including cosmic radiation studies, biomedical tracing and neutron dosimetry (Table 1) [18,[155][156][157][158]. 63 Ni is a pure beta emitting radionuclide (Table 4), the radiometric methods including windowless gas flow GM counters, beta spectrometry with semiconductor detectors and LSC have been used for its determination.…”

“…Detection limits of 1 mBq and 8 mBq were reported for GM counter and silicon detector, respectively for 50 hours counting [163,164]. LSC has a high counting efficiency for 63 Ni (70%), it is therefore widely used for the determination of 63 Ni [18,[165][166][167][168][169], the reported detection limit of LSC is 14-37 mBq for 30-1000 minutes counting time [18,169]. A slightly higher detection limit of LSC results from the relatively high background count rate of LSC (3-10 CPM) compared to GM counting and silicon detector (0.2 CPM).…”

“…Chemical separation of 63 Ni is usually carried out by precipitating nickel as a hydroxide and then extracting the Ni-DMG (dimethyl glyoxime) complex using either solvent extraction or extraction chromatography, sometimes combined with an anion exchange step. A decontamination factor of 10 5 or higher was obtained using a combination of these methods [18]. Chemical separation does not separate 63 Ni from 59 Ni, but since both 63 Ni and 59 Ni are produced by thermal neutron reactions with stable nickel 62 Ni (3.65%) and 58 Ni (68.1%), the initial activity ratio of 63 Ni/ 59 Ni is around 100 or higher, which means that only 63 Ni is measured by LSC counting.…”

“…Table 4 Energies of β particles of the radionuclides and the detection limits of beta counting methods [15][16][17][18][19] Table 5 Comparison of X-ray spectrometry, LSC, RIMS, TIMS and AMS for the determination of 41 Ca Table 6 Comparison of X-ray spectrometry, GM counter, ion implanted silicon detector, LSC, and AMS for the determination of 63 Ni and 59 Ni Table 7 Comparison of radiometric and mass spectrometric methods for the determination of 90 Sr Table 8 Potential interfering species on mass 99 in ICP-MS Table 9 Comparison of radiometric and mass spectrometric methods for the determination of 99 Tc Table 10 Comparison of radiometric and mass spectrometric methods for the determination of 129 I Table 11 Comparison of radiometric and mass spectrometric methods for determination of 226 Ra and 228 Ra Table 12 Comparison of radiometric and mass spectrometric methods for the determination of isotopes of plutonium Fig. 1 Plot of the specific radioactivity (Bq/g) vs. half-life of the radionuclides listed in Table 1 Fig .…”