Plutonium isotope ratio measurements

Table 8.8 Applications of ICP-MS and LA-ICP-MS for plutonium isotope ratio measurements.

Being a valuable isotope analytical technique in routine work for high precision isotope ratio measurements, TIMS is applied in many laboratories worldwide for isotope ratio measurements especially for elements with ionization potentials < 7 eV,7 such as alkali and earth alkali elements, rare earth elements (REE), uranium and plutonium. It is advantageous that the interference problem occurs relatively seldom in TIMS, especially if the negative thermal ionization technique for elements and molecules with electron affinities > 2eV (Ir, W, Os, Re, Pt, Cl and Br) is applied. TIMS with multiple ion collectors achieves a precision of up to 0.001 % thus permitting the study... 

Jakopic R, Richter S, Kuehn H, Aregbe Y (2008) Isotope ratio measurements of pg-size plutonium samples using TIMS in combination with the Multiple Ion Counting and filament carburization, INIS-FR-09-0127. In Atalante 2008 nuclear fuel cycle for a sustainable future, Montpellier, France, 19-23 May... 

For elements with low natural abundance, it can sometimes be found that the isotope ratio measurement limits the LOD. But even for naturally low abundant elements such as uranium, plutonium, and the PGEs, the corresponding isotope intensities are often subject to interferences by small contributions from polyatomic ions [25, 26]. Such interferences simulate an additional blank value, which is still covered by the blank measurement, at least if the corresponding procedure with the blank solution gives rise to the same polyatomic ions as the real sample. 

Becker,J. S., and Dietze, H.-J. (1999). Precise isotope ratio measurements for uranium, thorium and plutonium by quadrupole-based inductively coupled plasma mass spectrometry. Fresenius J. Anal. Chem. 364(5), 482. 

Plutonium (Pu) is an artificial element of atomic number 94 that has its main radioactive isotopes at 2 °Pu and Pu. The major sources of this element arise from the manufacture and detonation of nuclear weapons and from nuclear reactors. The fallout from detonations and discharges of nuclear waste are the major sources of plutonium contamination of the environment, where it is trapped in soils and plant or animal life. Since the contamination levels are generally very low, a sensitive technique is needed to estimate its concentration. However, not only the total amount can be estimated. Measurement of the isotope ratio provides information about its likely... 

Plutonium at a concentration level of 0.3 pgg" 1 in contaminated soil samples was determined directly by LA-ICP-SFMS using the isotope dilution technique and 240Pu/239Pu isotope ratios were measured by Boulyga et al.126... 

For tracing plutonium yield, Pu is available. The plutonium isotope peaks are measured with a Si diode and alpha-particle spectral analysis. The Pu activity is calculated from the product of the Pu activity and the Pu peak area ratio. The Pu activity includes any contribution from Pu because the energies of their peaks are almost identical. Other plutonium isotopes (except " Pu) are measured at the same time in terms of characteristic peak areas at the energies listed in Table 6.3. A mass spectrometer is used to separate Pu from " °Pu if they must be reported separately. As indicated in Table 6.3, the emitted gamma rays can be used for intense sources but are too weak for sensitive measurements. 

Betti (1996) and co-workers used GD-MS for sample screening in isotopic measurements of zirconium, silicon, lithium, boron, uranium, and plutonium in nuclear samples. The results obtained from the GD-MS were compared with results from thermal ionization mass spectrometry (TIMS). For boron and lithium concentrations from //g/g to ng/g levels, isotopic ratios determined by GD-MS were comparable to TIMS in terms of accuracy and precision. Uranium isotopic ratios determined by GD-MS were also in good agreement with values measured by TIMS with regards to accuracy. Chartier et al. (1999) used GD-MS to analyze erbium and uranium in molybdenum-uranium fuel samples. The ratio of 166Er to 238U was then compared to numbers determined by thermal ionization mass spectrometry. The ratio of erbium to uranium was accurate to within 3% of the number determined by TIMS. 

Oughton, D. H., Fifield, L. K., Day, J. P, Cresswell, R. C., Skipperud, L., Di Tada, M. L., Salbu, B., Strand, P, Drozcho, E., and Mokrov, Y. 2000. Plutonium from Mayak Measurement of isotope ratios and activities using accelerator mass spectrometry. Environ Sci Technol 34(10), 1938-1945. 

Quantities of plutonium-241, a beta-particle emitter, can be quantified from (1) assumed isotopic abundance ratios, (2) estimated in-growth of its progeny americion-241 by gamma spectrometry, or by (3) mass spectrometry (Bernhardt 1976). Americium-241 is produced from the beta decay of plutonium-241 and, therefore, can be used to indirectly measure the concentration of plutonium-241 (Metz and Waterbury 1962). Direct determination of plutonium-241 by measurement of its low energy beta-particle decay has been reported using liquid scintillation analysis (Martin 1986). 

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