Isotope dilution gamma spectrometry for Pu using low energy photons

Abstract

Gamma spectrometry / Isotope dilution / HPGe / Plutonium / Isotopic composition / ConcentrationSummary. Isotope dilution gamma spectrometry (IDGS) for determination of the Pu concentration, using high resolution gamma-ray spectrometry (HRGS) in the 40-150 keV energy range, is developed and described. The methodology involves purification of Pu by an anion exchange procedure, followed by the determination of Pu isotopic composition using HRGS. For isotope dilution, a precalibrated power reactor grade Pu (∼ 70 at. % 239 Pu) solution from an Indian PHWR was used as a spike for research reactor grade Pu (∼ 95 at. % 239 Pu) samples and vice versa. Changes in 240 Pu/ 239 Pu (45.24 keV/51.62 keV) and 241 Pu/ 239 Pu (148.57 keV/129.29 keV) activity ratios in the spiked samples were determined by gamma spectrometry. Using the atom ratios calculated from the measured activity ratios, the concentration of Pu in the sample was calculated using two different efficiency calibration methods. The isotopic composition and concentration of Pu samples both from power reactor and research reactor grade agreed well with the values obtained by isotope dilution-thermal ionization mass spectrometry. The present method also shows the superiority of using the 240 Pu/ 239 Pu atom ratio against the 241 Pu/ 239 Pu atom ratio in IDGS with respect to the accuracy and precision.

An isotope dilution mass spectrometry overview: tips and applications for the measurement of radionuclides

“…For applications where speciation is important, various reports have demonstrated the compatibility of the ID method with techniques such as laser ablation (LA)-ICP-MS, gas chromatography (GC)-MS, high-performance liquid chromatography (HPLC)-ICP-MS, gamma spectrometry, etc. 281–285…”

Rapid and precise determination of the 238Pu/239Pu isotope ratio using thermal ionization mass spectrometry

“…[1][2][3] Generally, methods such as alpha/gamma spectrometry, thermal ionization mass spectrometry (TIMS) and inductively coupled plasma mass spectrometry (ICPMS) are used for the determination of the isotope ratio of plutonium. [4][5][6][7][8][9][10][11][12] In order to acquire reliable data on the isotope ratio measurement of plutonium as a part of quality control for the day-to-day activities at commercial scale nuclear power plants, non-destructive analysis techniques such as gamma spectrometry are preferred. However, the measurement precision of gamma spectrometric methods for the isotope ratio of plutonium is limited to 2-5% because of the low abundance of gamma rays in plutonium isotopes and the complex nature of the spectral region of interest.…”

“…Another limitation of gamma spectrometry is the requirement of handling several milligrams of plutonium bearing samples as a result of the low abundance of gamma rays emitted by Pu isotopes. 12 Alpha spectrometry is widely used for the determination of isotopic composition of Pu samples, though precision of the technique is largely affected by the poor energy resolution, typically 15-20 keV at 5.50 MeV, depending on the characteristics of the detector and quality of the alpha source, and also by the degradation of the higher energy peak at 5.50 MeV ( 238 Pu) in the region of the lower energy peak at 5.16 MeV ( 239 Pu and 240 Pu). [13][14][15][16][17][18] Though mass spectrometric techniques are known to generate results with excellent precision and accuracy, determination of 238 Pu by TIMS/ICP-MS is usually not recommended.…”

Chemically selective polymer substrate based direct isotope dilution alpha spectrometry of Pu

“…The uncertainties at different steps can be minimized using an isotope dilution or standard addition with appropriate radiotracer coupled with a suitable radiometric technique [15][16][17][18][19]. Though multistep hybrid methods are highly precise and accurate, the time required for obtaining results is a bottleneck particularly for emergency preparedness as well as for risk assessment of contaminated areas resulting from nuclear weapon tests, nuclear accidents, and the discharge of nuclear waste.…”