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

The combination of thermal ionization mass spectrometry and alpha spectrometry is employed for the routine isotope ratio measurements of plutonium. A rapid and reliable method based only on TIMS has been proposed for the isotope ratio analysis of plutonium including 238 Pu/ 239 Pu for the routine chemical quality control of nuclear fuel samples. The use of a membrane for sample loading and systematic study of ion source chemistry of uranium and plutonium resulted in a reduction in overall sample preparation and isotopic analysis time from about 15 h to 3-4 h. N , N ′-Dioctyl-α-hydroxyacetamide (DOHA) in a room temperature ionic liquid (RTIL) viz. 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C 6 mim][NTf 2 ] immobilized in a polypropylene membrane was used for the purification of plutonium from nuclear fuel samples with U : Pu amount ratios up to 1000. The methodology is based on the isotope ratio measurements of 240 Pu/ 239 Pu, 241 Pu/ 239 Pu and 242 Pu/ 239 Pu at low vaporization filament currents and 238 Pu/ 239 Pu at high vaporization filament currents for the elimination of isobaric interference at m / z 238 a.m.u., due to uranium. The accuracy and precision of 238 Pu/ 239 Pu obtained by the proposed TIMS based method are better than 0.8%, which is comparable to those obtained by alpha spectrometry. Alternative filament regulation approach for TIMS alone measurement of 238 Pu/ 239 Pu in comparison to conventional TIMS and alpha spectrometry for routine plutonium isotope ratio determination.