ISOTOPIC ABUNDANCE MEASUREMENTS ON SOLID NUCLEAR-TYPE SAMPLES BY GLOW-DISCHARGE MASS-SPECTROMETRY

A double-focusing Glow Discharge Mass Spectrometer (GDMS) installed in a glovebox for nuclear sample screening has been employed for isotopi c measurements. Isotopic compositions of zirconium, silicon, lithium, boron, uranium and plutonium which are elements of nuclear concern hav e been determined. Interferences arising from the matrix sample and th e discharge gas (Ar) or each or these elements are discussed. The GDMS results are compared with those from Thermal Ionization Mass Spectrom etry (TIMS). For boron and lithium al mu g/g-ng/g levels, the two meth ods gave results in good agreement. In samples containing uranium the isotopic composition obtained by GDMS was in agreement with those from TIMS independently of the enrichment. Attempts for the determination of plutonium isotopic composition were also made. In this case, due to the interferences of uranium at mass 238 and americium at mass 241, t he GDMS raw data are complementary with those values obtained from phy sical non-destructive techniques.