Application of ICP-MS radionuclide analysis to “Real World” samples of department of Energy radioactive waste

Abstract

Disposal of Department of Energy (DOE) radioactive waste into repositories such as the Waste Isolation Pilot Plant (WIPP) and the Nevada Test Site (NTS) requires characterization to ensure regulatory and transportation requirements are met and to collect information regarding chemistry of the waste for processing concerns. Recent addition of an inductively coupled plasma quadrupole mass spectrometer in a radioactive contaminated laboratory at the Oak Ridge National Laboratory (ORNL) has allowed the evaluation of advantages of using ICP-MS over traditional techniques for some of these characterization needs. The measurement of long-lived beta nuclides (i.e.⁹⁹Tc) by ICP-MS has resulted in improved detection limits and accuracy than the traditional counting techniques as well as reducing the need for separation/purification techniques which increase personnel exposure to radiation. Using ICP-MS for the measurement of U isotopes versus the traditional Thermal Ionization Mass Spectrometer (TIMS) technique has reduced cost and time by more than half while still maintaining the needed accuracy to determine risk assessment of the waste tanks. In addition, the application of ICP-MS to ORNL waste tank characterization has provided the opportunity to estimate non-routine radionuclides (i.e.¹³⁵Cs and¹⁵¹Sm) and non-routine metals (i.e. Li, Ti, rare earths, etc.) using a rapid low cost screening method. These application methodologies and proficiencies on ORNL waste samples are summarized throughout the paper.