Evaluation of Measurements of 238Pu, 239Pu and 240Pu in Urine at the Microbecquerel Level Using Thermal Ionization Mass Spectrometry and Alpha Spectrometry at Los Alamos National Laboratory: Results of a Two Year Comparison Test (LA-UR-06-8055)

The Intercomparison Studies Program (ISP) at the Oak Ridge National Laboratory (ORNL, Oak Ridge, TN, USA) provides natural-matrix urine quality-assurance/quality-control (QA/QC) samples to radiobioassay analysis laboratories. In 2003, a single laboratory (Los Alamos National Laboratory LANL, Los Alamos NM USA) requested a change in the test-samples provided previously by the ISP. The change was requested to evaluate measurement performance for analyses conducted using thermal-ionization mass spectrometry (TIMS). Radionuclides included 239Pu at two activity levels (75-150 (micro)Bq (smbullet) sample-1 and 1200-1600 (micro)Bq (smbullet) sample-1) and 238Pu (3700-7400 (micro)Bq (smbullet) sample-1). In addition, 240Pu was added to the samples so that the 239+240Pu specific activity was 3700-7400 (micro)Bq (smbullet) sample-1. In this paper, the results of testing during the period May, 2003 through September, 2005 are presented and discussed.