Applications of thermal ionization mass spectrometry to the detection of 239Pu and 240Pu intakes

The United States Department of Energy requires routine bioassay monitoring for workers who may incur intakes of radioactive materials, that may result in a committed effective dose equivalent of 1 mSv. The radiochemistry/alpha-spectroscopy method, historically used for analysis of plutonium in urine, does not provide the level of measurement sensitivity to meet this monitoring requirement. Los Alamos National Laboratory has an established, ultrasensitive, actinide analysis program. Application of class-100 clean room radiochemistry and thermal ionization mass spectrometry to the determination of plutonium concentration in human urine samples yielded an average measurement uncertainty of 3.8 mu Bq 24 h(-1), a 40-fold improvement over the measurement uncertainties associated with radiochemistry/alpha-spectroscopy analytical methods. This measurement capability corresponds to an ability to detect intakes on the order of 30 Bq of Pu-239 and Pu-240, under conditions of annual routine monitoring. The resulting minimum detectable committed effective dose equivalent associated with this intake is 2 mSv. (Int J Mass Spectrom 178 (1998) 113-120) (C) 1998 Elsevier Science B.V.