Atom-Counting Measurement Techniques for Environmental Monitoring

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Objective for MPD B.9.2

  • Develop the capability and resources to provide NIST traceable reference materials and analytical performance testing of long-lived radionuclides in various media by mass spectrometry.

Background: Certain radiochemical analyses, especially those of the long-lived alpha emitters, can be long, laborious and costly. It is expected that cleanup and site remediation programs related to Department of Defense programs will require millions of assays over a period of 30 or more years, costing many billions of dollars. Furthermore, rapid analysis of radionuclides for emergency response and isotopic ratio determination of source identification are required. Thus, a need exists for reducing the cost of these programs by developing techniques that: (1) use atom-counting to reduce measurement time spent by factors of 10 per assay while increasing sensitivity by a factor of 1000, and (2) extends analytical sensitivity and selectivity over conventional radioactivity measurement techniques, and (3) perform measurements in situ if possible, thus avoiding laboratory analyses.

In addition to environmental sample analyses for the long-lived nuclides, current studies have shown that atom-counting is very applicable for radiobioassay for a number of radionuclides. Recently, the Brookhaven National Laboratory has demonstrated that Plutonium-239 (239Pu) in urine samples can be measured accurately down to the microBq per liter. The technique combines the isolation, concentration and purification steps of qualitative and quantitative chemistry in conjunction with inductively coupled plasma mass spectrometry. Similar mass spectrometric techniques have been developed by the Los Alamos National Laboratory (LANL) and the Lawrence Livermore National Laboratory (LLNL). The application of atom-counting to bioassay will produce cost savings and will enable health physicist to document internal uptakes orders of magnitude better than current levels. In addition, the mass spectrometric technique yields additional isotopic information to that obtained from traditional radioactivity measurement techniques.

Action Items:

1 – Conduct a third intercomparison study to evaluate the capability of various mass spectrometric techniques for the assay of isotopic uranium in synthetic urine specimens.

2 – Provide leadership and program manager to initiate a national program for physical and consensus standards, intercomparisons, and performance evaluations that will serve the needs of the emergency response and cleanup radionuclide mass spectrometric community.

3 – Update the needs of the mass spectrometry community and provide a formal needs report upon which program funding can be based and obtained.

4 – Develop a NIST capability to produce and verify long-lived radionuclide reference materials for various mass spectrometric applications.

5 – Develop a NIST capability to enable NIST traceability for a national performance evaluation program for the testing of laboratories engaged in the MS analysis of environmental and bioassay samples for radionuclides.

6 – Continue research and development of radiochemical separations, source and ionization optimization, and pulse counting optimization.

Resources Required:

1 – One-half full time employee or contractor equivalent at NIST for program development and administration and the development of the necessary technical capability for the funded program.

2 – Enhanced TIMS, RIMS, ICP-MS and MS-MS radionuclide metrology capabilities at NIST.

3 – Sufficient and dedicated laboratory facilities and resources to conduct the analytical portion of developed programs.

Figure B.9.1 – Resonance ionization mass spectrometry (RIMS) system (courtesy of NIST Ionizing Radiation Division)

NOTE: In the CIRMS “Second Report on National Needs in Ionizing Radiation Measurements and Standards,” published in October, 1998, this MPD appeared as MPD B.4. A new MPD number has been assigned, MPD B.9, to avoid confusion with MPD B.4 that had appeared in the first CIRMS “Report on National Needs in Ionizing Radiation Measurements and Standards,” published in January, 1995, that covered a different topic, and MPD B.4 in the second report.