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RAPID ANALYTICAL TECHNIQUE TO IDENTIFY ALPHA EMITTING ISOTOPES IN WATER, AIR-FILTERS, URINE, AND SOLID MATRICES USING A FRISCH GRID DETECTOR

Scarpitta, Salvatore C.; Miltenberger, Robert P.; Gaschott, Robert; Carte, Nina

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Abstract— A 5-inch-diameter Frisch Grid gas-proportional ionization chamber was utilized at Brookhaven National Laboratory (BNL) to rapidly characterize and quantify alpha-emitting actinides in unprocessed water, soil, air-filter, urine, and solid matrices. Instrument calibrations for the various matrices were performed by spiking representative samples with National Institute of Standards and Technology traceable isotopes of 230Th, 232U, 236Pu, and 243Am. Detection efficiencies were typically 15–20% for solid matrices (soil, concrete, filters, dry urine) and 45% for mass-less water samples. Instrument background over a 512-channel alpha-energy range of 3–8 MeV is very low at 0.01 cps. At optimum efficiency, minimum detectable levels of 0.56 mBq Kg−1, 74 mBq L−1 and 14.8 mBq filter−1 were achievable for 40 × 10−6 Kg soil, 1 × 10−3 L tap water (or urine), and 4.5 cm diameter air-filter samples, respectively, each counted for 60 min. Data and spectra are presented showing the quality of results obtained using untreated samples obtained from the BNL Graphite Research Reactor Decommissioning Project. These samples contained Bq to MBq per gram amounts of 239,240Pu, 241Am, and/or 234,235/238U (as well as other β/γ emitters). Data and spectra are also presented for a very finely pulverized and homogeneous U.S. DOE/RESL soil reference standard (spiked with 239Pu, 241Am, and 233U) that was used to assess precision, accuracy, and reproducibility. Although this technique has its limitations, the advantages are (1) minimal sample preparation, (2) no separation chemistry required, (3) no chemical or hazardous waste generated, and (4) ability to immediately characterize and quantify alpha-emitting nuclides in most matrices. The benefits of this technique to the BNL/DOE Project Managers were rapid (1–2 d) turn-around times coupled with significant cost savings, as compared to commercial off-site analyses.

*Brookhaven National Laboratory, Upton, NY 11973; Sandia National Laboratories, PO Box 5800, Albuquerque, NM 87185; University of Connecticut, Storrs, CT 06289.

Manuscript received 4 March 2002;

revised manuscript received 11 July 2002, accepted 1 December 2002

For correspondence or reprints contact: S.C. Scarpitta, Brookhaven National Laboratory, Upton, NY 11973, or email at scarpitta@bnl.gov.

Disclaimer—This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the Unites States Government nor any agency thereof, nor any of their employees, contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade, name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply it’s endorsement, recommendation, or favoring by United States Government of any agency, contractor of subcontractor thereof. The views and opinions of authors expressed herein do not necessarily state of reflect those of the United States Government or any agency, contractor of subcontractor thereof.

© 2003 by the Health Physics Society