Answer to Question #3288 Submitted to "Ask the Experts"

Category: Instrumentation and Measurements — Instrument Calibration (IC)

The following question was answered by an expert in the appropriate field:

Can I make a comparison between gross alpha and alpha spectrometry values? We are having laboratories perform a no-radioactivity-added (NRA) protocol which requires the labs to first perform gross alpha/gross beta analyses. If the results are greater than a certain value they must try to identify the isotopes using alternative methods and account for the gross activities.

This seems like a reasonable approach for screening what I assume might be laboratory liquid or solid waste.

In theory this should work if you had perfect instrument calibrations that accounted for differing sample geometry and self-absorption and that identified all the radionuclides specifically, every particle (for example, Auger and conversion electrons, x rays, etc.) emitted in the decay scheme, and how they're contributing to counts. In practice, this may be quite hard to do, especially if you have very low levels of "added" activity, confounding natural uranium/thorium/potassium-40 in the sample matrix, and perhaps large counting errors. Hopefully you're at least in the same order of magnitude. Not knowing the specifics, you might ask the laboratory and staff performing the counting for some assistance.

David J. Allard, CHP

Answer posted on December 16, 2003. The information and material posted on this Web site is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of materials and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Web site. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.