Answer to Question #3590 Submitted to "Ask the Experts"

Does anyone know of a proficiency-testing program that is available for licensees performing sealed source leak-testing analysis?

I do not believe there is a specific proficiency-testing program for licensees performing sealed source leak-testing analysis. The Nuclear Regulatory Commission or Agreement State radioactive materials license application reviewer should evaluate the licensee's proposed leak-test procedure. For example: What is the sealed source? Is there a traceable calibration source available? How will wipe of the source with filter paper or cotton-tipped swab be performed—placed in radiation detector, counted for a specific period to obtain an appropriate minimum detectable activity, recording of results, etc.? Action levels in the United States are typically 0.005 microcuries. Leak testing does require an accurate assessment of the radioactivity on the wipe or swab, and this is where traceability to a national standard is needed. A routine radioactivity proficiency-testing program would add to a licensee or laboratory’s test result credibility. I know that the Environmental Protection Agency and Department of Energy provided free cross-check program samples in the past for certain counting media (for example, filter paper and water) and radionuclides.

To ensure accurate measurements of radioactivity, one should replicate the sample and calibration source counting geometry as best possible. Several commercial firms provide standards and reference materials, and most are HPS Affiliates. Also, the National Institute of Standards and Technology provides radioactivity standards. You might also contact the Department of Homeland Security's Environmental Measurements Laboratory. Other organizations to contact are the U.S. Environmental Protection Agency, the International Atomic Energy Agency, and the relatively new Radiochemistry Society.

David J. Allard, CHP