Erin Poitras reports that he has previously written about getting proper XRF radiation safety training before using an XRF instrument. These handheld XRF instruments for metal alloy verification are safe if used properly. However, extra precautions must be taken for certain sample types. As mentioned in previous articles, you should never hold samples during analysis or place any part of your body in the path of the primary x-ray beam. For most sample types the sample itself absorbs the primary beam.
Under conditions of normal and proper use, operators can be exposed to small amounts of secondary (or “scattered”) radiation. Scattered radiation from a handheld XRF analyzer is low-level radiation that emanates from the sample being measured. This radiation emanates from the sample only during the measurement period. This low level radiation is a result of primary beam radiation scattering in the sample and primary beam radiation inducing the production of fluorescent x-rays in the sample.
Most samples can be analyzed safely on a work surface with the primary beam pointing down. However, when working with challenging sample types, you must consider transmission of the primary beam through a work surface if you have chosen not to use a test stand during analysis. The image below illustrates the hazard that can be present if you are working in a seated position while analyzing sample types that do not cover the measurement window or absorb the majority of the primary beam radiation.
Notice that the operator’s legs are now in the primary beam path. As discussed earlier, you should always be aware of the location of the primary beam and take proper precautions to ensure that no part of your body is exposed to the unshielded primary beam radiation during analysis. In the example of an operator who needs to routinely sit and analyze small, thin, or light samples, shielding can be added to the table, if necessary, to prevent exposure to the legs. A sheet of steel affixed to the underside of the table can be used to shield the primary beam. It takes about 6.5 mm (1/4 inch) of steel to fully shield the primary beam at maximum tube power settings.
Here are some additional recommendations on safely analyzing sample types that might not absorb the entire primary beam for small samples, irregularly shaped samples, low-density materials,
WARNING:
- Never operate the device with a part of your body in the primary beam path or with the primary beam path directed at anyone else.
- If you are a Thermo Fisher Scientific customer and have a safety emergency with your Thermo ScientificTM NitonTM handheld XRF analyzers, please call our service department at 800-875-1578 for further instructions.
- View the above-named ebook here: Portable XRF Technology for the Non-Scientist (here).
Original URL: https://www.thermofisher.com/blog/mining/how-to-safely-handle-challenging-xrf-mining-and-mineral-samples/
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