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21 November 2009

Answer to Question #4669 Submitted to "Ask the Experts"

Category: Consumer Products

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

What hazards are there, if any, from an item that has been welded with a thorium welding rod? Is the finished product radioactive from the thorium? Should any precautions be taken when handling it, etc.?

Any items that have been welded using a thorium welding rod will contain trace quantities of the radioactive thorium, but only at the weld site. So, technically the product will contain more radioactive material than it did before it was welded, but only at the weld site, and not throughout the product.
In addition to welding rods, thorium has also been used in making some lenses and some parts for airplanes, and it had been used for the mantles in outdoor kerosene-fueled lamps. Are they radioactive? Yes, but not to the extent that they create any radiation hazard.

Should any precautions be taken when handling? Yes, allow the welded items to cool to ambient temperature. Don't allow them to fall on any part of your body or impact it (heavy items can hurt!), don't run in to pointed ends, etc. As you'll note, there are still physical hazards, but not from any trace quantities of radioactive material.

If the item, however, is placed near some of the portal monitors typically found at metal recycling facilities, even this small amount of thorium may be detected by those large, super-sensitive radiation detectors; and they're doing what they are supposed to do—detecting small increases in the amount of radiation hitting them. The monitors were installed to prevent the metal recyclers from processing sealed sources of radioactive material that could put them out of business, if they were to shred or melt such a source, but they don't discriminate between the trivial amount of "good" radioactive materials (such as in the weld, perhaps holding parts of the vehicle together) and the larger amounts of "bad" radioactive materials (the kind that could contaminate their recycling facilities or get into other metal products).

James Yusko, CHP
Pennsylvania Department of Environmental Protection

Answer posted on 15 September 2005. 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.