NORM, TENORM, Source Material, and Byproduct Material
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NORM, TENORM, Source Material, and Byproduct Material

By Dr. Zoomie

Dear Dr. Zoomie – I’m confused about all the different types of radioactive materials. I hear people talk about NORM, TENORM, Source Material, Byproduct Material…I even heard someone mention NARM once. And it seems like different types are regulated differently! Can you help me understand what’s going on?

Yeah – it does get a bit confusing, doesn’t it? And I can even add a few different flavors of byproduct material to the list, just in case things aren’t quite challenging enough. But let’s see if I can help sort things out here.

NORM is Naturally Occurring Radioactive Material – this is stuff you can find in a shovelful of soil you might dig up in your garden. Potassium-40 is NORM – it’s been on Earth since it first formed and there will be K-40 on Earth until it’s gone. Uranium, thorium, and their decay series nuclides are also NORM (sort of – we’ll get to that shortly), C-14 and H-3 (tritium) formed in the atmosphere by cosmic rays colliding with atoms in the air are NORM, and so are all of the other radioactive atoms formed by natural means that are found on our planet. Somewhat confusingly, C-14 and H-3 that are created in nuclear reactors are not NORM – same atom, same radiation, but different means of production. NORM refers to how an atom was produced, not necessarily what that atom actually is. NORM is regulated by the states, with the exception of uranium and thorium.

TENORM is Technologically Enhanced NORM – this is natural radioactivity that, because of human activities, has been concentrated beyond the levels found in nature. Say you own a mining and mineral processing company, removing ore containing rare earth elements from the ground and extracting the rare earth elements from the rock. Rare earth elements are geochemically very similar to the actinide elements such as uranium and thorium – this means that ores of rare earth elements (monazite is one of these) tend to also contain uranium and/or thorium as well as their decay series nuclides. So when you crush the ore and remove the rare earth elements from the rock the residue holds all of the radioactivity of the original rock, but it weighs less than the original rock – the concentration of radioactivity in the residue is higher than it was in the original rock. Your use of technology has enhanced the concentration of NORM in the residue compared to the original rock – thus, the residue (called “tailings”) is TENORM. TENORM is largely regulated by state governments, although if you own a uranium or thorium mine or mill then the tailings are regulated by the federal government. And this brings us to Source Material!

Source Material is a special category of NORM – this is the stuff that can be turned into nuclear reactors or nuclear weapons: uranium and thorium. This includes uranium and thorium ores that contain more than “one twentieth of one percent by weight” of uranium or thorium; once the ores have been processed, though, the uranium and thorium continue to be considered source materials while the residue (the tailings) are now TENORM. Source materials are regulated by the NRC because of their potential to be processed and turned into reactor fuel or nuclear weapons. If you have what’s known as an “unimportant quantity of source material” – this is where the “one twentieth of one percent by weight” comes in – then it doesn’t need to be licensed, nor if it meets any of a number of other criteria specified in the section of regulations at the link above.

Everything I’ve talked about so far is natural – radioactivity that would be on Earth whether humans ever arrived on the scene. Now let’s talk about things that wouldn’t be radioactive if it weren’t for our intervention – byproduct material.

This brings up Special Nuclear Materials (SNM), which you didn’t ask about but which is sort of important. SNM is defined by the Atomic Energy Act as being plutonium, U-233, or materials in which the U-233 or U-235 concentrations have been enriched – but it does not include source material. In a nutshell, SNM can be made to fission in either a reactor or a weapon, depending on the degree of enrichment and the engineering details.

Byproduct Material is something that’s radioactive because humans made it that way. If I take a bar of cobalt (all natural cobalt consists of the stable isotope Co-59) and I put it into a nuclear reactor, some of the cobalt atoms will absorb a neutron, turning into radioactive Co-60; an activation product. If I put a sliver of enriched uranium into the nuclear reactor, some of the uranium atoms will fission, producing radioactive fission products that will include I-131, Tc-99, Cs-137, and many more. Both activation and fission products are byproduct materials; byproduct materials are regulated by the NRC or by Agreement States (these are states that, with the NRC’s concurrence, issue radioactive materials licenses and regulate licensees within their borders, with the exception of nuclear reactors and federal agencies).

One wrinkle is that materials that became radioactive as a result of being bombarded with particles in a particle accelerator used to be a separate category called Accelerator-produced Radioactive Materials – these were lumped in with NORM and called NARM. Now, however, these are lumped in with other byproduct materials. This makes sense – I-125 (for example) produced in an accelerator is identical to I-125 produced in a nuclear reactor. But when I worked in Ohio in the 1990s, I-125 from a reactor was byproduct material licensed by the NRC while I-125 from an accelerator was NARM licensed by the State of Ohio. At least that meaningless distinction went away a few decades ago.

Even though you didn’t ask about radiation-generating devices I ought to mention them for the sake of completeness. As the name suggests, a radiation-generating device is a machine that produces radiation – this can be an x-ray or CT machine; it can also be an electron microscope or a particle accelerator. Most radiation-generating devices are regulated by state governments, some fall under federal jurisdiction.

Finally, I suppose I should also mention that there are a LOT of things that are explicitly exempt from regulation for any of a number of reasons. There are exempt quantities of radioactive materials, below which they can be purchased without having a license. There are also specific exemptions such as those for unimportant quantities of source materials – most of these are laid out in 10 CFR 30.11 through 30.22. As one example, delivery firms such as Federal Express can transport licensable amounts of radioactive materials without, itself, needing to have a license; another example is instruments used to detect gases and aerosols – like smoke detectors. These sections of the regulations lay out consumer products, industrial instruments, and several other categories of sources that the government has chosen not to regulate – in some cases because the risk is so low, in other cases because the benefits are so great (e.g. smoke detectors). Regardless of the reason, they’re listed here.

I think that ought to do it – everything you asked about, and some bonus material to boot!