My previous article focused on radioactive waste primarily generated by the nuclear power industry. The piece mentioned that another major source of radioactive waste was that arising from naturally occurring radioactive materials, or NORM. Another term often used is TENORM, or “technologically enhanced” NORM, which is where an industrial process, has concentrated the amounts of radioactivity. Physically they are the same, and for simplicity, in this article, we will continue to just use the term NORM.
What is NORM?
The Earth contains a number of so called primordial, naturally occurring, radionuclides, most importantly uranium-235, uranium-238, thorium-232 and potassium-40. These are remnants of the Big Bang and were present when the Earth was formed about 4.5 billion years ago. They have extremely long half lives which is why they are still present today. In the case of uranium and thorium, these decay into various daughter products eventually ending up as stable (non-radioactive) isotopes of lead.
The International Atomic Energy Agency (IAEA) defines NORM as “radioactive material containing no significant amounts of radionuclides other than naturally occurring radionuclides.” In turn NORM Residue is “material that remains from a process and comprises or is contaminated by NORM.” NORM waste is “NORM for which no further use is foreseen.”
Sources of NORM
Uranium, of course, is utilised in the manufacture of nuclear fuel (and nuclear weapons). Uranium ore is extracted from the ground at locations where there are high concentrations of uranium such as in Kazakhstan, Canada and Australia. This is done through open cast or deep mining. The uranium is extracted from the ore through a process known as milling, the product of which is known as “yellowcake”, the raw material for nuclear fuel.
Uranium mining and milling gives rise to very large volumes of waste rock containing low concentrations of uranium (tailings), and contaminated waters and sludges. This is but one form of NORM waste. As well as natural uranium in these wastes there are the daughter products radium and radon gas, and lead-210.
NORM is a source of radiation exposure primarily to those who work with these materials and communities which may be located near to the where NORM wastes are stockpiled.
Potassium-40 is of interest, because of the high concentration of potassium in bananas. In our other article on the discharges of contaminated water from Fukushima-Daiichi, we noted that one scientist commenting on this case has said “a lifetime’s worth of seafood caught a few kilometres from the ocean outlet has the tritium radiation equivalent of one bite of a banana.”
Another example of where NORM wastes arise is in the oil and gas extraction industries. Groundwater within the oil and gas field can have high chloride concentrations which increases the solubility of certain elements including radium and lead-210. The drilling process brings the radioactive water and sludge to the surface. This causes issues when the pipework and storage tanks can become coated with scale deposits containing the radioactivity which is difficult to remove. NORM can thus pose a radiation protection issue to workers during maintenance and decommissioning.
Other sources of NORM and NORM wastes include:
- Coal and peat burning:
- Coal and peat contains uranium and thorium (and their daughters) and potassium 40;
- These are retained and concentrated in the flyash which can be used in the construction industry and for coal flyash, potentially for the extraction of uranium;
- Underground mines can contain increased levels of radon.
- Mining of metal ores other than uranium and rare earths:
- Tailings and smelter slag contain high concentrations of uranium and thorium;
- The mines have increased levels of radon (as in the case of the Cornish tin mines).
- Titanium dioxide, phosphate and fertiliser production.
- Radioluminescent (radium) paint products:
- Old watches, clocks, aircraft dials.
- Building materials such as sand, concrete, bricks, granite etc.:
- Increased levels of radium and thorium and potassium-40.
Also of potential concern are those areas with granitic geologies as these produce radon gas. Radon is an inert gas and can accumulate in homes built in these areas unless remedial action such as forced ventilation is taken. In the UK, nearly half of the average radiation does to an individual is due to radon. (Source: UK Heath Security Agency.)
We live in a radioactive environment made up of natural and anthropogenic sources, with the former being responsible for most of our radiation exposure. As with any human activity, there is always the potential for creating unwanted environmental challenges; in the case of NORM, we have presented a few examples here.
As with nuclear power and nuclear waste, certain countries have more experience than others when dealing with it and through the services of the IAEA and other international organisations share that experience to make the world a safer nuclear place. It is the same for NORM; continued international co-operation is key to achieving progress on all fronts when dealing with it.
Written by John Mathieson
John Mathieson has some 47 years’ experience in the nuclear industry, primarily involving the areas of radioactive waste management and decommissioning. John worked with the International Atomic Energy Agency and the European Commission, participating in expert missions, technical meetings and working groups. He has worked on projects assisting many overseas governments to develop financing, decommissioning and radioactive waste management strategies and infrastructures, including help establish a number of Waste Management Organisations.
John Mathieson has a BSc (Hons) in Physics and an MSc in Radiation and Environmental Protection from the University of Surrey. He is a Member of the Society for Radiological Protection, and is a Board Director and Secretary of Waste Management Symposia Inc. which runs the annual Waste Management conference in Phoenix, USA.
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