Coal

Coal contains a small amount of radioactive uranium, barium, thorium, and potassium but, in the case of pure coal, this is significantly less than the average concentration of those elements in the Earth’s crust. The surrounding strata, if shale or mudstone, often contain slightly more than average and this may also be reflected in the ash content of “dirty” coals (Gabbard 1993; Cosmic Origin of Uranium 2006). The more active ash minerals become concentrated in the fly ash precisely because they do not burn well (Gabbard 1993). The radioactivity of fly ash is about the same as black shale and is less than phosphate rocks, but it is more of a concern because a small amount of the fly ash ends up in the atmosphere where it can be inhaled (U.S. Geological Survey 1997). According to U.S. NCRP reports, population exposure is from 1000‐MWe power plants amounts to 490 person‐rem/year for coal power plants, and thus is 100 times as great as nuclear power plants (4.8 person‐rem/year). (The exposure from the complete nuclear fuel cycle from mining to waste disposal is 136 person‐rem/year; the corresponding value for coal use from mining to waste disposal is “probably unknown”) (Gabbard 1993).

Oil and Gas

Residues from the oil and gas industry often contain radium and its decay products. The sulfate scale from an oil well can be very radium rich, while the water, oil, and gas from a well often contain radon. The radon decays to form solid radioisotopes which form coatings on the inside of pipe‐work. In an oil‐processing plant, the area of the plant where propane is processed is often one of the more contaminated areas of the plant as radon has a similar boiling point to propane.

Low‐Level Waste

Low‐level waste (LLW) is generated from hospitals and industry, as well as the nuclear fuel cycle. LLWs include paper, rags, tools, clothing, filters, and other materials which contain small amounts of mostly short‐lived radioactivity. Materials that originate from any region of an Active Area are commonly designated as LLW as a precautionary measure even if there is only a remote possibility of being contaminated with radioactive materials. Such LLW typically exhibits no higher radioactivity than one would expect from the same material disposed of in a non‐active area, such as a normal office block.

Some high‐activity LLW requires shielding during handling and transport, but most LLW is suitable for shallow land burial. To reduce its volume, it is often compacted or incinerated before disposal. LLW is divided into four classes: class A, class B, class C, and greater than class C.

Intermediate‐Level Waste

Intermediate‐level waste (ILW) contains higher amounts of radioactivity and in general require shielding, but not cooling (USNRC, April 3 2017). ILWs includes resins, chemical sludge, and metal nuclear fuel cladding, as well as contaminated materials from reactor decommissioning. It may be solidified in concrete or bitumen for disposal. As a general rule, short‐lived waste (mainly nonfuel materials from reactors) is buried in shallow repositories, while LLW (from fuel and fuel reprocessing) is deposited in geological repository. US regulations do not define this category of waste; the term is used in Europe and elsewhere.

High‐Level Waste

High‐level waste (HLW) is produced by nuclear reactors. The exact definition of HLW differs internationally. After a nuclear fuel rod serves one fuel cycle and is removed from the core, it is considered HLW (Janicki 2013). Fuel rods contain fission products and transuranic elements generated in the reactor core. Spent fuel is highly radioactive and often hot. HLW accounts for over 95% of the total radioactivity produced in the process of nuclear electricity generation. The amount of HLW worldwide is currently increasing by about 12 000 MT every year, which is the equivalent to about 100 double‐decker buses or a two‐story structure with a footprint the size of a basketball court (Rogner 2010). A 1000‐MW nuclear power plant produces about 27 T of spent nuclear fuel (unreprocessed) every year (Myths and Realities of Radioactive Waste, Feb. 2017). In 2010, there was very roughly estimated to be stored some 250 000 T of nuclear HLW (World Nuclear Association, July 2015) that does not include amounts that have escaped into the environment from accidents or tests. Japan estimated to hold 17 000 T of HLW in storage in 2015 (Geere 2010). HLWs have been shipped to other countries to be stored or reprocessed, and in some cases, shipped back as active fuel.

The ongoing controversy over high‐level radioactive waste disposal is a major constraint on the nuclear power’s global expansion (Humber 2015). Most scientists agree (Findlay 2010) that the main proposed long‐term solution is deep geological burial, either in a mine or a deep borehole. However, almost six decades after commercial nuclear energy began, no government has succeeded in opening such a repository for civilian high‐level nuclear waste (Humber 2015), although Finland is in the advanced stage of the construction of such facility, the Onkalo spent nuclear fuel repository. Reprocessing or recycling spent nuclear fuel options already available or under active development still generate waste and so are not a total solution, but it can reduce the sheer quantity of waste, and there are many such active programs worldwide. Deep geological burial remains the only responsible way to deal with high‐level nuclear waste (World Nuclear Association 2015). The Morris Operation is currently the only de facto high‐level radioactive waste storage site in the United States.

Transuranic Waste

Transuranic waste (TRUW) as defined by US regulations is, without regard to form or origin, waste that is contaminated with alpha‐emitting transuranic radionuclides with half‐lives greater than 20 years and concentrations greater than 100 nCi/g (3.7 MBq/kg), excluding HLW. Elements that have an atomic number greater than uranium are called transuranic (“beyond uranium”). Because of their long half‐lives, TRUW is disposed more cautiously than either low‐ or intermediate‐level waste. In the United States, it arises mainly from weapons production and consists of clothing, tools, rags, residues, debris, and other items contaminated with small amounts of radioactive elements (mainly plutonium).

Under US law, transuranic waste is further categorized into “contact‐handled” (CH) and “remote‐handled” (RH) on the basis of the radiation dose rate measured at the surface of the waste container. CH TRUW has a surface dose rate not greater than 200 mrem/h (2 mSv/h), whereas RH TRUW has a surface dose rate of 200 mrem/h (2 mSv/h) or greater. CH TRUW does not have the very high radioactivity of HLW nor its high heat generation, but RH TRUW can be highly radioactive, with surface dose rates up to 1 000 000 mrem/h (10 000 mSv/h). The United States currently disposes of TRUW generated from military facilities at the Waste Isolation Pilot Plant in a deep salt formation in New Mexico (Biello 2011).