Of particular concern in nuclear waste management are two long-lived fission products, Tc-99 (half-life 220,000 years) and I-129 (half-life 15.7 million years), which dominate spent fuel radioactivity after a few thousand years. The most troublesome transuranic elements in spent fuel are Np-237 (half-life two million years) and Pu-239 (half-life 24,000 years). Nuclear waste requires sophisticated treatment and management to successfully isolate it from interacting with the
biosphere. This usually necessitates treatment, followed by a long-term management strategy involving storage, disposal or transformation of the waste into a non-toxic form. Governments around the world are considering a range of waste management and disposal options, though there has been limited progress toward long-term waste management solutions. '' is a planned deep geological repository for the final disposal of spent nuclear fuel near the
Olkiluoto Nuclear Power Plant in
Eurajoki, on the west coast of
Finland. Picture of a pilot cave at final depth in Onkalo. Several methods of disposal of radioactive waste have been investigated: •
Deep geological repository •
Dry cask storage •
Deep borehole disposal – not implemented. • Rock melting – not implemented. •
Ocean disposal – used by the USSR, the United Kingdom, Switzerland, the United States, Belgium, France, the Netherlands, Japan, Sweden, Russia, Germany, Italy and South Korea (1954–1993). This is no longer permitted by international agreements. • Disposal in ice sheets – rejected in
Antarctic Treaty. • Deep well injection – used by USSR and USA. •
Nuclear transmutation, using
neutron capture to convert the unstable atoms to those with shorter half-lives. •
Nuclear reprocessing such as the
PUREX process allows for reuse of some radioactive materials. • Disposal in outer space – not implemented as too expensive. In the United States, waste management policy broke down with the ending of work on the incomplete
Yucca Mountain Repository.
Ducrete,
Saltcrete, and
Synroc are methods for immobilizing nuclear waste.
Maritime transport of radioactive waste on
ships is regulated at sea by the
INF Code.
Initial treatment Vitrification Long-term storage of radioactive waste requires the stabilization of the waste into a form that will neither react nor degrade for extended periods. It is theorized that one way to do this might be through
vitrification. Currently at
Sellafield, the high-level waste (PUREX first cycle
raffinate) is mixed with
sugar and then calcined.
Calcination involves passing the waste through a heated, rotating tube. The purposes of calcination are to evaporate the water from the waste and de-nitrate the fission products to assist the stability of the glass produced. The 'calcine' generated is fed continuously into an induction heated furnace with fragmented
glass. The resulting glass is a new substance in which the waste products are bonded into the glass matrix when it solidifies. As a melt, this product is poured into
stainless steel cylindrical containers ("cylinders") in a batch process. When cooled, the fluid solidifies ("vitrifies") into the glass. After being formed, the glass is highly resistant to water. After filling a cylinder, a seal is
welded onto the cylinder head. The cylinder is then washed. After being inspected for external contamination, the steel cylinder is stored, usually in an underground repository. In this form, the waste products are expected to be immobilized for thousands of years. The glass inside a cylinder is usually a black glossy substance. All this work (in the United Kingdom) is done using
hot cell systems. Sugar is added to control the
ruthenium chemistry and to stop the formation of the volatile
RuO4 containing
radioactive ruthenium isotopes. In the West, the glass is normally a
borosilicate glass (similar to
Pyrex), while in the former
Soviet Union it is normal to use a
phosphate glass. The amount of fission products in the glass must be limited because some (
palladium, the other Pt group metals, and
tellurium) tend to form metallic phases which separate from the glass. Bulk vitrification uses electrodes to melt soil and wastes, which are then buried underground. In Germany, a vitrification plant is treating the waste from a small demonstration reprocessing plant which has since been closed.
Phosphate ceramics Another way to stabilize the waste into a form that will not react or degrade for extended periods is immobilization via direct incorporation into a phosphate-based crystalline ceramic host. The diverse chemistry of phosphate ceramics under various conditions demonstrates a versatile material that can withstand chemical, thermal, and radioactive degradation over time. The properties of phosphates, particularly ceramic phosphates, of stability over a wide pH range, low porosity, and minimization of secondary waste introduces possibilities for new waste immobilization techniques.
Ion exchange It is common for medium active wastes in the nuclear industry to be treated with
ion exchange or other means to concentrate the radioactivity into a small volume. The much less radioactive bulk (after treatment) is often then discharged. For instance, it is possible to use a
ferric hydroxide floc to remove radioactive metals from aqueous mixtures. After the radioisotopes are absorbed onto the ferric hydroxide, the resulting sludge can be placed in a metal drum before being mixed with cement to form solid waste. In order to get better long-term performance (mechanical stability) from such forms, they may be made from a mixture of
fly ash, or
blast furnace slag, and
portland cement, instead of normal concrete (made with portland cement, gravel and sand).
Synroc The Australian
Synroc (synthetic rock) is a more sophisticated way to immobilize such waste, and this process may eventually come into commercial use for civil wastes (it is currently being developed for U.S. military wastes). Synroc was invented by Ted Ringwood, a
geochemist at the
Australian National University. The Synroc contains
pyrochlore and cryptomelane type minerals. The original form of Synroc (Synroc C) was designed for the liquid high-level waste (PUREX raffinate) from a
light-water reactor. The main minerals in this Synroc are
hollandite (BaAl2Ti6O16),
zirconolite (CaZrTi2O7) and
perovskite (CaTiO3). The zirconolite and perovskite are hosts for the
actinides. The
strontium and
barium will be fixed in the perovskite. The
caesium will be fixed in the hollandite. A Synroc waste treatment facility began construction in 2018 at
ANSTO.
Long-term management The time frame in question when dealing with radioactive waste ranges from 10,000 to 1,000,000 years, according to studies based on the effect of estimated radiation doses. Researchers suggest that forecasts of health detriment for such periods should be examined critically. Practical studies only consider up to 100 years as far as effective planning and cost evaluations are concerned. Long term behavior of radioactive wastes remains a subject for ongoing research projects in
geoforecasting.
Remediation Algae has shown selectivity for strontium in studies, where most plants used in
bioremediation have not shown selectivity between calcium and strontium, often becoming saturated with calcium, which is present in greater quantities in nuclear waste.
Strontium-90 with a half-life around 30 years, is classified as high-level waste. Researchers have looked at the bioaccumulation of strontium by
Scenedesmus spinosus (
algae) in simulated wastewater. The study claims a highly selective
biosorption capacity for strontium of S. spinosus, suggesting that it may be appropriate for use of nuclear wastewater. A study of the pond alga
Closterium moniliferum using non-radioactive strontium found that varying the ratio of
barium to strontium in water improved strontium selectivity.
Geologic disposal leaked from a damaged storage drum due to the use of incorrect packing material. Analysis showed the lack of a "safety culture" at the plant since its successful operation for 15 years had bred complacency. The process of selecting appropriate deep final repositories for high-level waste and spent fuel is now underway in several countries with the first expected to be commissioned sometime after 2010. The basic concept is to locate a large, stable geologic formation and use mining technology to excavate a tunnel, or use large-bore
tunnel boring machines (similar to those used to drill the
Channel Tunnel from England to France) to drill a shaft below the surface where rooms or vaults can be excavated for disposal of high-level radioactive waste. The goal is to permanently isolate nuclear waste from the human environment. Many people remain uncomfortable with the immediate
stewardship cessation of this disposal system, suggesting perpetual management and monitoring would be more prudent. Because some radioactive species have half-lives longer than one million years, even very low container leakage and radionuclide migration rates must be taken into account. Moreover, it may require more than one half-life until some nuclear materials lose enough radioactivity to cease being lethal to living things. A 1983 review of the Swedish radioactive waste disposal program by the National Academy of Sciences found that country's estimate of several hundred thousand years—perhaps up to one million years—being necessary for waste isolation "fully justified." The proposed land-based subductive waste disposal method disposes of nuclear waste in a
subduction zone accessed from land and therefore is not prohibited by international agreement. This method has been described as the most viable means of disposing of radioactive waste, and as the state-of-the-art as of 2001 in nuclear waste disposal technology. Another approach termed Remix & Return would blend high-level waste with
uranium mine and mill tailings down to the level of the original radioactivity of the
uranium ore, then replace it in inactive uranium mines. This approach has the merits of providing jobs for miners who would double as disposal staff, and of facilitating a cradle-to-grave cycle for radioactive materials, but would be inappropriate for spent reactor fuel in the absence of reprocessing, due to the presence of highly toxic radioactive elements such as plutonium within it.
Deep borehole disposal is the concept of disposing of high-level radioactive waste from nuclear reactors in extremely deep boreholes. Deep borehole disposal seeks to place the waste as much as beneath the surface of the Earth and relies primarily on the immense natural geological barrier to confine the waste safely and permanently so that it should never pose a threat to the environment. The Earth's crust contains 120 trillion tons of thorium and 40 trillion tons of uranium (primarily at relatively trace concentrations of parts per million each adding up over the crust's 3 × 1019 ton mass), among other natural radioisotopes. Since the fraction of nuclides decaying per unit of time is inversely proportional to an isotope's half-life, the relative radioactivity of the lesser amount of human-produced radioisotopes (thousands of tons instead of trillions of tons) would diminish once the isotopes with far shorter half-lives than the bulk of natural radioisotopes decayed. In January 2013,
Cumbria county council rejected UK central government proposals to start work on an underground storage dump for nuclear waste near to the
Lake District National Park. "For any host community, there will be a substantial community benefits package and worth hundreds of millions of pounds" said Ed Davey, Energy Secretary, but nonetheless, the local elected body voted 7–3 against research continuing, after hearing evidence from independent geologists that "the fractured strata of the county was impossible to entrust with such dangerous material and a hazard lasting millennia."
Horizontal drillhole disposal describes proposals to drill over one km vertically, and two km horizontally in the earth's crust, for the purpose of disposing of high-level waste forms such as spent nuclear fuel, Caesium-137, or Strontium-90. After the emplacement and the retrievability period, drillholes would be backfilled and sealed. A series of tests of the technology were carried out in November 2018 and then again publicly in January 2019 by a U.S. based private company. The test demonstrated the emplacement of a test-canister in a horizontal drillhole and retrieval of the same canister. There was no actual high-level waste used in the test. The
European Commission Joint Research Centre report of 2021 (see above) concluded:
Ocean floor disposal in the North-East Atlantic dumping zone (NEA zone), between 4,500 and 4,700 m deep. From 1946 through 1993, thirteen countries used ocean disposal or ocean dumping as a method to dispose of nuclear/radioactive waste with an approximation of 200,000 tons sourcing mainly from the medical, research and nuclear industry.
Ocean floor disposal of radioactive waste has been suggested by the finding that deep waters in the North Atlantic Ocean do not present an exchange with shallow waters for about 140 years based on oxygen content data recorded over a period of 25 years. They include burial beneath a stable
abyssal plain, burial in a
subduction zone that would slowly carry the waste downward into the
Earth's mantle, and burial beneath a remote natural or human-made island. While these approaches all have merit and would facilitate an international solution to the problem of disposal of radioactive waste, they would require an amendment of the
Law of the Sea.
Nuclear submarines have been lost and these vessels reactors must also be counted in the amount of radioactive waste deposited at sea. Article 1 (Definitions), 7., of the 1996 Protocol to the Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, (the London Dumping Convention) states: :""Sea" means all marine waters other than the internal waters of States, as well as the seabed and the subsoil thereof; it does not include sub-seabed repositories accessed only from land."
Transmutation There have been proposals for reactors that consume nuclear waste and transmute it to other, less-harmful or shorter-lived, nuclear waste. In particular, the
integral fast reactor was a proposed nuclear reactor with a nuclear fuel cycle that produced no transuranic waste and, in fact, could consume transuranic waste. It proceeded as far as large-scale tests but was eventually canceled by the U.S. Government. Another approach, considered safer but requiring more development, is to dedicate
subcritical reactors to the transmutation of the left-over transuranic elements. An isotope that is found in nuclear waste and that represents a concern in terms of proliferation is Pu-239. The large stock of plutonium is a result of its production inside uranium-fueled reactors and of the reprocessing of weapons-grade plutonium during the weapons program. An option for getting rid of this plutonium is to use it as a fuel in a traditional light-water reactors (LWR). Several fuel types with differing plutonium destruction efficiencies are under study. Transmutation was banned in the United States in April 1977 by U. S. President Carter due to the danger of plutonium proliferation, but President Reagan rescinded the ban in 1981. Due to economic losses and risks, the construction of reprocessing plants during this time did not resume. Due to high energy demand, work on the method has continued in the
European Union (EU). This has resulted in a practical nuclear research reactor called
Myrrha in which transmutation is possible. Additionally, a new research program called ACTINET has been started in the EU to make transmutation possible on an industrial scale. According to U. S. President Bush's Global Nuclear Energy Partnership (GNEP) of 2007, the United States is actively promoting research on transmutation technologies needed to markedly reduce the problem of nuclear waste treatment. There have also been theoretical studies involving the use of
fusion reactors as so-called "actinide burners" where a fusion reactor
plasma such as in a
tokamak, could be "doped" with a small amount of the "minor" transuranic atoms which would be transmuted (meaning fissioned in the actinide case) to lighter elements upon their successive bombardment by the very high energy neutrons produced by the fusion of
deuterium and
tritium in the reactor. A study at
MIT found that only two or three fusion reactors with parameters similar to that of the
International Thermonuclear Experimental Reactor (ITER) could transmute the entire annual
minor actinide production from all of the
light-water reactors presently operating in the United States fleet while simultaneously generating approximately one
gigawatt of power from each reactor. Opportunities for managing nuclear waste by
transmutation are also being explored in
linear particle accelerators. Through
US DOE ARPA-E's Nuclear Energy Waste Transmutation Optimized Now, or NEWTON program, the DOE aims to explore economically viable transmutation at a scale for transmutation of commercially used US nuclear fuel stockpile within 30 years mainly focusing on
particle accelerator technology. The program expects to process used nuclear fuel to reduce the time it requires to reach
radiotoxicity of natural uranium ore, from 100,000 years of cooling to 300 years. High energy proton beams are used in production of neutron beams through collision with heavy element target, like lead or bismuth, in a process called spallation. Reducing the size and cost of such setup is a major area of focus for practical viability of the process. 2018
Nobel Prize for Physics-winner
Gérard Mourou has proposed using
chirped pulse amplification to generate high-energy and low-duration laser pulses either to accelerate
deuterons into a
tritium target causing fusion events yielding fast neutrons, or accelerating protons for
neutron spallation, with either method intended for transmutation of nuclear waste.
Re-use Spent nuclear fuel contains abundant fertile uranium and traces of fissile materials. Already, caesium-137, strontium-90 and a few other isotopes are extracted for certain industrial applications such as
food irradiation and
radioisotope thermoelectric generators. While re-use does not eliminate the need to manage radioisotopes, it can reduce the quantity of waste produced. The Nuclear Assisted Hydrocarbon Production Method, Canadian patent application 2,659,302, is a method for the temporary or permanent storage of nuclear waste materials comprising the placing of waste materials into one or more repositories or boreholes constructed into an
unconventional oil formation. The thermal flux of the waste materials fractures the formation and alters the chemical and/or physical properties of hydrocarbon material within the subterranean formation to allow removal of the altered material. A mixture of hydrocarbons, hydrogen, and/or other formation fluids is produced from the formation. The radioactivity of high-level radioactive waste affords proliferation resistance to plutonium placed in the periphery of the repository or the deepest portion of a borehole.
Breeder reactors can run on U-238 and transuranic elements, which comprise the majority of spent fuel radioactivity in the 1,000–100,000-year time span.
Space disposal Space disposal is attractive because it removes nuclear waste from the planet. It has significant disadvantages, such as the potential for catastrophic failure of a
launch vehicle, which could spread radioactive material into the atmosphere and around the world. A high number of launches would be required because no individual rocket would be able to carry very much of the material relative to the total amount that needs to be disposed. This makes the proposal economically impractical and increases the risk of one or more launch failures. To further complicate matters, international agreements on the regulation of such a program would need to be established. Costs and inadequate reliability of modern rocket launch systems for space disposal has been one of the motives for interest in
non-rocket spacelaunch systems such as
mass drivers,
space elevators, and other proposals.
National management plans in northern Germany Sweden and Finland are furthest along in committing to a particular disposal technology, while many others reprocess spent fuel or contract with France or Great Britain to do it, taking back the resulting plutonium and high-level waste. "An increasing backlog of plutonium from reprocessing is developing in many countries... It is doubtful that reprocessing makes economic sense in the present environment of cheap uranium." In many European countries (e.g., Britain, Finland, the Netherlands, Sweden, and Switzerland) the risk or dose limit for a member of the public exposed to radiation from a future high-level nuclear waste facility is considerably more stringent than that suggested by the International Commission on Radiation Protection or proposed in the United States. European limits are often more stringent than the standard suggested in 1990 by the International Commission on Radiation Protection by a factor of 20, and more stringent by a factor of ten than the standard proposed by the U.S. Environmental Protection Agency (EPA) for the
Yucca Mountain nuclear waste repository for the first 10,000 years after closure. The U.S. EPA's proposed standard for greater than 10,000 years is 250 times more permissive than the European limit. Over a timeframe of thousands of years, after the most active short half-life radioisotopes decayed, burying U.S. nuclear waste would increase the radioactivity in the top 2000 feet of rock and soil in the
United States (10 million km2) by approximately 1 part in 10 million over the cumulative amount of
natural radioisotopes in such a volume, but the vicinity of the site would have a far higher concentration of artificial radioisotopes underground than such an average.
Mongolia After serious opposition about plans and negotiations between
Mongolia with Japan and the United States to build nuclear-waste facilities in Mongolia, Mongolia stopped all negotiations in September 2011. These negotiations had started after U.S. Deputy Secretary of Energy
Daniel Poneman visited Mongolia in September 2010. Talks took place in Washington, D.C. between officials of Japan, the United States, and Mongolia in February 2011. After this the
United Arab Emirates (UAE), which wanted to buy nuclear fuel from Mongolia, joined in the negotiations. The talks were kept secret and, although the
Mainichi Daily News reported on them in May, Mongolia officially denied the existence of these negotiations. Alarmed by this news, Mongolian citizens protested against the plans and demanded the government withdraw the plans and disclose information. The Mongolian President
Tsakhiagiin Elbegdorj issued a presidential order on September 13 banning all negotiations with foreign governments or international organizations on nuclear-waste storage plans in Mongolia. The Mongolian government has accused the newspaper of distributing false claims around the world. After the presidential order, the Mongolian president fired the individual who was supposedly involved in these conversations.
Illegal dumping Authorities in Italy have investigated a
'Ndrangheta mafia clan accused of trafficking and illegally dumping nuclear waste. According to a
whistleblower, a manager of the Italy state energy research agency
Enea paid the clan to get rid of 600 drums of toxic and radioactive waste from Italy, Switzerland, France, Germany, and the United States, with
Somalia as the destination, where the waste was buried after buying off local politicians. Former employees of Enea are suspected of paying the criminals to take waste off their hands in the 1980s and 1990s. Shipments to Somalia continued into the 1990s, while the 'Ndrangheta clan also blew up shiploads of waste, including radioactive hospital waste, sending them to the sea bed off the
Calabrian coast. According to the environmental group
Legambiente, former members of the 'Ndrangheta have said that they were paid to sink ships with radioactive material for the last 20 years. In 2008, Afghan authorities accused
Pakistan of illegally dumping nuclear waste in the southern parts of
Afghanistan when the
Taliban were in power between
1996 and 2001. The Pakistani government denied the allegation. == Accidents ==