Ocean floor disposal is a method of sequestering
radioactive waste
Radioactive waste is a type of hazardous waste that contains radioactive material. Radioactive waste is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, rare-earth mining, and nuclear weapons r ...
in
ocean floor
The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'.
The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...
sediment where it is unlikely to be disturbed either geologically or by human activity.
Several methods of depositing material in the ocean floor have been proposed, including encasing it in concrete and as the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...
has previously done, dropping it in
torpedo
A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, s ...
es designed to increase the depth of penetration into the ocean floor, or depositing containers in shafts drilled with techniques similar to those used in
oil
An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturated ...
exploration.
Ocean floor sediment is saturated with water, but since there is no
water table
The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water. It can also be simply explained as the depth below which the ground is saturated.
T ...
per se and the water does not flow through it the migration of dissolved waste is limited to the rate at which it can
diffuse
Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical p ...
through dense
clay
Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4).
Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...
. This is slow enough that it could potentially take millions of years for waste to diffuse through several tens of meters of sediment so that by the time it reaches open ocean it would be highly
dilute and
decayed. Large regions of the ocean floor are thought to be completely geologically inactive and it is not expected that there will be extensive human activity there in the future. Water absorbs essentially all radiation within a few meters provided the waste remains contained.
One of the problems associated with this option includes the difficulty of recovering the waste, if necessary, once it is emplaced deep in the ocean. Also, establishing an effective international structure to develop, regulate, and monitor a sub-seabed repository would be extremely difficult.
Beyond technical and political considerations, the
London Convention places prohibitions on disposing of radioactive materials at sea and does not make a distinction between waste dumped directly into the water and waste that is buried underneath the ocean's floor. It remained in force until 2018, after which the sub-seabed disposal option can be revisited at 25-year intervals.
Depositing waste, in suitable containers, in
subduction zones has also been suggested. Here, waste would be transported by plate tectonic movement into the Earth's mantle and rendered harmless through dilution and natural decay. Several objections have been raised to this method, including vulnerabilities during transport and disposal, as well as uncertainties in the actual tectonic processes.
[{{Cite web, url=https://www.nwmo.ca/en/Reports, title=Reports | NWMO, website=www.nwmo.ca]
See also
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Horizontal drillhole disposal
Deep horizontal drillhole disposal is the concept of disposing of high-level radioactive waste from a nuclear reactor in deep horizontal boreholes instead of in more traditional deep geological repositories that are excavated like mines. The desi ...
*
Ocean disposal of radioactive waste
*
Deep borehole disposal
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Yucca Mountain nuclear waste repository
The Yucca Mountain Nuclear Waste Repository, as designated by the Nuclear Waste Policy Act amendments of 1987, is a proposed deep geological repository storage facility within Yucca Mountain for spent nuclear fuel and other high-level radio ...
*
Waste Isolation Pilot Plant
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Nuclear fuel cycle
The nuclear fuel cycle, also called nuclear fuel chain, is the progression of nuclear fuel through a series of differing stages. It consists of steps in the ''front end'', which are the preparation of the fuel, steps in the ''service period'' in w ...
*
Radioactive waste
Radioactive waste is a type of hazardous waste that contains radioactive material. Radioactive waste is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, rare-earth mining, and nuclear weapons r ...
References
Radioactive waste
Waste treatment technology
Ocean pollution