Ocean floor disposal
Encyclopedia
Ocean floor disposal is a method of sequestering radioactive waste
in ocean floor 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
has previously done, dropping it in torpedo
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
exploration.
Ocean floor sediment is saturated with water, but since there is no water table
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
through dense clay
. 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 decay
ed. 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 remains in force until 2018, after which the sub-seabed disposal option can be revisited at 25-year intervals.
Radioactive waste
Radioactive wastes are wastes that contain radioactive material. Radioactive wastes are usually by-products of nuclear power generation and other applications of nuclear fission or nuclear technology, such as research and medicine...
in ocean floor 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
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
has previously done, dropping it in torpedo
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...
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
Petroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...
exploration.
Ocean floor sediment is saturated with water, but since there is no water table
Water table
The water table is the level at which the submarine pressure is far from atmospheric pressure. It may be conveniently visualized as the 'surface' of the subsurface materials that are saturated with groundwater in a given vicinity. However, saturated conditions may extend above the water table as...
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
Molecular diffusion, often called simply diffusion, is the thermal motion of all particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size of the particles...
through dense clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
. 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
Dilution
Dilution may refer to:* Reducing the concentration of a chemical* Serial dilution, a common way of going about this reduction of concentration* Homeopathic dilution* Dilution , an equation to calculate the rate a gas dilutes...
and decay
Radioactive decay
Radioactive decay is the process by which an atomic nucleus of an unstable atom loses energy by emitting ionizing particles . The emission is spontaneous, in that the atom decays without any physical interaction with another particle from outside the atom...
ed. 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
Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter
The Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter 1972, commonly called the "London Convention" or "LC '72555" and also barbie abbreviated as Marine Dumping, is an agreement to control pollution of the sea by dumping and to encourage regional agreements...
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 remains in force until 2018, after which the sub-seabed disposal option can be revisited at 25-year intervals.