Radio isotope
A unstable isotope of an element. This material decays spontaneously and releases subatomic particles and electromagnetic energy.

Radioactive contamination
Radioactive contamination is radioactive material distributed over some area, equipment or person. It tends to be unwanted in the location where it is, and has to be cleaned up or decontaminated.

Radioactive decay
Process which occurs when energetically unstable atom transforms itself to a more energetically stable state. The unstable atom can emit ionizing radiation in order to become more stable. This atom is said to be “radioactive”, and the process of change is called “radioactive decay”.

Radioactive waste
Materials left over from making nuclear energy. Radioactive waste can harm people and the environment if it is not stored safely. The solid, liquid, or gaseous material containing radionuclides are regulated under the Atomic Energy Act of 1954, as amended.

Radioactive waste containment
Retention of radioactive waste so as to ensure that it is effectively prevented from dispersing into the environment, or released only at an acceptable level. Containment may occur in specially built containment spaces.

Radioactive waste immobilization
The process of converting radioactive waste to a stable, solid form to prevent or slow its migration to the environment.

Radioactive waste solidification
Solidification processes such as calcining and vitrification are used to treat non-solid radioactive waste. The liquid waste converted into a solid waste form can be safely disposed in a geologic repository.

Radioactive waste treatment
Any activity that alters the chemical or physical nature of a nuclear waste to reduce its toxicity, volume, mobility, or render it ready for transport, storage, or disposal. (SEE Conditioning, Containment, Immobilization of Radioactive waste).

A nuclide that emits radiation by spontaneous transfomation.

A radioactive gaseous element formed by the disintegration of radium; the heaviest of the inert gasses; occurs naturally (especially in areas over granite) and is considered a hazard to health.

Rain out
Erosion of rocks or soil surface by rainwater.

An administrative officer in charge of a unit of forest land, generally a subdivision of a public forest or park.

Rare species
Species whose numbers are small compared to its total biotic potential. Locally rare species are within the boundaries of a particular region; they may be abundant elsewhere.

Raw materials
Substances still in their natural, unprocessed state.

Usually refers to a substance that is degraded at an extremely slow rate if at all when released into the environment. Consequently, this type of material tends to accumulate in water, soil, and biota.

The reestablishment of organisms into habitats that they previously occupied.

Reconnaissance survey
A preliminary survey of ground based on the collection of geological and geophysical data.

Recovery factor
The amount of oil and/gas in a reservoir that can be economically extracted compared with the total amount estimated to be in the ground, using currently available techniques.

The process of reprocessing old products to use as raw materials. Applied commonly to metals, paper, glass and plastic. If no reprocessing is involved and the product remains in its original form (e.g. returnable beverage bottle), this is called re-use (see).

A series of processes for converting crude oil and its fractions to finished petroleum products. Following distillation, a petroleum fraction may undergo one or more additional steps to purify or modify it. These refining steps include; thermal cracking, catalytic cracking (see), polymerization (see), alkylation (see), reforming (see), hydrocracking, hydroforming, hydrogenation, hydrogen treating, hydrofining, solvent extraction, dewaxing, deoiling, acid treating, clay filtration, and deasphalting. Refined lubricating oils may be blended, and additives may be incorporated, to impart special properties.

The return of radiation by a surface without change of frequency of the monochromatic components of which the radiation is composed.

Reflection seismic surveys
A mode of seismic prospecting in which the seismic profile is examined for waves that have reflected from near-horizontal strata below the surface.

Artificial or natural re-establishment of forest in an area that was previously under forest cover. (Source: United Nations, Glossary of Environment Statistics)

A petroleum refining process, employing catalysis, in which heat and pressure are used to cause cracking and isomerization (see) of the hydrocarbon molecules in low-octane petroleum fractions. The reformed hydrocarbons have higher octane numbers than the original material. It’s aimed at improving gasoline quality.

Reformulated gasoline
Fuel prepared from municipal solid waste (MSW see) . Noncombustible materials such as rocks, glass, and metals are removed, and the remaining combustible portion of the solid waste is chopped or shredded. The RDF processing facility is typically located near the MSW source, while the RDF combustion facility can be located elsewhere because the RDF can be transported more economically.

Refuse Derived Fuel (RDF)
Fuel prepared from municipal solid waste (MSW see) . Noncombustible materials such as rocks, glass, and metals are removed, and the remaining combustible portion of the solid waste is chopped or shredded. The RDF processing facility is typically located near the MSW source, while the RDF combustion facility can be located elsewhere because the RDF can be transported more economically.

The slow lowering of sea level and/or raising of the edge of a continent such that the shoreline slowly moves away from the center of the continent, exposing more land above sea level.

Relative humidity
The ratio between the actual amount of water vapor held in the atmosphere (see) compared to the amount required for saturation. Relative humidity is influence by temperature and atmospheric pressure. The relative humidity is usually expressed in per cent, and can be computed from psychrometric data.

The improvement of a contaminated site to prevent, minimize, or mitigate injury to human health or the environment; remediation involves the development and application of a planned approach that monitors, removes, destroys, contains, or otherwise reduces the exposure of contaminants to receptors of concern.

Renewable energy resources
Energy resources that are naturally replenishing but flow-limited. They are virtually inexhaustible in duration but limited in the amount of energy that is available per unit of time. Renewable energy resources include: biomass, hydro, geothermal, solar, wind, ocean thermal, wave action, and tidal action.

Distillation, hydrotreating, and/or other treatment employing acid, caustic, solvent, clay and/or chemicals of used oil in order to produce high quality base stock for lubricants or other petroleum products.

Oil or natural gas contained in underground rock formations called reservoirs. Proved reserves are the estimated quantities that geologic and engineering data demonstrate can be produced with reasonable certainty from known reservoirs under existing economic and operating conditions. Recoverable reserves are those that can be produced using all known primary and enhanced recovery methods (see).

A porous and permeable underground rock formation containing a natural accumulation of crude oil or natural gas that is confined by impermeable rock or water barriers, and is separate from other reservoirs.

Reservoirs exploitation
The optimal development of an oil and gas reservoir to extract its hydrocarbons.

Residual waste
Those solid, liquid, or sludge substances from man’s activities in the urban, agricultural, mining, and industrial environments, remaining after collection and necessary treatment.

Material left over in process or consumption.

Capacity of a body to bear and/or to oppose itself to external forces.

Volumes of hydrocarbons that are deemed to be technically recoverable, but may not have been delineated or may not presently be economically produced.

Responsible care
A program initiated in 1984 by the chemical industry in Canada involving binding obligations in the areas of health, safety and the environment. This program was presented to the international community at the second World Conference on Environmental Management in Rotterdam in 1991. Voluntary commitments are laid down in fundamental guidelines and enforced by the national chemical industry associations.

Use of waste for a similar purpose (for example, returnable bottles) or a different purpose from that for which the material was originally intended (for example, using tyres to protect the hull of trawlers).

Reverse osmosis
An advanced method of water or wastewater treatment that relies on a semi-permeable membrane to separate waters from pollutants. An external force is used to reverse the normal osmotic process resulting in the solvent moving from a solution of higher concentration to one of lower concentration. Also the process of removing salts from water using a membrane.

When a change is not permanent and can be changed back.

The strip of land, usually 50 feet wide, that is the route of a pipeline and for which the company pays for the legal right of passage.

Rigs to reefs
Policy addressing the conversion of rigs no longer in use into artificial reefs.

Refers to the banks of a stream or river, usually characterized by hydrophilic (water-loving) vegetation.

The potential for realization of unwanted, adverse consequences to human life, health, property, or the environment.

A long narrow channel of water that flows as a function of gravity and elevation across the Earth’s surface. Many rivers empty into lakes, seas, or oceans.

A rock is an aggregate of minerals. Rocks are made of different kinds of minerals, or broken pieces of crystals, or broken pieces of rocks. Some rocks are made of the shells of once-living animals, or of compressed pieces of plants. Rocks are divided into three basic types, igneous, sedimentary and metamorphic, depending upon how they were formed.

Rotary kelly bushing
Device, through which the kelly slides, that fits into the rotary table. It transmits the torque of the rotary table to the kelly and consequently to the drillstring. It is sometimes also called the drive bushing or rotary kelly bushing (RKB).

The outer piece of a linear induction motor. The rotor rotates around the stator because the magnetic field generated by the stator induces a current in the rotor which opposes the direction of the magnetic field.

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