Background radiation is a measure of the level of ionizing radiation present in the environment at a particular location which is not due to deliberate introduction of radiation sources.
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferred to one of its electrons to release it as a conversion electron; or used to create and emit a new particle (alpha particle or beta particle) from the nucleus. During those processes, the radionuclide is said to undergo radioactive decay. These emissions are considered ionizing radiation because they are energetic enough to liberate an electron from another atom. The radioactive decay can produce a stable nuclide or will sometimes produce a new unstable radionuclide which may undergo further decay. Radioactive decay is a random process at the level of single atoms: it is impossible to predict when one particular atom will decay. However, for a collection of atoms of a single nuclide the decay rate, and thus the half-life (t1/2) for that collection, can be calculated from their measured decay constants. The range of the half-lives of radioactive atoms has no known limits and spans a time range of over 55 orders of magnitude.
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, nuclear decommissioning, rare-earth mining, and nuclear weapons reprocessing. The storage and disposal of radioactive waste is regulated by government agencies in order to protect human health and the environment.
Nuclear technology is technology that involves the nuclear reactions of atomic nuclei. Among the notable nuclear technologies are nuclear reactors, nuclear medicine and nuclear weapons. It is also used, among other things, in smoke detectors and gun sights.
In nuclear science, the decay chain refers to a series of radioactive decays of different radioactive decay products as a sequential series of transformations. It is also known as a "radioactive cascade". The typical radioisotope does not decay directly to a stable state, but rather it decays to another radioisotope. Thus there is usually a series of decays until the atom has become a stable isotope, meaning that the nucleus of the atom has reached a stable state.
Ionizing radiation, including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel up to 99% of the speed of light, and the electromagnetic waves are on the high-energy portion of the electromagnetic spectrum.
In petroleum exploration and development, formation evaluation is used to determine the ability of a borehole to produce petroleum. Essentially, it is the process of "recognizing a commercial well when you drill one".
In the oil and gas industry, the term wireline usually refers to the use of multi-conductor, single conductor or slickline cable, or "wireline", as a conveyance for the acquisition of subsurface petrophysical and geophysical data and the delivery of well construction services such as pipe recovery, perforating, plug setting and well cleaning and fishing. The subsurface geophysical and petrophysical information results in the description and analysis of subsurface geology, reservoir properties and production characteristics.
Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the release of heat energy, and gamma rays. The two smaller nuclei are the fission products..
Well logging, also known as borehole logging is the practice of making a detailed record of the geologic formations penetrated by a borehole. The log may be based either on visual inspection of samples brought to the surface or on physical measurements made by instruments lowered into the hole. Some types of geophysical well logs can be done during any phase of a well's history: drilling, completing, producing, or abandoning. Well logging is performed in boreholes drilled for the oil and gas, groundwater, mineral and geothermal exploration, as well as part of environmental and geotechnical studies.
Neutron activation is the process in which neutron radiation induces radioactivity in materials, and occurs when atomic nuclei capture free neutrons, becoming heavier and entering excited states. The excited nucleus decays immediately by emitting gamma rays, or particles such as beta particles, alpha particles, fission products, and neutrons. Thus, the process of neutron capture, even after any intermediate decay, often results in the formation of an unstable activation product. Such radioactive nuclei can exhibit half-lives ranging from small fractions of a second to many years.
Iodine-131 is an important radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley. It has a radioactive decay half-life of about eight days. It is associated with nuclear energy, medical diagnostic and treatment procedures, and natural gas production. It also plays a major role as a radioactive isotope present in nuclear fission products, and was a significant contributor to the health hazards from open-air atomic bomb testing in the 1950s, and from the Chernobyl disaster, as well as being a large fraction of the contamination hazard in the first weeks in the Fukushima nuclear crisis. This is because 131I is a major fission product of uranium and plutonium, comprising nearly 3% of the total products of fission. See fission product yield for a comparison with other radioactive fission products. 131I is also a major fission product of uranium-233, produced from thorium.
Radiochemistry is the chemistry of radioactive materials, where radioactive isotopes of elements are used to study the properties and chemical reactions of non-radioactive isotopes. Much of radiochemistry deals with the use of radioactivity to study ordinary chemical reactions. This is very different from radiation chemistry where the radiation levels are kept too low to influence the chemistry.
Radionuclides which emit gamma radiation are valuable in a range of different industrial, scientific and medical technologies. This article lists some common gamma-emitting radionuclides of technological importance, and their properties.
Uranium-232 is an isotope of uranium. It has a half-life of around 69 years and is a side product in the thorium cycle. It has been cited as an obstacle to nuclear proliferation using 233U as the fissile material, because the intense gamma radiation emitted by 208Tl makes the 233U contaminated with it more difficult to handle.
Gamma ray logging is a method of measuring naturally occurring gamma radiation to characterize the rock or sediment in a borehole or drill hole. It is a wireline logging method used in mining, mineral exploration, water-well drilling, for formation evaluation in oil and gas well drilling and for other related purposes. Different types of rock emit different amounts and different spectra of natural gamma radiation. In particular, shales usually emit more gamma rays than other sedimentary rocks, such as sandstone, gypsum, salt, coal, dolomite, or limestone because radioactive potassium is a common component in their clay content, and because the cation-exchange capacity of clay causes them to absorb uranium and thorium. This difference in radioactivity between shales and sandstones/carbonate rocks allows the gamma ray tool to distinguish between shales and non-shales. But it cannot distinguish between carbonates and sandstone as they both have similar deflections on the gamma ray log. Thus gamma ray logs cannot be said to make good lithological logs by themselves, but in practice, gamma ray logs are compared side-by-side with stratigraphic logs.
In health physics, whole-body counting refers to the measurement of radioactivity within the human body. The technique is primarily applicable to radioactive material that emits gamma rays. Alpha particle decays can also be detected indirectly by their coincident gamma radiation. In certain circumstances, beta emitters can be measured, but with degraded sensitivity. The instrument used is normally referred to as a whole body counter.
Potassium-40 (40K) is a radioactive isotope of potassium which has a long half-life of 1.25 billion years. It makes up about 0.012% of the total amount of potassium found in nature.
A gamma ray, also known as gamma radiation (symbol γ or ), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically shorter than those of X-rays. With frequencies above 30 exahertz (3×1019 Hz), it imparts the highest photon energy. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation gamma rays based on their relatively strong penetration of matter; in 1900 he had already named two less penetrating types of decay radiation (discovered by Henri Becquerel) alpha rays and beta rays in ascending order of penetrating power.
Hydraulic fracturing is the propagation of fractures in a rock layer by pressurized fluid. Induced hydraulic fracturing or hydrofracking, commonly known as fracking, is a technique used to release petroleum, natural gas, or other substances for extraction, particularly from unconventional reservoirs. Radionuclides are associated with fracking in two main ways. Injection of man-made radioactive tracers, along with the other substances in hydraulic-fracturing fluid, is often used to determine the injection profile and location of fractures created by fracking. In addition, fracking releases naturally occurring heavy metals and radioactive materials from shale deposits, and these substances return to the surface with flowback, also referred to as wastewater.
