The sum of the dose equivalents to the organ or tissue (HT) and the weighting factors (WT) applicable to each of the body organs or tissues that are irradiated.
The time required for the concentration of a radionuclide in a biological system to be reduced by one half. An effective half-life includes all processes of elimination, including radioactive decay.
The measure of criticality in a given system. Effective multiplication factor is an indication of whether the number of neutrons produced by a fissionable mass is increasing or decreasing. When the effective multiplication factor is less than 1.0, the system is sub-critical; when the effective multiplication factor exceeds 1.0, the system is super-critical; and when the effective multiplication factor is exactly 1.0, the system is critical.
Symbol: Keff.
Synonym: criticality factor.
Related to cent.
Related to dollar.
Related to inhour.
Related to reactivity.
The probability an incident radiation will interact with a detection medium forming a recordable event. Efficiency can also be defined as the probability an incident radiation will deposit all its energy inside the detection medium. This definition is especially appropriate for gamma-ray spectroscopy where Compton scattering and other photon-interaction processes result in a degraded electrical signal and thus a loss of detected energy.
A chemical element with atomic number 99. Einsteinium Albert Ghiorso, Glenn Seaborg, and colleagues discovered Einsteinium by studying debris from a 1952 thermonuclear explosion that occurred in the South Pacific. The name einsteinium was given in honor of Albert Einstein.
A radiation, particle or ion produced as the result of a nuclear reaction. It is used in the context of a nuclear reaction where the projectile interacts with a target nucleus, producing a product nucleus and an ejectile.
A basic constituent of the atom. The electron is a fundamental particle that has a mass of 0.000548579903 ± 0.000000000013 atomic mass units (0.51099907 ± 0.00000015 MeV). A free, unbound electron is stable against radioactive decay. The electron is a lepton with a spin of 1/2 and a charge of -1. The positron is the antiparticle of the electron.
Symbol: e-.
Synonym: corpuscle.
Synonym: negative thermion.
Synonym: negaton.
Synonym: negatron.
Related to positron.
A unit of energy defined as 1.60919x10-19 joules. It is the energy required to raise an electron through a potential difference of 1 volt. The electron volt is not an SI unit but its use is valid unit within the International System of units.
Symbol: eV.
Symbol: (obsolete)ev.
Related to joule.
(1) One or more nuclides, or a population of such nuclides with a specific number of protons. A chemical element.
(2) The chemical elements uranium or plutonium.
The relative concentration of a particular element (in any chemical form) as found in nature. This term should not be confused with isotopic abundance.
A backup coolant system for reactors that automatically activates when the primary coolant system fails. It is designed to limit the temperature of the reactor core and thereby prevent damage. Upon activation of the backup coolant system, the reactor scrams, reducing the heat output of the core. Latent heat produced from the decay of fission products in the core requires continued cooling after the reactor has been scrammed.
[From the Environmental Protection Agency Web Site.]
The mission of the U.S. Environmental Protection Agency is to protect human health and to safeguard the natural environment--air, water, and land--upon which life depends.
EPA's purpose is to ensure that:
All Americans are protected from significant risks to human health and the environment where they live, learn and work.
National efforts to reduce environmental risk are based on the best available scientific information.
Federal laws protecting human health and the environment are enforced fairly and effectively.
Environmental protection is an integral consideration in U.S. policies concerning natural resources, human health, economic growth, energy, transportation, agriculture, industry, and international trade, and these factors are similarly considered in establishing environmental policy.
All parts of society--communities, individuals, business, state and local governments, tribal governments--have access to accurate information sufficient to effectively participate in managing human health and environmental risks.
Environmental protection contributes to making our communities and ecosystems diverse, sustainable and economically productive.
The United States plays a leadership role in working with other nations to protect the global environment.
Any state where the creation or addition of a component equals the consumption or removal of that component. The term is often used in nuclear science in the context of the activity of a radioactive nuclide that is fed by a radioactive parent. The system is said to be in equilibrium when the rate of decay of the parent equals the rate of decay of the daughter.
The absorbed dose expressed in terms of the potential injury that it could cause. It is the product of the absorbed dose, the quality factor, and all other necessary modifying factors at the location of interest. The SI standard uni for dose equivalent is the sievert.
A chemical element with atomic number 68. Erbium was discovered in 1843 by Carl Gustaf Mosander. The name erbium is derived from Ytterby, a town in Sweden, the place of discovery.
A chemical element with atomic number 63. Europium was discovered in 1890 by Paul-émile Lecoq de Boisbaudran who was conducting experiments on compounds of samarium and gadolinium. In his experiments, de Boisbaudran noticed spectral lines which he suggested were due to a new element that he was never able to isolate. In 1901 Eugène-Anatole Demarçay was credited for the discovery of europium because he was able to successfully isolate it. The name europium is derived from Europe.
(1) The area surrounding a reactor in which the reactor operator (licensee) has the authority to determine all activities. This includes limiting or excluding access to the area by personnel or property.
(2) A security area for the protection of classified matter where mere access to the area would result in access to classified matter.
A rapid increase in reactor power. Excursions may be accidental or they may be deliberate. A safety system test is an example of a deliberate excursion.
An atom whose nucleus is made of a positively-charged fundamental particle or in which an electron has been replaced by a negatively-charged fundamental particle.
A hand, forearm, elbow, foot, ankle, lower leg, or knee. Extremities are often considered separately from the rest of the body because they are less susceptible to radiation.
