the amount of fissile material that is needed to support a self-sustaining nuclear chain reaction
(social dynamics) A sufficient number of adopters of an innovation in a social system so that the rate of adoption becomes self-sustaining and creates further growth
the minimum size that a market or industry is considered to need to operate at in order to be efficient
the minimum size of firm thought necessary to compete effectively, e g to finance R & D
The capacity to offer certain medical specialties or sub-specialties is dependent on having a large enough population in order to have a large enough number of patients to maintain competencies
the minimum amount (of something) required to start or maintain a venture; "the battle for the computer market has now reached critical mass"; "there is now a critical mass of successful women to take the lead"; "they sold the business because it lacked critical mass"
The minimum amount concentrated fissionable material required to sustain a chain reaction The exact mass of fissionable material needed to sustain a chain reaction varies according to the concentration (purity) and chemical form of the material, the particular fissionable isotope present, its geometrical properties, and its density When pure fissionable materials are compressed by high explosives in implosion-type atomic weapons, the critical mass needed for a nuclear explosion is reduced
The amount of a fissionable material , at a given density and mixed in a specified way with other material, where on average one neutron caused by a fission reaction will go on to cause another fission
The minimum mass required to sustain a chain reaction The exact mass varies with many factors such as the particular isotope present, its concentration and chemical form, the geometric arrangement of the material, and its density
In this document critical mass is used to describe the grouping together of visitor facilities to achieve a minimum desired level of activity It is the combination of visitor experience necessary to create a major attraction that provides high-quality interpretive services to the visitor
Spontaneous fission in uranium produces neutrons that induce fission of 235U, which releases neutrons that can produce a chain reaction The critical mass is the amount of fissable material necessary for this chain reaction to sustain itself
The smallest mass of fissile material that will support a self-sustaining chain reaction under specified conditions
The condition when enough educators in an organization are effectively using strategies such as cooperative learning, process writing, interdisciplinary instruction, or performance-based learning and assessment so that these new strategies have a high probability of becoming a permanent part of the culture of that organization (school or school district)
The minimum amount of fuel needed in the core of a nuclear reactor in order to start a self-sustaining chain reaction When a reactor starts up it is said to "go critical"
The minimum mass of a fissionable material that will just maintain a fission chain reaction under precisely specified conditions, such as the nature of the material and its purity, the nature and thickness of the tamper (or neutron reflector), the density (or compression), and the physical shape (or geometry) For an explosion to occur, the system must be supercritical (i e , the mass of material must exceed the critical mass under the existing conditions) See Supercritical
The minimum amount of concentrated fissionable material required to sustain a chain reaction
the mass of fissionable material required to produce a self-sustaining chain reaction
the minimum mass of fissionable material that can sustain a chain reaction the minimum amount (of something) required to start or maintain a venture; "the battle for the computer market has now reached critical mass"; "there is now a critical mass of successful women to take the lead"; "they sold the business because it lacked critical mass
A critical mass of something is an amount of it that makes it possible for something to happen or continue. Only in this way can the critical mass of participation be reached. Minimum amount of a given fissionable material necessary to achieve a self-sustaining nuclear chain reaction under specified conditions. Critical mass depends on several factors, including the kind of fissionable material used, its concentration and purity, and the composition and geometry of the surrounding reaction system