Criticality (nuclear): Difference between revisions
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In [[nuclear physics]] and [[Nuclear engineering|engineering]], '''criticality''' refers to the condition of a place where there is fissile material, specifying whether a [[nuclear fission chain reaction]] there can be sustained. The place can be an [[Atomic bomb|atomic (nuclear) bomb]], the core of a [[nuclear reactor]], or some other place where fissile material is stored or processed | In [[nuclear physics]] and [[Nuclear engineering|engineering]], '''criticality''' refers to the condition of a place where there is fissile material, specifying whether a [[nuclear fission chain reaction]] there can be sustained. The place can be an [[Atomic bomb|atomic (nuclear) bomb]], the core of a [[nuclear reactor]], or some other place where fissile material is stored or processed. | ||
For a nuclear chain reaction to be sustained, there must be a minimum ''critical mass'' of fissile material. Furthermore, the criticality depends on the geometry of the material. When a critical mass of fissile material is sufficiently compacted, it reaches a critical or supercritical condition and a chain reaction starts up. This causes a multitude of [[neutron]]s to be released and creates [[nuclear fission product]]s, which emit a high level of radiation, which can be harmful or fatal to people nearby. Therefore, unintended criticality is to be avoided. Such a criticality accident can occur if too much uranium or plutonium is brought together in one place. Nuclear reactors have copious radiation shielding and are in a reactor containment to avoid exposing personnel to radiation. | For a nuclear chain reaction to be sustained, there must be a minimum ''critical mass'' of fissile material. Furthermore, the criticality depends on the geometry of the material. When a critical mass of fissile material is sufficiently compacted, it reaches a critical or supercritical condition and a chain reaction starts up. This causes a multitude of [[neutron]]s to be released and creates [[nuclear fission product]]s, which emit a high level of radiation, which can be harmful or fatal to people nearby. Therefore, unintended criticality is to be avoided. Such a criticality accident can occur if too much uranium or plutonium is brought together in one place. Nuclear reactors have copious radiation shielding and are in a reactor containment to avoid exposing personnel to radiation. | ||
Latest revision as of 11:40, 26 November 2012
In nuclear physics and engineering, criticality refers to the condition of a place where there is fissile material, specifying whether a nuclear fission chain reaction there can be sustained. The place can be an atomic (nuclear) bomb, the core of a nuclear reactor, or some other place where fissile material is stored or processed.
For a nuclear chain reaction to be sustained, there must be a minimum critical mass of fissile material. Furthermore, the criticality depends on the geometry of the material. When a critical mass of fissile material is sufficiently compacted, it reaches a critical or supercritical condition and a chain reaction starts up. This causes a multitude of neutrons to be released and creates nuclear fission products, which emit a high level of radiation, which can be harmful or fatal to people nearby. Therefore, unintended criticality is to be avoided. Such a criticality accident can occur if too much uranium or plutonium is brought together in one place. Nuclear reactors have copious radiation shielding and are in a reactor containment to avoid exposing personnel to radiation.