The single primordial beryllium isotope < sup > 9 </ sup > Be also undergoes a ( n, 2n ) neutron reaction with neutron energies over about 1. 9 MeV, to produce < sup > 8 </ sup > Be, which almost immediately breaks into two alpha particles.

Thus, natural beryllium bombarded either by alphas or gammas from a suitable radioisotope is a key component of most radioisotope-powered nuclear reaction neutron sources for the laboratory production of free neutrons.

For example, the probability that an alpha particle striking a beryllium target will produce a neutron can be expressed as the equivalent cross section of beryllium for this type of reaction.

A nuclear chain reaction was proposed by Leó Szilárd in 1933, shortly after the neutron was discovered, but more than five years before nuclear fission was discovered.

Neon-21 may also be produced in a nucleogenic reaction, when < sup > 20 </ sup > Ne absorbs a neutron from various natural terrestrial neutron sources.

Fission as encountered in the modern world is usually a deliberately-produced manmade nuclear reaction induced by a neutron.

Another neutron is simply lost and does not collide with anything, also not continuing the reaction.

In-situ plutonium production also contributes to the neutron chain reaction in other types of reactors after sufficient plutonium-239 has been produced, since plutonium-239 is also a fissile element which serves as fuel.

After nuclear fission was discovered by others in 1938, Szilárd and Enrico Fermi in 1939 searched for, and discovered, neutron multiplication in uranium, proving that a nuclear chain reaction by this mechanism was indeed possible.

This nuclear chain reaction can be controlled by using neutron poisons and neutron moderators to change the portion of neutrons that will go on to cause more fissions.

Long before all possible fission has taken place, the buildup of long-lived neutron absorbing fission byproducts impedes the chain reaction.

The natural nuclear reactors formed when a uranium-rich mineral deposit became inundated with groundwater that acted as a neutron moderator, and a strong chain reaction took place.

* Reactors Designed by Argonne National Laboratory The “ firsts ” among these reactors were many, but they include the first man-made self-sustaining neutron chain reaction, and the first generation of electricity from nuclear energy.

In a nuclear reactor, such a chain reaction is slowed and controlled by a neutron poison, absorbing some of the free neutrons.

Th-232 is a fertile material that can undergo a neutron capture reaction and two beta minus decays, resulting in the production of fissile U-233.

A neutron bomb is a fission-fusion thermonuclear weapon ( hydrogen bomb ) in which the burst of neutrons generated by a fusion reaction is intentionally allowed to escape the weapon, rather than being absorbed by its other components.

In an NSWR the nuclear salt-water would be made to flow through a reaction chamber and out an exhaust nozzle in such a way and at such speeds that the peak neutron flux in the fission reaction would occur outside of the vehicle.

Because the peak neutron flux and fission reaction rates would occur outside of the vehicle, these activities could be much more vigorous than they could be if it was necessary to house them in a vessel ( which would have temperature limits due to materials constraints ).

These devices would deliver a successive stream of targets to the reaction chamber, several a second typically, and capture the resulting heat and neutron radiation from their implosion and fusion to drive a conventional steam turbine.

One proposed reaction is that of the olivine-rich rock dunite, or its hydrated equivalent serpentinite with carbon dioxide to form the carbonate mineral magnesite, plus silica and iron oxide ( magnetite ).

A benefit of using nanoscale for medical technologies is that smaller devices are less invasive and can possibly be implanted inside the body, plus biochemical reaction times are much shorter.

The reaction equation for elementary reactions coincides with the process taking place at the atomic level, i. e. n molecules of type A colliding with m molecules of type B ( n plus m is the molecularity ).

Since a negative enthalpy change in a reaction means that energy is being released to the surroundings, then the ' isolated ' system includes the chemical reaction plus its surroundings.

The " spent " catalyst then flows into a fluidized-bed regenerator where air ( or in some cases air plus oxygen ) is used to burn off the coke to restore catalyst activity and also provide the necessary heat for the next reaction cycle, cracking being an endothermic reaction.

The scramble time plus the two-minute identification ' window ' meant that, during the Cold War, the Northern NORAD Region's reaction time, from detecting an aircraft to interceptor take-off, was seven minutes.

These 2 incidents, plus the bad reaction to post-flight anesthesia in the US monkey, Able, 4 days after return to earth were never followed up as a potential impact of spaceflight contraindicating anesthesia during or shortly after spaceflght.

Ozone is lost by reaction with atomic oxygen ( plus other trace atoms ).

His opposition to the status quo plus his aggressive style in art caused him problems in his own country at times, including violent public reaction to his work, written insults, threats and even having his house machine-gunned once.

An attempt to organize a chapter in Ottawa failed after the police and city refused to cooperate plus a negative reaction and lack of interest from the majority of its population.

During electrolysis, the amount of electrical energy that must be added equals the change in Gibbs free energy of the reaction plus the losses in the system.

Examples of such agents include baking soda ( sodium bicarbonate ) plus an acid, such as cream of tartar, lemon juice or cultured buttermilk, to elicit an acid-base reaction that releases carbon dioxide.

The catalytic recovery of sulfur consists of three substeps: heating, catalytic reaction and cooling plus condensation.

The end of series report in Wisden commented that: " Evans did not miss one Test catch, but he caught some which became chances only through lightning mental reaction plus acrobatic agility " commenting on his batting added: " Evans played one praiseworthy innings in the second Test but in others inability to curb his natural ebullience caused him to do less than justice to his talents.

The introduction of emergency telephone call boxes linked to a central dispatcher, plus bicycles, motorcycles and automobiles shifted the patrolman's duties from passively walking the beat to fast reaction to reported incidents, as well as handling automobile traffic.

Specifically, if one or more of the produced neutrons themselves interact with other fissionable nuclei, and these also undergo fission, then there is a possibility that the macroscopic overall fission reaction will not stop, but continue throughout the reaction material.

As noted above, the subgroup of fissionable elements that may be fissioned efficiently with their own fission neutrons ( thus potentially causing a nuclear chain reaction in relatively small amounts of the pure material ) are termed " fissile.

Not all fissionable isotopes can sustain a chain reaction.

An alternative definition defines fissile nuclides as those nuclides that can be made to undergo nuclear fission ( i. e., are fissionable ) and also produce neutrons from such fission that can sustain a nuclear chain reaction in the correct setting.

Under this definition, nuclides that are only fissionable are those nuclides that can be made to undergo nuclear fission but produce insufficient neutrons, in either energy or number, to sustain a nuclear chain reaction.

Under all definitions above, uranium-238 ( U-238 ) is fissionable, but because it cannot sustain a neutron chain reaction, it is not fissile.

Uranium's most common isotope, U-238, is fissionable but not fissile ( meaning that it cannot sustain a chain reaction by itself but can be made to fission, specifically by fast neutrons from a fusion reaction ).

Nuclear power relies on fissionable material that can sustain a chain reaction with neutrons.

In order to achieve an effective fission chain reaction, the neutrons produced during fission must be captured by fissionable nuclei, which then split, releasing more neutrons.

< sup > 238 </ sup > U is fissionable by fast neutrons, but cannot support a chain reaction because inelastic scattering reduces neutron energy below the range where fast fission of one or more next-generation nuclei is probable.

* Accelerator-driven sub-critical reactor, a nuclear reactor using a particle accelerator to generate a fission reaction in a sub-critical assembly of fissionable material

One of the main clarifications provided by the analysis is the definition of " fissionable material " (" plutonium, enriched uranium, and any other material which the Commission determines to be capable of releasing substantial quantities of energy through nuclear chain reaction of the material, or any material artificially enriched by any of the foregoing ; but does not include

# The fusion fuel of the secondary stage may be surrounded by depleted uranium or natural uranium, whose U-238 is not fissile and cannot sustain a chain reaction, but which is fissionable when bombarded by the high-energy neutrons released by fusion in the secondary stage.