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Topic: Nuclear reaction

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In the News (Tue 20 Aug 19)

  Nuclear Reactions
Nuclear reactions and nuclear scattering are used to measure the properties of nuclei.
Reactions that exchange energy or nucleons can be used to measure the energies of binding and excitation, quantum numbers of energy levels, and transition rates between levels.
Nuclear reactions can also be produced in nature by high-velocity particles from cosmic rays, for instance in the upper atmosphere or in space.
www.lbl.gov /nsd/education/ABC/wallchart/chapters/07/0.html   (1138 words)

 Nuclear reaction - Wikipedia, the free encyclopedia
A nuclear reaction can be represented by an equation similar to a chemical equation, and balanced in an analogous manner.
This is a large amount of energy for a nuclear reaction; the amount is so high because the binding energy per nucleon of the helium-4 nucleus is unusually high, because the He-4 nucleus is doubly magic.
Direct nuclear reactions are most often calculated by some form of distorted wave Born approximation.
en.wikipedia.org /wiki/Nuclear_reaction   (1737 words)

 Teachers' Domain: Nuclear Reaction: Fission
Nuclear power is generated by reactions that take place inside the nuclei of certain atoms.
Nuclear power generation relies on a process called fission, which begins when a fast-moving free neutron "bullet" strikes the nucleus of a uranium or plutonium atom.
In the detonation of an atomic bomb, the reaction is controlled for only as long as it takes for most of the material to undergo fission: a few millionths of a second.
www.teachersdomain.org /9-12/sci/phys/matter/fission/index.html   (553 words)

 Nuclear Reactions | World of Chemistry
Nuclear decay, neutron capture, fission, and fusion are the four major nuclear reactions.
The nuclear reactions of fission and fusion have profound scientific and controversial social consequences.
Fusion is the nuclear reaction that fuels the Sun and stars, the reaction involves the combining of two nuclei into one nucleus.
www.bookrags.com /research/nuclear-reactions-woc   (918 words)

Nuclear fission works best if isotopes - atoms with the same atomic number, but different numbers of neutrons - of uranium 235 (or plutonium 239) are used.
Uranium-235 is known as a "fissile isotope" because of its propensity to split in a chain reaction, releasing energy in the form of heat.
A nuclear reaction will only take place if there are enough u-235 atoms present to allow this process to continue as a self-sustaining chain reaction.
news.bbc.co.uk /2/shared/spl/hi/sci_nat/05/nuclear_fuel/html/mining.stm   (274 words)

 How Things Work - Nuclear Weapons   (Site not responding. Last check: 2007-09-10)
When this nuclear fuel is at critical mass, each nucleus that fissions directly induces an average of one subsequent fission.
Steady chain reactions of this sort are used in nuclear reactors.
Tritium is an artificial, radioactive isotope with one proton and two neutrons in its nucleus, and can be formed in nuclear reactors or, during a nuclear explosion, by the exposure of lithium nuclei to the neutrons formed in that explosion.
howthingswork.virginia.edu /nuclear_weapons.html   (2860 words)

 Nuclear chain reaction - Wikipedia, the free encyclopedia
One of those neutrons is absorbed by an atom of uranium-238, and does not continue the reaction.
The neutrons leave the reaction at a high rate of speed, and may collide with other heavy atoms in a phenomenon known as "fission capture".
The first artificial self-sustaining nuclear chain reaction was initiated by the Metallurgical Laboratory, led by Enrico Fermi and Leó Szilárd, in a racquets court below the bleachers of Stagg Field at the University of Chicago on December 2, 1942 during the Manhattan Project.
en.wikipedia.org /wiki/Nuclear_chain_reaction   (1279 words)

 nuclear chemistry
Nuclear chain reactions are used in nuclear reactors and nuclear bombs.
MU #1 Energy released during nuclear reactions is much greater than the energy released during chemical reactions.
Energy released in a nuclear reaction (fission or fusion) comes from the fractional amount of mass converted into energy.
www.chemcool.com /regents/nuclearchemistry/aim4.htm   (616 words)

 Nuclear PowerPlant Safety: Operations
The Nuclear Regulatory Commission (NRC) requires that the containment structure for a nuclear powerplant be capable of withstanding severe outside events such as an earthquake, a tornado, or the impact of a large aircraft.
Nuclear powerplants develop extensive plans for warning the public and notifying the authorities within a ten-mile radius in case of any unexpected event that could affect public health and safety.
Nuclear powerplants maintain strict security to help ensure operating safety and prevent the loss of nuclear materials or acts of sabotage that could cause and unplanned release of radioactive material.
www.nuc.umr.edu /nuclear_facts/design/design.html   (2020 words)

 Nuclear weapon at AllExperts
Nuclear weapons delivery— the technology and systems used to bring a nuclear weapon to its target—is an important aspect of nuclear weapons relating both to nuclear weapon design and nuclear strategy.
Nuclear weapons were symbols of military and national power, and nuclear testing was often used both to test new designs as well as to send political messages.
Nuclear weapons have been at the heart of many national and international political disputes and have played a major part in popular culture since their dramatic public debut in the 1940s and have usually symbolized the ultimate ability of mankind to utilize the strength of nature for destruction.
en.allexperts.com /e/n/nu/nuclear_weapon.htm   (2702 words)

 World Nuclear Association | Articles, Editorials and Opinion | Labour Worries Over Nuclear Reaction   (Site not responding. Last check: 2007-09-10)
The examination will focus, not on the actual safety risks of oil and gas, but on the perception of risk in the nuclear industry, an industry that was, thanks to the efforts of Greenpeace and Friends of the Earth, widely thought to be facing extinction.
Without big public investment, the revival of Britain’s nuclear industry could be made in the US and run by the French.
Inevitably, a nuclear revival will not happen without a financial carrot from the Government, and if BNFL is to be the vehicle, it will need wholesale financial restructuring.
www.world-nuclear.org /opinion/times270601.htm   (1032 words)

 Basic Nuclear Science Information
A change in nuclear charge means that the element has been changed into a different element.
Fusion is a nuclear reaction in which nuclei combine to form a heavier nucleus.
An example of a fission reaction that was used in the first atomic bomb and is still used in nuclear reactors is
www.lbl.gov /abc/Basic.html   (2359 words)

Nuclear fusion is a process where two or more nuclei combine to form an element with a higher atomic number (more protons in the nucleus).
For a fusion reaction to occur it is necessary to bring the reactants so close together that nuclear forces become important and "glue" the reactants together.
On Earth, nuclear fusion was reached first in the explosion of the Hydrogen bomb.
www.windows.ucar.edu /tour/link=/sun/Solar_interior/Nuclear_Reactions/Fusion/fusion_reactions.html&edu=high   (336 words)

 Nuclear Chemistry - First Chain Reaction (1942)
The first nuclear reactor, called a pile, was a daring and sophisticated experiment that required nearly 50 tons of machined and shaped uranium and uranium oxide pellets along with 385 tons - the equivalent of four railroad coal hoppers - of graphite blocks, machined on site.
The pile itself was assembled in a squash court under the football field at the University of Chicago from the layered graphite blocks and uranium and uranium oxide lumps (Fermi's term) arranged roughly in a sphere with an anticipated 13 foot radius.
The achievement of the first sustained nuclear reaction was the beginning of a new age in nuclear physics and the study of the atom.
chemcases.com /nuclear/nc-05.htm   (824 words)

 Sch002: Nuclear Reactions   (Site not responding. Last check: 2007-09-10)
The interaction between nuclear radiation and matter is called a "nuclear reaction" (although gamma rays can also interact with the electrons of an atom through photoatomic reactions).
Nuclear reactions are described by specifying the type of the incident radiation, the nuclear target, the products of the reaction, the probability that the reaction will take place, which is called the "cross section," and the distributions in energy and angle of the reaction products.
Most of the nuclear reaction data available from this WWW site are neutron data because of their technological importance.
t2.lanl.gov /tour/sch002.html   (1765 words)

 Foreign Affairs - NUCLEAR REACTION - Richard L. Garwin
Rhodes and Beller observe that "large nuclear power plants require larger capital investments than comparable coal or gas plants only because nuclear utilities are required to build and maintain costly systems to keep their radioactivity from the environment." But there is a good reason for this: they have a millionfold more radioactivity to retain.
Nuclear energy in the short term needs access to proper storage for waste: competitive and commercial geological repositories for properly packaged spent fuel or reprocessing wastes (encased in glass and steel) from countries throughout the world.
Certainly, there is room for market-driven innovations in nuclear reactors and the fuel cycle, including reductions in radiation exposure from mining and milling and from reprocessing.
www.foreignaffairs.org /20000301faresponse4378/richard-l-garwin/nuclear-reaction.html?mode=print   (546 words)

 Nuclear Energy: An Overview
Nuclear energy in California (and imported from outside the state) accounted for 36,970 gigwatt-hours, represents 12.8 perecent of electricity from all sources in 2004.
Nuclear fission is the process of splitting the nuclei of atoms, which releases energy from within those atoms.
A fusion reaction occurs when nuclei of light elements, specifically hydrogen and its isotopes (deuterium, or "heavy water," and tritium), are forced together at extremely high temperatures and densities until they fuse into nuclei of heavier elements and release enormous amounts of energy.
www.energy.ca.gov /nuclear/overview.html   (1583 words)

 McGraw-Hill AccessScience: Nuclear reaction   (Site not responding. Last check: 2007-09-10)
While nuclear reactions occur in nature, understanding of them and use of them as tools have taken place primarily in the controlled laboratory environment.
In the usual experimental situation, nuclear reactions are initiated by bombarding one of the interacting particles, the stationary target nucleus, with nuclear projectiles of some type, and the reaction products and their behaviors are studied.
The study of nuclear reactions is the largest area of nuclear and subnuclear (or particle) physics; the threshold for producing pions has historically been taken to be the energy boundary between the two fields.
www.accessscience.com /Encyclopedia/4/46/Est_460000_frameset.html   (176 words)

 Nuclear Reactions   (Site not responding. Last check: 2007-09-10)
The probability of a given type of nuclear reaction taking place is often stated as a "cross section".
The nuclear reaction in the atmosphere which produces carbon-14 for radiocarbon dating.
To characterize the probability that a certain nuclear reaction will take place, it is customary to define an effective size of the nucleus for that reaction, called a cross section.
hyperphysics.phy-astr.gsu.edu /hbase/nuclear/nucrea.html   (280 words)

 Nuclear Energy
Nuclear energy is energy that comes from the nucleus (core) of an atom.
Nuclear energy is released from an atom through one of two processes: nuclear fusion or nuclear fission.
Nuclear fission is the only method currently used by nuclear plants to generate electricity.
lsa.colorado.edu /essence/texts/nuclear.htm   (2092 words)

 Nuclear Files: Library: Welcome Desk
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, and the physical shape.
Nuclear fusion is a process during which light atoms fuse to form heavier ones.
Nuclear fuel elements that are discharged from a nuclear reactor after they have been used to produce power.
www.nuclearfiles.org /menu/library/terms-acronyms/index.htm   (1766 words)

 Natural Nuclear
Nuclear power is controversial - it produces relatively pollutant-free energy and is independent of oil, but is dangerous and generates extraordinary radioactive waste.
A natural nuclear reactor like this could never occur today: conditions just happened to be perfect two billion years ago — the right amount of the right kind of uranium existed in the right spot.
Modern nuclear power plants — or nuclear reactors - face two huge issues: The first one is the careful management of the dangerous nuclear reactions that produce the plant’s energy.
www.acfnewsource.org /science/natural_nuclear.html   (1005 words)

 Nuclear Data Program: Technology Development Division (ANL), Programs -Nuclear Applications
The mission of this program is to contribute to the preparation of comprehensive nuclear reaction and nuclear structure databases, and to the development of nuclear data measurement, analysis, modeling, and evaluation methodologies for implementation in basic science research and technology.
A significant portion of the effort is devoted to the compilation and evaluation of existing nuclear structure and decay, and nuclear reactions data.
The program focuses on the manner in which nuclear data are used in science and engineering, and on development of new applications for nuclear data.
www.td.anl.gov /NDP   (263 words)

 Nuclear Reactions | World of Physics
Although chemical reactions of everyday experience generally take place between the electrons surrounding an atom there are important and fundamental processes that take place in the nucl eus of an atom.
It is important to remember that radioactivity is a process not a term to be applied to the energy or substance emitted as a result of the radioactive p rocess.
Scientists study nuclear reactions by accelerating atomic particles (e.g., neutrons) that, upon collision with the target nucleus, transfer enough energy to stimulate nuclear reactions.
www.bookrags.com /research/nuclear-reactions-wop   (927 words)

 Nuclear accident in Japan is the country's worst
Nuclear experts say they've contained a dangerous leak of radioactive material at a uranium processing plant in Japan.
The "chain reaction" effect was heightened by the presence of water at the plant in Japan.Workers spent much of the night draining coolant water that had helped feed a "chain reaction" of uranium.
Officials spent more than 24 hours worrying about chemical reactions continuing inside the plant, the same kind of reactions that occur when uranium is heating up to be used as nuclear fuel.
www.cbc.ca /world/story/1999/09/30/japan_nuclear990930.html   (1624 words)

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