Nuclear engineering
Nuclear engineering is the branch of engineering concerned with the application of breaking down atomic nuclei or of combining atomic nuclei, or with the application of other sub-atomic processes based on the principles of nuclear physics. In the sub-field of nuclear fission, it includes the design and maintenance of systems and components like nuclear reactors, nuclear power plants, or nuclear weapons; the field includes the study of medical and other applications of radiation Ionizing radiation, nuclear safety, heat/thermodynamics transport, nuclear fuel, or other related technology and the problems of nuclear proliferation. The United States generates about 18% of its electricity from nuclear power plants. Nuclear engineers in this field work, directly or indirectly, in the nuclear power industry or for national laboratories. Current research in the industry is directed at producing economical and proliferation-resistant reactor designs with passive safety features; some government labs provide research in the same areas as private industry and in other areas such as nuclear fuels and nuclear fuel cycles, advanced reactor designs, nuclear weapon design and maintenance.
A principal pipeline/source of trained personnel for US reactor facilities is the US Navy Nuclear Power Program, including its Nuclear Power School in South Carolina. Employment in nuclear engineering is predicted to grow about nine percent to year 2022 as needed to replace retiring nuclear engineers, provide maintenance and updating of safety systems in power plants, to advance the applications of nuclear medicine. Medical physics is an important field of nuclear medicine. Specialized and intricately operating equipment, including x-ray machines, MRI and PET scanners and many other devices provide most of modern medicine's diagnostic capability—along with disclosing subtle treatment options. Nuclear materials research focuses on two main subject areas, nuclear fuels and irradiation-induced modification of nuclear materials. Improvement of nuclear fuels is crucial for obtaining increased efficiency from nuclear reactors. Irradiation effects studies have many purposes, including studying structural changes to reactor components and studying nano-modification of metals using ion-beams or particle accelerators.
Radiation measurement is fundamental to the science and practice of radiation protection, sometimes known as radiological protection, the protection of people and the environment from the harmful effects of uncontrolled radiation. Nuclear engineers and radiological scientists are interested in developing more advanced ionizing radiation measurement and detection systems, using these advances to improve imaging technologies. American Nuclear Society Nuclear Institute International Atomic Energy Agency Gowing, Margaret. Britain and Atomic Energy, 1939–1945. Gowing and Lorna Arnold. Independence and Deterrence: Britain and Atomic Energy, Vol. I: Policy Making, 1945–52. "Creating a Canadian Profession: The Nuclear Engineer, 1940–68," Canadian Journal of History, Winter 2009, Vol. 44 Issue 3, pp 435–466 Johnston, Sean F. "Implanting a discipline: the academic trajectory of nuclear engineering in the USA and UK," Minerva, 47, pp. 51–73 Ash, Milton, "Nuclear reactor kinetics", McGraw-Hill, Nuclear Safety Info Resources Science and Technology of Nuclear Installation Open-Access Journal Nuclear Engineering International magazine Nuclear Science and Engineering technical journal Electric Generation from Commercial Nuclear Power Hacettepe University Department of Nuclear Engineering
Caesium-137
Caesium-137, or radiocaesium, is a radioactive isotope of caesium, formed as one of the more common fission products by the nuclear fission of uranium-235 and other fissionable isotopes in nuclear reactors and nuclear weapons. It is among the most problematic of the short-to-medium-lifetime fission products because it moves and spreads in nature due to the high water solubility of caesium's most common chemical compounds, which are salts. Caesium-137 has a half-life of about 30.17 years. About 94.6 percent decays by beta emission to a metastable nuclear isomer of barium: barium-137m. The remainder directly populates the ground state of barium-137, stable. Ba-137m has a half-life of about 153 seconds, is responsible for all of the emissions of gamma rays in samples of caesium-137. 85.1% of metastable barium decays to ground state by emission of gamma rays having energy 0.6617 MeV. One gram of caesium-137 has an activity of 3.215 terabecquerel. The main photon peak of Ba-137m is 662 keV. Caesium-137 has a number of practical uses.
In small amounts, it is used to calibrate radiation-detection equipment. In medicine, it is used in radiation therapy. In industry, it is used in flow meters, thickness gauges, moisture-density gauges, in gamma ray well logging devices. Caesium-137 is not used for industrial radiography because it is quite chemically reactive, hence difficult to handle; the salts of caesium are soluble in water, this complicates the safe handling of caesium. Cobalt-60, 6027Co, is preferred for radiography, since it is chemically a rather nonreactive metal and produces higher energy gamma-ray photons; as a purely man-made isotope, caesium-137 has been used to date wine and detect counterfeits and as a relative-dating material for assessing the age of sedimentation occurring after 1954. Caesium-137 is used as a radioactive tracer in geologic research to measure soil erosion and deposition. Caesium-137 reacts with water; the biological behavior of caesium is similar to that of rubidium. After entering the body, caesium gets more or less uniformly distributed throughout the body, with the highest concentrations in soft tissue.
The biological half-life of caesium is rather short, at about 70 days. A 1972 experiment showed that when dogs are subjected to a whole body burden of 3800 μCi/kg of caesium-137, they die within 33 days, while animals with half of that burden all survived for a year. Accidental ingestion of caesium-137 can be treated with Prussian blue, which binds to it chemically and reduces the biological half-life to 30 days. Caesium-134 and caesium-137 were released into the environment during nearly all nuclear weapon tests and some nuclear accidents, most notably the Chernobyl disaster and the Fukushima Daiichi disaster; as of 2005 and for the next few hundred years, caesium-137 is the principal source of radiation in the zone of alienation around the Chernobyl nuclear power plant. Together with caesium-134, iodine-131, strontium-90, caesium-137 was among the isotopes distributed by the reactor explosion that constitute the greatest risk to health; the mean contamination of caesium-137 in Germany following the Chernobyl disaster was 2000 to 4000 Bq/m2.
This corresponds to a contamination of 1 mg/km2 of caesium-137, totaling about 500 grams deposited over all of Germany. In Scandinavia, some reindeer and sheep exceeded the Norwegian legal limit 26 years after Chernobyl; as of 2016 the Chernobyl caesium-137 has decayed by half, but could have been locally concentrated by much larger factors. In April 2011, elevated levels of caesium-137 were being found in the environment after the Fukushima Daiichi nuclear disasters in Japan. In July 2011, meat from 11 cows shipped to Tokyo from Fukushima Prefecture was found to have 1,530 to 3,200 becquerels per kilogram of Cs-137 exceeding the Japanese legal limit of 500 becquerels per kilogram at that time. In March 2013, a fish caught near the plant had a record 740,000 becquerels per kilogram of radioactive caesium, above the 100 becquerels per kilogram government limit. A 2013 paper in Scientific Reports found that for a forest site 50 km from the stricken plant, Cs-137 concentrations were high in leaf litter and detritivores, but low in herbivores.
By the end of 2014, "Fukushima-derived radiocesium had spread into the whole western North Pacific Ocean", transported by the North Pacific current from Japan to the Gulf of Alaska. It has been measured in the surface layer down to 200 meters and south of the current area down to 400 meters. Caesium-137 is reported to be the major health concern in Fukushima; the government is under pressure to clean up radioactivity from Fukushima from as much land as possible so that some of the 110,000 people can return. A number of techniques are being considered that will be able to strip out 80% to 95% of the caesium from contaminated soil and other materials efficiently and without destroying the organic material in the soil; these include hydrothermal blasting. The caesium precipitated with ferric ferricyanide would be the only waste requiring special burial sites; the aim is to get annual exposure from the contaminated environment down to 1 millisievert above background. The most contaminated area where radiation doses are greater than 50 mSv/year must remain off limits, but some areas that are less than 5 mSv/year may be decontaminated, allowing 22,000 residents to return.
Caesium-137 in the environment is anthropogenic. Caesium-137 is produced from the nuclear fission of plutonium and uran
Fermium
Fermium is a synthetic element with symbol Fm and atomic number 100. It is an actinide and the heaviest element that can be formed by neutron bombardment of lighter elements, hence the last element that can be prepared in macroscopic quantities, although pure fermium metal has not yet been prepared. A total of 19 isotopes are known, with 257Fm being the longest-lived with a half-life of 100.5 days. It was discovered in the debris of the first hydrogen bomb explosion in 1952, named after Enrico Fermi, one of the pioneers of nuclear physics, its chemistry is typical for the late actinides, with a preponderance of the +3 oxidation state but an accessible +2 oxidation state. Owing to the small amounts of produced fermium and all of its isotopes having short half-lives, there are no uses for it outside basic scientific research. Fermium was first discovered in the fallout from the'Ivy Mike' nuclear test, the first successful test of a hydrogen bomb. Initial examination of the debris from the explosion had shown the production of a new isotope of plutonium, 24494Pu: this could only have formed by the absorption of six neutrons by a uranium-238 nucleus followed by two β− decays.
At the time, the absorption of neutrons by a heavy nucleus was thought to be a rare process, but the identification of 24494Pu raised the possibility that still more neutrons could have been absorbed by the uranium nuclei, leading to new elements. Element 99 was discovered on filter papers, flown through the cloud from the explosion, it was identified in December 1952 by Albert Ghiorso and co-workers at the University of California at Berkeley. They discovered the isotope 253Es, made by the capture of 15 neutrons by uranium-238 nuclei – which underwent seven successive beta decays: Some 238U atoms, could capture another amount of neutrons; the discovery of fermium required more material, as the yield was expected to be at least an order of magnitude lower than that of element 99, so contaminated coral from the Enewetak atoll was shipped to the University of California Radiation Laboratory in Berkeley, for processing and analysis. About two months after the test, a new component was isolated emitting high-energy α-particles with a half-life of about a day.
With such a short half-life, it could only arise from the β− decay of an isotope of einsteinium, so had to be an isotope of the new element 100: it was identified as 255Fm. The discovery of the new elements, the new data on neutron capture, was kept secret on the orders of the U. S. military until 1955 due to Cold War tensions. The Berkeley team was able to prepare elements 99 and 100 by civilian means, through the neutron bombardment of plutonium-239, published this work in 1954 with the disclaimer that it was not the first studies, carried out on the elements; the "Ivy Mike" studies were declassified and published in 1955. The Berkeley team had been worried that another group might discover lighter isotopes of element 100 through ion-bombardment techniques before they could publish their classified research, this proved to be the case. A group at the Nobel Institute for Physics in Stockholm independently discovered the element, producing an isotope confirmed to be 250Fm by bombarding a 23892U target with oxygen-16 ions, published their work in May 1954.
The priority of the Berkeley team was recognized, with it the prerogative to name the new element in honour of the deceased Enrico Fermi, the developer of the first artificial self-sustained nuclear reactor. There are 20 isotopes of fermium listed in NUBASE 2016, with atomic weights of 241 to 260, of which 257Fm is the longest-lived with a half-life of 100.5 days. 253Fm has a half-life of 3 days, while 251Fm of 5.3 h, 252Fm of 25.4 h, 254Fm of 3.2 h, 255Fm of 20.1 h, 256Fm of 2.6 hours. All the remaining ones have half-lives ranging from 30 minutes to less than a millisecond; the neutron-capture product of fermium-257, 258Fm, undergoes spontaneous fission with a half-life of just 370 microseconds. This means that neutron capture cannot be used to create nuclides with a mass number greater than 257, unless carried out in a nuclear explosion; as 257Fm is an α-emitter, decaying to 253Cf, no known fermium isotopes undergo beta minus decay to the next element, fermium is the last element that can be prepared by a neutron-capture process.
Because of this impediment in forming heavier isotopes, these short-lived isotopes 258-260Fm constitute the so-called "fermium gap." Fermium is produced by the bombardment of lighter actinides with neutrons in a nuclear reactor. Fermium-257 is the heaviest isotope, obtained via neutron capture, can only be produced in picogram quantities; the major source is the 85 MW High Flux Isotope Reactor at the Oak Ridge National Laboratory in Tennessee, USA, dedicated to the production of transcurium elements. Lower mass fermium isotopes are available in greater quantities, these isotopes are short lived. In a "typical processing campaign" at Oak Ridge, tens of grams of curium are irradiated to produce decigram quantities of californium, milligram quantities of berkelium and einsteinium and picogram quantities of fermium. However, nanogram quantities of fermium can be prepared for specific experiments; the quantities of fermium produced in 20–200 kiloton thermon
Neutron
The neutron is a subatomic particle, symbol n or n0, with no net electric charge and a mass larger than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons behave within the nucleus, each has a mass of one atomic mass unit, they are both referred to as nucleons, their properties and interactions are described by nuclear physics. The chemical and nuclear properties of the nucleus are determined by the number of protons, called the atomic number, the number of neutrons, called the neutron number; the atomic mass number is the total number of nucleons. For example, carbon has atomic number 6, its abundant carbon-12 isotope has 6 neutrons, whereas its rare carbon-13 isotope has 7 neutrons; some elements occur in nature with only one stable isotope, such as fluorine. Other elements occur with many stable isotopes, such as tin with ten stable isotopes. Within the nucleus and neutrons are bound together through the nuclear force. Neutrons are required for the stability of nuclei, with the exception of the single-proton hydrogen atom.
Neutrons are produced copiously in nuclear fusion. They are a primary contributor to the nucleosynthesis of chemical elements within stars through fission and neutron capture processes; the neutron is essential to the production of nuclear power. In the decade after the neutron was discovered by James Chadwick in 1932, neutrons were used to induce many different types of nuclear transmutations. With the discovery of nuclear fission in 1938, it was realized that, if a fission event produced neutrons, each of these neutrons might cause further fission events, etc. in a cascade known as a nuclear chain reaction. These events and findings led to the first self-sustaining nuclear reactor and the first nuclear weapon. Free neutrons, while not directly ionizing atoms, cause ionizing radiation; as such they can be a biological hazard, depending upon dose. A small natural "neutron background" flux of free neutrons exists on Earth, caused by cosmic ray showers, by the natural radioactivity of spontaneously fissionable elements in the Earth's crust.
Dedicated neutron sources like neutron generators, research reactors and spallation sources produce free neutrons for use in irradiation and in neutron scattering experiments. An atomic nucleus is formed by a number of protons, Z, a number of neutrons, N, bound together by the nuclear force; the atomic number defines the chemical properties of the atom, the neutron number determines the isotope or nuclide. The terms isotope and nuclide are used synonymously, but they refer to chemical and nuclear properties, respectively. Speaking, isotopes are two or more nuclides with the same number of protons; the atomic mass number, symbol A, equals Z+N. Nuclides with the same atomic mass number are called isobars; the nucleus of the most common isotope of the hydrogen atom is a lone proton. The nuclei of the heavy hydrogen isotopes deuterium and tritium contain one proton bound to one and two neutrons, respectively. All other types of atomic nuclei are composed of two or more protons and various numbers of neutrons.
The most common nuclide of the common chemical element lead, 208Pb, has 82 protons and 126 neutrons, for example. The table of nuclides comprises all the known nuclides. Though it is not a chemical element, the neutron is included in this table; the free neutron has 1.674927471 × 10 − 27 kg, or 1.00866491588 u. The neutron has a mean square radius of about 0.8×10−15 m, or 0.8 fm, it is a spin-½ fermion. The neutron has no measurable electric charge. With its positive electric charge, the proton is directly influenced by electric fields, whereas the neutron is unaffected by electric fields; the neutron has a magnetic moment, however. The neutron's magnetic moment has a negative value, because its orientation is opposite to the neutron's spin. A free neutron is unstable, decaying to a proton and antineutrino with a mean lifetime of just under 15 minutes; this radioactive decay, known as beta decay, is possible because the mass of the neutron is greater than the proton. The free proton is stable. Neutrons or protons bound in a nucleus can be stable or unstable, depending on the nuclide.
Beta decay, in which neutrons decay to protons, or vice versa, is governed by the weak force, it requires the emission or absorption of electrons and neutrinos, or their antiparticles. Protons and neutrons behave identically under the influence of the nuclear force within the nucleus; the concept of isospin, in which the proton and neutron are viewed as two quantum states of the same particle, is used to model the interactions of nucleons by the nuclear or weak forces. Because of the strength of the nuclear force at short distances, the binding energy of nucleons is more than seven orders of magnitude larger than the electromagnetic energy binding electrons in atoms. Nuclear reactions therefore have an energy density, more than ten million times that of chemical reactions; because of the mass–energy equivalence, nuclear binding energies reduce the mass of nuclei. The ability of the nuclear force to store energy arising from the electromagnetic repulsion of nuclear components is the basis for most of the energy that makes nuclear reactors or bombs possible.
In nuclear fission, the absorption of a neutron by a heavy nuclide causes the nuclide to become unstable and break into light nuclides and additional neu
Nuclear weapon yield
The explosive yield of a nuclear weapon is the amount of energy released when that particular nuclear weapon is detonated expressed as a TNT equivalent, either in kilotons, in megatons, or sometimes in terajoules. An explosive yield of one terajoule is equal to 0.239 kilotonnes of TNT. Because the accuracy of any measurement of the energy released by TNT has always been problematic, the conventional definition is that one kiloton of TNT is held to be equivalent to 1012 calories; the yield-to-weight ratio is the amount of weapon yield compared to the mass of the weapon. The practical maximum yield-to-weight ratio for fusion weapons has been estimated to six megatons of TNT per metric ton of bomb mass. Yields of 5.2 megatons/ton and higher have been reported for large weapons constructed for single-warhead use in the early 1960s. Since the smaller warheads needed to achieve the increased net damage efficiency of multiple warhead systems have resulted in decreases in the yield/mass ratio for single modern warheads.
In order of increasing yield: As a comparison, the blast yield of the GBU-43 Massive Ordnance Air Blast bomb is 0.011 kt, that of the Oklahoma City bombing, using a truck-based fertilizer bomb, was 0.002 kt. Most artificial non-nuclear explosions are smaller than what are considered to be small nuclear weapons; the yield-to-weight ratio is the amount of weapon yield compared to the mass of the weapon. According to nuclear-weapons designer Ted Taylor, the practical maximum yield-to-weight ratio for fusion weapons is about 6 megatons of TNT per metric ton; the "Taylor limit" is not derived from first principles, weapons with yields as high as 9.5 megatons per metric ton have been theorized. The highest achieved values are somewhat lower, the value tends to be lower for smaller, lighter weapons, of the sort that are emphasized in today's arsenals, designed for efficient MIRV use, or delivery by cruise missile systems; the 25 Mt yield option reported for the B41 would give it a yield-to-weight ratio of 5.1 megatons of TNT per metric ton.
While this would require a far greater efficiency than any other current U. S. weapon, this was attainable by the use of higher than normal Lithium-6 enrichment in the lithium deuteride fusion fuel. This results in the B41 still retaining the record for the highest yield-to-weight weapon designed; the W56 demonstrated a yield-to-weight ratio of 4.96 kt per kg of device mass, close to the predicted 5.1 kt/kg achievable in the highest yield to weight weapon built, the 25 megaton B41. Unlike the B41, never proof tested at full yield, the W56 demonstrated its efficiency in the XW-56X2 Bluestone shot of Operation Dominic in 1962, from information available in the public domain, the W56 may hold the distinction of demonstrating the highest efficiency in a nuclear weapon to date. In 1963 DOE declassified statements that the U. S. had the technological capability of deploying a 35 Mt warhead on the Titan II, or a 50-60 Mt gravity bomb on B-52s. Neither weapon was pursued, but either would require yield-to-weight ratios superior to a 25 Mt Mk-41.
This may have been achievable by utilizing the same design as the B41 but with the addition of a HEU tamper, in place of the cheaper but lower energy density U-238 tamper, the most used tamper material in Teller-Ulam thermonuclear weapons. For current smaller US weapons, yield is 600 to 2200 kilotons of TNT per metric ton. By comparison, for the small tactical devices such as the Davy Crockett it was 0.4 to 40 kilotons of TNT per metric ton. For historical comparison, for Little Boy the yield was only 4 kilotons of TNT per metric ton, for the largest Tsar Bomba, the yield was 2 megatons of TNT per metric ton; the largest pure-fission bomb constructed, Ivy King, had a 500 kiloton yield, in the range of the upper limit on such designs. Fusion boosting could raise the efficiency of such a weapon but all fission-based weapons have an upper yield limit due to the difficulties of dealing with large critical masses. However, there is no known upper yield limit for a fusion bomb. Large single warheads are a part of today's arsenals, since smaller MIRV warheads, spread out over a pancake-shaped destructive area, are far more destructive for a given total yield, or unit of payload mass.
This effect results from the fact that destructive power of a single warhead on land scales only as the cube root of its yield, due to blast "wasted" over a hemispherical blast volume while the strategic target is distributed over a circular land area with limited height and depth. This effect more than makes up for the lessened yield/mass efficiency encountered if ballistic missile warheads are individually scaled down from the maximal size that could be carried by a single-warhead missile; the following list is of milestone nuclear explosions. In addition to the atomic bombings of Hiroshima and Nagasaki, the first nuclear test of a given weapon type for a country is included, tests which were otherwise notable. All yields are given in their estimated energy equivalents in
Atomic number
The atomic number or proton number of a chemical element is the number of protons found in the nucleus of an atom. It is identical to the charge number of the nucleus; the atomic number uniquely identifies a chemical element. In an uncharged atom, the atomic number is equal to the number of electrons; the sum of the atomic number Z and the number of neutrons, N, gives the mass number A of an atom. Since protons and neutrons have the same mass and the mass defect of nucleon binding is always small compared to the nucleon mass, the atomic mass of any atom, when expressed in unified atomic mass units, is within 1% of the whole number A. Atoms with the same atomic number Z but different neutron numbers N, hence different atomic masses, are known as isotopes. A little more than three-quarters of occurring elements exist as a mixture of isotopes, the average isotopic mass of an isotopic mixture for an element in a defined environment on Earth, determines the element's standard atomic weight, it was these atomic weights of elements that were the quantities measurable by chemists in the 19th century.
The conventional symbol Z comes from the German word Zahl meaning number, before the modern synthesis of ideas from chemistry and physics denoted an element's numerical place in the periodic table, whose order is but not consistent with the order of the elements by atomic weights. Only after 1915, with the suggestion and evidence that this Z number was the nuclear charge and a physical characteristic of atoms, did the word Atomzahl come into common use in this context. Loosely speaking, the existence or construction of a periodic table of elements creates an ordering of the elements, so they can be numbered in order. Dmitri Mendeleev claimed. However, in consideration of the elements' observed chemical properties, he changed the order and placed tellurium ahead of iodine; this placement is consistent with the modern practice of ordering the elements by proton number, Z, but that number was not known or suspected at the time. A simple numbering based on periodic table position was never satisfactory, however.
Besides the case of iodine and tellurium several other pairs of elements were known to have nearly identical or reversed atomic weights, thus requiring their placement in the periodic table to be determined by their chemical properties. However the gradual identification of more and more chemically similar lanthanide elements, whose atomic number was not obvious, led to inconsistency and uncertainty in the periodic numbering of elements at least from lutetium onward. In 1911, Ernest Rutherford gave a model of the atom in which a central core held most of the atom's mass and a positive charge which, in units of the electron's charge, was to be equal to half of the atom's atomic weight, expressed in numbers of hydrogen atoms; this central charge would thus be half the atomic weight. In spite of Rutherford's estimation that gold had a central charge of about 100, a month after Rutherford's paper appeared, Antonius van den Broek first formally suggested that the central charge and number of electrons in an atom was equal to its place in the periodic table.
This proved to be the case. The experimental position improved after research by Henry Moseley in 1913. Moseley, after discussions with Bohr, at the same lab, decided to test Van den Broek's and Bohr's hypothesis directly, by seeing if spectral lines emitted from excited atoms fitted the Bohr theory's postulation that the frequency of the spectral lines be proportional to the square of Z. To do this, Moseley measured the wavelengths of the innermost photon transitions produced by the elements from aluminum to gold used as a series of movable anodic targets inside an x-ray tube; the square root of the frequency of these photons increased from one target to the next in an arithmetic progression. This led to the conclusion that the atomic number does correspond to the calculated electric charge of the nucleus, i.e. the element number Z. Among other things, Moseley demonstrated that the lanthanide series must have 15 members—no fewer and no more—which was far from obvious from the chemistry at that time.
After Moseley's death in 1915, the atomic numbers of all known elements from hydrogen to uranium were examined by his method. There were seven elements which were not found and therefore identified as still undiscovered, corresponding to atomic numbers 43, 61, 72, 75, 85, 87 and 91. From 1918 to 1947, all seven of these missing elements were discovered. By this time the first four transuranium elements had been discovered, so that the periodic table was complete with no gaps as far as curium. In 1915 the rea
Nuclear explosive
A nuclear explosive is an explosive device that derives its energy from nuclear reactions. All nuclear explosive devices that have been designed and produced are nuclear weapons intended for warfare. Other, non-warfare, applications for nuclear explosives have been proposed. For example, nuclear pulse propulsion is a form of spacecraft propulsion that would use nuclear explosives to provide impulse to a spacecraft. A similar application is the proposal to use nuclear explosives for asteroid deflection. From 1958 to 1965 the United States government ran a project to design a nuclear explosive powered nuclear pulse rocket called Project Orion. Never built, this vessel would use repeated nuclear explosions to propel itself and was considered practical, it is thought to be a feasible design for interstellar travel. Nuclear explosives were once considered for use in large-scale excavation. A nuclear explosion could be used to create a harbor, or a mountain pass, or large underground cavities for use as storage space.
It was thought that detonating a nuclear explosive in oil-rich rock could make it possible to extract more from the deposit, e.g. note the Canadian Project Oilsand. From 1958 to 1973 the U. S. government exploded. The purpose of the operation was to use peaceful nuclear explosions for moving and lifting enormous amounts of earth and rock during construction projects such as building reservoirs; the Soviet Union conducted a much more vigorous program of 122 nuclear tests, some with multiple devices, between 1965 and 1989 under the auspices of Program No. 7 – Nuclear Explosions for the National Economy. As controlled nuclear fusion has proven difficult to use as an energy source, an alternate proposal for producing fusion power has been to detonate nuclear fusion explosives inside large underground chambers and using the heat produced, which would be absorbed by a molten salt coolant which would absorb neutrons; the 1970s PACER project investigated fusion detonation as a power source. Failure to meet objectives, along with the realization of the dangers of nuclear fallout and other residual radioactivity, with the enactment of various agreements such as the Partial Test Ban Treaty and the Outer Space Treaty, has led to the termination of most of these programs.
Nuclear Weapons Frequently Asked Questions
