Isotope separation in the context of Deuterium

Maurice Hugh Frederick Wilkins CBE FRS (15 December 1916 – 5 October 2004) was a New Zealand-born British biophysicist and Nobel laureate whose research spanned multiple areas of physics and biophysics, contributing to the scientific understanding of phosphorescence, isotope separation, optical microscopy, and X-ray diffraction. He is most noted for initiating and leading early X-ray diffraction studies on DNA at King's College London, and for his pivotal role in enabling the discovery of the double helix structure of DNA.

Wilkins began investigating nucleic acids in 1948. By 1950, he and his team had produced some of the first high-quality X-ray diffraction images of DNA fibers. He presented this work in 1951 at a conference in Naples, where it significantly influenced James Watson, prompting Watson to pursue DNA structure research with Francis Crick.

A centrifuge is a device that uses centrifugal force to subject a specimen to a specified constant force – for example, to separate various components of a fluid. This is achieved by spinning the fluid at high speed within a container, thereby separating fluids of different densities (e.g., cream from milk) or liquids from solids. It works by causing denser substances and particles to move outward in the radial direction. At the same time, objects that are less dense are displaced and moved to the centre. In a laboratory centrifuge that uses sample tubes, the radial acceleration causes denser particles to settle to the bottom of the tube, while low-density substances rise to the top. A centrifuge can be a very effective filter that separates contaminants from the main body of fluid.

Industrial scale centrifuges are commonly used in manufacturing and waste processing to sediment suspended solids, or to separate immiscible liquids. An example is the cream separator found in dairies. Very high speed centrifuges and ultracentrifuges able to provide very high accelerations can separate fine particles down to the nano-scale, and molecules of different masses. Large centrifuges are used to simulate high gravity or acceleration environments (for example, high-G training for test pilots). Medium-sized centrifuges are used in washing machines and at some swimming pools to draw water out of fabrics. Gas centrifuges are used for isotope separation, such as to enrich nuclear fuel for fissile isotopes.

Nazi Germany undertook several research programs relating to nuclear technology, including nuclear weapons and nuclear reactors, before and during World War II. These were variously called Uranverein (Uranium Society) or Uranprojekt (Uranium Project). The first effort started in April 1939, just months after the discovery of nuclear fission in Berlin in December 1938, but ended shortly ahead of the September 1939 German invasion of Poland, for which many German physicists were drafted into the Wehrmacht. A second effort under the administrative purview of the Wehrmacht's Heereswaffenamt began on September 1, 1939, the day of the invasion of Poland. The program eventually expanded into three main efforts: Uranmaschine (nuclear reactor) development, uranium and heavy water production, and uranium isotope separation. Eventually, the German military determined that nuclear fission would not contribute significantly to the war, and in January 1942 the Heereswaffenamt turned the program over to the Reich Research Council (Reichsforschungsrat) while continuing to fund the activity.

The program was split up among nine major institutes where the directors dominated research and set their own objectives. Subsequently, the number of scientists working on applied nuclear fission began to diminish as many researchers applied their talents to more pressing wartime demands. The most influential people in the Uranverein included Kurt Diebner, Abraham Esau, Walther Gerlach, and Erich Schumann. Schumann was one of the most powerful and influential physicists in Germany. Diebner, throughout the life of the nuclear weapon project, had more control over nuclear fission research than did Walther Bothe, Klaus Clusius, Otto Hahn, Paul Harteck, or Werner Heisenberg. Esau was appointed as Reichsmarschall Hermann Göring's plenipotentiary for nuclear physics research in December 1942, and was succeeded by Walther Gerlach after he resigned in December 1943.

Gilbert Newton Lewis ForMemRS (October 23 or October 25, 1875 – March 23, 1946) was an American physical chemist and a dean of the college of chemistry at University of California, Berkeley. Lewis was best known for his discovery of the covalent bond and his concept of electron pairs; his Lewis dot structures and other contributions to valence bond theory have shaped modern theories of chemical bonding. Lewis successfully contributed to chemical thermodynamics, photochemistry, and isotope separation, and is also known for his concept of acids and bases. Lewis also researched on relativity and quantum physics, and in 1926 he coined the term "photon" for the smallest unit of radiant energy.

G. N. Lewis was born in 1875 in Weymouth, Massachusetts. After receiving his PhD in chemistry from Harvard University and studying abroad in Germany and the Philippines, Lewis moved to California in 1912 to teach chemistry at the University of California, Berkeley, where he became the dean of the college of chemistry and spent the rest of his life. As a professor, he incorporated thermodynamic principles into the chemistry curriculum and reformed chemical thermodynamics in a mathematically rigorous manner accessible to ordinary chemists. He began measuring the free energy values related to several chemical processes, both organic and inorganic. In 1916, he also proposed his theory of bonding and added information about electrons in the periodic table of the chemical elements. In 1933, he started his research on isotope separation. Lewis worked with hydrogen and managed to purify a sample of heavy water. He then came up with his theory of acids and bases, and did work in photochemistry during the last years of his life.

Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written U) has been increased through the process of isotope separation. Naturally occurring uranium is composed of three major isotopes: uranium-238 (U with 99.2732–99.2752% natural abundance), uranium-235 (U, 0.7198–0.7210%), and uranium-234 (U, 0.0049–0.0059%). U is the only nuclide existing in nature (in any appreciable amount) that is fissile with thermal neutrons.

Enriched uranium is a critical component for both civil nuclear power generation and military nuclear weapons. Low-enriched uranium (below 20% U) is necessary to operate light water reactors, which make up almost 90% of nuclear electricity generation. Highly enriched uranium (above 20% U) is used for the cores of many nuclear weapons, as well as compact reactors for naval propulsion and research, as well as breeder reactors. There are about 2,000 tonnes of highly enriched uranium in the world.

A pure fusion weapon is a hypothetical hydrogen bomb design that does not need a fission "primary" explosive to ignite the fusion of deuterium and tritium, two heavy isotopes of hydrogen used in fission-fusion thermonuclear weapons. Such a weapon would require no fissile material and would therefore be much easier to develop in secret than existing weapons. Separating weapons-grade uranium (U-235) or breeding plutonium (Pu-239) requires a substantial and difficult-to-conceal industrial investment, and blocking the sale and transfer of the needed machinery has been the primary mechanism to control nuclear proliferation to date.

A gas centrifuge is a device that performs isotope separation of gases. A centrifuge relies on the principles of centrifugal force accelerating molecules so that particles of different masses are physically separated in a gradient along the radius of a rotating container.

A prominent use of gas centrifuges is for the separation of uranium-235 (U) from uranium-238 (U). The gas centrifuge was developed to replace the gaseous diffusion method of U extraction. High degrees of separation of these isotopes relies on using many individual centrifuges arranged in series that achieve successively higher concentrations. This process yields higher concentrations of U while using significantly less energy compared to the gaseous diffusion process.

The Zippe-type centrifuge is a gas centrifuge designed to enrich the rare fissile isotope uranium-235 (U) from the mixture of isotopes found in naturally occurring uranium compounds. The isotopic separation is based on the slight difference in mass of the isotopes. The Zippe design was originally developed in the Soviet Union by a team led by 60 Austrian and German scientists and engineers captured after World War II, working in detention. In the West and now generally, the type is known by the name of the man who recreated the technology after his return to the West in 1956, based on his recollection of his contributions in the Soviet program, Gernot Zippe. To the extent that it might be referred to in Soviet/Russian usage by any one person's name, it was known at an earlier stage in development as a Kamenev centrifuge, after Evgeni Kamenev.

Klaus Paul Alfred Clusius (19 March 1903 – 28 May 1963) was a German physical chemist. During World War II, he worked on the German nuclear energy project, also known as the Uranium Club; he worked on isotope separation techniques and heavy water production. After the war, he was a professor of physical chemistry at the University of Zurich.

Weapons-grade nuclear material is any fissionable nuclear material that is pure enough to make a nuclear weapon and has properties that make it particularly suitable for nuclear weapons use. Plutonium and uranium in grades normally used in nuclear weapons are the most common examples. (These nuclear materials have other categorizations based on their purity.)

Only fissile isotopes of certain elements have the potential for use in nuclear weapons. For such use, the concentration of fissile isotopes uranium-235 and plutonium-239 in the element used must be sufficiently high. Uranium from natural sources is enriched by isotope separation, and plutonium is produced in a suitable nuclear reactor.

A medical isotope is an isotope used in medicine. The first uses of isotopes in medicine were in radiopharmaceuticals, and this is still the most common use. However more recently, separated stable isotopes have come into use.

In nuclear engineering, critical mass is the minimum mass of the fissile material needed for a sustained nuclear chain reaction in a particular setup. The critical mass of a fissionable material depends upon its nuclear properties (specifically, its nuclear fission cross-section), density, shape, enrichment, purity, temperature, and surroundings. It is an important parameter of a nuclear reactor core or nuclear weapon. The concept is important in nuclear weapon design.

Critical size is the minimum size of the fissile material needed for a sustained nuclear chain reaction in a particular setup. If the size of the reactor core is less than a certain minimum, too many fission neutrons escape through its surface and the chain reaction is not sustained. A perfect sphere, which has the lowest surface-area-to-volume ratio, gives the minimal critical size.