A breeder reactor is a nuclear reactor that generates more fissile material than it consumes. These reactors can be fuelled with more commonly available isotopes of uranium and thorium, such as uranium-238 or thorium-232, as opposed to the rare uranium-235 which is used in conventional reactors. These materials are called fertile materials since they can be bred into fuel by these breeder reactors. Breeder reactors achieve this because their neutron economy is high enough to create more fissile fuel than they use. These extra neutrons are absorbed by the fertile material that is loaded into the reactor along with fissile fuel. This irradiated fertile material in turn transmutes into fissile material which can undergo fission reactions. Breeders were at first found attractive because they made more complete use of uranium fuel than light-water reactors, but interest declined after the 1960s, as more uranium reserves were found, and new methods of uranium enrichment reduced fuel costs. Fuel resources Breeder reactors could, in principle, extract almost all of the energy contained...

Cobalt-60 (60Co) is a synthetic radioactive isotope of cobalt with a half-life of 5.2713 years.: 39  It is produced artificially in nuclear reactors. Deliberate industrial production depends on neutron activation of bulk samples of the monoisotopic and mononuclidic cobalt isotope 59Co. Measurable quantities are also produced as a by-product of typical nuclear power plant operation and may be detected externally when leaks occur. In the latter case (in the absence of added cobalt) the incidentally produced 60...

Control rods are used in nuclear reactors to control the rate of fission of the nuclear fuel – uranium or plutonium. Their compositions include chemical elements such as boron, cadmium, silver, hafnium, or indium, that are capable of absorbing many neutrons without themselves decaying. These elements have different neutron capture cross sections for neutrons of various energies. Boiling water reactors (BWR), pressurized water reactors (PWR), and heavy-water reactors (HWR) operate with thermal neutrons, while breeder reactors operate with fast neutrons. Each reactor design can use different control rod materials based on the energy spectrum of its neutrons. Control rods have been used in nuclear aircraft engines like Project Pluto as a method of control. Operating principle Control rods are inserted into the core of a nuclear reactor and adjusted in order to control the rate of the nuclear chain reaction and, thereby, the thermal power output of the reactor, the rate of steam production, and the electrical power output of the power station. The number of control rods inserted, and the distance to which they...

Caesium (IUPAC spelling) (or cesium in American English) is a chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-golden alkali metal with a melting point of 28.5 °C (83.3 °F), which makes it one of only five elemental metals that are liquid at or near room temperature. Caesium has physical and chemical properties similar to those of rubidium and potassium. It is pyrophoric and reacts with water even at −116 °C (−177 °F). It is the least electronegative element, with a value of 0.79 on the Pauling scale. It has only one stable isotope, caesium-133. Caesium is mined mostly from pollucite. The element has 40 known isotopes, making it, along with barium and mercury, one of the elements with the most isotopes. Caesium-137, a fission product, is extracted from waste produced by nuclear reactors. The German chemist Robert Bunsen and physicist Gustav Kirchhoff discovered caesium in 1860 by the newly developed method of flame spectroscopy. The first small-scale applications for caesium were as a "getter" in vacuum tubes and in photoelectric cells. In 1967, acting on Einstein's proof that the speed of...

Marine propulsion is the mechanism or system used to generate thrust to move a watercraft through water. While paddles and sails are still used on some smaller boats, most modern ships are propelled by mechanical systems consisting of an electric motor or internal combustion engine driving a propeller, or less frequently, in pump-jets, an impeller. Marine engineering is the discipline concerned with the engineering design process of marine propulsion systems. Human-powered paddles and oars, and later, sails were the first forms of marine propulsion. Rowed galleys, some equipped with sail, played an important early role in early human seafaring and warfares. The first advanced mechanical means of marine propulsion was the marine steam engine, introduced in the early 19th century. During the 20th century it was replaced by two-stroke or four-stroke diesel engines, outboard motors, and gas turbine engines on faster ships. Marine nuclear reactors, which appeared in the 1950s, produce steam to propel warships and icebreakers; commercial application, attempted late that decade, failed to catch on. Electric motors using battery packs have been used for propulsion on submarines...

The MAUD Committee was a British scientific working group formed during the Second World War. It was established to perform the research required to determine if an atomic bomb was feasible. The name MAUD came from a strange line in a telegram from Danish physicist Niels Bohr referring to his housekeeper, Maud Ray. The MAUD Committee was founded in response to the Frisch–Peierls memorandum, which was written in March 1940 by Rudolf Peierls and Otto Frisch, two physicists who were refugees from Nazi Germany working at the University of Birmingham under the direction of Mark Oliphant. The memorandum argued that a small sphere of pure uranium-235 could have the explosive power of thousands of tons of TNT. The chairman of the MAUD Committee was George Thomson. Research was split among four different universities: the University of Birmingham, University of Liverpool, University of Cambridge and the University of Oxford, each having a separate programme director. Various means of uranium enrichment were examined, as was nuclear reactor design, the properties of uranium-235, the use of the then-hypothetical element plutonium, and theoretical aspects of nuclear weapon...

Canadarm or Canadarm1 (officially Shuttle Remote Manipulator System or SRMS, also SSRMS) is a series of robotic arms that were used on the Space Shuttle orbiters to deploy, manoeuvre, and capture payloads. After the Space Shuttle Columbia disaster, the Canadarm was always paired with the Orbiter Boom Sensor System (OBSS), which was used to inspect the exterior of the shuttle for damage to the thermal protection system. Development In 1969, Canada was invited by the National Aeronautics and Space Administration (NASA) to participate in the Space Shuttle program. At the time what that participation would entail had not yet been decided but a manipulator system was identified as an important component. Canadian company DSMA ATCON had developed a robot to load fuel into CANDU nuclear reactors; this robot attracted NASA's attention. In 1975, NASA and the Canadian National Research Council (NRC) signed a memorandum of understanding that Canada would develop and construct the Canadarm.NRC awarded the manipulator contract to Spar Aerospace (now MDA). Three systems...