Nanoscale structures at interfaces formed by lipids and from polymer/surfactant mixtures - deeper understanding provided by large-scale facilities
June 24 14:30 - 15:30
- The deposition to form soft matter nano-scale structures at interfaces is a delicate balance...
A measurement of the antineutrino spectrum of the fission products of U238
July 01 14:30 - 15:30
- In the last years, antineutrinos from nuclear reactors helped todetermine the parameters in the...
Implementation of a Longitudinal NRSE option for RESEDA at FRM II
July 15 14:45 - 15:45
- Longitudinal NRSE (lNRSE) has the possibilities to extend the accesible dynamic range of both NSE...
This popular naming of the research reactor Munich (FRM) derives from the spandrel form of its structure. The "Atom-Ei" was the nucleus of the Garching research establishment.
- Absorber (or control) rod
It is a rod used to control the radioactivity of a nuclear reactor. The central absorber rod of the FRM II is made out of hafnium , a strong neutron absorber. Its depth of immersion in the centre of the fuel element determines the number of the nuclear fissions and the current thermical capacitance of the reactor. The reactor is also shut down with the absorber rod (see shutdown rod).
- Absorber element
The central absorber rod and the shutdown rods in the moderator tank are called absorber elements, since they are made out of a material (in the case of FRM II hafnium), which is a strong absorber of slow neutrons or other ionizing radiations.
The process of inducing radioactivity by bombardment with neutrons.
A gaseous suspension of ultramicroscopic particles in a liquid or solid.
Any of the smallest particles of an element that combine with similar particles of other elements to produce compounds: atoms combine from molecules and consist of a coupled arrangement of electrons revolving about a positively charged nucleus containing (except for hydrogen) protons and neutrons and other particles.
- Atomic statute
It regulates by law the peaceful use of the atomic energy and the protection against its risks. It is completed by prescriptions and guidelines.
- abbreviation for:Becquerel
The unit for measuring radioactive decay, equal to the number of atoms that disintegrate per second.
The physicist Henri Becquerel (1852-1908) discovered in Paris magnetical effects and phosphorescence. He was influential in the discovery of the radioactive radiation of uranium and was awarded (together with Marie and Pierre Curie) the Nobel Prize in Physics.
- Cold neutron source
The cold (neutron) source consists of a container with ca. 25 litres of liquid deuterium at a temperature of ca. 25 Kelvin (- 248 °C). It is used for the slowing down of slow neutrons from 0,025 eV to 0,005 eV.
A device for confining the beam with an assigned solid angle.
- Compact core (FRM II)
The reactor core is the active portion of a nuclear reactor, containing the fissioanble material. The core of the FRM-II contains a single, cylindrical fuel element with a diameter of only 24 cm and about 70 cm high uranium zone. It contains about 8 kg of nuclear fuel in the form of uranium silicide (U3Si2), an extremely stable ceramic material with a high melting point.
The deposit of radioactive materials, such as fission fragments or radiological warfare agents, on any object or surface in the atmosphere.
The transfer of heat by its absorption by a fluid at one point followed by motion of the fluid and rejection of the heat at another point.
s.a. converter beam tube
- Converter beam tube
It provides an intensive beam of fast neutrons for medical use or technical tomography. A uranium plate is pushed in the pool water before the nose of the beam tube in the field of slow neutrons. The slow neutrons influence the nuclear fissions in the uranium plate. In this process fast neutrons are set free (i.e. slow neutrons are converted into fast ones).
- Pierre and Marie Curie
French scientists and codiscoverers of radium and polonium. After A. Becquerel discovered radioactivity, Marie began her own investigations. She was joined by Pierre in 1898, and in that year they jointly isolated radium and polonium. With Becquerel they were awarded the 1903 Nobel Prize in Physics. Following Pierre's death (1906), Marie continued her work on radium and received the 1911 Nobel Prize in Chemistry. The unit of radioactivity, (curie, c or Ci) defined as that quantity of any radioactive nuclide which has the number of 3.7 X 1010 disintegrations per second has been named after them.
- Deuterium (D, d, H2, 2H)
A hydrogen isotope with one neutron and one proton in the nucleus, used in nuclear reactors, accelerators, etc. See also isotope and heavy water.
- Dose radiation
The radiation dosage absorbed per unit of time (e.g. H-hour + 1 hour) and would be called H-hour + 1 radiation dose rate (i.e. the rate at which nuclear radiation is delivered). The unity measure used is mSv/h.
- Dose rate
The rate at which nuclear radiation is delivered.
A stable elementary particle that forms a part of all atoms and has a negative charge of 1.602 X 10-19 coulomb: the mass of an electron is about 1/1837 that of a proton with a rest mass of 9.10939 X 10-28 gram, and the number of electons circulating around a nucleus is equal to the number of positive charges on the nucleus.
Air pollution, noise, vibrations, light, heat or (radioactive) radiation and similar effects on the environment emitted by an installation. The possible ways of emission of radioactive substances from the FRM-II are air and water. They will lead to no harm of the population.
- acronym of:
The headquarters of the European Supporting Agency (ESA) are in Bruxelles. It belongs to EURATOM. One of the tasks of the ESA is to lead the negotiations for the nuclear fuel supplies of its member states, i.e. of their research reactors.
- acronym of:European Atomic Energy Community
European Atomic Energy Community, a unit of the European Communities, which monitors the correct use of the nuclear fuel in the nuclear facilities.
- abbreviation for:Electron-volt
A unit of energy equal to that attained by an electron falling unimpeded through a potential difference of one volt; 1.602 X 10-12.
See Radiant exposure .
- Fast shutdown
This engine automatically shuts down a reactor and keeps it in this state safely. In the FRM-II the shutdown occurs through the driving in of the central control rod and in case of failure through the independent shutdown rods in the moderator tank.
- Fault analysis
A fault analysis provides information about the process and the consequences of a single fault or of a combination of two faults.
- Fission products
Any radioactive or stable nuclide resulting from fission, including both primary fission fragments and their radioactive decay products.
- acronym of:Forschungs-Reaktor München
Forschungs-Reaktor München, research reactor Munich, also called "FRM-I" or "Atom-Ei" (# Atom-Egg). It is located on the grounds of the Technische Universität München ( TUM) and came into scientific operation in 1957. Since then it has faultlessly been supplying neutrons for research. In the facility basic reseach and research on the development of new methods and measuring systems have been carried out.
- FRM II
- acronym of:Forschungsreaktor Heinz Maier-Leibnitz (FRM II)
Forschungsreaktor Heinz Maier-Leibnitz (FRM II)
- FRM II
- acronym of:Forschungsneutronenquelle Heinz Maier-Leibnitz FRM II
Als FRM II wird die Forschungsneutronenquelle Heinz Maier-Leibnitz FRM II abgekürzt. Er ist der Nachfolger des FRM und dient der kontinuierlichen, verbesserten Weiterführung des Forschungsprogramms. Er bietet erweiterte und neuartige Messmöglichkeiten durch einen höheren Neutronenfluss und höhere Kapazität.
- fuel cycle
- (Reactor) fuel cycle (or nuclear fuel cycle)
The process of preparing fuel elements and assemblies for use in a reactor, using these elements in reactor operation, recovering radioactive byproducts from spent fuel, and reprocessing remaining fissionable material into new fuel elements. A fuel element will last for 52 days in the new reactor. 5 reactor fuel cycles will take place in a year.
- Fuel element
A plate into which nuclear fuel (uranium) is fabricated for use in a reactor. Since the uranium is closely packed in aluminium, no radioactive products of the nuclear fission can be emitted. Cooling water fills the interspaces between the single plates.
- (Radioactive) half-life (or half-value period)
The physical half-life is the average time interval required for any quantity of identical radioactive atoms to undergo radioactive decay. It can vary from splits of seconds to several thousand years. The biological half-life is the average time interval required by a biological system (a human or an animal) to eliminate the half of the amount of the absorbed substances (also from # radionuclides). Both processes take place in the biological systems independently and simultaneously. This combination shortens the time interval required to eliminate half of the amount of the absorbed substaces (effective half-life).
- Heat-removal circuit
The fuel element of the FRM II is cooled with light water from the reactor-pool. At the exit ot the fuel element, the pressure of the closed primary cycle is in equilibrium with the static pressure of the reactor pool. The heat transfer to a secondary cooling system, in which the port for using the waste heat is located, occurs in the heat exchangers. The rest of the unused thermal output is lead toward a tertiary cooling system, which transmits the heat off over the cooling towers to the environment.
- Heavy water
- Heavy water (or deuterium oxide, D2O)
A compound of hydrogen and oxygen, containing a higher proportion of the hydrogen isotope deuterium that does naturally occur water. It is used as optimal moderator and reflector for neutrons.
- Hot neutron source
In the FRM II the hot neutron source consists of a graphite cylinder with a diameter of 200 mm and height 300 mm. It is heated up through gamma radiation from the reactor core. In the steady state it reaches 2600oC in the cenre. The source is outside double-skin isolated. The internal wall has a temperature of only 82oC. It is therefore impossible for a "fusion" to take place. The hot neutron source is used to increase the energy of the neutrons from 0,025eV to ca. 0,1 to 1eV.
- acronym of:International Atomic-Energy-Agency
The "International Atomic-Energy-Agency", short IAEA, is an independent special organisation of the United Nations for the promotion and the control of the peaceful use of nuclear energy. It was founded in 1957 and has its headquarters in Vienna. There are 123 member countries, among them all industrial states and China.
Any of two of more atoms having the same or very closely related chemical properties and the same atomic number but different atomic weights (or mass numbers). The nucleus of the simplest atom, oxygen, consists of only one proton. If it catches a neutron, their mass doubles. This is "heavy hydrogen" or deuterium. With a further neutron the mass doubles again and makes a "superheavy hydrogen" (tritium). The atomic nucleus of uranium consists of 92 protons. The isotope 238U consists of 146 neutrons, the fissile uranium 235U has got three neutrons less.
Any of a group of neoplastic diseases of the blood-forming organs, resulting in an abnormal increase in the production of leukocytes, often accompanied by anemia and enlargement of the lymph nodes, spleen, and liver.
- Light water (H2O)
Water in which both the hydrogen atoms in each molecule are of the isotope protium.
- Low radiation
Dose rates in the range below 10 mSv/a. The dose rate emitted by the FRM-II will be at least 105 times lower.
A substance used in a nuclear reactor (in case of FRM-II heavy water), used to moderate or slow down high-energy neutrons from the high velocities at which they are created in the fission process. This process takes place in the moderator.
The smallest particle of an element or compound that can exist in the free state and still retain the characteristics of the element or compound: the molecules of elements consist of one atom or two or more similar atoms; those of compounds consist of two or more different atoms
Any of three leptons having a mass approaching zero and no charge; emitted from radioactive nuclei during beta decay, and in other processes. They are produced in enormous quantities in the nuclear reactions in stars and may constitute a substantial part of the mass of the universe. They have almost no interaction with matter. They are of enormous importance in astrophysics. Any of three leptons having a mass approaching zero and no charge: a neutrino has almost no interaction with matter.
About 50% of the physical world consists of neutrons. They are components of all atomic nuclei except the hydrogen nucleus. Neutrons have a little more mass than a proton and no electric charge.The only way in which neutrons can be released in higher quantities in today's state of nuclear engineering technology, is in reactor environment by applying the methods of nuclear fission. Free neutrons are not stable; with a half-life of 12.8 minutes, they decay into a proton, emitting in the process an electron and an antineutrino. This period is long enough for experimental purposes in which neutrons are used as probes.
- Neutron research
Neutrons are a very important tool in research. Their importance has been proved not only in physics, but also in the fields of radiochemistry, medicine, biology, pollution control and in the improvement of analysis techniques. The neutron research supplies all the disciplines with valuable scientific findings, which cannot be obtained with other methods.
- Neutron source
Neutron sources are used to set free large amounts of bound neutrons from the atom nucleus. When the scientists speak of high-flux neutron source, usually a neutron flux density of ca. 5x1014 per cm2 is meant.
- Nuclear chain reaction
A succession of a generation after generation of acts of nuclear division such that the neutrons set free in the nuclear disruptions of the nth generation split the fissile nuclei (233U, 235U, 239Pu) of the (n+1)st generation.A self-sustaining series of nuclear reactions in which the products of the reaction contribute directly to the process: started by bombardment with neutrons.
- Nuclear power plant
A power plant in which nuclear energy is converted into heat, which is used to produce steam for turbines, which in turn drive generators that produce electric power.
A specific tipe of atom that is characterized by its nuclear properties, such as the number of neutrons and protons and the energy state of its nucleus (see also adionuclide). About 1500 nuclides (1200 radioactive) distributed among the 92 natural elements are known at the present state of the art.
- Official permissions
The authorities competent for the authorization for the construction and the operation of nuclear facilities are the STLMU (Bayrisches Staatsministerium fuer Landesentwicklung und Umweltfragen) with headquarters in Munich and the BMU (Bundesministerium fuer Umwelt, Naturschutz und Reaktorsicherheit) with headquarters in Bonn.
The positive antiparticle of an electron, having approximately the same mass and magnitude of charge and the same spin and statistics. Positrons are created through the decay of some radionuclides or in the interaction of high-energy gamma-radiation with the matter.
An elementary particle found in the nucleus of all atoms and comprising the atomic nucleus of the protium isotope of hydrogen: it carries a unit positive charge equal to the negative charge of an electron and has a mass of 1.673 X 1024 gram, approximately 1836 times that of an electron: the atomic number of an atom is equal to the number of protons in its nucleus.
- Pu, Plutonium
- Plutonium (Pu), atomic number 94, atomic weight 239.13
A radioactive, metallic chemical element of the actinide series similar to uranium and neptunium and found in trace quantities in native uranium ores: its most important isotope, plutonium-239, is used as a reactor fuel and for production of nuclear weapons (see also # transuranic elements). Melting point 641oC, boiling point 3,232oC.
- Radiant exposure
The effect of ionizing radiation on the human body. Every human being is exposed to natural radiation. The internal radiant exposure is originated from radiation sources inside the body. The sum of the natural radiant exposure in Munich is approximately 2,4mSv per year. To this natural radiation influence other, artificial ones, especially from the applications in medicine (e.g. X-rays) must be added. They amount to approximately 1,6 mSv per year.
Also the total quantity of radiation at a given point, measured in air.
Particular type of radiation emitted by a radioactive substance, such as alfa-radioactivity. The radioactive decay is the spontaneous transformation of a nuclide into one or more different nuclides accompanied by either the emission of particles form the nucleus, nuclear capture or ejection of orbital electrons, or fission.
The technique of producing a photographic image of an opaque specimen by transmitting a beam of x-rays o gamma-rays through it onto an adjacent photographic film; the image results from variation in thickness, density, and chemical composition of the specimen. It is used in medicine and in industry. One of the advantages of the neutron-radiography compared to other methods (e.g. X-ray photographs) is the possiblity to make visible the differences of the hydrogen concentration.
A nuclide that exhibits radioactivity. About 1200 are known today.
The deliberate duplication or partial duplication of circuitry to decrease the probability of a system failure.
Um die maximal vom FRM II ausgehende Dosis abzuschätzen, wird eine "Referenzperson" definiert: Diese hält sich das ganze Jahr über permanent ohne Dach über dem Kopf am Ort der maximalen Strahlenbelastung auf. Für den Luftpfad ist dieser Ort in Hauptwindrichtung in der Nähe des Zaunes des Reaktorgeländes, für den Wasserpfad flußabwärts von der Einleitungsstelle. Eine solche Referenzperson dürfte sich ausschließlich von auf dem Gelände erzeugten Lebensmitteln ernähren. Die zusätzliche Strahlendosis für diese fiktive Person würde pro Jahr maximal 0,003 mSv betragen. Der gesetzlich zulässige Wert liegt bei 0,3 mSv/a; ein Durchschnitts-Münchner ist einer natürlichen Strahlendosis von 2,4 mSv/a ausgesetzt (siehe Vergleichswerte S. 109). Für die Bevölkerung mit realen Lebensgewohnheiten ist damit sichergestellt, daß sie keinerlei Strahlenbelastung durch den FRM II unterliegt.
- Residual heat
The radioactive fission products which develop in a fuel element during the operation of the reactor undergo a decay and lead to the creation of residual heat in the fuel element and in the surrounding medium.
- acronym of:Reactor safety commission
This is an advisory committe of the German Federal Government set up in 1958. The commission is advising the Federal Ministry of Enviromnent and Reactor Safety in matters such as safety of nuclear power plants and other nuclear facilities.
- Shutdown bars
n the FRM II there are five shutdowm bars made out of hafnium, which are placed outside of the uranium zone. They are an independent system, which can safely shutdown the reactor any time.
- abbreviation for:International System of Units
A system of physical units in which the fundamental quantities are length, time, mass, electric current, temperature, luminous intensity and amount of substance, and the corresponding units are metre, second, kilogram, Ampere, Kelvin, candela and mole. It has been given official status and recommended for universal use by the General conference of Weights and measures. International System of weights and measures, using the metric system augmented by scientific units used in technology.
- Spallations source
In the spallations sources high energetic protons are fired to a block made out of heavy metal (lead or uranium), which breaks into splitters. Every time about 10 neutrons are set free. In the neutron balance a spallations source is more productive than a reactor, but it is not yet suitable for many experiments.
The branch of physics concerned with the production, measurement, and interpretation of electromagnetic spectra arising form either emission or absorption of radiant energy by various substances.
- acronym of:Radiation protection commission
The radiation protection commission (Strahlenschutzkommission - SSK) is an experts' committee, founded in 1974. It is advising the Federal Ministry for Environment and Reactor Safety in topics about the protection from the dangers of radioactive radiation.
Man unterscheidet zwischen Wellen- und Teilchenstrahlung. Gammastrahlung ist - ähnlich wie Licht - eine Wellenstrahlung. Teilchenstrahlung besteht aus meist schnell bewegten materiellen Teilchen wie z.B. Elektronen (ß-Strahlen), He-Kerne (a-Strahlen) oder Neutronen.
- Superthermal source
This is a special experiment installation, which produces even slower newtrons than the cold source. The cooling substance used is liquid helium.
- abbreviation for:Sievert
A unit of radiation dose, equal to the dose delivered by a point source of one miligram of radium, enclosed in a platinum container with walls 0.5 milimeter thick, to a sample at a distance of one centimeter, over a period of one hour. It corresponds to approximately 8.38 roentgen and a Joule per kg.
The simultaneus action of separate agencies which, together, have greater total effect than the sum of their individual effects: said esp. of drugs.
- The FRM II concept
The FRM II concept is a particularly small, light water-cooled reactor core in the centre of a big heavy water moderator tank. This moderator tank is incorporated in a light water reactor-pool. In this concept a particularly big useful neutron flux denisity is going to be achieved by an as low as possible thermic output. It is going to be the world best neutron flux density in proportion to the thermic output.
- The target of the FRM II
FRM II is going to be used as a highly efficient neutron source, which is running a high thermal neutron flux outside of the fuel element at low reactor output. The high thermal neutron flux will be used for many ecperiments with greater spectral clearness. Secondary sources, such as cold source, hot source or beam tube converter will be placed the FRM II in order to supply some experiments with particular neutron spectres.
- Tritium (H-3)
A radioactive isotope of hydrogen having a half life of ca. 12.5 years and a biological half life of 100 days; it decays by beta-particle emission and is used in thermonuclear bombs, thermonuclear fusion devices, as a radioactive tracer, etc.
- acronym of:Technische Universität München
Short for Technische Universität München.
- Uranium (U): atomic number 92, atomic weight 238.03
A very hard, heavy, silvery, moderately malleable, radioactive metallic chemical element in the actinide series: it si found only in combination, chiefly in pitchblende, and is important in work on atomic energy, esp. in the isotope (uranium-235) which can undergo neutron-induced fission and in the more plentiful isotope (uranium-238) from which plutonium is produced. Melting point: 1132oC, boiling point 3818oC.
- Uranium enrichment
A process carried out on uranium, in which the ratio of the abundance of the isotope uranium-235 to that of the isotope uranium-238 is increased above that found in natural uranium.
- Weapon-grade uranium
For atomic bombs plutonium and highly enriched uranium in metallic form are used. The fuel which is going to be used for the FRM-II is highly enriched uranium-23, too, but is chemically bound as sylicide.
- Wiederkehrende Prüfungen
Wiederkehrende Prüfungen werden aufgrund von Rechtsvorschriften, Auflagen seitens der zuständigen Behörden oder anderweitiger Festlegungen in regelmäßigen Zeitabständen durchgeführt. Diese Prüfungen dienen der Kontrolle von Funktion und Zuverlässigkeit von Anlageteilen.