Research neutron source Heinz Maier-Leibnitz

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Research neutron source Heinz Maier-Leibnitz
The Munich II research reactor (right) together with its decommissioned predecessor from 1957 (left).

The Munich II research reactor (right) together with its decommissioned predecessor from 1957 (left).

location
Research Neutron Source Heinz Maier-Leibnitz (Bavaria)
Research neutron source Heinz Maier-Leibnitz
Coordinates 48 ° 15 '57 "  N , 11 ° 40' 33"  E Coordinates: 48 ° 15 '57 "  N , 11 ° 40' 33"  E
country Germany
Data
owner Free State of Bavaria
operator Technical University of Munich
start of building August 1, 1996
Installation March 2, 2004
Reactor type Swimming pool reactor
Thermal performance 20 MW
Neutron flux density 8 × 10 14  n / (cm 2 s)
Website www.frm2.tum.de
was standing February 1, 2009

The research neutron source Heinz Maier-Leibnitz (after the German nuclear physicist Heinz Maier-Leibnitz ; also Research Reactor Munich II , FRM II for short ) in Garching near Munich is the most powerful German research reactor with a nominal thermal output of 20  MW . The reactor is operated by the Technical University of Munich as a central scientific facility that is not assigned to any faculty. The neutrons produced are mainly used for basic research in physics, chemistry, biology and materials science.

history

The fundamental decision to build a new research reactor was prepared when plans to build a national spallation neutron source failed in 1985 . In 1981, preliminary studies for a compact core for a new source of funds flow began, and from 1984 project funds were available. The assessment took place from 1989 to 1992, most recently by the Science Council , which recommended the construction of the FRM II with high priority.

The decision to build the FRM II was criticized from various sides for various reasons. Since the first partial construction permit was issued on April 29, 1996, every individual permit has been contested in court; however, all appeals were ultimately dismissed. An initiated by opponents 2003 referendum , with a slim majority of Garching calling their city council to stand against the commissioning of the reactor, had no lasting effect. After exhausting all legal examination options, the then Federal Environment Minister Jürgen Trittin (who was responsible for the federal state of Bavaria, which is actually responsible for enforcing nuclear law ) had to sign the third partial construction permit on May 2, 2003, which essentially consists of the operating permit.

In addition to safety concerns (leakage of radiation or core meltdown ), the particular hazard due to the proximity (around 10 km) to Munich Airport was mentioned . To counter this danger, the reactor hall was built with a 1.8 meter thick concrete wall and ceiling. After the construction decision had been made, the criticism focused on the use of highly enriched uranium, and thus, if it can be isolated from the existing U 3 Si 2 compound, nuclear weapons- grade uranium . The currently valid operating license contains the requirement to switch to a fuel that is still to be developed in the medium term, which will enable a lower degree of nuclear enrichment through an even higher chemical uranium density. Research is currently being carried out on uranium-molybdenum compounds in particular.

The reactor was built by Siemens AG and cost over 400 million euros. It was started up for the first time on March 2, 2004, and on August 24, 2004, it reached the nominal output of 20 MW. In April 2005 it was formally handed over by Siemens to the Technical University of Munich and then put into routine operation.

Break in operation

The reactor has been out of operation since March 11, 2019. There is not enough fuel. The fuel elements delivered from France in the past are ready there, but may not be delivered due to changed regulations. It is less about the risks associated with the transport of radioactivity than about security risks related to the weapons-grade uranium in the core.

Replacement for highly enriched uranium

Research into new fuel with low enrichment for the FRM II, which has been taking place since 2004, had only revealed possible alternatives for the reactor until 2014. The research takes place in cooperation with the operators of the high-performance research reactors in Europe ( SCK-CEN , ILL and CEA ) and the fuel element manufacturer Framatome-CERCA . This will continue to be done in close cooperation with partners from the USA and Korea.

Because of the spatial limitation for a core conversion, a lower enrichment can only be achieved by increasing the uranium density. There were three promising fuel candidates that differ significantly in terms of the possible uranium density. There are practicable approaches for the production of low-enriched (<50%) fuel elements. A monolithic U-Mo fuel with an enrichment of 19.75% should be available in early 2021 from prototypical production for irradiation tests, which are necessary for approval. It is expected that the series production of LEU fuel elements (low-enriched uranium) for research reactors will start from 2022.

Buildings

FRM I (Atomei) and FRM II in the background

The reactor is located on the campus of the Technical University of Munich in the immediate vicinity east of its predecessor, the first German research reactor FRM-I (in operation 1957-2000). The below listed properties distinctive dome of the FRM-I, became known as "nuclear egg Garchinger", now partially serves as an extension of the neutron guide hall of the FRM II. The area is structurally separated by a solid fence from the rest of the campus. An originally existing moat was dismantled.

Structurally, the FRM II consists of the reactor building that houses the so-called experimental hall, a neutron guide hall and ancillary buildings with offices, workshops and laboratories. The reactor building, which has a square base with an edge length of 42 m and is 30 m high, contains the actual nuclear reactor as well as the surrounding "experimental hall" with various facilities that are supplied with neutrons via beam pipes. The neutron guide hall, a 55 × 30 square meter cultivation is about neutron guide supplied with neutrons. In the future, further experiments will be accommodated in the so-called "Neutron Guide Hall East", which will be supplied with neutrons from the reactor via neutron guides that are guided through specially provided openings in the outer wall of the reactor building.

An additional building, the Industrial User Center (IAZ) on the FRM II site, is used by the radiochemical industry for the production of radiopharmaceuticals . The main tenant is currently ITM Isotope Technologies Munich .

In addition, there are other, mostly older buildings on the area that date from the FRM-I or the construction phase. In addition to a cyclotron and workshops, these mainly accommodate offices.

Plant security

According to the operator, the FRM II has the most comprehensive safety equipment for research reactors in the world. In addition to constant surveillance and strict controls, particular importance was attached to the inherent safety of the reactor: due to the design of the fuel element, the plant automatically switches to a stable operating state in the event of conceivable faults due to the laws of physics. This includes a negative temperature coefficient of reactivity for both the fuel and the coolant and a negative local bubble coefficient . Mixing light and heavy water in the cooling duct or in the moderator tank would also lead to the reactor being switched off for physical reasons.

In addition, there are active safety devices such as five shut-off rods made of hafnium , which are magnetically suspended on springs and which are immediately fired into the vicinity of the fuel element in the event of irregularities in operation and shut down the reactor ( reactor shutdown ). Even if the control rod were lost, four of the five shutdown rods would be sufficient to safely shut down the reactor.

In particular after the attacks of September 11, 2001 , calculations were carried out again which confirm the safety of the FRM II with regard to the crash of fast military aircraft, large commercial aircraft and a kerosene fire. Before the operating license was issued, a large number of possible accidents were examined by independent experts, so that the safety of the plant was ultimately verified by the responsible supervisory authority.

With regard to the concerns about an increased radiation dose in the vicinity of the FRM II, measurements and calculations for the inhabited area resulted in an additional effective radiation dose that is less than 0.01% of the exposure to natural radioactivity. The ventilation system of the FRM II is also a closed system in which the air is cleaned using filters. Only a small fraction is released into the environment; this is also filtered, the delivery measured and documented. These can be followed online on the website of the Bavarian State Office for the Environment . The high safety requirements for the reactor are one reason why the Technical University of Munich is the only German university apart from the University of the Federal Armed Forces in Munich to have an independent university fire department on the Garching campus .

Nuclear technology and cooling

The reactor concept follows basic ideas that were first implemented around 1970 on the 55 MW high-flux reactor of the Laue-Langevin Institute (ILL) in Grenoble . What is particularly innovative at the FRM II is the use of a denser uranium compound. This compound was originally developed in order to convert existing research reactors from high to low enriched uranium without disproportionate loss of performance. At the FRM II, the combination of a high chemical uranium density with a high level of nuclear enrichment enables a particularly compact reactor core and thus a particularly high ratio of neutron flux to thermal power. Like all other high-performance research reactors, the FRM II is also operated with highly enriched uranium .

Fuel element of the FRM II with its 113 involute-shaped fuel plates (view from below).

In contrast to most other reactors, the FRM II manages with a single fuel element that has to be changed after a cycle time of currently 60 days. The element's fuel zone is approximately 70 cm high and contains 8 kg of fissile 235 U. The uranium is in the form of a uranium silicide-aluminum dispersion fuel. The fuel element is hollow-cylinder, the 113 fuel plates, each 1.36 mm thick, are curved involute and are inclined between the inner and outer walls. On the outside, less dense fuel is used than on the inside (uranium density 1.5 g / cm³ instead of 3.0 g / cm³) in order to avoid thermal peaks caused by higher neutron flux and the associated higher gap densities. Light water as a coolant flows in 2.2 mm wide gaps between the fuel plates, which are packed in an Al-Fe-Ni alloy. The fuel plates have a fuel rod cladding typical of research reactors, 0.38 mm thick, and are therefore designed in such a way that the fission products remain in the fuel. The fuel itself has a thickness of 0.60 mm. The control rod is located in the inner cavity, the fuel assembly is surrounded by the moderator.

Involute curved fuel plate as used in the fuel element of the FRM II. The upper cladding has been removed in this illustration in order to reveal the fuel zone (dark red: high uranium density, lighter: lower uranium density). In this illustration, the control rod would be attached at the bottom parallel to the plate.

The fuel element is housed in a moderator tank filled with heavy water . Compared to normal water, heavy water is characterized by a significantly lower absorption of neutrons with only insignificantly poorer moderation behavior. The fuel assembly is cooled with light water. At the maximum output of 20 MW, the cooling water is heated from 37 ° C to a maximum of 53 ° C. The reactor is controlled with a control rod made of hafnium with a beryllium follower located in the fuel element . The control rod is connected to the drive by a magnetic coupling . If this is released, the control rod is pressed into its lower end position both by gravity and by the flow of the cooling water and the reactor is thus switched off immediately.

The moderator tank is located in the 700 m³ reactor basin, which is filled with the desalinated cooling water. Due to the enclosed construction, only a low level of Cherenkov radiation can be observed on the FRM II from outside the moderator tank .

Neutron statistics

The arrangement described above means that 72.5% of the neutrons generated leave the fissure zone with the light water area and so the maximum of the neutron flux is not to be found in the fuel assembly itself, but outside, 12 cm from the surface of the fuel assembly, in the moderator tank. In this area, some of the nozzles end, which do not point directly at the core, but past it. The advantage of this technology is a particularly pure spectrum that is only very little disturbed by intermediate and fast neutrons. The gamma radiation in the beam pipe is also significantly reduced. The neutron flux here is around 800 trillion neutrons per second and square centimeter (8 × 10 14  n / cm²s). Due to the numerous installations in the moderator, this flow is reduced on average to around 80% of this value. At the actual experimental sites at the end of the neutron guide, the flux density is still up to 10 10  n / cm²s. These flux densities are comparable to those of the ILL reactor. Other elements are also housed in the flow maximum of the moderator tank: the cold source supplies particularly long-wave neutrons, the hot source short-wave neutrons. An extendable converter plate attached to the edge of the moderator tank generates fast fission neutrons for the medical irradiation facility (corresponding to a temperature of around 10 billion Kelvin).

Of 100 neutrons that are produced in the core, about 72.5 get into the heavy water, as already mentioned, of which about 34.8%, corresponding to about 25.2 of the neutrons originally present, return from the D 2 O to the fuel zone be reflected back. These neutrons are fast or epithermal . In the fuel zone, they are then decelerated to thermal energies by the coolant H 2 O, together with the 27.5 neutrons remaining there (52.7 in total) . Around 18.4 neutrons are lost through absorption, partly also in the fuel, which leads to 22.2 new fission neutrons. The remaining 34.3 neutrons generate 47.4 new neutrons through fission - the rest is lost in other absorption processes. Of the neutrons that got into the heavy water tank and were also moderated there, 18.3 diffuse as thermal neutrons from the D 2 O back into the fuel zone. They lead to 30.5 new neutrons via fission.

In total, around 1.54 × 10 18 neutrons per second are produced in FRM II during normal operation .

cooling

FRM II with its cell coolers

The FRM II is operated with three cooling circuits. The primary system uses the pool water and has a flow rate of around 1000 m³ / h, i.e. around 280 l / s, corresponding to a speed of 17 m / s in the 2.2 mm wide cooling channels between the fuel plates. The secondary system is a closed water cycle. The tertiary system consists of wet cooling units through which the heat is dissipated to the atmosphere. In addition to the 20 MW thermal output of the core, around 4 MW of output of the operating components must be dissipated.

In the primary cooling circuit, four pumps ensure the necessary flow, of which two pumps are combined into one line. Three pumps are enough to cool the core sufficiently at full rated output. In the event of a reactor shutdown, three after-cooling pumps are switched on to pump the pool water through the core. These pumps are switched off again three hours after being switched off, then natural convection is sufficient to dissipate the residual heat from the core. One of these pumps is sufficient to safely dissipate the decay heat . In addition, the pumps are connected to an emergency diesel generator so that a complete power failure can be bridged. Even in the hypothetical scenario of a failure of all three pumps, the core would not melt because there would be too little residual heat. In addition, the system is designed in such a way that, in the event of a failure of all pumps, the pool water could absorb all of the residual heat from the fuel assembly without boiling.

In addition to the heat from the primary cooling circuit, the waste heat from other operating components is also fed into the secondary circuit.

use

The FRM II is optimized for neutron scattering experiments on beamlines and neutron guides . There are also facilities for material irradiation, medical irradiation and nuclear physics experiments.

The experimental facilities are not operated by the FRM II itself, but by various chairs at the Technical University of Munich as well as by other universities and research institutions that maintain branch offices on the FRM II site for this purpose. The institutes represented are the Max Planck Society , the Leibniz Association and the Helmholtz Association . The latter is the largest branch with the Jülich Center for Neutron Science at Forschungszentrum Jülich with over 30 employees. Around two thirds of the measuring time of each instrument is available to visiting scientists from all over the world. In total, 30% of the capacity is intended for commercial use.

The instruments at FRM II are mostly spectrometers and diffractometers and cover a wide range of applications, both in terms of research and industrial use:

For pure element and isotope analysis, there is an instrument for prompt gamma activation analysis (PGAA) in addition to the classic neutron activation analysis. Conventional irradiation facilities are available inside the moderator tank with different neutron flows and spectra. They are a prerequisite for neutron activation analysis, but are also used to generate radioactive sources, for example for medical treatment in the form of radiopharmaceuticals. Density measurements are also possible in this way. The largest irradiation facility is the one for silicon doping , in which silicon is converted into phosphorus through neutron capture and subsequent beta decay .

Two radiography and tomography systems use the high ability of neutrons to penetrate matter to illuminate technical, static and moving objects. Both 2D images can be made (radiography) and complete three-dimensional reconstructions of the internal structure can be made. In combination with the prompt gamma activation analysis, this internal structure can also be broken down into isotopes.

Another irradiation facility is the medical irradiation facility, in which tumor tissue is irradiated with the fast neutrons from nuclear fission. This is not the better known boron neutron capture therapy , the effect of which is based on thermal neutrons absorbed in boron , but the effect of recoil protons pushed by neutrons.

In materials science and catalysis, there are options for structure analysis and structure determination. In addition, the instruments available at the FRM II can be used to carry out phase analyzes for multi-component alloys . Residual stresses and textures can be analyzed with and without load. This is used, for example, in residual stress analysis in manufacturing technology, component manufacturing and material development and texture determination after rolling and forming processes . With regard to the life sciences, there are possibilities to determine the state of organic compounds and to study the dynamics of complex molecules. Structures and bonds in organic compounds (for single crystals ) can also be analyzed.

The positron source opens up a further range of applications, mainly in surface and defect analysis. For example, an element analysis close to the surface can be carried out or the surface morphology can be determined. Lattice defects in crystals can be determined by means of a defect analysis.

Ultra cold neutrons

The construction of a facility for the generation of ultra-cold neutrons (UCN) is planned at FRM II. In frozen deuterium (D 2 ), the neutrons are cooled down to an energy of around 250 neV (nanoelectron volt). It will primarily be used to study the fundamental properties of the neutron.

Cold neutrons

Around 50% of the experiments at the FRM II use cold neutrons, i.e. neutrons with an average energy of less than 5  meV . The cold source is an additional moderator filled with around 16 l of liquid, around 25 K cold deuterium, which is placed in the heavy water tank of the FRM II. The cold source has its own cooling circuit to compensate for the heating up due to heat conduction, gamma radiation and neutron impacts. The deuterium area is enveloped with protective gas in order to prevent contact between the deuterium and air even in the event of malfunctions. In the cold source, the flux density of cold neutrons is approximately 9.1 × 10 13 n / cm²s. The following experiments work with cold neutrons:

Surname Type operator description
ANTARES Radio & tomography TUM Radiography and tomography
DNS spectrometer JCNS Diffuse neutron scattering
J-NSE spectrometer JCNS Jülich Neutron Spin Echo Spectrometer
KWS-1, -2, -3 Diffractometer JCNS Small angle scattering
MARIA Reflectometer JCNS Magnetic reflectometer with a high angle of incidence
MEPHISTO Nuclear & Particle Physics TUM Nuclear and Particle Physics with Cold Neutrons
MIRA Multi-purpose spectrometer TUM Various options for diffractometry and spectrometry
N-REX + Diffractometer MPI Metal Research Neutron X-ray contrast reflectometer
PANDA spectrometer Helmholtz / IFP TU Dresden Three-axis spectrometer
PGAA Irradiation IKP Cologne / PSI / TUM Prompt gamma-ray activation analysis
REFSANS Diffractometer HZG / TUM / LMU Reflectometer for the analysis of soft and liquid interfaces and surfaces
RESEDA spectrometer TUM Neutron resonance spin echo
SANS-1 Diffractometer TUM / GKSS Small angle scattering (Small angle neutron scattering, under construction)
SPHERES spectrometer JCNS Backscatter spectrometer
TOFTOF spectrometer TUM High resolution time-of-flight spectrometer

Thermal neutrons

Thermal neutrons have an average energy of about 25 meV, corresponding to the temperature of the moderator.

Surname Type operator description
PUMA spectrometer University of Göttingen / TUM Three-axis spectrometer with polarization analysis and multi-analyzer detector
RESI Diffractometer LMU / University of Augsburg Single crystal diffractometer
SPODI Diffractometer TU Darmstadt / LMU Structural powder diffractometer
STRESS SPEC Diffractometer TUM / Helmholtz / TU Clausthal / GKSS Residual stress and texture diffractometer
TRISP spectrometer MPI Solid State Research Neutron resonance spin echo three-axis spectrometer

Hot neutrons

The hot neutrons come from the hot spring (~ 2400 ° C, moderator: 14 kg graphite ). They are mainly used for structural studies on condensed matter. These neutrons have an energy between 0.1 eV and 1 eV. The hot spring is housed in the moderator tank near the maximum flow. The graphite is heated by gamma radiation and, to a lesser extent, by neutrons from the reactor core. The source is from the environment by a double-walled Zircaloy vessels for containing embedded insulating felt isolated, so that the temperature on the outside of only about 100 ° C. The final temperature results from the thermal equilibrium between heating and heat dissipation to the environment.

Surname Type operator description
HEIDI Diffractometer RWTH Aachen Hot single crystal diffractometer

Fission neutrons

The beam converter system (SKA) for generating the fission neutrons consists of two plates containing 498 g of 235 U, which generate fast fission neutrons (energy: 0.1 MeV - 10 MeV) by capturing thermal neutrons and then splitting them. The plates are located on the edge of the moderator tank and have a nominal output of 80 kW. If necessary, they can be pulled out of the neutron field in order to prevent unnecessary burn-up (loss through fission) of the uranium.

Surname Type operator description
MEDAPP Irradiation TUM Medical irradiation system ( neutron therapy, radiation)
NECTAR Radio & tomography TUM Neutron computed tomography and radiography facility

Positron source

The positron source NEPOMUC ( NE utron induced PO sitron Source MU ni C h) is the world's strongest source for monoenergetic positrons (as of 3/2008). It generates about 9 × 10 8 moderated positrons per second. To generate the positrons, thermal neutrons are captured in cadmium , which creates hard gamma radiation up to a maximum energy of 9 MeV. By absorbing this gamma radiation in platinum foils , positrons ( antimatter ) and electrons (matter) are created through pair formation . In platinum, positrons that are primarily generated are moderated to ambient temperature and can be emitted into a vacuum after diffusion to the foil surface. The positrons moderated in this way are accelerated to an energy of 1 keV and guided magnetically. The monoenergetic positron beam arrives at various experiments via a beam switch: The positron source is operated by the TU Munich itself.

Surname description
CDBS Coincidence Doppler Spectroscopy
OP An open beam place for additional experiments: Currently generation of the negatively charged positronium ion
PAES Positron annihilation-induced Auger electron spectroscopy
PLEPS Pulsed Low Energy Positron System
SPM Scanning Positron Microscope

Irradiation systems

In addition to the above-mentioned experiments, there are irradiation systems inside the moderator tank for generating radioactive isotopes, for neutron activation analysis (NAA) or for neutron transmutation doping of silicon . The doped silicon obtained in this way is doped very homogeneously.

Reportable Events and Other Occurrences

So far there have been 18 reportable events at the FRM II, two of them in the "Urgent" category and 16 in the "Normal" category. The events are distributed as follows: 2004: 1; 2005: 1; 2006: 3; 2007: 1; 2008: 1; 2009: 5; 2010: 2; 2011: 1; 2014: 1; 2016: 1; 2020: 1. In none of the reportable events was radioactivity released; all events have been classified in the INES 0 category .

  • February 18, 2007 : Reactor shutdown after failure of the moderator tank cooling . Due to neutron collisions and gamma radiation, the heavy water in the moderator tank is heated up. The moderator tank has its own cooling system to dissipate the heat.
  • May 13, 2009 : Non-compliant closing of a non-return valve in the primary cooling system during recurring inspection. "Urgent" category, event number 09/002. The check valve is important for the transition from forced cooling to natural convection when removing residual heat.
  • July 30, 2009 : One of three redundant non-return valves on the primary cooling system was stiff.
  • On May 16, 2020 it was reported that radioactive C-14 had leaked due to an assembly error in the research reactor FRM II. The C-14 was released into the atmosphere via a chimney and is said to have slightly exceeded the limit value by around 15%. The incident was assessed as urgent ( category E ) according to the nuclear reporting ordinance . On the international rating scale (INES), the value remained at level 0, according to which an incident has at most a minor safety significance. There should not have been any danger to people or the environment.

Other non-reportable events that aroused supraregional media attention:

  • In 2006 , iron oxide deposits a few nanometers thick (referred to as "rust" in the media) were found in the reactor basin, the causes of which have not yet been clarified and which have not been remedied (as of January 2012). However, several independent reports ruled out any impairment of the safety of the reactor, so that no further measures were taken.
  • In November 2012 , the reactor was shut down unscheduled because there was a threat that the limit value for the emission of the radioactive isotope 14 C would be exceeded . Contrary to reports to the contrary, the limit value, which for the FRM II is only one fifth of the exemption limit for use without a permit under the Radiation Protection Ordinance , was not reached. After clarifying the cause, a modified cleaning procedure for the heavy water, the reactor was restarted and continued to operate as planned until the end of the year without further incidents.

Web links

Commons : Research Reactor Munich II  - Collection of images, videos and audio files

Individual evidence

  1. ^ Research reactors. Federal Office for the Safety of Nuclear Waste Management , January 9, 2018, accessed on March 2, 2018 .
  2. ↑ Use of the source by industry and authorities. (No longer available online.) Technical University of Munich, May 2014, archived from the original on May 22, 2014 ; accessed on January 6, 2020 .
  3. ↑ Use by industry and medicine. FRM II, TU Munich, accessed on January 7, 2020 .
  4. ↑ Wolf-Michael Catenhusen : The end of the spallation neutron source (SNQ) in Jülich . In: Social Democratic Press Service . No. 110 , June 13, 1985, pp. 1 ( online [PDF; 185 kB ]).
  5. ↑ BT-Drs. 12/2984 : Reply of the Federal Government
  6. ↑ Upper Austria non-partisan platform against nuclear threat: German nuclear opponent files criminal charges for research reactor near Munich. ( Memento of February 26, 2005 in the Internet Archive ) Press release, August 22, 2003.
  7. ↑ The year 2004 was eventful - the struggle continues. (No longer available online.) Citizens against Atomreaktor Garching e. V., December 17, 2004, archived from the original on April 6, 2005 ; Retrieved February 17, 2010 .
  8. ↑ Garching city council disregards the will of the Garching citizens - vote on FRM2. Bündnis 90 / Die Grünen - Kreisverband München-Land, May 28, 2003, accessed on February 17, 2010 .
  9. ↑ a b c d Wolfgang A. Herrmann : Neutrons are light: The "Research Neutron Source Heinz Maier-Leibnitz" (FRM-II) in Garching. (PDF; 1.9 MB) (No longer available online.) In: Plenary lecture on the occasion of the Annual Nuclear Technology Conference 2004 in Düsseldorf, May 25, 2004. Technical University of Munich , archived from the original on February 3, 2014 ; Retrieved February 17, 2010 .
  10. ↑ FRM II: The Neutron Source. (No longer available online.) Technical University of Munich, archived from the original on August 1, 2012 ; accessed on January 7, 2020 .
  11. ↑ Umweltinstitut München eV: Compulsory break for the research reactor. June 13, 2019, accessed January 5, 2020 .
  12. ↑ Michael Bauchmüller: France takes a stand when it comes to uranium procurement. In: Süddeutsche Zeitung, SZ online. June 13, 2019, accessed January 5, 2020 .
  13. ↑ FAQ on the FRM II reactor. Technical University of Munich, 2019, accessed on January 5, 2020 .
  14. ^ Fuel development. Technical University of Munich, accessed on January 5, 2020 .
  15. ↑ Manufacture of fuel elements from new materials. Technical University of Munich, 2019, accessed on January 5, 2020 .
  16. ↑ Pioneering work: prototype of a new fuel. In: Public Relations at FRM II. Technical University of Munich, May 6, 2020, accessed on May 25, 2020 .
  17. ↑ Site plan. (PDF) Maier-Leibnitz Zentrum, accessed on March 2, 2018 .
  18. ↑ Site plan for devices and experiments. (jpg) Retrieved March 2, 2018 .
  19. ↑ Industry and Medicine. TUM, accessed on March 2, 2018 .
  20. ↑ Inherent security features. (No longer available online.) Technical University of Munich , archived from the original on October 5, 2013 ; Retrieved February 17, 2010 .
  21. ↑ Security systems. TUM, accessed on March 2, 2018 .
  22. ↑ a b c Anton Röhrmoser: Neutron physical optimization and design of a research reactor of medium power with the aim of achieving a high flow for beam tube experiments . Dissertation. Technical University of Munich 1991.
  23. ↑ Shutdown system. (No longer available online.) Technical University of Munich , archived from the original on October 4, 2013 ; Retrieved February 17, 2010 .
  24. ^ New research reactor Munich II (FRM II) - 3rd partial license. (PDF; 683 kB) (No longer available online.) Reactor Safety Commission , September 13, 2001, archived from the original on August 8, 2007 ; Retrieved February 17, 2010 .
  25. ↑ Measured values ​​of individual nuclear power plants and the research reactor. Bavarian State Office for the Environment , accessed on February 17, 2010 .
  26. ↑ Nazare, Ondracek and Thümmler: UAl 3 -Al as a dispersion fuel for high-flow reactors . Ed .: Nuclear Research Center Karlsruhe. August 1970, doi : 10.5445 / IR / 270004095 ( online [accessed January 7, 2020]).
  27. ↑ a b Fuel element of the FRM II. Technical University of Munich , accessed on March 2, 2018 .
  28. ↑ a b c d Active safety features: cooling system. Technical University of Munich , accessed on March 2, 2018 .
  29. ↑ a b Active safety features: shutdown system. (No longer available online.) Technical University of Munich , archived from the original on October 4, 2013 ; Retrieved May 19, 2010 .
  30. ↑ beam guidance of neutrons; Nozzles. (No longer available online.) Technical University of Munich, September 2013, archived from the original on October 5, 2013 ; accessed on January 7, 2020 .
  31. ↑ Image of the nozzle positions. (No longer available online.) Technical University of Munich, archived from the original on July 31, 2012 ; accessed on January 7, 2020 .
  32. ↑ Neutron source. Maier-Leibnitz Zentrum, accessed on March 2, 2018 .
  33. ↑ cooling circuits. Technical University of Munich , accessed on March 2, 2018 .
  34. ↑ Scientific partners. Maier-Leibnitz Zentrum, accessed on March 2, 2018 .
  35. ↑ About us. In: Forschungszentrum Jülich. Retrieved January 7, 2020 .
  36. ^ Research at FRM II. Technical University of Munich , accessed on March 2, 2018 .
  37. ↑ a b Industry and Medicine. Technical University of Munich , accessed on March 2, 2018 .
  38. ↑ Irradiation facilities. Technical University of Munich , accessed on March 2, 2018 .
  39. ↑ Irradiation facilities: silicon doping. Technical University of Munich , accessed on March 2, 2018 .
  40. ↑ Non-destructive testing. Technical University of Munich , accessed on March 2, 2018 .
  41. ^ T. Bücherl, B. Schillinger: Radiography and tomography with cold neutrons. (PDF) Accessed March 2, 2018 (presentation slides).
  42. ↑ Lea Canella, Petra Kudějová, Ralf Schulze, Andreas Türler and Jan Jolie: "PGAA, PGAI and NT with cold neutrons: Test measurement on a meteorite sample", in: Applied Radiation and Isotopes , 2009 , 67 (12) , p. 2070-2074; doi: 10.1016 / j.apradiso.2009.05.008 .
  43. ↑ Franz M. Wagner, Peter Kneschaurek, Anton Kastenmüller, Birgit Loeper-Kabasakal, Severin Kampfer, Harald Breitkreutz, Wolfgang Waschkowski, Michael Molls and Winfried Petry: "The munich fission neutron therapy facility MEDAPP at the research reactor FRM II", in: Radiotherapy and Oncology , 2008 , 184 (12) , pp. 643-646; doi: 10.1007 / s00066-008-1878-3 .
  44. ↑ Industrial use: life sciences. Maier-Leibnitz Zentrum, accessed on March 2, 2018 .
  45. ↑ Surface and defect analysis with positrons. (No longer available online.) Technical University of Munich , archived from the original on September 11, 2012 ; accessed on January 7, 2020 .
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