OPAL
Encyclopedia
OPAL is a 20 megawatt (MW) pool-type nuclear research reactor
that was officially opened on 20 April 2007 at the Australian Nuclear Science and Technology Organisation
(ANSTO) Research Establishment at Lucas Heights, located in South Sydney, Australia
.
The main reactor uses are:
The reactor runs on an operation cycle of 28 days nonstop at fullpower, followed by a stop of 2 days to reshuffle the fuel.
During year 2010 OPAL ran a total of 286 days at power which represents a worldwide leading availability.
company INVAP
was fully responsible through a turn key contract for the delivery of the reactor, performing the design, construction and commissioning. The facility is currently in operation.
OPAL was opened on 20 April 2007 by then Australian Prime Minister
John Howard
and is the replacement for the HIFAR
reactor. ANSTO received an operating license from the Australian Radiation Protection and Nuclear Safety Agency
(ARPANSA) in July 2006, allowing commencement of hot commissioning, where fuel is first loaded into the reactor core. OPAL went critical
for the first time on 12 August 2006 and reached full power on 3 November 2006.
consists of 16 low-enriched plate-type fuel assemblies
and is located under 10 metres of water in an open pool. Light water (normal H2O) is used as the coolant and moderator
while heavy water
(D2O) is used as the neutron
reflector.
OPAL is the centrepiece of the facilities at ANSTO, providing efficient and rapid radiopharmaceutical
and radioisotope production, irradiation
services (including neutron transmutation
doping of silicon), neutron activation analysis
and neutron beam research. OPAL is able to produce four times as many radioisotopes for nuclear medicine
treatments, and a wider array of radioisotopes for the treatment of disease than the old HIFAR
reactor. The modern design includes a cold neutron source
(CNS).
The OPAL reactor already has received seven awards in Australia.
at ANSTO hosts OPAL's neutron scattering
facility. It is now running as a user facility serving the scientific community in Australia and around the world. New fundings have been received in 2009 in order to install further competitive instruments and beamlines. The actual facility comprises the following instruments:
ECHIDNA is the name of the high-resolution neutron
powder diffractometer
. The instrument serves to determine the crystalline structures of materials using neutron radiation
analogical to X-ray techniques. It is named after the Australian monotreme
echidna
, as the spiny peaks of the instrument looks like an echidna.
It operates with thermal neutron
s. One of the main features is the array of 128 collimators and position sensitive detectors for rapid data acquisition. ECHIDNA allows for structure determinations, texture measurements and reciprocal space mapping of single crystals in most different sample environments serving the physics, chemistry, materials, minerals and earth-science communities. ECHIDNA is part of the Bragg Institute
's park of neutron scattering
instruments.
A set of 128 detectors each equipped which a 5' collimator in front are arranged in a 160° sector focusing to the sample. The collimators select the scattered radiation into the well defined ranges of 128 angular positions. All the collimator and detector setup is mounted on a common table which is scanned in finer steps around the sample, to be combinded further to a continuous diffraction pattern.
reflectometer
built on the cold neutron
. The instrument serves to determine the structure of interfaces using highly collimated neutron beams
. These beams are shone on to the surface at low angles (typically less than 2 degrees) and the intensity of the reflected radiation is measured as a function of angle of incidence.
It operates using cold neutrons, with a wavelength band of 0.2–2.0 nm. Although up to three different angles of incidence are required for each reflectivity curve, the time-of-flight nature means that timescales of kinetic processes are accessible. By analysing the reflected signal one builds a picture of the chemical structure of the interface. This instrument can be used for examining biomembranes, lipid bilayers, magnetism, adsorbed surfactant layers, etc.
powder diffractometer
. The instrument serves to determine the crystalline structures of materials using neutron radiation analogical to X-ray techniques. It is named after the wombat
, a marsupial
indigenous to Australia.
It will operate with thermal neutrons. It has been designed for highest flux and data acquisition speed in order to deliver time resolved diffraction patterns in a fraction of a second. WOMBAT will concentrate on in-situ studies and time critical investigations, such as structure determinations, texture measurements and reciprocal space mapping of single crystals in most different sample environments serving the physics, chemistry, materials, minerals and earth-science communities.
residual stress
diffractometer. Strain
scanning using thermal neutrons is a powder diffraction
technique in a polycrystalline block of material probing the change of atomic spacing due to internal or external stress
. It is named after the kowari
, an Australian marsupial.
It provides a diagnostic non-destructive tool to optimize e.g. post-weld heat treatment (PWHT, similar to tempering
) of welded structures. Tensile stresses for example drive crack growth in engineering components and compressive stresses inhibit crack growth (for example cold-expanded holes subject to fatigue cycling). Life extension strategies have high economic impact and strain scanning provides the stresses needed to calculate remaining life as well as the means to monitor the condition of components since it is non-destructive. One of the main features is the sample table that will allow to examine large engineering components while orienting and positioning them very accurately.
announced on 27 July 2007 that the reactor would be shut down for 8 weeks to fix the fuel plates and a minor fault causing light water to seep into the reactor's heavy water
.
In the end, the shutdown lasted 10 months. The supply of radiopharmaceuticals was rationed, causing the postponement of some treatments for patients.
OPAL returned to full operational power on 23 May 2008, following approval by the nuclear regulator, ARPANSA to use a modified fuel design.
Research reactor
Research reactors are nuclear reactors that serve primarily as a neutron source. They are also called non-power reactors, in contrast to power reactors that are used for electricity production, heat generation, or maritime propulsion.-Purpose:...
that was officially opened on 20 April 2007 at the Australian Nuclear Science and Technology Organisation
Australian Nuclear Science and Technology Organisation
The Australian Nuclear Science and Technology Organisation is a statutory body of the Australian government, formed in 1987 to replace the Australian Atomic Energy Commission. Its head office and main facilities are in southern outskirts of Sydney at Lucas Heights, in the Sutherland Shire...
(ANSTO) Research Establishment at Lucas Heights, located in South Sydney, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
.
The main reactor uses are:
- Irradiation of target materials to produce radioisotopes for medical and industrial applications
- Research in the field of material science using neutron beams and its sophisticated suite of experimental equipment
- Analysis of minerals and samples using the neutron activation technique and the delay neutron activation technique
- Irradiation of Silicon ingots in order to dope them with phosphorus and produce the basic material used in the manufacturing of semiconductor devices
The reactor runs on an operation cycle of 28 days nonstop at fullpower, followed by a stop of 2 days to reshuffle the fuel.
During year 2010 OPAL ran a total of 286 days at power which represents a worldwide leading availability.
History
The ArgentineArgentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
company INVAP
INVAP
INVAP S.E. is an Argentine high-technology company dedicated to the design, integration, construction and delivery of high complexity equipment, plants and devices.-Background:...
was fully responsible through a turn key contract for the delivery of the reactor, performing the design, construction and commissioning. The facility is currently in operation.
OPAL was opened on 20 April 2007 by then Australian Prime Minister
Prime Minister of Australia
The Prime Minister of the Commonwealth of Australia is the highest minister of the Crown, leader of the Cabinet and Head of Her Majesty's Australian Government, holding office on commission from the Governor-General of Australia. The office of Prime Minister is, in practice, the most powerful...
John Howard
John Howard
John Winston Howard AC, SSI, was the 25th Prime Minister of Australia, from 11 March 1996 to 3 December 2007. He was the second-longest serving Australian Prime Minister after Sir Robert Menzies....
and is the replacement for the HIFAR
HIFAR
High Flux Australian Reactor was Australia's first nuclear reactor. It was built at the Australian Atomic Energy Commission Research Establishment at Lucas Heights....
reactor. ANSTO received an operating license from the Australian Radiation Protection and Nuclear Safety Agency
Australian Radiation Protection and Nuclear Safety Agency
The Australian Radiation Protection and Nuclear Safety Agency is an Australian body that monitors and identifies solar radiation and nuclear radiation risks to the population of Australia....
(ARPANSA) in July 2006, allowing commencement of hot commissioning, where fuel is first loaded into the reactor core. OPAL went critical
Critical mass
A critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. The critical mass of a fissionable material depends upon its nuclear properties A critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. The...
for the first time on 12 August 2006 and reached full power on 3 November 2006.
Facility details
The reactor coreNuclear reactor core
A nuclear reactor core is the portion of a nuclear reactor containing the nuclear fuel components where the nuclear reactions take place.- Description :...
consists of 16 low-enriched plate-type fuel assemblies
Nuclear fuel
Nuclear fuel is a material that can be 'consumed' by fission or fusion to derive nuclear energy. Nuclear fuels are the most dense sources of energy available...
and is located under 10 metres of water in an open pool. Light water (normal H2O) is used as the coolant and moderator
Neutron moderator
In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction involving uranium-235....
while heavy water
Heavy water
Heavy water is water highly enriched in the hydrogen isotope deuterium; e.g., heavy water used in CANDU reactors is 99.75% enriched by hydrogen atom-fraction...
(D2O) is used as the neutron
Neutron
The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...
reflector.
OPAL is the centrepiece of the facilities at ANSTO, providing efficient and rapid radiopharmaceutical
Radiopharmacology
Radiopharmacology is the study and preparation of radiopharmaceuticals, which are radioactive pharmaceuticals. Radiopharmaceuticals are used in the field of nuclear medicine as tracers in the diagnosis and treatment of many diseases. Many radiopharmaceuticals use technetium-99m which has many...
and radioisotope production, irradiation
Irradiation
Irradiation is the process by which an object is exposed to radiation. The exposure can originate from various sources, including natural sources. Most frequently the term refers to ionizing radiation, and to a level of radiation that will serve a specific purpose, rather than radiation exposure to...
services (including neutron transmutation
Nuclear transmutation
Nuclear transmutation is the conversion of one chemical element or isotope into another. In other words, atoms of one element can be changed into atoms of other element by 'transmutation'...
doping of silicon), neutron activation analysis
Neutron activation analysis
In chemistry, neutron activation analysis is a nuclear process used for determining the concentrations of elements in a vast amount of materials. NAA allows discrete sampling of elements as it disregards the chemical form of a sample, and focuses solely on its nucleus. The method is based on...
and neutron beam research. OPAL is able to produce four times as many radioisotopes for nuclear medicine
Nuclear medicine
In nuclear medicine procedures, elemental radionuclides are combined with other elements to form chemical compounds, or else combined with existing pharmaceutical compounds, to form radiopharmaceuticals. These radiopharmaceuticals, once administered to the patient, can localize to specific organs...
treatments, and a wider array of radioisotopes for the treatment of disease than the old HIFAR
HIFAR
High Flux Australian Reactor was Australia's first nuclear reactor. It was built at the Australian Atomic Energy Commission Research Establishment at Lucas Heights....
reactor. The modern design includes a cold neutron source
Neutron source
A Neutron source is a device that emits neutrons. There is a wide variety of different sources, ranging from hand-held radioactive sources to neutron research facilities operating research reactors and spallation sources...
(CNS).
The OPAL reactor already has received seven awards in Australia.
Neutron scattering at OPAL
The Bragg InstituteBragg Institute
The Bragg Institute is a neutron and X-ray scattering group in Australia. It is part of the Australian Nuclear Science and Technology Organisation's site outside Sydney, in New South Wales, Australia...
at ANSTO hosts OPAL's neutron scattering
Neutron scattering
Neutron scattering,the scattering of free neutrons by matter,is a physical processand an experimental technique using this processfor the investigation of materials.Neutron scattering as a physical process is of primordial importance...
facility. It is now running as a user facility serving the scientific community in Australia and around the world. New fundings have been received in 2009 in order to install further competitive instruments and beamlines. The actual facility comprises the following instruments:
ECHIDNA
Neutron diffraction
Neutron diffraction or elastic neutron scattering is the application of neutron scattering to the determination of the atomic and/or magnetic structure of a material: A sample to be examined is placed in a beam of thermal or cold neutrons to obtain a diffraction pattern that provides information of...
powder diffractometer
Powder diffraction
Powder diffraction is a scientific technique using X-ray, neutron, or electron diffraction on powder or microcrystalline samples for structural characterization of materials.-Explanation:...
. The instrument serves to determine the crystalline structures of materials using neutron radiation
Neutron radiation
Neutron radiation is a kind of ionizing radiation which consists of free neutrons. A result of nuclear fission or nuclear fusion, it consists of the release of free neutrons from atoms, and these free neutrons react with nuclei of other atoms to form new isotopes, which, in turn, may produce...
analogical to X-ray techniques. It is named after the Australian monotreme
Monotreme
Monotremes are mammals that lay eggs instead of giving birth to live young like marsupials and placental mammals...
echidna
Echidna
Echidnas , also known as spiny anteaters, belong to the family Tachyglossidae in the monotreme order of egg-laying mammals. There are four extant species, which, together with the platypus, are the only surviving members of that order and are the only extant mammals that lay eggs...
, as the spiny peaks of the instrument looks like an echidna.
It operates with thermal neutron
Neutron temperature
The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term temperature is used, since hot, thermal and cold neutrons are moderated in a medium with a certain temperature. The neutron energy distribution is...
s. One of the main features is the array of 128 collimators and position sensitive detectors for rapid data acquisition. ECHIDNA allows for structure determinations, texture measurements and reciprocal space mapping of single crystals in most different sample environments serving the physics, chemistry, materials, minerals and earth-science communities. ECHIDNA is part of the Bragg Institute
Bragg Institute
The Bragg Institute is a neutron and X-ray scattering group in Australia. It is part of the Australian Nuclear Science and Technology Organisation's site outside Sydney, in New South Wales, Australia...
's park of neutron scattering
Neutron scattering
Neutron scattering,the scattering of free neutrons by matter,is a physical processand an experimental technique using this processfor the investigation of materials.Neutron scattering as a physical process is of primordial importance...
instruments.
Components
- Neutron guide
- The instrument is located on the TG1 thermal neutronNeutron temperatureThe neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term temperature is used, since hot, thermal and cold neutrons are moderated in a medium with a certain temperature. The neutron energy distribution is...
guide of the OPAL reactor. The distance from the reactor is 58 m. The position is the second on the guide after the WOMBAT instrument. The size of the guide is 300 mm height X 50 mm width and it is plated with supermirrorNeutron supermirrorA neutron supermirror is a highly polished surface used in connection with neutron beams.Supermirrors are produced by depositing and polishing large numbers of layers of a reflecting substance, such as silicon, nickel, titanium or nickel/titanium composite, on a substrate....
coatings.
- The instrument is located on the TG1 thermal neutron
- Primary collimatorCollimatorA collimator is a device that narrows a beam of particles or waves. To "narrow" can mean either to cause the directions of motion to become more aligned in a specific direction or to cause the spatial cross section of the beam to become smaller.- Optical collimators :In optics, a collimator may...
- There are Söller collimators prior to the monochromator in order to reduce the divergence of the beam and to increase the angular resolution of the instrument. Since this is an intensity compromise, two items of 5'Minute of arcA minute of arc, arcminute, or minute of angle , is a unit of angular measurement equal to one sixtieth of one degree. In turn, a second of arc or arcsecond is one sixtieth of one minute of arc....
and 10'Minute of arcA minute of arc, arcminute, or minute of angle , is a unit of angular measurement equal to one sixtieth of one degree. In turn, a second of arc or arcsecond is one sixtieth of one minute of arc....
, respectively, can be interchanged or fully removed by an automated mechanism. The collimators cover the full size of the beam delivered by the neutron guide.
- There are Söller collimators prior to the monochromator in order to reduce the divergence of the beam and to increase the angular resolution of the instrument. Since this is an intensity compromise, two items of 5'
- MonochromatorCrystal monochromatorA crystal monochromator is a device in neutron and X-ray optics to select a defined wavelength of the radiation for further purpose on a dedicated instrument or beamline. It operates through the diffraction process according to Bragg's law....
- The monochromator is made by slabs of
[115] Miller indexMiller indices form a notation system in crystallography for planes and directions in crystal lattices.In particular, a family of lattice planes is determined by three integers h, k, and ℓ, the Miller indices. They are written , and each index denotes a plane orthogonal to a direction in the...
oriented Germanium crystals which are inclined towards each other in order to focus down the Bragg reflected beam. The device has been acquired from the Brookhaven National LaboratoryBrookhaven National LaboratoryBrookhaven National Laboratory , is a United States national laboratory located in Upton, New York on Long Island, and was formally established in 1947 at the site of Camp Upton, a former U.S. Army base...
in the USA after the shutdown of their neutron facility.
- The monochromator is made by slabs of
- Secondary collimator
- Optionally a secondary collimator with 10'Minute of arcA minute of arc, arcminute, or minute of angle , is a unit of angular measurement equal to one sixtieth of one degree. In turn, a second of arc or arcsecond is one sixtieth of one minute of arc....
angular acceptance and 200 mm X 20 mm can be placed in the monochromatic beam between the monochromator and the sample, which again influences the resolution function of the instrument.
- Optionally a secondary collimator with 10'
- Slit system
- Two automated sets of horizontal and vertical pairs of absorbing plates allow to cut down the size of the monochromatic beam prior to the secondary collimator and sample size. They remove unwanted neutrons and reduce the background near the detector. In addition, they allow to select the sample position to be studied.
- Beam monitor
- A 235UUranium-235- References :* .* DOE Fundamentals handbook: Nuclear Physics and Reactor theory , .* A piece of U-235 the size of a grain of rice can produce energy equal to that contained in three tons of coal or fourteen barrels of oil. -External links:* * * one of the earliest articles on U-235 for the...
fission monitor measures the amount of neutrons incident to the sample. The efficiency is 10-4Orders of magnitude (numbers)This list contains selected positive numbers in increasing order, including counts of things, dimensionless quantity and probabilities. Each number is given a name in the short scale, which is used in English speaking countries, as well as a name in the long scale, which is used in some of the...
and most neutrons traverse the device undisturbed. The monitor counts are important to correct for beam flux variations due to changes in the reactor or at the upstream instrument.
- A 235U
- Sample stage
- The sample is supported by a heavy load goniometerGoniometerA goniometer is an instrument that either measures an angle or allows an object to be rotated to a precise angular position. The term goniometry is derived from two Greek words, gōnia, meaning angle, and metron, meaning measure....
consisting of a 360° vertical omega rotation axis, x-y translation tables and a chi - phi cross tilt stage of ±20° range. It can hold a few hundred kilograms in order to support heavier sample environment, such as cryostats, furnaces, magnets, load frames, reaction chambers and others. A typical powder sample is filled into vanadium cans which give little, unstructured background. The mentioned sample environment allows to measure changes of the sample as a function of external parameters, like temperature, presser, magnetic field, etc. The goniometer stage is redundant for most powder diffraction measurements, but will be important for single crystal and texture measurements, where the orientation of the sample plays a role.
- The sample is supported by a heavy load goniometer
- Detector collimatorCollimatorA collimator is a device that narrows a beam of particles or waves. To "narrow" can mean either to cause the directions of motion to become more aligned in a specific direction or to cause the spatial cross section of the beam to become smaller.- Optical collimators :In optics, a collimator may...
s
A set of 128 detectors each equipped which a 5' collimator in front are arranged in a 160° sector focusing to the sample. The collimators select the scattered radiation into the well defined ranges of 128 angular positions. All the collimator and detector setup is mounted on a common table which is scanned in finer steps around the sample, to be combinded further to a continuous diffraction pattern.
- Detector tubes
- The 128 linear position sensitive 3HeHelium-3Helium-3 is a light, non-radioactive isotope of helium with two protons and one neutron. It is rare on Earth, and is sought for use in nuclear fusion research...
gas detector tubes cover the full opening height of 300 mm behind the collimators. They determine the position of the neutron event by charge division over the resistive anode towards each end of the detector. Overall and local count rates lie in the several 10000 Hz range.
- The 128 linear position sensitive 3He
PLATYPUS
PLATYPUS is a time-of-flightTime-of-flight
Time of flight describes a variety of methods that measure the time that it takes for an object, particle or acoustic, electromagnetic or other wave to travel a distance through a medium...
reflectometer
Neutron Reflectometry
Neutron reflectometry is a neutron diffraction technique for measuring the structure of thin films, similar to the often complementary techniques of X-ray reflectivity and ellipsometry...
built on the cold neutron
Neutron temperature
The neutron detection temperature, also called the neutron energy, indicates a free neutron's kinetic energy, usually given in electron volts. The term temperature is used, since hot, thermal and cold neutrons are moderated in a medium with a certain temperature. The neutron energy distribution is...
. The instrument serves to determine the structure of interfaces using highly collimated neutron beams
Neutron radiation
Neutron radiation is a kind of ionizing radiation which consists of free neutrons. A result of nuclear fission or nuclear fusion, it consists of the release of free neutrons from atoms, and these free neutrons react with nuclei of other atoms to form new isotopes, which, in turn, may produce...
. These beams are shone on to the surface at low angles (typically less than 2 degrees) and the intensity of the reflected radiation is measured as a function of angle of incidence.
It operates using cold neutrons, with a wavelength band of 0.2–2.0 nm. Although up to three different angles of incidence are required for each reflectivity curve, the time-of-flight nature means that timescales of kinetic processes are accessible. By analysing the reflected signal one builds a picture of the chemical structure of the interface. This instrument can be used for examining biomembranes, lipid bilayers, magnetism, adsorbed surfactant layers, etc.
WOMBAT
WOMBAT is a high-intensity neutronNeutron diffraction
Neutron diffraction or elastic neutron scattering is the application of neutron scattering to the determination of the atomic and/or magnetic structure of a material: A sample to be examined is placed in a beam of thermal or cold neutrons to obtain a diffraction pattern that provides information of...
powder diffractometer
Powder diffraction
Powder diffraction is a scientific technique using X-ray, neutron, or electron diffraction on powder or microcrystalline samples for structural characterization of materials.-Explanation:...
. The instrument serves to determine the crystalline structures of materials using neutron radiation analogical to X-ray techniques. It is named after the wombat
Wombat
Wombats are Australian marsupials; they are short-legged, muscular quadrupeds, approximately in length with a short, stubby tail. They are adaptable in their habitat tolerances, and are found in forested, mountainous, and heathland areas of south-eastern Australia, including Tasmania, as well as...
, a marsupial
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...
indigenous to Australia.
It will operate with thermal neutrons. It has been designed for highest flux and data acquisition speed in order to deliver time resolved diffraction patterns in a fraction of a second. WOMBAT will concentrate on in-situ studies and time critical investigations, such as structure determinations, texture measurements and reciprocal space mapping of single crystals in most different sample environments serving the physics, chemistry, materials, minerals and earth-science communities.
KOWARI
KOWARI is a neutronNeutron diffraction
Neutron diffraction or elastic neutron scattering is the application of neutron scattering to the determination of the atomic and/or magnetic structure of a material: A sample to be examined is placed in a beam of thermal or cold neutrons to obtain a diffraction pattern that provides information of...
residual stress
Residual stress
Residual stresses are stresses that remain after the original cause of the stresses has been removed. They remain along a cross section of the component, even without the external cause. Residual stresses occur for a variety of reasons, including inelastic deformations and heat treatment...
diffractometer. Strain
Strain (materials science)
In continuum mechanics, the infinitesimal strain theory, sometimes called small deformation theory, small displacement theory, or small displacement-gradient theory, deals with infinitesimal deformations of a continuum body...
scanning using thermal neutrons is a powder diffraction
Powder diffraction
Powder diffraction is a scientific technique using X-ray, neutron, or electron diffraction on powder or microcrystalline samples for structural characterization of materials.-Explanation:...
technique in a polycrystalline block of material probing the change of atomic spacing due to internal or external stress
Stress (physics)
In continuum mechanics, stress is a measure of the internal forces acting within a deformable body. Quantitatively, it is a measure of the average force per unit area of a surface within the body on which internal forces act. These internal forces are a reaction to external forces applied on the body...
. It is named after the kowari
Kowari
The Kowari , also known as the Brush-tailed Marsupial Rat, Kayer Rat, Byrne's Crest-tailed Marsupial Rat, Bushy-tailed Marsupial Rat and Kawiri, is a small carnivorous marsupial native to the dry grasslands and deserts of central Australia...
, an Australian marsupial.
It provides a diagnostic non-destructive tool to optimize e.g. post-weld heat treatment (PWHT, similar to tempering
Tempering
Tempering is a heat treatment technique for metals, alloys and glass. In steels, tempering is done to "toughen" the metal by transforming brittle martensite or bainite into a combination of ferrite and cementite or sometimes Tempered martensite...
) of welded structures. Tensile stresses for example drive crack growth in engineering components and compressive stresses inhibit crack growth (for example cold-expanded holes subject to fatigue cycling). Life extension strategies have high economic impact and strain scanning provides the stresses needed to calculate remaining life as well as the means to monitor the condition of components since it is non-destructive. One of the main features is the sample table that will allow to examine large engineering components while orienting and positioning them very accurately.
Others
- TAIPAN - Thermal 3-Axis Spectrometer
- KOALA - Quasi Laue Diffractometer.
- QUOKKA - Small-Angle Neutron Scattering
- PELICAN - Time of Flight Polarisation Analysis Spectrometer
- SIKA - Cold Neutron 3-Axis Spectrometer
July 2007 shutdown
Following the discovery of loose fuel plates during a routine inspection, ANSTOAustralian Nuclear Science and Technology Organisation
The Australian Nuclear Science and Technology Organisation is a statutory body of the Australian government, formed in 1987 to replace the Australian Atomic Energy Commission. Its head office and main facilities are in southern outskirts of Sydney at Lucas Heights, in the Sutherland Shire...
announced on 27 July 2007 that the reactor would be shut down for 8 weeks to fix the fuel plates and a minor fault causing light water to seep into the reactor's heavy water
Heavy water
Heavy water is water highly enriched in the hydrogen isotope deuterium; e.g., heavy water used in CANDU reactors is 99.75% enriched by hydrogen atom-fraction...
.
In the end, the shutdown lasted 10 months. The supply of radiopharmaceuticals was rationed, causing the postponement of some treatments for patients.
OPAL returned to full operational power on 23 May 2008, following approval by the nuclear regulator, ARPANSA to use a modified fuel design.
See also
- High Flux Australian Reactor
- Research reactorResearch reactorResearch reactors are nuclear reactors that serve primarily as a neutron source. They are also called non-power reactors, in contrast to power reactors that are used for electricity production, heat generation, or maritime propulsion.-Purpose:...
s - Spallation Neutron SourceSpallation Neutron SourceThe Spallation Neutron Source is an accelerator-based neutron source facility that provides the most intense pulsed neutron beams in the world for scientific research and industrial development...
- Neutron scatteringNeutron scatteringNeutron scattering,the scattering of free neutrons by matter,is a physical processand an experimental technique using this processfor the investigation of materials.Neutron scattering as a physical process is of primordial importance...