Research reactors are nuclear reactors that serve as a neutron source. They are called non-power reactors, in contrast to power reactors that are used for electricity production, heat generation, or maritime propulsion; the neutrons produced by a research reactor are used for neutron scattering, non-destructive testing and testing of materials, production of radioisotopes and public outreach and education. Research reactors that produce radioisotopes for medical or industrial use are sometimes called isotope reactors. Reactors that are optimised for beamline experiments nowadays compete with spallation sources. Research reactors operate at lower temperatures, they need far less fuel, far less fission products build up as the fuel is used. On the other hand, their fuel requires more enriched uranium up to 20% U-235, although some use 93% U-235, they have a high power density in the core, which requires special design features. Like power reactors, the core needs cooling natural or forced convection with water, a moderator is required to slow the neutron velocities and enhance fission.
As neutron production is their main function, most research reactors benefit from reflectors to reduce neutron loss from the core. The International Atomic Energy Agency and the U. S. Department of Energy initiated a program in 1978 to develop the means to convert research reactors from using enriched uranium to the use of low enriched uranium, in support of its nonproliferation policy. By that time the U. S. had supplied research reactors and enriched uranium to 41 countries as part of its Atoms for Peace program. In 2004, the U. S. Department of Energy extended its Foreign Research Reactor Spent Nuclear Fuel Acceptance program until 2019. In 2004, the Texas A&M reactor switched to LEU after decades using HEU; these changes are a part of an anti-terrorism initiative since 9/11 begun by the Bush Administration. While in the 1950s, 1960s and 1970s there were a number of companies that specialized in the design and construction of research reactors, the activity of this market cooled down afterwards, many companies withdrew.
The market has consolidated today into a few companies that concentrate the key projects on a worldwide basis. The most recent international tender for a research reactor was that organized by ANSTO for the design and commissioning of the OPAL reactor. Four companies were prequalified: AECL, INVAP, Siemens and Technicatom; the project was awarded to INVAP. In recent years, AECL withdrew from this market, Siemens and Technicatom activities were merged into AREVA. Aqueous homogeneous reactor Argonaut class reactor DIDO class, six high-flux reactors worldwide TRIGA, a successful class with >50 installations worldwide SLOWPOKE reactor class, developed by AECL, Canada Miniature neutron source reactor, based on the SLOWPOKE design, developed by AECL exported by China Complete list can be found at the List of nuclear research reactors. Research centers that operate a reactor: Decommissioned research reactors: WNA Information Paper # 61: Research Reactors Nuclear Nonproliferation: DOE Needs to Take Action to Further Reduce the Use of Weapons-Usable Uranium in Civilian Research Reactors, GAO, July 2004, GAO-04-807 IAEA searchable list of Nuclear Research Reactors in the world The National Organization of Test and Training Reactors, Inc.
Corymbia opaca known as the desert bloodwood, is a species of tree, endemic to northern Australia. It has rough bark on part or all of the trunk, lance-shaped leaves, club-shaped flower buds and urn-shaped fruit. Several part of this plant are used by Australian Aboriginal in traditional medicine. Corymbia opaca is a tree a mallee, that grows to a height of 3–15 m and forms a lignotuber, it has rough, reddish brown bark over some or all of its trunk. Young plants and coppice regrowth have petiolate, egg-shaped to lance-shaped leaves, 40–90 mm long and 11–28 mm wide, with a small point on the tip. Adult leaves are arranged alternately, the same shade of green or greyish green on both sides, lance-shaped, 110–190 mm long and 14–32 mm wide with a petiole 13–25 mm long; the flower buds are arranged in groups of seven on an unbranched, cylindrical peduncle 8–15 mm long, the individual buds on pedicels 3–7 mm long. Mature buds are club-shaped, with an oval floral cup about 7 mm long and 7–8 mm wide and a saucer-shaped operculum that has a central point and is about 2 mm long and 6–7 mm wide.
The flowers are creamy white and the fruit is an urn-shaped capsule 16–24 mm long and 12–16 mm wide. The desert bloodwood was first formally described in 1985 by Denis John Carr and Stella Grace Maisie Carr who gave it the name Eucalyptus opaca and published the description in their book Eucalyptus 1 - New or little-known species of the Corymbosae; the type specimens were collected in 1983 from the Lasseter Highway near Kata Tjuta. In 1995, Ken Hill and Lawrie Johnson changed the name to Corymbia opaca, publishing the change in the journal Telopea; the specific epithet is derived from the Latin word opacus meaning "darkened, not shining or opaque". Some authors and herbaria accept C. opaca as a distinct species and others consider it to be inseparable from C. terminalis and C. tumescens. To the extent that the species can be reliably differentiated, C. terminalis has thinner leaves, larger buds and fruit and thicker pedicels than C. opaca. Corymbia opaca occurs in scattered population in desert areas of the southwest Kimberley and northern desert regions of Western Australia, in central and southern parts of the Northern Territory and in the Mann and Musgrave Ranges in the far northwest of South Australia.
It grows in sandy soils in alluvial areas and on lower hillslopes. This eucalypt is classified as "not threatened" by the Western Australian Government Department of Parks and Wildlife and as "least concern" in South Australia. A bloodwood tree will shed a piece of bark, hence opening a "wound" through which a blood-like kino will flow; the sap flows. Australian Aboriginals collect this substance as bush medicine, they apply the sticky gum directly to sores or cuts and it works as an antiseptic. If the sap is in a dried form, it can be crushed into powder and boiled in water to use as an antiseptic wash. Another use of the bloodwood sap by Aboriginal people is to tan "kangaroo-skin waterbags". People collect bush coconuts from the tree; the roots of the bloodwood tree store water. Aboriginal peoples would dig up the roots and drain the water into a container
According to Akilattirattu Ammanai, for ten months, Ayya Vaikundar revealed to the people all about the past and future in the form of songs. He sang definitively about the future; some of those who heard him, took his words as meaningless mutterings. Vaikundar, realising that forbearance and fortitude were the essential virtues needed in his project of transforming the world, becalmed himself and performed the Tavam. Having justice in his breath, the thought of mercy in his mind, renouncing the desires of the body and containing the tendencies of his ego, Vaikundar performed the Tavam concentrating on the commands he had received from his father, his appearance was squalid, with holy ashes smeared on him, the long unkempt hair flowing in the air. This tavam was so effective that it surpassed the Tavam undertaken by Isvaran previously, he undertook to perform a six-year tavam, divided into three phases, for three different causes. First phase for the dawn of Dharma Yukam Second phase the abolition of caste discrimination Third phase for the well being of his predecessors and for the Seven VirginsWithin these six years, a great multitude of people - old and young and women- came to him from all directions.
They all gathered there as one humanity, as children of a single parentage without any discrimination on the basis of might or caste. Vaikundar cured the sick, blessed those without progeny to have with offspring, made the dumb speak, the blind see, rooted out the curses, engulfing the people. Whoever came and experienced him exclaimed. Seeing the multitude of people coming together as children of one family, drinking from the same well and dining in one place, the learned persons surmised that what had been said in the Akamankal - was coming true. Ayyavazhi mythology List of Ayyavazhi-related articles Ayya Vaikundar Swamithope pathi G. Patrick's Religion and Subaltern Agency, University of Madras