Neutron activation analysis (NAA) is a nuclear process used for determining the concentrations of elements in many materials. NAA allows discrete sampling of elements as it disregards the chemical form of a sample, and focuses solely on atomic nuclei. The method is based on neutron activation and thus requires a neutron source. The sample is bombarded with neutrons, causing its constituent elements to form radioactive isotopes. The radioactive emissions and radioactive decay paths for each element have long been studied and determined. Using this information, it is possible to study spectra of the emissions of the radioactive sample, and determine the concentrations of the various elements within it. A particular advantage of this technique is that it does not destroy the sample, and thus has been used for the analysis of works of art and historical artifacts. NAA can also be used to determine the activity of a radioactive sample.
NRX was a heavy-water-moderated, light-water-cooled, nuclear research reactor at the Canadian Chalk River Laboratories, which came into operation in 1947 at a design power rating of 10 MW (thermal), increasing to 42 MW by 1954. At the time of its construction, it was Canada's most expensive science facility and the world's most powerful nuclear research reactor. NRX was remarkable both in terms of its heat output and the number of free neutrons it generated. When a nuclear reactor such as NRX is operating, its nuclear chain reaction generates many free neutrons. In the late 1940s, NRX was the most intense neutron source in the world.
Control rods are used in nuclear reactors to control the rate of fission of the nuclear fuel – uranium or plutonium. Their compositions include chemical elements such as boron, cadmium, silver, hafnium, or indium, that are capable of absorbing many neutrons without themselves decaying. These elements have different neutron capture cross sections for neutrons of various energies. Boiling water reactors (BWR), pressurized water reactors (PWR), and heavy-water reactors (HWR) operate with thermal neutrons, while breeder reactors operate with fast neutrons. Each reactor design can use different control rod materials based on the energy spectrum of its neutrons. Control rods have been used in nuclear aircraft engines like Project Pluto as a method of control.
TRIGA is a class of nuclear research reactor designed and manufactured by General Atomics. The design team for TRIGA, which included Edward Teller, was led by the physicist Freeman Dyson.
Nuclear fuel is material used in nuclear power stations to produce heat to power turbines. Heat is created when nuclear fuel undergoes nuclear fission.
Research reactors are nuclear fission-based 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.
The National Research Universal (NRU) reactor was a 135 MW nuclear research reactor built in the Chalk River Laboratories, Ontario, one of Canada’s national science facilities. It was a multipurpose science facility that served three main roles. It generated radionuclides used to treat or diagnose over 20 million people in 80 countries every year. It was the neutron source for the NRC Canadian Neutron Beam Centre: a materials research centre that grew from the Nobel Prize-winning work of Bertram Brockhouse. It was the test bed for Atomic Energy of Canada Limited to develop fuels and materials for the CANDU reactor. At the time of its retirement on March 31, 2018, it was the world's oldest operating nuclear reactor.
The SLOWPOKE is a family of low-energy, tank-in-pool type nuclear research reactors designed by Atomic Energy of Canada Limited (AECL) beginning in the late 1960s. John W. Hilborn is the scientist most closely associated with their design. They are beryllium-reflected with a very low critical mass, but provide neutron fluxes higher than available from a small particle accelerator or other radioactive sources.
A swimming pool reactor, also called an open pool reactor, is a type of nuclear reactor that has a core immersed in an open pool usually of water.
The High Flux Isotope Reactor (HFIR) is a nuclear research reactor at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee, United States. Operating at 85 MW, HFIR is one of the highest flux reactor-based sources of neutrons for condensed matter physics research in the United States, and it has one of the highest steady-state neutron fluxes of any research reactor in the world. The thermal and cold neutrons produced by HFIR are used to study physics, chemistry, materials science, engineering, and biology. The intense neutron flux, constant power density, and constant-length fuel cycles are used by more than 500 researchers each year for neutron scattering research into the fundamental properties of condensed matter. HFIR has about 600 users each year for both scattering and in-core research.
Nuclear reactor physics is the field of physics that studies and deals with the applied study and engineering applications of chain reaction to induce a controlled rate of fission in a nuclear reactor for the production of energy. Most nuclear reactors use a chain reaction to induce a controlled rate of nuclear fission in fissile material, releasing both energy and free neutrons. A reactor consists of an assembly of nuclear fuel, usually surrounded by a neutron moderator such as regular water, heavy water, graphite, or zirconium hydride, and fitted with mechanisms such as control rods which control the rate of the reaction.
In applications such as nuclear reactors, a neutron poison is a substance with a large neutron absorption cross-section. In such applications, absorbing neutrons is normally an undesirable effect. However, neutron-absorbing materials, also called poisons, are intentionally inserted into some types of reactors in order to lower the high reactivity of their initial fresh fuel load. Some of these poisons deplete as they absorb neutrons during reactor operation, while others remain relatively constant.
The Pennsylvania State University (PSU) Radiation Science & Engineering Center (RSEC) houses the Breazeale Nuclear Reactor (BNR). This reactor is the oldest operating in the nation and has undergone numerous power upgrades, renovations, and other changes. The reactor serves the research purposes of the Penn State Department of Mechanical and Nuclear Engineering as well as researchers from industry and other universities. Its total licensed thermal output is 1.1 MW, however the reactor is procedurally limited to 1.0 MW (for 100% operation).
The Oregon State University Radiation Center (OSURC) is a research facility that houses a nuclear reactor at Oregon State University (OSU) in Corvallis, Oregon, United States. The Oregon State TRIGA Reactor (OSTR) serves the research needs of the OSU nuclear engineering department along with other departments.
The Maria reactor is Poland's second nuclear research reactor and is the only one still in use. It is located at Narodowe Centrum Badań Jądrowych (NCBJ) at Świerk-Otwock, near Warsaw and named in honor of Maria Skłodowska-Curie. It is the only reactor of Polish design.
The MIT Nuclear Research Reactor (MITR) serves the research purposes of the Massachusetts Institute of Technology. It is a tank-type 6 megawatt reactor that is moderated and cooled by light water and uses heavy water as a reflector. It is the second largest university-based research reactor in the U.S. and has been in operation since 1958. It is the fourth-oldest operating reactor in the country.
Iran's nuclear program is made up of a number of nuclear facilities, including nuclear reactors and various nuclear fuel cycle facilities.
A nuclear reactor coolant is a coolant in a nuclear reactor used to remove heat from the nuclear reactor core and transfer it to electrical generators and the environment. Frequently, a chain of two coolant loops are used because the primary coolant loop takes on short-term radioactivity from the reactor.
The Pakistan Atomic Research Reactor or (PARR) are two nuclear research reactors and two other experimental neutron sources located in the PINSTECH Laboratory, Nilore, Islamabad, Pakistan.
FiR 1 was Finland's first nuclear reactor. It was a research reactor that was located in the Otaniemi campus area in the city of Espoo. The TRIGA Mark II reactor had a thermal power of 250 kilowatts. It started operation in 1962, and it was permanently shut down in 2015. At first, the reactor was operated by Helsinki University of Technology (TKK), and since 1971 by VTT Technical Research Centre of Finland.
