Research and Test Reactors Activities
A research reactor’s key output is the radiation it produces, not the very minor amount of heat energy produced. The most common use of this radiation (primarily neutrons and gamma rays) is for experiments. Some experiments require more of one type radiation than the other. The amount and types of radiation may be controlled by placing different types of “filters” between the reactor and the experiment, or positioning the experiment at different locations relative to the radioactive fuel in the core.
Experimenters use different types of facilities to expose the material to the required types of radiation. Experimental facilities include in-core radiation “baskets,” pneumatic (air-operated) tubes (similar to systems used at drive-through banks), and beam tubes (holes in the shielding around the reactor which can direct a beam of radiation to the experiment). Researchers use radiation to study material characteristics that cannot be readily measured otherwise.
One widely used type of experiment is neutron scattering. Radiation from the reactor is directed at the material to be studied. The manner in which the radiation interacts and bounces off, or scatters, from the material yields information on structure and properties. Neutron scattering is an important tool in experiments dealing with superconductors, polymers, metals, and proteins. Researchers can analyze molecular structure, surfaces and interfaces, measure electronic and magnetic properties, stress and strain conditions, and gauge other characteristics.
Neutron radiography is another experimental technique. It is similar to medical or dental X-rays. These experiments are used to determine structural integrity for aerospace, automotive and medical components.
Neutron activation analysis is another powerful tool used in the detection of very small (trace) amounts of material. It is used to measure the presence of trace elements such as environmental pollutants in soil, water, air, and foods with an accuracy of several parts per billion. Neutron activation may also be used to create new radioactive isotopes such as radio-pharmaceuticals (radioactive material used in medicine) and to process silicon prior to use in computer chips.
Research and test reactors also are involved in medical research using neutrons for the treatment of cancerous tumors or making radioisotopes for research and therapy. In addition, research and test reactors irradiate materials used in nuclear power plants to assess how the materials change after exposure to radiation. These changes are important in assessing safety functions and in considering license extension for nuclear power plants.
Research and Test Reactors Design and Safety Features
Research and test reactors may be classified by their moderator, the material used to slow down the neutrons which cause the nuclear reaction. Typical moderators include water (H2O), heavy water (D2O), polyethylene, and graphite.
The NRC has primarily licensed water-moderated reactors, which can be further classified as either pool-type or tank-type. Pool-type reactors have a core immersed in an open pool of water. The pools typically have about 20 feet of water above the core to provide cooling and radiation shielding. At pool-type reactors, the operating core can be observed through the pool water. Tank-type reactors have a core that is in a tank with water, sealed at the top.
Reactors may also be classified by the type of fuel used, such as MTR (plate-type fuel) or TRIGA fuel. TRIGA fuel is unique fuel in that a moderator (hydrogen) is chemically bonded to the fuel.
All NRC-licensed research and test reactors have a built-in safety feature, which reduces reactor power during potential accidents before an unacceptable power level or temperature could be reached.
Research and test reactors are typically licensed by NRC according to the total thermal (heat) energy produced by the reactor. These facilities range in size from 0.10 watt to 20 megawatts-thermal. In contrast, a typical commercial nuclear power reactor is rated at 3,000 megawatts-thermal. Because of this large difference in power generated, the consequence of an accident at a research and test reactor is limited when compared to a commercial power reactor. For this reason, research reactors’ emergency planning zones to protect the public from potential radiological accidents are well within owner-controlled areas -- often the boundary of the room in which the reactor is housed.
All research and test reactors have radiation monitors with larger facilities having monitors which measure particulate and gaseous releases to the environment.
Unlike power plants, research and test reactor control rooms are usually in the confinement or containment area where the reactor is located. Facility staff and personnel work in the reactor room or building during operation. Most research and test reactors are in rooms or buildings that have a dedicated ventilation system and all have systems that control the release of radiation.
These reactors have fail-safe shutdown systems that monitor facility conditions, and before an unsafe condition occurs, control rods can be used to rapidly reduce the reactor power level. There are also redundant systems to shut down a reactor to provide added protection of the public.
Because of the low power levels at which research and test reactors operate, they require no or minimal cooling for short periods after shutdown. In addition, many of these reactors operate on a very limited schedule and have a limited amount of radioactive material on hand at any given time.
To be licensed, research and test reactor operators must have the required knowledge, skills and abilities to control the reactor during both routine operations and emergencies. As part of the initial operator licensing process, NRC prepares and administers both a comprehensive written examination and a hands-on operating test. These examinations are based on requirements in the Commission's regulations (10 CFR Part 55). The NRC issues six-year licenses to operators who successfully complete the examination process. An operator’s license is limited to a reactor at a specific location and is not portable; to operate a research reactor at another location, the individual must train on that reactor and pass another licensing examination.
Licensed operators must maintain their expertise through a requalification program that covers both refresher training on material covered during initial licensing and training on new or modified systems, procedures and programs. Operators must pass a comprehensive written test every two years and an annual operating test, both of which are developed and administered by reactor management. The NRC reviews these examinations as part of the inspection program and determines if the operator meets the requalification program requirements. Every six years operators are required to submit an application to renew their license. As part of the application, reactor management must certify satisfactory participation in the requalification program.
Operating Research and Test Reactors
Aerotest Operations Inc., San Ramon, CAArmed Forces Radiobiological Research Institute, Bethesda, MDDow Chemical Company, Midland, MIGeneral Electric Company, Sunol, CAIdaho State University, Pocatello, IDKansas State University, Manhattan, KS Massachusetts Institute of Technology, Cambridge, MANational Institute of Standards and Technology, Gaithersburg, MDNorth Carolina State University, Raleigh, NCOhio State University, Columbus, OHOregon State University, Corvallis, ORPenn State University, University Park, PAPurdue University, West Lafayette, INReed College, Portland, ORRensselaer Polytechnic Institute, Schenectady, NYRhode Island Atomic Energy Commission, Narrangansett, RITexas A&M University, College Station, TX (two reactors)University of Arizona, Tucson, AZUniversity of California-Davis, Sacramento, CAUniversity of California, Irvine, CAUniversity of Florida, Gainesville, FLUniversity of Maryland, College Park, MDUniversity of Massachusetts, Lowell, MAUniversity of Missouri, Columbia, MOUniversity of Missouri, Rolla, MOUniversity of New Mexico, Albuquerque, NMUniversity of Texas, Austin, TXUniversity of Utah, Salt Lake City, UTUniversity of Wisconsin, Madison, WIU.S. Geological Survey, Denver, COWashington State University, Pullman, WA