Research reactors are nuclear reactors that are not used for the generation of electricity. Instead they provide uses for research and training, material testing, and production of isotopes for medical and industrial uses. For more than 60 years, research reactors have been providing a source of neutrons for a wide variety of scientific purposes, and there are around 240 research reactors operating in 56 countries worldwide.
They are small in relation to the reactors that provide electricity to the grid, with their power output ranging from 0 to 200 MWt (thermal rating rather than electrical output rating, since they do not produce electricity!). In fact, the total power of all of the research reactors worldwide is just under a 3000 MWt, comparable to a single power reactor. They are also simpler and operate at lower temperatures. They require far less uranium fuel than power generating reactors, however the uranium enrichment must be higher, typically up to 20% concentration of 235U.
There is a much wider array of designs for research reactors compared to power reactors. The number beside each shows how many there are operating worldwide.
- Pool type (67)- The core of these reactors is a cluster of fuel elements sitting in a large pool of water. There are submerged control rods, along with empty channels to perform tests. The water moderates and cools the reactor, and there are apertures in the walls to access the neutron beams. An example of such a reactor is the SLOWPOKE-2, designed and built in Canada, with 4 still in use around the country. Tank type (32) are similar but use a more active cooling system.
- TRIGA (40)- This reactor is very versatile. It uses graphite or beryllium as neutron reflectors in order to minimize neutron loss, and zirconium hydride as a moderator. It can operate in either steady state or be pulsed to very high power levels (25 000 MW) for a brief time. The rapid increase in power is cut short by a highly negative reactivity from the moderator.
- Other designs- Some other types are moderated and cooled by heavy water (12) or graphite. Less common are fast reactors, which use a combination of uranium and plutonium as fuel. Homogeneous reactors (5) have a core with a uranium salt liquid solution.
There are many uses for research reactors. Their production of neutrons are very useful because neutron beams are suited to studying materials at the atomic level. Neutrons are also used for radioisotope production for medical industries, irradiation for material testing for fission and fusion reactors, neutron transmutation doping (NTD) of silicon, and more.
Their use for training of all areas in the nuclear industry are extremely important, as operators, maintenance staff, radiation protection personnel, teachers and students can make use of their facilities.
For Further Reading
- Personal photo submitted by a member of the Energy Education team.
- World Nuclear Association. (June 18 2015). Research Reactors [Online], Available: http://www.world-nuclear.org/info/Non-Power-Nuclear-Applications/Radioisotopes/Research-Reactors/
- IAEA. (June 18 2015). Research Reactors: Purpose and Future [Online], Available: https://www.iaea.org/OurWork/ST/NE/NEFW/Technical-Areas/RRS/documents/RR_Purpose_and_Future_BODY.pdf