While research reactors are not used to generate electricity, some are contributing to the development of innovative nuclear energy solutions, such as research into nuclear fission and fusion materials. Two recent IAEA missions highlighted the role and potential of research reactors, which provide a source of neutrons for a variety of scientific purposes including neutron imaging and irradiation. International teams of experts completed two IAEA Integrated Research Reactor Utilization Review (IRRUR) missions at research reactors in the United States of America last month. The IRRUR teams visited Idaho National Laboratory (INL) from 5 to 9 June and the Nuclear Reactor Laboratory at the Massachusetts Institute of Technology (MIT) from 12 to 16 June. The missions were aimed at enhancing the utilization and sustainability of the research reactor facilities in both sites.
The INL research reactor is mainly utilized for research on neutron radiography and other non-destructive techniques, and for neutron irradiations, which explore how nuclear fuel and structural materials react to normal and extreme conditions. The MIT reactor carries out irradiations, which complement the work of INL and other US nuclear research facilities and supports research in both nuclear fission and fusion materials development.
"Since research reactors are able to reproduce realistic conditions and study changes undergone by materials in power reactors, they provide essential support to optimize advanced reactors and to test fuels and materials for innovative reactors," said Nuno Pessoa Barradas, an IAEA research reactor specialist.
I believe that MIT's Nuclear Reactor Laboratory has the potential to become a world-leading facility for the custom irradiation of nuclear fuels and materials."
Research reactor utilization
At INL, the IRRUR mission examined the utilization of the 250 kW TRIGA MARK II research reactor, NRAD. "The NRAD has unique experimental capabilities," Barradas, who led the mission, said. "It can routinely analyse highly radioactive samples, enabling staff to conduct research on irradiated nuclear fuels and nuclear materials, to aid the development of innovative nuclear energy solutions."
The IRRUR team examined how the INL could better utilize the research reactor in characterization of nuclear fuel and reactor materials using non-destructive techniques. "While there are many examples of state-of-the-art neutron radiography methods at the NRAD already in place, the mission team found some capabilities in digital neutron imaging were lagging," Barradas said. Neutron imaging is a non-destructive technique for analysing the structure of a sample. "In the last years, NRAD staff have started to address this issue and have already implemented digital neutron imaging," he added.
INL research scientist Aaron Craft said, "We are revising our strategic plans to incorporate the feedback provided by the IRRUR mission and are actively pursuing expanded utilization of NRAD to better support INL's mission to discover, demonstrate and secure innovative nuclear energy solutions."
At the MIT laboratory, a 6 MW research reactor is used for materials irradiation and testing, research and development. The IRRUR team recommended that the laboratory integrate more fully within MIT. (Photo: MIT)
At the MIT laboratory, a 6 MW research reactor is used for materials irradiation and testing, research and development, as well as education and training. MIT's nuclear research reactor (MITR) is the second largest university-based research reactor in the USA (after the University of Missouri Research Reactor) and has been in operation since 1958.
"The MITR is the only university research reactor in the USA carrying out irradiations that are complementary to research at Oak Ridge National Laboratory and INL," said Danas Ridikas, Head of the Physics Section at the IAEA, who participated in the mission. "Its partnership with the MIT Plasma Science and Fusion Center also has the potential to enable research into fusion materials and relevant technology components development and engineering scale testing, filling an important research gap in the USA."
While the MITR is well known among its present users and stakeholders, a more strategic approach is needed to help strengthen the impact of its scientific research, the IRRUR team concluded. The team recommended that the laboratory integrate more fully within MIT. "MIT faculty and students should be encouraged to carry out research at the facility, and there is an opportunity for the lab to engage more productively with the global nuclear science and technology community," Ridikas said. For example, the MITR could be utilized for research into radioisotopes, which can be produced in research reactors by exposing target materials to neutrons.
The team also found it was important for the MIT lab to revitalize its ageing infrastructure, not only to improve the safe and reliable reactor utilization but also to provide a more attractive environment for outside users, students and staff.
"I believe that MIT's Nuclear Reactor Laboratory has the potential to become a world-leading facility for the custom irradiation of nuclear fuels and materials," said Ron Crone, Associate Laboratory Director of Materials and Fuels Complex at INL and a member of the IRRUR team. "With additional infrastructure investment and more external engagement, I believe it will support important research into innovative energy solutions involving nuclear fission, as well as nuclear fusion, for the coming decades."
About the IRRUR and IAEA review services
Four experts from Switzerland, USA and the IAEA took part in the IRRUR mission in Idaho, while eight experts from Canada, Czech Republic, Netherlands, USA and the IAEA joined the mission to MIT.
The IRRUR service assists countries in enhancing the utilization and sustainability of nuclear research reactor facilities. Unlike the reactors in a nuclear power plant, which use the energy released when neutrons split atoms of uranium to generate electrical power, research reactors use the neutrons themselves for research, development, as well as for education and training purposes.
In addition to IRRUR, the IAEA offers other peer review services related to research reactors, including the Operational and Maintenance Assessment for Research Reactors, Integrated Safety Assessment of Research Reactors and Integrated Nuclear Infrastructure Review for Research Reactors.
The IAEA also provides guidelines for reviewing the safety and assessing the operation and maintenance of research reactors. The IRRUR guidelines not only provide information on the preparation, implementation and reporting of IRRUR missions but could also support self-assessments by operating organizations of research reactor facilities. In 2020, the IAEA launched an e-learning course on strategic planning for enhancing the utilization of research reactors.
