A. Zrodnikov

Research reactors in the United States and Russia serve a variety of in­dustrial and biomedical missions and enable research in fields such as phys­ics and nuclear engineering. Missions mentioned during the course of the symposium that seem likely to continue include silicon doping, radioisotope production, notably including molybdenum-99, and neutron therapy. It is essential to maintain the capability to meet these research and industrial needs. Other means (e. g., particle accelerators) may be developed in the future for generating some radioisotopes and producing neutron beams, but research reactors will be far more difficult to replace for some other applications. In particular, future research related to nuclear energy and the nuclear fuel cycle will necessitate maintaining and improving current research reactor capabilities in the United States and Russia as well as in other countries. Research reactors are especially needed to conduct basic research for nuclear power development.

Nuclear power generation faces major challenges in the coming de­cades. Increasing quantities of commercial spent nuclear fuel are being ac­cumulated around the world, and in the long-term, supplies of uranium-235 will begin to decrease. Fast neutron reactors (“fast reactors”) are being studied in the United States and in Russia for their potential to help meet these challenges. Such reactors have the potential to “burn” long-lived actinides in spent fuel and also to produce and operate using plutonium, thereby extending current fuel supplies. However, more research remains to be done on these topics to effectively design the needed facilities and processes.

Beyond the design and testing of future fast reactors, further research could also help to extend the capability of nuclear power plants to meet new tasks. For example, research on heat — and radiation-resistant materials could lead to the deployment of high-temperature nuclear plants to meet the needs of heat-intensive industrial processes, including water desalination, production of synthetic fuels, and hydrogen production. If fossil resources that currently fuel these processes are exhausted, nuclear power will be needed to fill the gap.

Several research problems related to these topics will need to be investi­gated in the coming decades, including improving the scientific understand­ing of: [77] [78]

3. Changes in macroscopic material properties caused by neutron and charged particle irradiation.

Research reactors will also be used in theoretical, computational, and experimental studies on thermo-physical, physical-chemical, corrosion, and physical-mechanical properties of advanced high-temperature coolants, fuel materials, and core structural materials. Moreover, data generated from such studies will help researchers to develop complete nuclear data libraries. This knowledge can be used to develop new nuclear technologies.

Much of the research work involving fast reactors may require capabili­ties that only a few current research reactors possess. A research reactor with a stationary steady-state fast neutron flux of about 1016 neutrons/ cm2-s will be required to support this research.

In the subsequent discussion, Thomas Newton (Massachusetts Institute of Technology [MIT]) agreed that this need for fast neutrons was also true at MIT, and observed that, after conversion, MIT plans to take advantage of the harder neutron spectrum that can be acquired with low enriched uranium (LEU) for fast neutron experiments.