Nuclear Waste Management and Reactor Safety
Radioactive waste from nuclear power plants consists up to 99 percent of different cleavage products of the nuclear fuel uranium. The activity of the products subsides only after a few hundred years. But one percent of the waste also consists of heavier elements with higher atomic numbers such as plutonium, americium, neptunium and curium. These transuranic or minor actinides are formed when uranium nuclei are split and their derivatives capture neutrons or are divided themselves. They have half-lives of several hundred thousand years and are extremely radiotoxic, so dangerous to humans and other living organisms. For this reason, the total waste volume over these long periods must be securely isolated from the biosphere.
In the field of reactor theory, reactor safety research focuses on fuel element behaviour under the specific conditions in German reactors after the phase-out decision. As German light water reactors have to adopt their power production in favour of electricity generation by renewables, the different irradiation history, neutron flux and power distribution as well as the nuclide inventory distributions need to be investigated by means of high-resolution coupled neutronic and mechanical simulations. In the field of severe accident research, IEK-6 contributes to the international research activities and projects with specific focus on hydrogen recombination, aerosol behaviour, wall condensation, and on containment thermal hydraulics as the major driving force for these phenomena.
Work at IEK-6 focuses on materials science aspects of the disposal of high-level radioactive waste and on the safety of existing nuclear reactors.
In Nuclear Waste Management research on the long-term safety of deep geological disposal and innovative waste management strategies focuses on the materials science aspects. Towards this goal researchers address fundamental questions of actinide solid-state chemistry and atomistic modeling approaches using supercomputers. Innovative waste management concepts include the separation of certain radionuclides, their conditioning in ceramic waste forms and their transmutation into short-lived or stable nuclides, and the treatment of nuclear graphite. Furthermore IEK-6 coordinates the German contribution to the joint program on the technical development and further improvement of IAEA safeguards, and thus helps to consolidate international verification schemes for the non-proliferation of weapons of mass destruction.
The section Reactor Safety Research makes an important contribution to the safe operation of nuclear facilities all over the world. It develops scientific methods to answer safety-related questions for reactors currently operated in Germany and abroad (generations II and III). The scientific programme includes the simulation of reactor systems, the analysis of containment phenomena in case of an accident as well as CFD modeling. The institute places great emphasis on closely coordinating experiments with simulation. An experimental hall with set-ups for studying aerosol behavior, wall condensation and high-temperature fluid dynamics, all of which are relevant in case of an accident, and a hydrogen laboratory for hydrogen safety experiments are available to enable and underpin model development.