Kontakt
Maud Emilie Zilbermann
Doktorandin - Radiochemische Analysen von Materialien aus einem deutschen KKW für den Rückbau.
Grenzflächenprozesse
m.zilbermann
hzdr.de
Ph.D. projects
Radiochemical analyses on concrete and metal samples from a German Nuclear Power Plant to facilitate decommissioning
Germany’s decision to phase out nuclear energy and decommission its nuclear power plants (NPPs) presents several challenges and opportunities in terms of safety, environmental protection, and cost management. It becomes necessary to develop efficient and cost-effective decommissioning strategies and practices. Dismantling NPPs creates large amounts of waste of various kinds, including millions of tons of structural materials. Only a very small portion of the waste created is radioactive, and as the storage space for radioactive material is limited, it is crucial to sort the waste before disposal. A thorough understanding of the radioactivity levels of the NPP waste is also necessary to ensure the safety of the workers during the decommissioning.
The operation of a reactor creates neutrons that travel through, are slowed down, and activate trace elements in the structural materials, such as Europium and Cobalt, into their radioactive isotopes 60Co, 152Eu and 154Eu. The areas of concrete and steel closest to the reactor are the most highly activated. To accurately map the radioactivity in the entire structure, expensive and time-intensive experimental measurement campaigns are undertaken. However, to make this process faster, a numerical code can be developed using the Monte-Carlo N-Particle method to calculate neutron fluences including geometric data on the reactor and its surroundings. This information helps to estimate where the neutrons travel and which materials they activate. This code must be validated with experimental measurements at the locations of highest anticipated activity levels.
This Ph.D. project aims to provide a comprehensive inventory of the radioisotopes and their activities in various parts of the structures surrounding the reactor of a German NPP. The goal is to classify the waste and assist in refining a calculation model. Concrete and steel samples will be collected from multiple locations, and their chemical composition and activity will be determined experimentally. To achieve an accurate inventory, various radioanalytical methods will be developed and optimized, especially to precisely evaluate the activity of difficult-to-measure radionuclides (3H, 14C, 55Fe, 63Ni). The experimentally obtained activities will be compared with the calculated activities. If they align well, it would drastically reduce the amount of sampling and experimental activity measurements required for dismantling, meaning an enormous reduction in time and costs. Additionally, leaching tests will be carried out in various conditions to gain more insight into the behavior of the materials during the process of dismantling. The Ph.D. research is part of the project EBENE – Experimentally supported calculations of neutron fields and the resulting activities in spaces far from the reactor – funded by the German Federal Ministry of Education and Research (BMBF, contract number 15S9447A) and is in close cooperation with the Technische Universität Dresden, Institute of Nuclear and Particle Physics, as well as PreussenElektra GmbH.
