DECON INTERVIEW nuclear waste management and interim storage
John Kettler: Let me ask you a question about foreign countries: Do these properties also have an impact outside the home market, or what differences can be seen in this respect worldwide?
Dr. Linus Bettermann: There are definitely differences worldwide. For example, we use different fuel elements in Germany than abroad. This is evident in the case of pressurized water: we have longer fuel assemblies - a good half meter longer than most fuel assemblies in an international comparison. In addition, the edge dimension is larger, i.e. many fuel assemblies have a larger diameter. At the same time, the fuel assemblies in Germany are hotter, which is why we have higher burnups than in most other countries in the world. Because of the small pools we have in Germany, the decay time is also lower.
We already know pretty well that we will deliver the last Castor casks around the turn of the year 2026/27. That's why we have built up an international expansion strategy in the cask sector in recent years.
Prof. Dr. Giuseppe Modolo: Extensive experience has been gained worldwide in the decommissioning and also dismantling of various nuclear facilities. The treatment and conditioning of low and intermediate level radioactive waste is now considered routine work, even on an industrial scale. However, there are also problematic waste materials that are produced especially during the dismantling of nuclear and research facilities. These have not been the focus of research in the past. The challenge, therefore, is to investigate the unknown properties in terms of radionuclides and chemotoxic inventory. The volumes are often small and the properties are unknown during treatment and interim storage. For many hazardous wastes, strategies, especially for characterization, treatment and disposal have not yet been defined.
Essentially, we are talking about depleted uranium, with estimates in Germany of 100,000 cubic meters of residual waste. In addition, there is other waste, such as C14 waste or waste containing tritium. So what happens to the waste - such as coal rock and graphite materials - from the dismantling of high-temperature reactors in Germany?
Dr. Jörn Becker: When it comes to interim storage, we basically distinguish between the concept of dry interim storage and wet storage. The "Clab" project from Sweden serves as an example of wet storage. There, a large wet storage facility with pools is used to store fuel elements before they are transported to their final repository. In the concept of dry interim storage, as it is pursued for example in Germany, a distinction is made between the so-called "dual purpose casks" - transport and storage container - and a vault or silo concept.
We have a time pressure with regard to our research program, as the first permits expire in 2034/36. On the other hand, we see the large time span that interim storage has to cover, which is limited at the back, depending on when the final repository will be available. At this point, we are in close exchange with BGE (Bundesgesellschaft für Endlagerung), as the availability of the final repository is the decisive milestone for us. However, we expect to have to consider interim storage periods of up to 100 years.
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