A new uranium oxide (U3O8) storage facility has been commissioned at the Gronau plant. This facility is part of the plant's expansion license, granted in 2005 by the nuclear licensing authority of North Rhine-Westphalia, which permits an annual capacity of up to 4.5 million separative work units (SWU). The state government mandated the construction of an additional storage hall capable of holding up to 59,000 tonnes of uranium oxide on the Gronau site.
The storage facility is a key component of the strategy for managing depleted uranium, also known as tails, which is generated during the 
uranium enrichment process. Depleted uranium from Gronau will be transported to Orano's Pierrelatte facility in France and Urenco's Tails Management Facility in Capenhurst in the UK for chemical conversion from uranium hexafluoride (UF6) into U3O8. U3O8 is considered suitable for long-term storage due to its insolubility in water, non-combustibility, chemical stability, and non-volatility at elevated temperatures. Following conversion, the U3O8 can be returned to Gronau for long-term storage.
The storage building was completed in 2014 under the existing license. Its formal commissioning ensures all legal and operational requirements for the safe storage of U3O8 on the site are met. Depleted uranium is currently classified as a potentially reusable material resource. A safety report from 2002 for the Gronau enrichment plant's final expansion stage noted that depleted uranium retains a significant proportion of its original uranium-235, indicating potential future uses, though no specific reuse pathway is currently planned.
Jörg Harren, managing director of Urenco Deutschland GmbH, stated that the commissioning of the U3O8 storage facility implements a long-planned component of their site strategy. He emphasized that storage is conducted in a form considered safe and stable according to current scientific and technological standards, while responsibly preserving depleted uranium for the future. The goal is to combine safety, sustainability, and long-term planning.
