Uranium storage facility for 65,000 tons of nuclear by-product enters service

A uranium storage hall completed in 2014 has now officially entered service at Urenco’s enrichment site in Gronau, Germany.

Designed to hold up to 65,000 tons (59,000 metric tons) of uranium oxide, the facility provides long-term storage for depleted uranium produced during enrichment.

Urenco commissioned the building after fulfilling the legal and operational requirements for storing the material on site.

Its operation forms part of a management strategy under which depleted uranium from Gronau undergoes chemical conversion at facilities in France and the UK before returning for storage.

From enrichment by-product to stable oxide

Uranium enrichment increases the concentration of uranium-235, the fissile isotope used to generate energy in nuclear reactors. The process also produces depleted uranium, a by-product commonly called tails, which remains in uranium hexafluoride, or UF6, form.

Urenco’s strategy involves transporting material from Gronau to Orano’s Pierrelatte facility in France and its own Tails Management Facility at Capenhurst in the UK. Both sites chemically convert UF6 into uranium oxide, known as U3O8.

This oxide is well-suited for long-term storage because it does not dissolve in water, is non-combustible, and remains chemically stable. It is also non-volatile even at elevated temperatures.

With the Gronau storage hall formally commissioned, material originating at the site and converted at those facilities can return for long-term storage.

Storage hall completes a longstanding plan

The facility falls under an expansion license granted in 2005 by the nuclear licensing authority of North Rhine-Westphalia. That license permits the Gronau enrichment plant to operate at an annual capacity of up to 4.5 million separative work units.

Separative work units, or SWU, measure the work involved in separating uranium-235 from uranium-238. As part of the expansion, the state government required Urenco to construct an additional storage hall with capacity for up to 65,000 tons of uranium oxide.

Construction finished in 2014 under the existing license. Formal commissioning marks the fulfillment of all legal and operational requirements for safe U3O8 storage at the site.

“With the commissioning of the U3O8 storage facility, we are implementing a component of our site strategy that has been planned for many years,” said Jörg Harren, managing director of Urenco Deutschland GmbH.

“Storage is carried out in a form that is regarded as particularly safe and stable according to the current state of science and technology,” he added.

Future reuse remains an option

Under current legislation, depleted uranium is classified as a potentially reusable material resource.

A 2002 safety report for the Gronau plant’s final expansion stage noted that the material retains a significant proportion of the uranium-235 originally present.

Urenco has no specific reuse pathway planned, although it said potential utilization options remain possible in principle.

“Although no specific future use is currently planned, potential utilization options remain available in principle. Our goal is to combine safety, sustainability and long-term thinking,” Harren said.

The Capenhurst facility, which supports this strategy, officially opened in June 2019 and is operated by Urenco subsidiary Urenco ChemPlants.