U.S. Department of Energy Provides Notice to Proceed to AtkinsRéalis Joint Venture for Operation and Maintenance of Nuclear Assets

Oak Ridge, TN: June 5, 2025 – AtkinsRéalis Group Inc. (TSX: ATRL), a world-class engineering services and nuclear company with offices around the world, announces today that the U.S. Department of Energy (DOE) has provided the joint venture of AtkinsRéalis, Westinghouse Government Services LLC and Amentum, – Mission Conversion Services Alliance, LLC (MCSA MSCAlliance.com) – the notice to proceed on the Operations & Site Mission Support Contract (OSMS) at the DOE’s Portsmouth and Paducah Gaseous Diffusion Plants. Swift & Staley Inc. and Akima Centerra Integrated Services, LLC are also business Teaming Partners.

“AtkinsRéalis unique end-to-end capabilities in nuclear engineering, design, project management, operations and disposition within this highly regulated industry enable our team to provide unrivalled services for our most trusted clients,” said Joe St Julian, President, Nuclear, AtkinsRéalis.

An AtkinsRéalis led joint venture has been operating and maintaining the depleted uranium hexafluoride (DUF6) conversion facilities for the DOE Portsmouth Paducah Project Office (PPPO) since 2016. The MCSA contract is currently valued at US $2.3 Billion for a period of up to 10 years, including a transition period of up to 120 days.

“With decades of experience tackling some of the most challenging and complex cleanups and projects in our industry, we have earned recognition for our expertise and our solutions,” said Jeff Kendall, President, AtkinsRéalis US Nuclear. “We are honored to continue our support for DOE PPPO at Portsmouth and Paducah and to help support the broader DOE mission well into the next decade.”

AtkinsRéalis US Nuclear is a premier nuclear solutions company delivering first-in-class engineering, operations and project management services to its federal and commercial clients.

About AtkinsRéalis

Created by the integration of long-standing organizations dating back to 1911, AtkinsRéalis is a world-class engineering services and nuclear company dedicated to engineering a better future for our planet and its people. We create sustainable solutions that connect people, data and technology to transform the world's infrastructure and energy systems. We deploy global capabilities locally to our clients and deliver unique end-to-end services across the whole life cycle of an asset including consulting, advisory & environmental services, intelligent networks & cybersecurity, design & engineering, procurement, project & construction management, operations & maintenance, decommissioning and capital. The breadth and depth of our capabilities are delivered to clients in strategic sectors such as Engineering Services, Nuclear and Capital.  News and information are available at www.atkinsrealis.com or follow us on LinkedIn.