AtkinsRéalis Confirms CANDU® Monark Reactor Power Rating

Reactor capability to be uprated to 1000MW

MONTREAL, April 20, 2026 /CNW/ – AtkinsRéalis Group Inc. (TSX: ATRL), a world-class engineering services and nuclear company with offices around the world, confirms that its formal submission to the Canadian Nuclear Safety Commission (CNSC) is for a reactor with a net electrical output of 925 megawatts (MW) and not the information posted on the CNSC website. The 925‑MW net licensing is intentional, prioritizing replicability, regulatory confidence, and execution discipline. The Company has engaged the CNSC to update its website.

The CANDU^® Monark design submitted to the CNSC is aligned with the requirements and deployment objectives of the domestic nuclear utility clients, and it reflects a deliberate focus on proven performance, regulatory familiarity, and execution certainty.

Importantly, the CANDU^® Monark is engineered with the capability to be potentially uprated to approximately 1,000 MW, subject to owner decisions, site‑specific conditions, and regulatory approvals. This uprate potential is enabled through well‑understood design margins, turbine‑generator selection, and balance‑of‑plant optimization, rather than unproven core design changes.

As stated above, the Monark design has not been redesigned downward. The decision to license at 925 MW net is intentional and reflects a commitment to avoid first‑of‑a‑kind (FOAK) risk, replication of an operating, regulator‑trusted design and cost, schedule, and execution discipline for owners and ratepayers.

As with all nuclear projects, final operating parameters are determined through detailed design development and regulatory and client engagement. AtkinsRéalis remains confident that the CANDU^® Monark offers a competitive, scalable, and de‑risked large‑reactor solution, particularly for jurisdictions seeking fleet deployment, domestic supply chain benefits, and proven CANDU operational experience.

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 LinkedIn. 

About AtkinsRéalis’ Nuclear Sector

AtkinsRéalis has over 70 years of global nuclear expertise, delivering nuclear technology products and full-service solutions to nuclear utilities around the world. AtkinsRéalis is the steward of CANDU^® nuclear technology, operating on four continents, and provides advisory and engineering services to other nuclear developers. With an innovative technology portfolio, including access to over 500 patented solutions, AtkinsRéalis solves technically complex challenges across the whole nuclear lifecycle from design and new build through asset management and from life extension and late life management through decommissioning and waste management. AtkinsRéalis operates and manages government nuclear research sites, transforming ageing infrastructure and safely managing legacy nuclear waste. AtkinsRéalis’ CANDU technology also allows for the co-production of medical radioisotopes for cancer detection and treatment. The company also supports cancer treatment through its partnership with TerraPower to extract isotopes from legacy nuclear material. Learn more on our Nuclear market page.

Forward-Looking Statements

References in this press release to the “Company”, “AtkinsRéalis”, “we”, “us” and “our” mean, as the context may require, AtkinsRéalis Group Inc. or all or some of its subsidiaries or joint arrangements or associates. Statements made in this press release that describe the Company’s expectations or strategies constitute “forward-looking statements”, which can be identified by the use of the conditional or forward-looking terminology such as “aims”, “anticipates”, “assumes”, “believes”, “cost savings”, “estimates”, “expects”, “forecasts”, “goal”, “intends”, “likely”, “may”, “objective”, “outlook”, “plans”, “projects”, “should”, “synergies”, “target”, “vision”, “will” , or other variations thereon. Forward-looking statements also include any other statements that do not refer to historical facts. The Company cautions that, by their nature, forward-looking statements involve risks and uncertainties, and that its actual actions or results could differ materially from those expressed or implied in such forward-looking statements. Forward-looking statements are presented for the purpose of assisting investors and others in understanding certain key elements of the Company’s current objectives, strategic priorities, expectations and plans, and in obtaining a better understanding of the Company’s business and anticipated operating environment. Readers are cautioned that such information may not be appropriate for other purposes. Forward-looking statements made in this press release are based on a number of assumptions believed by the Company to be reasonable as at the date hereof. The assumptions are set out throughout the Company’s 2025 annual management disclosure & analysis (“2025 MD&A”) (particularly in the sections entitled “Critical Accounting Judgments and Key Sources of Estimation Uncertainty” and “How We Analyze and Report our Results”) filed with the securities regulatory authorities in Canada, available on SEDAR+ at www.sedarplus.com and on the Company’s website at www.atkinsrealis.com under the “Investors” section. If these assumptions are inaccurate, the Company’s actual results could differ materially from those expressed or implied in such forward-looking statements. In addition, important risk factors could cause the Company’s assumptions and estimates to be inaccurate and actual results or events to differ materially from those expressed in or implied by these forward-looking statements. Those risks are identified in the 2025 MD&A (particularly in the section entitled “Risk and Uncertainties”), as may be updated from time to time in the Company’s interim quarterly MD&A, are not exhaustive. The forward-looking statements herein reflect the Company’s expectations as at the date of this press release and are subject to change after this date. The Company does not undertake to update publicly or to revise any such forward-looking statements whether as a result of new information, future events or otherwise, unless required by applicable legislation or regulation. The forward-looking information and statements contained herein are expressly qualified in their entirety by this cautionary statement. 

SOURCE AtkinsRéalis