Nuclear Waste Disposal Innovator Deep Isolation Appoints Renée Hornbaker to Board of Directors (Form 8-K)

Nuclear Waste Disposal Innovator Deep Isolation Appoints Renée Hornbaker to Board of Directors

BERKELEY, CA, October 21, 2025 - Deep Isolation Nuclear, Inc. ("Deep Isolation" or the "Company"), a leading innovator in nuclear waste disposal technology, today announced the appointment of Renée Hornbaker to its Board of Directors, effective immediately.

Ms. Hornbaker brings more than four decades of corporate leadership experience to Deep Isolation. In her roles as C-suite leader and CFO for both public and private companies, Renee has proven to be a strategic business leader with extensive experience delivering growth, business transformation, and profit improvement. Ms. Hornbaker is a CPA, Audit Committee Financial Expert, and Director Certified by the National Association of Corporate Directors (NACD). During her career, Ms. Hornbaker served as CFO at Stream Energy, Shared Technologies, and Flowserve Corporation, where she also served as Vice President of Business Development and Information Technologies. Ms. Hornbaker began her career with the audit practice of Deloitte.

Renée Hornbaker

"We welcome Renée to the Deep Isolation board," said Rod Baltzer, President & CEO of Deep Isolation. "Renée's vast experience with high-tech global businesses in the energy and industrial sectors, combined with her strong background in accounting, audit and regulatory oversight will be invaluable to Deep Isolation. We believe Renée's extensive track record of overseeing successful business transformations will be instrumental as Deep Isolation works toward deploying its innovative nuclear waste storage and disposal solutions globally."

"It's an honor to join Deep Isolation as it embarks on a mission to deliver a safe, scalable, and cost-effective solution for nuclear waste disposal," said Renée Hornbaker, newly appointed board member. "I see a tremendous opportunity for Deep Isolation as nuclear energy expands rapidly around the world and the need for permanent storage and disposal of nuclear waste grows with it. I look forward to working with the Deep Isolation team as they continue to execute against their strategy."

Ms. Hornbaker currently serves on the boards of Eastman Chemical Company, Freeman Company, and Berry Corporation, where she serves as Board Chair. She earned an MBA with Beta Gamma Sigma Honors and BA from Indiana University in Bloomington, Indiana. She has earned credentials from NACD including board leadership fellow, director certified, cybersecurity board oversight, and climate oversight and is chair emeritus of the NACD North Texas Chapter. Ms. Hornbaker has been recognized for her governance expertise and business leadership as an outstanding director, including NACD's 2023 Private Company Director of the Year and outstanding CFO.

Deep Isolation is revolutionizing the nuclear waste disposal industry through its innovative deep borehole technology, delivering a safe, scalable, and cost-effective solution for permanent nuclear waste disposal. The Company's proprietary solution will place corrosion-resistant canisters containing nuclear waste in deep boreholes over one kilometer below the Earth's surface, utilizing proven directional drilling technology to provide permanent isolation at a fraction of the cost of traditional mined repositories.

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About Deep Isolation

Deep Isolation is the first company to commercialize nuclear waste disposal in deep boreholes. It offers a uniquely tailored solution to help countries complete the necessary steps to dispose of their nuclear waste inventories. With 87 patents issued to date, Deep Isolation's technology leverages proven drilling practices to safely isolate waste deep underground in horizontal, vertical, or slanted borehole repositories. Deep Isolation's Universal Canister System (UCS) was developed through a three-year project funded by the U.S. Department of Energy's Advanced Research Projects Agency-Energy (ARPA-E) and is engineered to support integrated management of spent fuel and high-level waste from advanced reactors across storage, transportation and eventual disposal.

For more information, visit: https://www.deepisolation.com

Media Contact:

Sophie McCallum

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Investor Contact:

Caldwell Bailey

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Forward-Looking Statements

Statements contained in this news release that are not historical facts are "forward-looking information" or "forward-looking statements" (collectively, "forward-looking statements") within the meaning of Section 27A of the Securities Act and Section 21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements include, but are not limited to, statements regarding our plans, objectives and expectations for our business, the future growth of our business and the nuclear energy and nuclear waste disposal industries as a whole, and future benefits expected to arise from our strategic partnerships. In certain cases, forward-looking statements can be identified by the use of words and phrases or variations of words and phrases or statements such as "may," "should," "expect," "intend," "plan," "anticipate," "believe," "estimate," "predict," "will," "could," "project," "target," "potential," "continue" and similar expressions. Forward-looking statements are based on management's belief and assumptions, including current expectations and projections about future events and trends, and on information currently available to management.