Mr. Kevin Himbeault reports

DENISON ANNOUNCES $16 MILLION CONTRACT AWARD TO WOOD FOR COMPLETION OF DETAILED DESIGN ENGINEERING FOR FLAGSHIP PHOENIX ISR PROJECT

Denison Mines Corp. has awarded to Wood Canada Ltd., part of the leading global consulting and engineering firm Wood PLC, a contract for the completion of detailed design engineering for the in situ recovery (ISR) mining project planned for Denison's flagship Phoenix uranium deposit.

Phoenix and the nearby Gryphon uranium deposit are part of the Wheeler River uranium project, which is the largest undeveloped uranium mining project in the infrastructure-rich eastern portion of the Athabasca basin region in Northern Saskatchewan, Canada. Denison has an effective 95-per-cent ownership interest in Wheeler River and is the project operator.

A National Instrument 43-101 feasibility study was completed by Wood in 2023 to evaluate the use of the ISR mining method at Phoenix. The results of the Phoenix feasibility study reflected several years of technical derisking efforts successfully completed by Denison and demonstrated very robust base-case after-tax (adjusted) economics -- including a net present value (NPV) of $1.56-billion (100-per-cent basis), an internal rate of return (IRR) of 90 per cent and an NPV to initial capital cost ratio in excess of 3.7 to one. The base case in the Phoenix feasibility study assumed uranium selling prices in the range of $66.53 (U.S.) to $70.11 (U.S.) per pound triuranium octoxide. The current spot price for uranium is approximately $105 (U.S.) per pound U3O8, reflecting an increase of over 50 per cent from the average of the base-case pricing assumptions used in the Phoenix feasibility study of $68.99 (U.S.) per pound U3O8.

Following completion of the Phoenix feasibility study, Denison's board of directors approved the continuation of efforts to advance Phoenix toward a final investment decision, and in late 2023, the management committee of the Wheeler River joint venture approved a budget for the applicable 2024 expenditures. Detailed engineering design constitutes a significant portion of the work remaining to advance Phoenix to the point where a decision can be made to proceed to construction and, ultimately, production.

Kevin Himbeault, Denison's vice-president of operations, commented: "In recognition of Wood's performance leading the Phoenix feasibility study, competitive pricing and alignment with our bid evaluation process, we are pleased to announce the award of a detailed design engineering contract to Wood. Maintaining continuity through completion of the Phoenix feasibility study, front-end engineering design and detailed design allows us to build on our combined knowledge and working relationship to deliver an engineering package that will ultimately support the construction and operation of the first ISR uranium mining operation in the Athabasca basin."

The scope of the facilities to be designed by Wood under this contract is extensive, including: (i) site civil earthworks and distribution of utility piping throughout the main project site; (ii) electrical power distribution on site; (iii) surface piping and services for the mine well field; (iv) the process plant and related infrastructure; (v) operations complex; (vi) maintenance and related buildings; (vii) metallurgical and analytical laboratories; and (viii) site-wide communications systems.

Based on the currently anticipated scopes of work, the detailed design engineering contract with Wood is estimated to be up to approximately $16-million in value, with the scope of work planned to commence in the first quarter of 2024 and to potentially continue into the first half of 2025.

About Denison Mines Corp.

Denison is a uranium exploration and development company with interests focused in the Athabasca basin region of Northern Saskatchewan, Canada. In addition to Denison's effective 95-per-cent interest in its flagship Wheeler River uranium project, Denison's interests in Saskatchewan include a 22.5-per-cent ownership interest in the McClean Lake joint venture, which comprises several uranium deposits and the McClean Lake uranium mill that is contracted to process the ore from the Cigar Lake mine under a toll milling agreement, plus a 25.17-per-cent interest in the Midwest Main and Midwest A deposits and a 67.41-per-cent interest in the Tthe Heldeth Tue (THT) and Huskie deposits on the Waterbury Lake property. The Midwest Main, Midwest A, THT and Huskie deposits are located within 20 kilometres of the McClean Lake mill.

Through its 50-per-cent ownership of JCU (Canada) Exploration Company Ltd., Denison holds additional interests in various uranium project joint ventures in Canada, including the Millennium project (JCU, 30.099 per cent), the Kiggavik project (JCU, 33.8118 per cent) and Christie Lake (JCU, 34.4508 per cent).

Denison's exploration portfolio includes further interests in properties covering approximately 285,000 hectares in the Athabasca basin region.

Qualified persons

The technical information contained in this release has been reviewed and approved by Chad Sorba, PGeo, Denison's vice-president of technical services and project evaluation, and Andrew Yackulic, PGeo, Denison's vice-president of exploration, each of whom is a qualified person in accordance with the requirements of NI 43-101.

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