Denison Mines Corp. announced it has completed the inaugural In-Situ Recovery (?ISR?) field test program (the ?Program?) at Denison?s 25.17% owned Midwest Uranium Project (?Midwest?). The Program involved drilling 10 small diameter boreholes within the Midwest Main deposit primarily undertaken to evaluate site-specific conditions for ISR mining.

A series of tests were successfully performed on each borehole, creating an extensive database of geological, hydrogeological, geotechnical, and metallurgical data and validating certain key assumptions in the previously completed internal conceptual mining study (the ?Concept Study?) evaluating the potential use of ISR mining at Midwest. Denison carried out the Program in collaboration with Orano Canada Inc. (?Orano Canada?), as operator and owner of 74.83% of the Midwest Joint Venture (?MWJV?). Midwest is located approximately 25 kilometres, by existing roads, from the Denison-Orano Canada owned McClean Lake Operation, which is currently processing ore for the Cigar Lake mine under a toll milling agreement and has excess licensed processing capacity.

Orano Canada is part of the Orano Group, which is recognized as a leading international operator in the field of nuclear materials, with activities including uranium mining, conversion, enrichment, and other fuel services. Highlights from the Program include the following: Confirmed Hydraulic Conductivity: Pump and injection tests validated hydraulic connectivity in the test wells within the mineralized zone and achieved hydraulic conductivity values (a measure of permeability) consistent with the Concept Study. Sufficient permeability within the mineralized zone is a key criterion for the successful deployment of the ISR mining method.

Demonstrated the Effectiveness of Permeability Enhancement: One method of permeability enhancement was successfully deployed within two wells, demonstrating the suitability of the method to the Midwest Main deposit. Efficiency of permeability enhancement was verified by comparison of pre- and post-permeability enhancement hydraulic testing. Metallurgical Samples Defined and Collected for Leaching Characteristics: Core samples representative of the Midwest deposit were collected during the Program for use in future metallurgical tests to determine the leaching characteristics.

2024 ISR Field Test Program: The 2024 ISR field test program was designed to validate various deposit-specific characteristics of the Midwest Main deposit, and to collect a database of geotechnical, hydrogeological, and metallurgical data to further evaluate the ISR mining conditions present at the deposit. Ten small-diameter test wells were installed within the Midwest Main deposit during the Program ? including a 4-well test pattern (the ?Test Pattern?) and 6 individual wells to test specific areas of the deposit for various characteristics.

The Test Pattern included one injection well, one extraction well, a recharge well, and a monitoring well outfitted with a multi-channel vibrating wire piezometer. The six additional wells were drilled to their target depths and, as applicable, outfitted with well screens and/or pressure monitoring devices to facilitate hydrogeological testing. All wells were decommissioned at conclusion of the Program consistent with regulatory commitments.

Core collected from the test wells within the mineralized zone is also expected to be used to verify and update the current mineral resource estimate for the deposit and support future wellfield design and mineral processing assessments. Successful Completion of Hydrogeologic Test Work: The Program included the completion of various pump, injection, and packer tests designed to assess the permeability of the Midwest Main deposit. The test program measured pressure changes within the mineralized zone, which provides evidence of the deposit?s hydraulic conditions and is indicative of the potential for the movement of mining solution in an ISR mining operation.

Sufficient permeability within the mineralized zone is a key criterion for the successful deployment of the ISR mining method. The results from the hydrogeological testing at Midwest Main produced hydraulic conductivity values that are consistent with those assumed in the Concept Study. Additional supportive test work completed during the Program included permeability and porosity tests conducted either downhole or on mineralized drill core recovered during the test program.

Demonstration of the Effectiveness of Permeability Enhancement Method: One method of permeability enhancement was successfully evaluated on two test wells within the mineralized zone, with efficacy verified by the comparison of pre- and post-permeability enhancement hydraulic conductivity tests. Permeability enhancement has been demonstrated to increase and normalize hydraulic conductivity in the area proximal to the wellbore, allowing for increased contact of injected fluids within the mineralized zone in order to maximize uranium recoveries in an ISR mining environment. Collection of Other Supporting Datasets: In addition to the tests described above, data and samples were collected from the drill core recovered from the test wells to facilitate: (1) the assessment of matrix permeability, to inform an initial model of the hydrogeological variations of the deposit; (2) geotechnical evaluations; (3) sediment analysis using Standard Penetration Test (?SPT?) for measuring mud depths and the overburden below lake bottom; and (4) testing of compressive and tensile strength for incorporation into future geotechnical assessments.