Denison Mines Corp. reported the discovery of multiple new high-grade intercepts of unconformity-hosted uranium mineralization in the final three drill holes completed during the winter 2022 exploration program on the Waterfound River property ("Waterfound"). The results were highlighted by drill hole WF-68, which returned a broad zone of uranium mineralization, including a peak interval of 5.91% eU3O8 over 3.9 metres (0.05% eU3O8 cut-off) with a sub-interval grading 25.30% eU3O8 over 0.7 m, located approximately 800 metres west, along the La Rocque Conductive Corridor, of the previously discovered high-grade mineralization (including 4.49% U3O8 over 10.53 metres) at the Alligator Zone.

Denison has an effective 24.68% ownership interest in the Waterfound River Joint Venture ("Waterfound JV") to which each of Orano Canada Inc. ("Orano Canada"), Denison, and JCU (Canada) Exploration Company, Limited ("JCU") are participants. Orano Canada has a 62.42% interest in the Waterfound JV and is the project operator. Drill holes WF-67, WF-68, and WF-68-1 were all drilled on line 4000E, approximately 800 m along strike to the west of the Alligator Zone, to test the potential for uranium mineralization along the up-dip projection of a graphitic structure intersected at depth in historical drill hole WF-50.

All three drill holes successfully identified high-grade uranium mineralization, highlighted by hole WF-68, which returned 5.91% eU3O8 over 3.9 metres. The 2022 exploration program was designed to test for the potential expansion of previously discovered mineralization in the Alligator Zone, as well as to test for new mineralization in the surrounding area along the La Rocque conductive corridor. The program was planned to occur during both the winter and summer drilling seasons with approximately 7,400 metres of diamond drilling in an estimated 12 drill holes.

Six diamond drill holes, totaling 3,175.4 metres, were completed as part of the winter drill program. The first two drill holes of the winter program (WF-64 and WF-65) were completed on the eastern end of the property to test the D-1 conductor, located within the La Rocque conductive corridor. While each of these holes encountered elevated radioactivity at the unconformity, no mineralization above a 0.05% eU3O8 cut-off was identified.

WF-66, the third drill hole of the winter program, was drilled to test the D-1 conductor approximately 500 metres west of the Alligator Zone. WF-66 failed to intersect significantly elevated radioactivity. The final three drill holes (WF-67, WF-68, and WF-68-1), were successful in intersecting significant uranium mineralization associated with the D-1 conductor, which lies within the La Rocque conductive corridor.

This newly identified mineralization remains open along strike in both directions. Additional drilling to test the extent of mineralization is expected to be completed during the planned summer exploration drilling program. Following the completion of a drill hole, the hole is radiometrically logged using a downhole slimline gamma probe, which collects continuous readings of radioactivity along the length of the drill hole.

Probe results are then calibrated using an algorithm calculated from the comparison of probe results against geochemical analyses in the area. The gamma-log results provide an immediate radiometric equivalent uranium value (eU%, then converted to eU3O8%) for the hole, which, except in very high-grade zones, is reasonably accurate. The Company typically reports eU3O8, as a preliminary result and subsequently reports definitive assay grades following sampling and chemical analysis of the mineralized drill core.

Assay sample intervals are generally 50 centimetres long, except where higher or lower grade mineralization boundaries fall within the interval. In that case, two 25 centimetre samples are collected. Flank samples of 1.0 metre are always collected where mineralization is located.

Systematic geochemistry samples are collected every 10 metres down the hole. All assayed core is split in half, with one half retained and the other sent to the SRC Geoanalytical Laboratory in Saskatoon for analysis. Control samples are routinely assayed with each batch of core samples analyzed.