Phoenix Feasibility Study 2023

Denison Mines Phoenix ISR Freeze Wall: Isometric View at Ore Level Unconformity C Phase 5 Phoenix Zone B Phoenix Zone A Phase 1 Phase 2 Phase 3 Phase 4 D N Phoenix Zone B2 Phoenix Zone B1 750 m Notes: Isometric view centered at 400 m depth below ground surface (ore level) • Window 35 m above and below the ore zone level ⚫Frozen cross walls are thawed as freeze wall expands to accommodate subsequent phases Robust mine Freeze Wall (No planning process evaluation of production potential for individual well patterns: 74 extraction, 172 injection, and 22 monitoring wells Mineralized Zone Footprint MINING PHASE 1 MINING PHASE 2 Freeze Wall Mineralized Zone Footprint (No Flow Boundary) MINING PHASE 3 Extraction Well Injection Well (large diameter) Injection Well (narrow diameter) Injection Well (exploration borehole) N637 4500 N6375000 N 27 N04000 (28) N6323500 7.2 (7.3) 38) 16 26 LEGEND: FREEZE WALL OUTLINE NEW SITE FEATURE FUTURE 10 120m SHORELINE 540 CONTOUR ORE BODY FEATURE ITEM NO. 20 -124 (12) $2 125 17 10: (103) 10.1 Environmental disturbance limited by compact site Primary site facilities contained within area estimated to be less than 1 sq. km (31) (25) Om 100 200 300 400 500 1:10000 Item Description 1 ISR Well Field 2 Freeze Plant 3 ISR Plant 4 Contaminated Runoff Pond and Pumphouse 5 Process Precipitates Solids Pad 6.1 Gypsum Waste Pond 6.2 Gypsum Waste Pond (Future) 7.1 Industrial Landfill 7.2 Industrial Leachate Collection Pond 7.3 Industrial Landfill (Future) 8 Special Waste Pad 9.1 Clean Waste Pad 9.2 Clean Waste Runoff Pond Effluent Monitoring and Release Pond and Pumphouse 10.1 Effluent Monitoring and Release Pond Effluent Monitoring and Release Pond Lenison Phoenix Feasibility Study: Expected to provide an excellent basis to advance engineering designs in support of a future final investment decision 10.2 10.3 11 Process Water Pond and Pumphouse 12 Industrial Waste Water Treatment Plant 13 Wash Bay/Scanning Facility 14 Propane Storage (1 Camp, 1 Mill) 15 Potable Water Plant 16 Camp 17 Standby Diesel Generator (2) 18 138kV Substation Yard N ROAD ALIGNMENT ADJUSTMENT AIRPORT CHANNEL CROSSING APRON 19 Operations Centre, Gate House 20 Plant Support Facilities 21 Covered Storage 22 Fenced Storage 23 Hazardous Storage Short Term Storage Pad RUNWAY 24 Potable Water Tank and Pumphouse (41) 25 Fire Water Tank and Pumphouse 26 Fuel Storage 27 Monitoring Wells 28 Fresh Water Wells (Quantity of 2) 29 (Intentionally Blank) 30 Lake Water Intake THIS DRAWING 31 Lake Water Discharge 32 UBS Settling Pond PROPOSED ACCESS (34) 33 OVERHEAD ROAD TO SITE POWER LINE (33) EXISTING OVERHEAD POWER LINE HWY 914 34 35 Domestic Wastewater Treatment Facility 36 (Intentionally Blank) 37 Main Electrical Switch room 38 Diesel Fuel Storage Tank 39 SaskPower 138kV Overhead Power Line 40 Transformers (2) 41 Airport (See Key Plan) KEY PLAN 42 Communication Tower Domestic Landfill (See Key Plan) Construction Waste Laydown Area (See Key Plan) NOTES: (1) Refer to the Wheeler River Technical Report titled "NI 43-101 Technical Report on the Wheeler River Project, Athabasca Basin, Saskatchewan, Can ada" dated June 23, 2023. 12

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