Denison Mines Corp 6-K, filed Oct 10, 2025

Denison Mines Corp. (DNN)

6-K 2025-10-10 For: 2025-10-09

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Denison Mines Corp filed this 6-K on October 10, 2025.

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	Denison Mines Corp.

	/s/ Amanda Willett
Date: October 10, 2025	Amanda Willett
	Vice President Legal and Corporate Secretary

Exhibit Number		Description

99.1		Coverletter dated October 10, 2025

99.2		Report entitled “Preliminary Economic Assessment for the Midwest Property, Northern Saskatchewan, Canada, Using the In-Situ Recovery Mining Method”

List of Figures		11
List of Tables		14
1.       SUMMARY		16
1.1.	Introduction	16
1.2.	Technical Summary	17
1.2.1.	Property Description and Location	17
1.2.2.	Ownership	18
1.2.3.	Geology and Mineralization	19
1.2.4.	Exploration and Development	20
1.2.5.	Mineral Resource Estimate	21
1.2.6.	Mineral Processing and Metallurgical Testing	22
1.2.7.	Mining Methods	24
1.2.8.	Recovery Methods	28
1.2.9.	Production Schedule	30
1.2.10.	Infrastructure	31
1.2.11.	Environmental Studies, Permitting, Social & Community Considerations	31
1.2.12.	Capital and Operating Costs	32
1.2.13.	Economic Analysis	35
1.3.	Risks and Opportunities	37
1.3.1.	Risks	37
1.3.2.	Opportunities	39
1.4.	Conclusions & Recommendations	39
1.4.1.	Mineral Resources	40
2.     INTRODUCTION		43
2.1.	Denison Mines Corp.	43
2.2.	Terms of Reference	44
2.3.	Purpose of the Report	44
2.4.	Sources of Information	45
2.5.	Inspection on Property	45
2.6.	Abbreviations and Definitions	46
2.6.1.	Abbreviations of Units and Names	46
3.    RELIANCE ON OTHER EXPERTS		48
4.    PROPERTY DESCRIPTION AND LOCATION		49
4.1.	Location	49
4.2.	Mineral Disposition and Tenure	49

4.3.	Ownership	51
4.4.	Nature and Extent of Title	52
4.5.	Royalties, Agreements and Encumbrances	52
4.6.	Permitting	52
4.7.	Environmental Liabilities	53
4.8.	Other Significant Factors and Risks	54
5.    ACCESSIBILTY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY		55
5.1.	Access to Property	55
5.2.	Proximity to Population Centres and Transport	55
5.3.	Climate	56
5.4.	Local Resources and Infrastructure	56
5.5.	Physiography	56
6.    HISTORY		57
6.1.	Prior Ownership	57
6.2.	Discovery, Past Exploration, and Development	58
6.2.1.	Numac Oil & Gas Limited – Operator 1969-1977	58
6.2.2.	Esso Resources Canada Limited – Operator 1977-1987	58
6.2.3.	Denison Mines Limited – Operator 1987 – 1993	59
6.2.4.	Minatco – Operator 1993 – 1994	60
6.2.5.	COGEMA/AREVA/Orano – Operator 1994 – Present	60
6.3.	Historical Mineral Resource and Mineral Reserve Estimates	61
6.4.	Historical Production	61
7.    GEOLOGICAL SETTING AND MINERALIZATION		62
7.1.	Regional Geology	62
7.1.1.	Sub-Athabasca Crystalline Metamorphic Basement	64
7.1.2.	Hudsonian Granites/pegmatites	66
7.1.3.	Paleoweathering	67
7.1.4.	Athabasca Group Sandstone	67
7.1.5.	Quaternary Geology	68
7.1.6.	Uranium Mineralization	69
7.2.	Local Geology	69
7.2.1.	Sub-Athabasca Crystalline Metamorphic Basement	74
7.2.2.	Athabasca Group Sandstone	74
7.2.3.	Quaternary Geology	75
7.3.	Uranium Mineralization	75

8.    DEPOSIT TYPES		79
8.1.	Uranium Deposit Type	79
8.2.	Host-Rock Alteration	81
9.    EXPLORATION		84
10.  DRILLING		89
10.1.	Type, Methodology, and Extent of Drilling	89
10.2.	Midwest Main Drilling	92
10.2.1.	Summary	92
10.2.2.	Historic Drilling	92
10.2.3.	Drilling Completed by or on Behalf of Denison	93
10.3.	Midwest A Drilling	95
10.3.1.	Summary	95
10.3.2.	Historic Drilling	95
10.3.3.	Drilling Completed by Current Ownership	95
10.4.	Drillhole Collar Locations	96
10.4.1.	Downhole Surveying	100
10.4.2.	Drilling Procedures	101
10.5.	Reliability	101
11. SAMPLE PREPARATION, ANALYSIS AND SECURITY		102
11.1.	Drill Core Preparation	102
11.2.	Radiometric Logging	103
11.3.	Geological Logging	104
11.4.	Oriented Core Measurements	104
11.5.	Drill Core Recovery	104
11.6.	Downhole Probing	105
11.6.1.	Gamma Probing	105
11.6.2.	Radiometric Gamma Probes	106
11.6.3.	Probing Procedures	106
11.6.4.	Probe Calibration and Check	106
11.6.5.	Equivalent Uranium Grade	107
11.6.6.	Downhole Resistivity Probing	107
11.7.	Geotechnical Logging	107
11.8.	Drill Core Sample Security	107
11.9.	Sampling for Chemical Analysis	109
11.9.1.	Analytical Laboratories	111
11.9.2.	Disequilibrium Analysis	112
11.9.3.	Mineralogical Sampling	112
11.9.4.	Accompanying Elements and REE Assays	112
11.9.5.	Sample Preparation	113

11.9.6.	Quality Control Samples	113
11.9.6.1.	Field Duplicates	115
11.9.6.2.	Laboratory Repeats	116
11.9.6.3.	U₃O₈ Assay Laboratory Standards	117
11.9.6.4.	Analytical Blanks	120
11.10.	Dry Bulk Density and Specific Gravity Measurements	122
11.11.	Conclusions	123
12.  DATA VERIFICATION		124
12.1.	Site Visit	124
12.2.	Database Validation	127
12.2.1.	Internal Validation	127
12.2.2.	UMR Validation	128
12.3.	Opinion on Adequacy of Data	129
12.4.	Limitations	129
12.5.	Qualified Person’s Opinion	129
13.  MINERAL PROCESSING AND METALLURGICAL TESTING		130
13.1.	Midwest Historical Metallurgical Leach Testing	130
13.1.1.	Continuously Stirred Tank Reactor (CSTR) Leaching Tests	130
13.1.1.1.	Composite Preparation	130
13.1.1.2.	Leaching Test Methods	131
13.1.1.3.	Leaching Test Results	131
13.1.2.	Conclusions	131
13.2.	Midwest PEA Metallurgical Leach Testing	132
13.2.1.	Bottle Rolls Leach Tests	132
13.3.	Conclusions	134
13.4.	Recommendations	135
14.  MINERAL RESOURCE ESTIMATE		136
14.1.	Introduction	136
14.2.	Midwest Main	136
14.2.1.	Drillhole Database	137
14.2.1.1.	Calculation of Equivalent Uranium Grades	140
14.2.1.2.	Combination of Equivalent and Geochemical Uranium Grades	140
14.2.1.3.	Radiometric Grade Correlation	140
14.2.1.4.	Density Data	142
14.2.2.	Geological Model	143
14.2.3.	Statistics and Data Analysis	148
14.2.3.1.	Declustering	152
14.2.4.	Capping and High-Grade Restrictions	153

14.2.5.	Variogram Analysis and Modelling	157
14.2.6.	Block Model and Estimation Parameters	163
14.2.7.	Validation of Resource Estimation	167
14.2.8.	Resource Classification	172
14.2.9.	Grade Sensitivity Analysis	174
14.2.10.	Audit Findings and Recommendations	175
14.3.	Midwest A	177
14.3.1.	Drillhole Database	177
14.3.1.1.	Database Changes	177
14.3.1.2.	Calculation of Equivalent Uranium Grades	178
14.3.1.3.	Combination of Equivalent and Geochemical Uranium Grades	178
14.3.1.4.	Radiometric Grade Correlation	179
14.3.1.5.	Density Data	180
14.3.2.	Geological Model	182
14.3.3.	Statistics and Data Analysis	187
14.3.3.1.	Declustering	188
14.3.4.	Capping and High-Grade Restrictions	188
14.3.5.	Variogram Analysis and Modelling	191
14.3.6.	Block Model and Estimation Parameters	196
14.3.7.	Estimation Sensitivity	198
14.3.8.	Validation of Resource Estimation	199
14.3.9.	Resource Classification	200
14.3.10.	Grade Sensitivity Analysis	202
14.3.11.	Audit Findings and Recommendations	204
14.4.	Reasonable Prospects for Eventual Economic Extraction	205
14.5.	Mineral Resource Statement	206
14.6.	Mineral Resource Uncertainty	207
14.6.1.	Specific Identified Risks	207
14.6.2.	Generic Mineral Resource Uncertainty	208
14.7.	Reconciliation with Previous Mineral Resource Estimate	208
14.7.1.	Midwest Main	208
14.7.2.	Midwest A	210
14.8.	Relevant Factors	212
15.  MINERAL RESERVE ESTIMATE		213
16.  MINING METHODS		214
16.1.	Summary	214
16.2.	Estimated Resources included in Mine Plan	215
16.3.	ISR Mining	215

16.4.	Midwest ISR Concept	217
16.4.1.	Hydrogeology	218
16.4.2.	Assessment of Mineralized Zone Permeability	219
16.4.3.	Mine Geotechnical	222
16.5.	Mining Methods	222
16.5.1.	Wellfield	222
16.5.2.	Freeze Wall	223
16.5.3.	Drilling Methodology	227
16.5.3.1.	Drilling	227
16.5.3.2.	Permeability Enhancement	227
16.5.3.3.	Well Design	228
16.5.3.4.	Freeze Holes	229
16.5.4.	Production	230
16.5.5.	Wellfield Piping System	230
16.5.6.	Header Houses	231
16.5.7.	Wellfield Reagents, Electricity and Other Consumables	232
16.5.8.	Mining Equipment	232
16.6.	Development and Production Schedule	232
16.6.1.	Estimated Production Rates	232
16.6.2.	Mine Development Sequence	233
16.6.2.1.	Evaluation and Mine Development Phase	234
16.6.2.2.	Operations Phase	235
16.6.2.3.	Restoration and Decommissioning Phase	235
16.6.3.	Definition Drilling	236
17.  RECOVERY METHODS		237
17.1.	Mineral Processing – McClean Lake	237
17.1.1.	Transportation	237
17.1.2.	Mill History and Flowsheet	238
17.1.3.	Current Mill Configuration and General Process Description	239
17.1.4.	Tailings Neutralization	241
17.1.5.	Clarification	241
17.1.6.	Solvent Extraction	241
17.1.7.	McClean Lake Tailings Management Facility (TMF)	241
17.2.	Metallurgy and Mineral Processing – Midwest Mine Site	242
17.2.1.	Lixiviant	242
17.2.2.	Uranium Bearing Solution	244
17.3.	Recovery	244
17.4.	Conclusions	244
17.5.	Recommendations	245

18.  PROJECT INFRASTRUCTURE		246
18.1.	Access Road and Site Preparation	247
18.2.	Camp	248
18.3.	Operations Centre	248
18.4.	Fuel Storage and Dispensing	248
18.5.	Propane Storage and Dispensing	249
18.6.	Electrical Power	249
18.7.	Back-up Electrical Power	249
18.8.	Freezing Plant Surface Infrastructure	249
18.9.	Water Supply	250
18.10.	Water Management	250
18.11.	Waste Management	250
18.12.	ISR Wellfield Waste Rock Management	250
18.13.	UBS Handling Infrastructure	250
19.  URANIUM MARKET AND CONTRACTING		251
19.1.	The Uranium Industry	251
19.2.	Uranium Demand	252
19.3.	Primary Uranium Supply	253
19.4.	Outlook	254
19.5.	Competition	255
20.  ENVIRONMENTAL STUDIES, PERMITTING, SOCIAL AND COMMUNITY IMPACT		256
20.1.	Previous Environmental Assessment and Permitting	256
20.2.	Environmental Assessment	259
20.2.1.	Provincial Requirements	259
20.2.2.	Federal Requirements	260
20.3.	Licensing and Permitting	261
20.3.1.	Provincial	261
20.3.2.	Federal	261
20.4.	Environmental Considerations	261
20.4.1.	Environmental Baseline Studies	261
20.5.	Approval Schedule and Estimated Costs	262
20.6.	Corporate Social Responsibility Considerations	262
21.  CAPITAL AND OPERATING COSTS		263
21.1.	Capital Costs	263
21.1.1	Summary	263
21.1.2	Milestone Project Schedule	264
21.1.3	Initial Capital Cost Breakdown	265
21.2	Operating Costs	267

21.3	Decommissioning Costs	269
21.3.1	ISR Restoration	269
21.3.2	Site Infrastructure Removal (Demolition)	269
21.3.3	Post-decommissioning Monitoring	270
22.  ECONOMIC ANALYSIS		271
22.1.	Taxes and Royalties	274
22.1.1.	Saskatchewan Uranium Resource Surcharge	275
22.1.2.	Saskatchewan Basic Royalty and Resource Credit	275
22.1.3.	Saskatchewan Profit-Based Tiered Royalty	275
22.1.4.	Saskatchewan and Canada Income Taxes	275
22.1.5.	Property Royalties	275
22.2.	Basis of the Discount Rate	276
22.3.	Economic Analysis	276
22.3.1.	Economic Analysis - 100% Project After Tax	276
22.4.	Sensitivity Analysis	280
22.5.	Price Variances – 100% Project After Tax	281
22.6.	MRMR Variance – 100% Project Pre and Post Tax	282
22.7.	Mining Recovery Variance – 100% Project After Tax	283
23.  ADJACENT PROPERTIES		285
24.  OTHER RELEVANT DATA AND INFORMATION		286
24.1.	Risks	286
24.2.	Opportunities	287
25.  INTERPRETATION AND CONCLUSIONS		288
25.1.	Mineral Resources	288
26.  RECOMMENDATIONS		290
26.1.	Mineral Resources	290
27.  REFERENCES		292
28.  CERTIFICATES OF QUALIFIED PERSONS		294

Figure 1-1: Midwest Project Location and Athabasca Properties Map	17
Figure 1-2: Midwest Project Location Map	18
Figure 1-3: Mining Phases for the Midwest Main Deposit	25
Figure 1-4: Isometric Representation of the Proposed Wellfield Design	27
Figure 1-5: Midwest Main Deposit Overall Production	30
Figure 1-6: 100% Project Cash Flow Pre-Tax & After Tax	37
Figure 2-1: Midwest Project Location Map	44
Figure 4-1: General Location Map, Midwest Project	50
Figure 7-1: Location of the Athabasca Basin relative to the geology of the northwestern Canadian Shield. Legend: Red squares - U deposits/prospects	63
Figure 7-2: Geological setting of the Athabasca Basin and unconformity type U occurrences, northern Saskatchewan and Alberta	64
Figure 7-3: Litho-tectonic geology of the eastern Athabasca region with locations of uranium deposits, including Midwest (circled in red)	65
Figure 7-4: Midwest Main Basement Geology at the Unconformity (transluscent blue envelope represents the unconformity mineralization outline at a 0.05% U cut-off)	70
Figure 7-5: Schematic Geological Section for the Midwest Main Deposit	71
Figure 7-6: Midwest Main (formerly Midwest Lake) deposit cross-section on L7865N, with host-rock alteration and mineralization	72
Figure 7-7: Schematic Geological Section for the Midwest A Deposit	73
Figure 7-8: Geological Section for the Midwest Main Deposit Differentiated by Hydrogeological Units	77
Figure 8-1: Geological Elements of Mono-metallic and Poly-metallic Unconformity-type Uranium Deposits	81
Figure 8-2: Egress Versus Ingress-style Alteration Zones for Unconformity-type Uranium Deposits	82
Figure 9-1: Ground Resistivity Anomaly at Depth of 250 Metres (30 Metres Above the Unconformity) over the Midwest Project Area	85
Figure 9-2: Inverted Ground Resistivity Anomaly (Colour Enhanced) in the Lower Sandstone Bench over the Midwest Project Area (2006 and 2008 Surveys)	86
Figure 9-3: Geophysical Lines from the 2006 Exploration Program	87
Figure 9-4: 2021 Geophysical Lines and Resistivity Compared to Previous Grids and Drilling	88
Figure 10-1: Disposition and Drillhole Collar Locations on the Midwest Property	98
Figure 10-2: Drillhole Collar Locations in the Midwest Main Area (2024 Drillholes in Red)	99
Figure 10-3: Drillhole Collar Locations in the Midwest A Area	100
Figure 11-1: Scatter Plot of Uranium (Total Digestion) for Field Duplicates	115
Figure 11-2: Lab Repeat Comparison 2018 - 2024	116
Figure 11-3: Lab Repeat Comparison	117

Figure 11-4: U₃O₈ Assay Standard Results	118
Figure 11-5: U₃O₈ Assay Standard Results	118
Figure 11-6: U₃O₈ Assay Standard Results	119
Figure 11-7: U₃O₈ Assay Standard Results	120
Figure 11-8: Analytical Blanks Results for Midwest Main for ICP-OES	121
Figure 11-9: Analytical Blanks Results for Midwest Main for ICP-MS	121
Figure 11-10: Analytical Blanks Results for Midwest A	122
Figure 12-1: Midwest Core Review	125
Figure 12-2: Confirmation of Mineralization via a RS 121 Scintillometer in MW-867	126
Figure 12-3: Drill Collar Demarcation of MW-858 (left) and MW-860 (right).	127
Figure 14-1: 70 m Plan Section with UC Mineralized Lenses (LG – Blue, HG – Red) and Structures (Orange and Green) Related to Midwest Main Mineralization	144
Figure 14-2: 5 m Cross-Section Looking SW with Structures Related to Midwest Main Mineralization [UC Surface – Yellow; Mineralized Lenses – Blue (UC-LG), RED (UC-HG), Brown (Perched), Purple (Basement); Faults – Orange]	145
Figure 14-3: Inclined View Looking North of the Midwest Main Mineralized Zones (Blue (UC-LG), RED (UC-HG), Brown (Perched)	147
Figure 14-4: 10 m Cross-Section Looking SW with Structures Related to Midwest Main Mineralization [UC Surface – Yellow; Mineralized Lenses – Blue (UC-LG), RED (UC-HG), Brown (Perched), Purple (Basement)]	148
Figure 14-5: UC – LG Zone Cumulative Probability Plot of DG and D	156
Figure 14-6: UC – HG1 Zone Cumulative Probability Plot of DG and D	156
Figure 14-7: UC – HG2 Zone Cumulative Probability Plot of DG and D	157
Figure 14-8: UC – HG3N Zone Cumulative Probability Plot of DG and D	157
Figure 14-9: DG Variogram Models for the UC-LG Zone	158
Figure 14-10: DG Variogram Models for the UC-HG1 Zone	159
Figure 14-11: DG Variogram Models for the UC-HG2 Zone	160
Figure 14-12: DG Variogram Models for the UC-HG3 North and South (combined) Zones	161
Figure 14-13: UC Zones Swath Plot of %U Along Strike – X Direction (HG – Left, LG – Right)	171
Figure 14-14: UC Zones Swath Plot of %U Across Strike – Y Direction (HG – Left, LG – Right)	171
Figure 14-15: UC Zones Swath Plot of %U – Z Direction (HG – Left, LG – Right)	172
Figure 14-16: Plan View of the Classification of UC Zone Mineral Resources	173
Figure 14-17: Longitudinal View of Resource Categories for All Zones (looking West)	174
Figure 14-18: Single Element Density Correlation for Uranium	182
Figure 14-19: 40 m Plan Section with Structures Relative to Midwest A Mineralization (LG = Purple, HG = Red)	183
Figure 14-20: 10 m Vertical Section Looking SW Showing Structures and the Unconformity Relative to Mineralization at 555,250 UTM East	184

Figure 14-21: Plan View of LG Zone (Purple) with Internal HG Zone (Red)	186
Figure 14-22: 10 m Vertical Section Looking SW Showing Sample Grades Relative to Block Grades	187
Figure 14-23: Cumulative Probability Plot of DG for the LG Zone	189
Figure 14-24: Cumulative Probability Plot of Density for the LG Zone	190
Figure 14-25: Cumulative Probability Plot of DG for the HG Zone	190
Figure 14-26: Cumulative Probability Plot of Density for the HG Zone	191
Figure 14-27: Directional Variograms and Models for LG Zone for DG	192
Figure 14-28: Directional Variograms and Models for LG Zone for Density	193
Figure 14-29: Omni Directional Variogram and Model for HG Zone for DG	194
Figure 14-30: Omni Directional Variogram and Model for HG Zone for Density	195
Figure 14-31: Oblique Northwest View of Low-Grade Domain and Search Ellipsoid in Midwest A Zone	196
Figure 14-32: Classification of Mineral Resources for Midwest A – Plan View	201
Figure 14-33: Classification of Mineral Resources for Midwest A – Long section (325 Azi)	201
Figure 14-34: Midwest A Grade-Tonnage Sensitivity Curve	203
Figure 14-35: Midwest A Sensitivity of Contained Pounds U₃O₈ to Cut-off Grade	203
Figure 14-36: Plan View of the Midwest UC Lenses (2018 versus 2024)	210
Figure 16-1: Midwest Main Mining Phases	214
Figure 16-2: Boxplot of Descriptive Statistics of Measured Permeability at Test Spots on Drill Core Using Pressure-decay Permeameter Probe	221
Figure 16-3: Conceptual 5-Spot ISR Wellfield Design	223
Figure 16-4: Isometric View of Freeze Wells and ISR Wells	224
Figure 16-5: Location of Historic Exploration Drift in Midwest Main Deposit: a) Plan View and b) Cross-Section Looking North, in Relation to Proposed Freeze Holes	226
Figure 16-6: Typical Recovery Well Design	229
Figure 16-7: Midwest Main Site and ISR Wellfield Layout	231
Figure 16-8: Midwest Deposit Overall Production	233
Figure 16-9: Midwest Project Phases	234
Figure 17-1: Mill Process Overview	239
Figure 17-2: Location of Nearby Deposits in the Athabasca Basin	242
Figure 20-1: Mink Arm of South McMahon Lake, Showing Location of the Mink Arm Dam	258
Figure 21-1: Milestone Project Schedule	265
Figure 22-1: 100% Project U₃O₈ Production	272
Figure 22-2: 100% Project Cash Flow Pre-Tax & After Tax	279
Figure 22-3: Sensitivity Analysis – 100% Project After Tax	281
Figure 22-4: Impact of MRMR on NPV – 100% Project Pre-tax and Post-tax	282
Figure 22-5: Impact of MRMR on IRR – 100% Project Pre and Post Tax	283
Figure 22-6: Impact of Mining Recovery on NPV – 100% Project After Tax	283
Figure 22-7: Impact of Mining Recovery on IRR – 100% Project After Tax	284

Table 1-1: Total Mineral Resources at 0.085% U Cut-off	21
Table 1-2: Composite Sample Characteristics	22
Table 1-3: Composite Uranium Recovery per Cycle	23
Table 1-4: Capital Cost Summary (CA$ 000’s)	34
Table 1-5: Operating Cost Summary	35
Table 1-6: 100% Project Cash Flow Evaluation	36
Table 1-7: 100% Project DCF Metrics	37
Table 4-1: Midwest Project – Land Status Summary	50
Table 7-1: Description of HGUs Characteristic to the Midwest Main Deposit	76
Table 10-1: Midwest Property Drilling Summary (Historic)	89
Table 10-2: Midwest Property Drilling Summary (Conducted by or on Behalf of Denison)	91
Table 11-1: Sample Designations and Methodology	110
Table 13-1: Summary of Composite Sample Features	130
Table 13-2: Assays for Uranium, Gold and Other Constituents for the Five Studied Composites used for Leaching Tests	130
Table 13-3: Composite Sample Characteristics	132
Table 13-4: Composite Uranium Recovery per Cycle	133
Table 14-1: Summary of Parts or Entire Drillholes not used in Estimate	137
Table 14-2: Sample Statistics by Zone for Uranium (%U) – Density x Length Weighted	149
Table 14-3: Composite Statistics by Zone	151
Table 14-4: Declustered Statistics – Density x Length Weighted	153
Table 14-5: Capping Level of Composites	153
Table 14-6: Comparison of Composites Before and After Capping (length weighted only)	154
Table 14-7: Summary of Variogram Parameters (in Vulcan convention)	162
Table 14-8: Comparison of Triangulation Volumes to Block Model Volumes	163
Table 14-9: Estimation Parameters	166
Table 14-10: High-Grade Restrictions During Estimation	166
Table 14-11: Comparison of Capped and Declustered Composite Statistics to Best Estimate Statistics (OK for Unconformity Zones and ID2 for Basement and Perched Zones)	168
Table 14-12: Comparison of Estimation Techniques	168
Table 14-13: Cut-Off Grade Sensitivity (Declared Cut-Off Grade is 0.085% U)	175
Table 14-14: Sample Statistics by Zone	188
Table 14-15: Composite Statistics by Zone	188
Table 14-16: Midwest A Estimation Parameters	197
Table 14-17: Summary of Sensitivity Analyses Conducted with Preferred Scenario Highlighted	198
Table 14-18: Comparison of Composites to Ordinary Kriged Estimate Statistics	199

Table 14-19: Comparison of Estimation Techniques	199
Table 14-20: Comparison of Triangulation Volumes to Block Model Volumes	200
Table 14-21: Cut-Off Grade Sensitivity (Chosen Cut-Off Grade is 0.085% U)	202
Table 14-22: Total Resources at 0.085% U Cut-off	206
Table 14-23: Comparison of 2024 Estimate to Previous Estimate	209
Table 14-24: Comparison to 2008 Geostat Estimate for Midwest A	211
Table 16-1: Midwest Production Rate Assumptions	232
Table 17-1: Midwest Composite Bottle Roll Leach Tests	244
Table 17-2: Recovery and Production Data	244
Table 21-1: Capital Cost Summary (CAD$ 000’s)	264
Table 21-2: Capital Cost Summary (CAD$ 000’s)	265
Table 21-3: Sustaining Capital Cost Summary (CAD$ 000’s)	267
Table 21-4: Operating Cost Summary	268
Table 22-1 - Taxes Included in the Full Project “After-Tax” Case	271
Table 22-2: 100% Project Production	272
Table 22-3: 100% Project Operating Costs	273
Table 22-4: 100% Project Capital Costs	274
Table 22-5: Midwest 100% Project After Tax Annual Cash Flow Model	277
Table 22-6: 100% Project Cash Flow Evaluation	278
Table 22-7: 100% Project DCF Metrics	279
Table 22-8: Sensitivity Analysis – 100% Project After Tax	280
Table 22-9: Price Variance – 100% Project After Tax	281

				Tonnage		Grade		Metal		Metal		Denison’s Share
Deposit	Category	Zone		(kt)		(% U)		(tonnes U)		(Mlbs U₃O₈)		(Mlbs U₃O₈)
	Indicated		UC		510		2.92		14,900		38.7		9.7
Midwest			UC		389		0.80		3,100		8.1		2.0
Main	Inferred		PER		449		0.36		1,600		4.1		1.0
			BSMT		67		0.30		200		0.4		0.1
	Indicated		LG		566		0.74		4,200		10.8		2.7
Midwest A	Inferred		LG		43		0.23		100		0.4		0.1
			HG		10		24.00		2,400		6.4		1.6
	Total Indicated				1,076		1.78		19,100		49.5		12.5
	Total Inferred				958		0.77		7,400		19.4		4.9

Composite	# of Samples	Uranium % (%U)	Arsenic %	Nickel %
1	23	2.1	5.6	2.4
2	7	9.2	10.2	5.1

Cycle #	Composite 1 Uranium Recovery (%)	Composite 1 UBS Uranium Concentration (g/L)	Composite 2 Uranium Recovery (%)	Composite 2 UBS Uranium Concentration (g/L)
1	19.3	5.38	2.8	2.11
2	32.4	2.12	13.8	6.31
3	42.3	1.65	22.0	4.57
4	57.3	2.56	33.5	6.60
5	69.9	2.09	44.2	5.74
Washate	78.3	0.57	51.6	1.79
Overall Recovery	80.3	-	66.6	-

Description	Initial ^{Note 1}		Sustaining		Total
ISR Wellfield		95,630		239,254		334,884
Milling (McClean Mill Modifications)		2,860				2,860
McClean Lake Sustaining Capital				37,400		37,400
Surface Facilities		1,612				1,612
Utilities		884				884
Electrical		11,249				11,249
Civil & Earthworks		46,298		39,735		86,033
Road Upgrades (Midwest to McClean)		1,223				1,223
SaskPower Line to Midwest		2,860				2,860
Surface Mobile Equipment		1,827				1,827
Remediation				86,849		86,849
Demolition				21,570		21,570
Contractor Direct Field Support Costs		12,333		5,393		17,726
Subtotal Direct Costs		176,776		430,201		606,977
Project Indirect Costs		18,816		6,651		25,467
Subtotal Direct + Indirect Costs		195,592		436,852		632,444
Contingency		58,677		10,084		68,761
Total Capital Cost (CAD$ 000's)		254,629		446,936		701,205

Operating Cost Summary	100% Project		Mill Feed		Recovered 98.5%
Midwest Main Deposit	CAD$1,000		CAD$/lb U₃O₈		CAD$/lb U₃O₈
OpEx – Mining		106,490		2.846		2.889
Opex – Milling		430,375		11.500		11.675
Opex – Transport, Weigh, Assay (Converter)		19,703		0.526		0.534
Opex – G&A Site Support		3,958		0.106		0.107
Opex – G&A Administration and Other		19,736		0.527		0.535
Total Opex		580,262		15.505		15.741

Mill Processing Costs		374,239		10.000		10.152
Mill Toll		56,136		1.500		1.523
Milling Total		430,375		11.500		11.675

Transport to Converter - CAD$/lb		7,741		0.207		0.210
Converter Weighing, Sampling & Assaying		11,962		0.320		0.325
Transport Total		19,703		0.526		0.534

Applicable pounds of U₃O₈				37,423,944		36,862,585

Cash Flow Evaluation 100% Project
Project Cash Flow Summary	From Yr -2
	C$1000
U3O8 Revenue		3,981,159
Opex - Mining		-106,490
Opex - Milling		-430,375
Opex - Transport, Weigh, Assay re Convertor		-3,958
Opex - G&A Site Support		-21,148
Opex - G&A Admin / Other		-19,703
Operating Cash Flow with Tolling		3,399,485
Saskatchewan Resource Surcharge		-118,844
Saskatchewan Basic Royalty		-168,362
Operating Cash Flow With Basic Royalties		3,112,280
Capex - Project Evaluation / Development (Pre-FID)		0
Capex - Off-Site Infrastructure		-4,083
Capex - Surface Infrastructure / Mining / Milling		-566,574
Capex - Decommissioning		-130,546
Project Total Cash Flow - Pre-Tax		2,411,075
Sask. Profit Based Tiered Royalty - Midwest		-389,756
Fed. / Prov. Income Tax - Midwest		-571,100
Project Total Cash Flow - After Tax		1,450,219

100% Projct DCF Metrics
DCF Metrics			Project	Project
Midwest Project			"Pre-Tax"	After Tax
IRR		%	111.1%	82.7%
Payback		Years	0.5	0.7
NPV	0.0%	C$1000	2,411,075	1,450,219
NPV	8.0%	C$1000	1,618,018	964,268
U3O8 Wtd Avg Price			80.00	US$/lb
			108.00	C$/lb

Abbreviation	Description
%	Percent
°	degree (degrees)
°C	degrees Celsius
µm	micron or micrometre
CAD	Canadian dollar
cm	Centimetre
cm2	square centimetre
cm3	cubic centimetre
cps	counts per second
Denison	Denison Mines Corp.
eU	equivalent uranium
eU₃O₈	equivalent uranium oxide
g	Gram
ha	Hectares
HADD	Harmful Alteration, Disruption or Destruction of Fish
ICP	inductively coupled plasma emission spectroscopy, an analytical procedure
ID2	inverse-distance squared, an estimation methodology
ID3	inverse-distance cubed, an estimation methodology
kg	Kilograms
km	Kilometre

Abbreviation	Description
kt	thousand tonnes
l	Litre
lb	Pound
M	Million
m	Metre
m2	square metre
m3	cubic metre
Ma	million years
mL	Millilitre
mm	Millimetre
mPa.s	millipascal seconds
m a.s.l.	metres above sea level
MeV	mega-electron volt
NWPA	Navigable Waters Protection Act
KWULP	Korea Waterbury Uranium Limited Partnership
KHNP	Korea Hydro & Nuclear Power
NI 43-101	Canadian National Instrument 43-101
ppm	parts per million
REE	Rare Earth Elements
RQD	Rock Quality Description
s	Second
SAR	Species at Risk
SG	specific gravity
SRC	Saskatchewan Research Council
t	tonne (metric ton) (2,204.6 pounds)
U	Uranium
%U	percent uranium (% U x 1.179 = % U₃O₈)
U₃O₈	uranium oxide (% U₃O₈ x 0.848 = % U)
% U₃O₈	percent uranium oxide
UBS	uranium bearing solution
USD	U.S. Dollar
UTM	Universal Transverse Mercator
WLULP	Waterbury Lake Uranium Limited Partnership
XRD	x-ray diffraction, an analytical procedure
yr	year

Claim/Lease Number	Size (ha)	Annual Assessment		Excess Credit		Recorded Date	Lapse Date	Good Standing Date
ML 5115	556		$41,700.00		$695,000.00	1973-12-02	2044-12-01	2045-03-01
ML 5264	446		$33,450.00		$635,550.00	1978-12-02	2043-12-01	2044-02-29
ML 5265	424		$31,800.00		$31,800.00	1978-12-02	2043-12-01	2044-02-29
Total:	1,426		$106,950.00		$1,934,750.00

Period	Operator	Summary
1969-1977	Numac Oil & Gas	Initial operator performed regional airborne radiometric surveys, lake sample surveys, radioactive sandstone boulder train surveys, ground reflection seismic, magnetic, VLF-EM, gravity, and AFMAG geophysical surveys, and drilling to unsuccessfully evaluate a mineralized boulder trend. The program generally used shallow drill holes which had a maximum depth of <50 metres and did not reach the sub-Athabasca unconformity.

1977-1987	Esso Resources	The new operator subsequently discovered the Midwest deposit during the 1977 drill program. Further geophysics and drilling to the NE and SW along the main EM-defined conductor were carried out to evaluate the unconformity-type U model.

1987-1994	Denison (PNC conducted exploration)	The project operator performed an EM-37 survey, geotechnical drilling on the Midwest deposit, as well as test mining in the vicinity of the deposit (1988-1989). Exploration drilling was conducted to the east (1988) and along the conductive trend to the north of main deposit (1989).

1994-Current	COGEMA/AREVA/Orano	Active exploration on the Midwest property was resumed in 2005 and resulted in the discovery of the Midwest A (Mae) deposit within the northern lease (ML 5264). Additional geophysical programs were conducted, as was preliminary drill testing of the southern claim (ML 5265).

		No new drilling has been completed on Midwest A since 2008.

		The majority of the drilling for the Midwest Main Zone was undertaken from 1970 to 2006 with some additional drilling in 2018, 2021, and 2024.

	Sandstone, conglomerate
	M1A	Sandstone friable by leaching, poorly cemented
	M1B	Clayey-sand, sandy-clay (intense alteration)
	M1C	Sand grains darkened, coated with sooty sulphides along fractures
	M1D	Sand soaked by hydrocarbon-like alteration (friable/permeable)
	M1E	Sandstone with redox front coloration
	Rocks altered with Ni-As-S or with U mineralization
	M2A	Ni sulfarsenides/arsenides with clayey sand (U content none to low)
	M2B	Low to high-grade U ore as dispersed pitchblende aggregates in Ni-As-S / Ni-As + clay
	M2C	High-grade U ore as pitchblende enveloped by crystalline Ni-As-S / Ni-As
	M2D	High grade U ore as pitchblende in clay
	Basement rock
	M3A	High-grade U in regolith as patchy black pitchblende within red hematite-rich clayey rock
	M3B	Basement rocks (intense mica/clay alteration, leaching)
	M3C	Regolith hematite-rich zone, or hematite-stained leached zone

Company	Year/Region	Metres	# of Holes	Drilling Info	Comments
	1970	1,231.0	11
	Exploration	1,231.0	11	Unknown	Exploration drilling. No drillholes reached basement. No uranium mineralization was discovered.
	1971	1,690.2	91
Esso	Exploration	954.4	51	BQ-size; vertical &	Exploration drilling. No drillholes reached basement.
	Midwest-Main	735.8	40	inclined	No uranium mineralization was intersected.
	1975	800.1	25
	Exploration	800.1	25	AQ-size; inclined	Exploration drilling. No drillholes reached basement. No radioactivity higher than background was detected in the core.
	1977	930.6	3

	Midwest-Main	930.6	3	NQ-size; vertical	Exploration drilling targeting the pre-Athabasca unconformity. Drillhole 77-2 intersected weak uranium mineralization in unconsolidated sand located in a steeply dipping sheared zone above the unconformity.
	1978	39,784.7	179
	Exploration	17,628.6	79	NQ-size; vertical & inclined	Exploration drilling assessing the significance of the weak mineralization intersected in 1977 led to the discovery of the Midwest Lake deposit. The first drillhole (MW-1) intersected two mineralized intervals: 9.5 m at 0.13% U₃O₈ and 1.2 m at 8.73% U₃O₈.
	Midwest-Main	22,156.1	100		Included some geotechnical drillholes.
	1979	35,785.5	170
	Exploration	11,598.3	58		Delineation drilling for mineralization definition as well as additional exploration and geotechnical drilling.
	Midwest-A	3,535.7	16	NQ-size; vertical	First mineralized occurrences in the Midwest A area were intersected
	Midwest-Main	20,651.5	96		*with the best results encountered in MW-331 (3.27% U over 3 m).**
Canada West Mine Ltd.	1980	26,594.0	121
	Exploration	4,211.9	23		Delineation drilling for mineralization definition as well as additional exploration and geotechnical drilling.
	Midwest-A	3,484.1	15	NQ-size; vertical	Follow-up to the north-east of the encouraging results from 1979 encountered HG mineralization at the
	Midwest-Main	18,898.0	83		Midwest A deposit (termed Mae Deposit at the time). Best intersection was MW-338 (6.51% U over 3.8 m*).
	1981	41,571.4	193
	Exploration	2,611.4	10	NQ & PQ-size;	Delineation drilling for mineralization definition and included
	Midwest-Main	38,960.0	183	vertical	additional exploration and geotechnical drilling.
	TOTAL	148,387.5	793

Company	Year/Region	Metres	# of Holes	Drilling Info	Comments
Denison	1987	241.6	1
	Midwest-Main	241.6	1	NQ-size; vertical	Shaft test drillhole. Started in Dec. 1987, finished in Jan. 1988.
	1988	357.5	14
	Exploration	64.0	5	NQ-size; vertical	An additional shaft test drillhole with hydraulic conductivity and grouting tests performed. A series of short drillholes (0.7 m to 16.4 m in depth) with no information were also completed.
	Midwest-Main	293.5	9	NQ-size; vertical
	1989	2,479.1	20
	Exploration	1,029.2	4	NQ-size; vertical	Mine testing program. Underground geotechnical blind bore holes (BB Series) and extensometer holes (WRM Series). Drilling records are missing for the additional piezometer holes. Several holes drilled within the Midwest A deposit area, but no HG mineralization was intersected. Weak mineralization was found in three holes with the best results encountered in MW-652 (0.05% U over 3 m*).
	Midwest-A	978.7	4
	Midwest-Main	471.1	12
Cogema/AREVA/Orano	2004	1,227.0	4
	Midwest-Main	1,227.0	4	NQ-size; inclined	Geotechnical drilling for pit slope design studies around the provisional open pit margins.
	2005	4,596.0	16
	Exploration	1,080.0	4	NQ & BQ-size; inclined	Exploration drilling focused in the northern area to follow-up sandstone mineralization encountered within historical drilling (MW-338). Intersection of HG sandstone mineralization with several LG zones extending to the unconformity. Best results occurred in MW-662 (1.12% U over 32.2 m*).
	Midwest-A	3,516.0	12	NQ & BQ-size; inclined
	2006	11,132.0	43
	Exploration	507.0	2	HQ, NQ, & BQ-size; vertical and inclined	Exploration drilling focused on basement mineralization targets. Geotechnical drilling to determine waste rock pile geochemistry. Several delineation drillholes following up on the 2005 results in the Midwest-A deposit encountered significant uranium mineralization. Best results were encountered in MW-691 (3.42% combined U/eU over 43.7 m*).
	Midwest-A	9,356.2	34
	Midwest-Main	1,268.8	7
	2007	14,273.0	51
	Exploration	547.6	2	NQ-size; vertical and inclined	Drilling focused on central and SW portions of the Midwest-A deposit. Several new HG intercepts were encountered and three holes contained >10 m of U mineralization with grades locally greater than 10% U. Best results occurred in MW-749 (6.06% combined U and eU over 57.9 m*).
	Midwest-A	13,725.4	49	NQ-size; vertical and inclined
	2008	12,033.5	48
	Exploration	4,410.3	18	NQ-size; vertical and inclined	Drilling focused on the NE and SW extensions of the Midwest A deposit, increasing the extensions of the LG mineralization. Only one hole (MW-766) intersected medium-grade mineralization (0.45% mixed U and eU over 4.6m*).
	Midwest-A	7,623.2	30	NQ-size; vertical and inclined
	2009	8,895.9	34
	Exploration	8,895.9	34	NQ-size; vertical and inclined	Drilling tested prospective targets between Midwest Main and Midwest A. Highlight of the program featured 3.06 % U₃O₈ over 0.6 m from MW-828.
	2018	4,709.0	16
	Exploration	2,269.4	7	HQ & NQ-size; inclined	Investigate the basement potential under the deposit as well as acquiring oriented structural data to confirm geological 3D model interpretations.
	Midwest-Main	2,439.6	9	HQ & NQ-size; inclined
	2021	2,669.0	8
	Exploration	1,946.0	6	HQ & NQ-size; inclined	Drillholes were designed to test for continuity of the high-grade basement mineralization intersected in historic drillhole MW-38 as well as additional exploration to the NW and SE of Midwest Main.
	Midwest-Main	723.0	2	HQ & NQ-size; inclined
	2024	2,213.8	10
	Midwest-Main	2,213.8	10	NQ-sized; vertical	Drillholes targeted the Midwest Main deposit for resource delineation and ISR investigation.
	TOTAL	64,827.3	265

Analyses Type	Sample Type	Description	Sample Methodology
Geochemistry	1SYS	Systematic sandstone	Chip sample taken from the start of every box row. 20 m samples until 100 m above the unconformity. 10 m samples in the basal 100 m sandstone. One metre sample taken directly above the unconformity.
	1SYB	Systematic basement	Chip sample taken from the start of every box row within individual lithological/alteration units (10 m samples). One metre sample taken directly below the unconformity.
	1SYSD/1SYBD	Duplicate	One sample is duplicated within the sandstone and the basement of each drillhole.
	HS	Hand Sample	Selective sample chosen in basement and sandstone in areas of specific interest
	1SEL	Selective sandstone	Split core sample taken every 0.5 m (or less) of intervals with SPPγ radiometry ≥ 200 cps or at points of interest.
	1BAS	Selective basement
Spectral Clay	1TER	Sandstone TerraSpec	Chip sample taken at every 3 m at the run marker. Dark samples and silicified samples avoided. Extra sample taken where an unusual feature is noted.
Spectral Clay	1TERB	Basement TerraSpec
Petrophysics	1MAS	Petrophysical sample	Approx. 10 cm of unbroken and unfractured core taken. Extra analyses (geochemistry, mineralogy, petrography, etc.) may also be completed on these samples.
Petrography	TS	Thin Section	Approx. 10 cm whole core sample taken within each formation/lithology change.

	·	Review of drill core from three representative recently completed drill holes,
	·	Review of drill core from one historic drill hole,
	·	Confirmation of two recent drill hole collar locations,
	·	Attempted confirmation of four historic drill hole collar locations,
	·	Review and verification of the geological setting / environment of the Project,
	·	Review of drilling, logging, sampling, analytical and QA/QC procedures, and
	·	Review of overall site facilities.

Composite Sample #	Number of Individual Samples Included	Total weight (kg)	Sample Source Area
1	45	30.8	Midwest Deposit, holes 2,3,4

Composite Sample	U (%)	Ni (%)	As (%)	Mo (%)	Fe (%)
Composite 1	4.11	4.96	9.28	0.15	5.85

	o	pH / ORP / conductivity
	o	Temperature
	o	Specific gravity
	o	Free acid
	o	Metals assay