Denison Announces Summer Drilling Plans for Wheeler River and Reports Winter Assay Results

TORONTO, June 6, 2018 /PRNewswire/ - Denison Mines Corp. ("Denison" or the "Company") (TSX: DML) (NYSE MKT: DNN) (NYSE American: DNN) is pleased to announce summer 2018 drilling plans, and report assay results from the winter 2018 drilling program, for the Company's 63.3% owned Wheeler River project in northern Saskatchewan. View PDF Version

Summer 2018 Drilling Program

The summer 2018 diamond drilling program for Wheeler River is scheduled to commence this week and is expected to include approximately 20,500 metres in 28 drill holes. The drilling program is planned to focus on the following target areas:

• K-North - Follow-up of high-grade uranium mineralization discovered during the winter 2018 drilling program at 600 metres and 1 kilometre to the northeast of the Gryphon uranium deposit (see Winter 2018 Assay Highlights below).
• High-Priority Regional - Testing of high-priority targets along known fertile trends (Q Central, K-West) and reconnaissance exploration of high-priority targets generated from previous ground geophysical surveys (K-South and Q South).
• Gryphon Unconformity - Testing of targets immediately along strike of the Gryphon deposit at the sub-Athabasca unconformity, including extensions of the E series lenses to the northeast and the up-plunge extents of the D series lenses to the southwest.

Dale Verran, Vice President Exploration of Denison commented, "The summer 2018 drilling program will largely be results driven, focused on high-priority regional targets outside of the immediate Gryphon resource area, and will include both the follow-up of high-grade mineralization and the testing of geophysical anomalies on geologically favourable trends. With 3 drill rigs turning on the project we are looking forward to a productive summer with the potential to deliver the next discovery at Wheeler River."

A location map of the summer 2018 drilling target areas is provided in Figure 1. View Figure 1

Winter 2018 Assay Highlights

Chemical assay ("U₃O₈") results have been received for the Wheeler River winter 2018 drilling program, which included 21,153 metres of drilling in 29 diamond drill holes.  The assay results were on average 26% higher, in terms of combined grade and thickness, than the preliminary equivalent uranium ("eU₃O₈") results reported previously (see Denison's press release dated April 18, 2018).  The program was focused on step-out drilling from the Gryphon deposit and regional exploration along the K-North and K-West trend. 

• Regional Exploration: Assay results confirmed high-grade intercepts from reconnaissance drill holes targeting the sub-Athabasca unconformity, to the northeast of Gryphon, along the K-North trend. Highlight assay results include:

The results confirm the continuation of the Gryphon mineralizing system to the northeast, and highlight the potential for the discovery of an additional high-grade uranium deposit within the basement or at the unconformity along strike of Gryphon.

• Gryphon Exploration: Multiple basement uranium intercepts were confirmed from step-out drilling on 50 to 100 metre centres immediately along strike to the northeast of the Gryphon deposit. Assay highlights from the Gryphon step-out drilling include:

The results confirm potential to continue to expand the Gryphon mineral resource outside of the current extents of the deposit.

Comprehensive drilling tables of composited assay results are provided in Table 1 and 2 below. The location of the drill holes and the highlight assay results are shown in Figure 2. View Figure 2

Table 1: Composited assay results from the winter 2018 regional exploration drilling program.

Table 2: Composited assay results from the winter 2018 Gryphon exploration drilling program.

Sampling and Assay Procedures

Drill core with anomalous total gamma radioactivity (>300 counts per second using a RS-120 or RS-125 scintillometer) was sampled over 0.5 metre intervals. Sampling is undertaken on site by splitting the core in half, with one half submitted for analysis and the other half retained in the core box for future reference. Uranium chemical assays are performed by the Saskatchewan Research Council ("SRC") Geoanalytical Laboratories located in Saskatoon. Sample preparation involves crushing and pulverizing core samples to 90% passing -106 microns. Splits of the resultant pulps are initially submitted for multi-element ICP-MS analysis following partial (HNO₃:HCl) and total (HF:HNO₃:HClO₄) digestions.  Samples with ≥ 1,000 ppm U (partial digest) are re-assayed for U₃O₈ using an ISO/IEC 17025:2005 accredited method for the determination of U₃O₈ weight %. Pulp splits are digested using aqua-regia and the solution analyzed for U₃O₈ weight % using ICP-OES. In addition to internal checks by SRC Geoanalytical Laboratories, the Company has rigorous quality assurance and quality control ("QAQC") procedures including the insertion of standard reference materials, blanks and field duplicates. The assay data is subject to verification procedures by qualified persons employed by Denison prior to disclosure. For further details on the assay, QAQC and data verification procedures please see Denison's Annual Information Form dated March 27, 2018 filed under the Company's profile on SEDAR (www.sedar.com).

Qualified Persons

Dale Verran, MSc, P.Geo, Pr.Sci.Nat., Denison's Vice President, Exploration, who is a Qualified Person in accordance with the requirements of NI 43-101 has reviewed and approved the technical information contained in this release.

About Wheeler River

Wheeler River is the largest undeveloped high-grade uranium project in the infrastructure rich eastern portion of the Athabasca Basin region, in northern Saskatchewan – including combined Indicated Mineral Resources of 132.1 million pounds U₃O₈ at an average grade of 3.3% U₃O₈, plus combined Inferred Mineral Resources of 3.0 million pounds U₃O₈ at an average grade of 1.7% U₃O₈.  The project is host to the high-grade Gryphon and Phoenix uranium deposits (discovered by Denison in 2014 and 2008, respectively), and is a joint venture between Denison (63.3% and operator), Cameco Corp. ("Cameco") (26.7%), and JCU (Canada) Exploration Company Limited ("JCU") (10%). 

A Pre-Feasibility Study ("PFS") was initiated for the Wheeler River project in Q3'2016 and is expected to be completed during 2018. Prior to initiation of the PFS, a Preliminary Economic Assessment ("PEA") was completed in 2016, which considered the potential economic merit of co-developing the high-grade Gryphon and Phoenix deposits as a single underground mining operation. The PEA returned a base case pre-tax Internal Rate of Return ("IRR") of 20.4% based on the then current long term contract price of uranium (US$44.00 per pound U₃O₈), and Denison's share of estimated initial capital expenditures ("CAPEX") of CAD$336M (CAD$560M on 100% basis). 

The PEA is preliminary in nature and includes inferred mineral resources that are considered too speculative geologically to have the economic considerations applied to them to be categorized as mineral reserves, and there is no certainty that the preliminary economic assessment will be realized. Mineral resources are not mineral reserves and do not have demonstrated economic viability.

In January, 2017, Denison entered into an agreement with its Wheeler River Joint Venture partners, Cameco and JCU, to fund 75% of Joint Venture expenses in 2017 and 2018 (ordinarily 60%) in exchange for an increase in Denison's interest in the project to up to approximately 66%. Under the terms of the agreement, Cameco will fund 50% of its ordinary 30% share in 2017 and 2018, and JCU is expected to continue to fund its 10% interest in the project. Pursuant to the agreement, as at December 31, 2017, Denison had increased its interest in the Wheeler River project from 60% to 63.3%.

Further details regarding the Wheeler River project are provided in the NI 43-101 Technical Report for the Wheeler River project titled "Technical Report with an Updated Resource Estimate for the Wheeler River Property, Northern Saskatchewan, Canada" dated March 15, 2018 with an effective date of March 9, 2018.   A copy of this report is available on Denison's website and under its profile on SEDAR at www.sedar.com and on EDGAR at www.sec.gov/edgar.shtml.

About Denison

Denison is a uranium exploration and development company with interests focused in the Athabasca Basin region of northern Saskatchewan, Canada. In addition to its 63.3% owned Wheeler River project, which ranks as the largest undeveloped high-grade uranium project in the infrastructure rich eastern portion of the Athabasca Basin region, Denison's Athabasca Basin exploration portfolio consists of numerous projects covering approximately 353,000 hectares. Denison's interests in Athabasca Basin also include a 22.5% ownership interest in the McClean Lake joint venture ("MLJV"), which includes several uranium deposits and the McClean Lake uranium mill, which is currently processing ore from the Cigar Lake mine under a toll milling agreement, plus a 25.17% interest in the Midwest and Midwest A deposits, and a 65.45% interest in the J Zone deposit and Huskie discovery on the Waterbury Lake property. Each of Midwest, Midwest A, J Zone and Huskie are located within 20 kilometres of the McClean Lake mill.

Denison is also engaged in mine decommissioning and environmental services through its Denison Environmental Services division and is the manager of Uranium Participation Corp., a publicly traded company which invests in uranium oxide and uranium hexafluoride.

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Cautionary Statement Regarding Forward-Looking Statements

Certain information contained in this press release constitutes "forward-looking information", within the meaning of the United States Private Securities Litigation Reform Act of 1995 and similar Canadian legislation concerning the business, operations and financial performance and condition of Denison. Generally, these forward-looking statements can be identified by the use of forward-looking terminology such as "plans", "expects", "budget", "scheduled", "estimates", "forecasts", "intends", "anticipates", or "believes", or the negatives and/or variations of such words and phrases, or state that certain actions, events or results "may", "could", "would", "might" or "will be taken", "occur", "be achieved" or "has the potential to". In particular, this press release contains forward-looking information pertaining to the following: exploration (including drilling) and evaluation activities, plans and objectives; potential mineralization of drill targets and identified trends; estimates of Denison's mineral resources and the results of its PEA; plans and objectives with respect to preparing a PFS to assess on a preliminary basis the potential for mine development an whether to proceed with a detailed feasibility study; and Denison's percentage interest in its properties and its plans and agreements with its joint venture partners, as applicable.  Statements relating to "mineral reserves" or "mineral resources" are deemed to be forward-looking information, as they involve the implied assessment, based on certain estimates and assumptions that the mineral reserves and mineral resources described can be profitably produced in the future.

Forward looking statements are based on the opinions and estimates of management as of the date such statements are made, and they are subject to known and unknown risks, uncertainties and other factors that may cause the actual results, level of activity, performance or achievements of Denison to be materially different from those expressed or implied by forward-looking statements. Factors, such as environmental impacts, stakeholder approvals, and capital needs can significant alter plans and achievements.  Denison believes that the expectations reflected in this forward-looking information are reasonable but no assurance can be given that these expectations will prove to be accurate and may differ materially from those anticipated in this forward looking information. For a discussion in respect of risks and other factors that could influence forward-looking events, please refer to the factors discussed in Denison's Annual Information Form dated March 27, 2018 under the heading "Risk Factors". These factors are not, and should not be construed as being exhaustive. Accordingly, readers should not place undue reliance on forward-looking statements.

The forward-looking information contained in this press release is expressly qualified by this cautionary statement. Any forward-looking information and the assumptions made with respect thereto speaks only as of the date of this press release. Denison does not undertake any obligation to publicly update or revise any forward-looking information after the date of this press release to conform such information to actual results or to changes in Denison's expectations except as otherwise required by applicable legislation.

Cautionary Note to United States Investors Concerning Estimates of Measured, Indicated and Inferred Mineral Resources: This press release may use the terms "measured", "indicated" and "inferred" mineral resources. United States investors are advised that while such terms are recognized and required by Canadian regulations, the United States Securities and Exchange Commission does not recognize them. "Inferred mineral resources" have a great amount of uncertainty as to their existence, and as to their economic and legal feasibility. It cannot be assumed that all or any part of an inferred mineral resource will ever be upgraded to a higher category. Under Canadian rules, estimates of inferred mineral resources may not form the basis of feasibility or other economic studies.  United States investors are cautioned not to assume that all or any part of measured or indicated mineral resources will ever be converted into mineral reserves. United States investors are also cautioned not to assume that all or any part of an inferred mineral resource exists, or is economically or legally mineable.

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