RK-25-254 and RK-25-256 (both intersecting 2.0 and 2.1 m of off-scale (>61,000 cps)) are located 51 m and 119 m away from RK-25-232 (15 m at 15.9% U₃O₈).

Results highlight the repetition of upgrading high-grade shoots within growing mineralized footprint.

The following new holes intersected broad intercepts of cumulative mineralization (>500cps):

• RK-25-246: 20.5m including 2.5m >10,000cps
• RK-25-247: 18.0m including 2.5m >10,000cps
• RK-25-251: 9.5m
• RK-25-254: 19.5m including 5.0m >10,000cps including 2.0m >61,000cps
  RK-25-256: 10.0m including 3.3m >10,000cps including 2.1m >61,000cps

NexGen Energy Ltd. (TSX: NXE) (NYSE: NXE) (ASX: NXG) is pleased to announce continued exciting results from the summer drill program at the rapidly advancing PCE. Step-out holes RK-25-254 and RK-25-256 intersected 2.0 m and 2.1 m of cumulative >61,000 counts per second (cps), respectively, located 51 m up-dip and 119 m down-dip of PCE’s best hole to date, RK-25-232 (Figures 1 and 2). These represent the best holes from the summer program to date and validate the growth in high-grade continuity. Overall, an upgraded high-grade shoot plunges a minimum 200 m from RK-25-254 to RK-24-222 as part of an emerging interpreted pattern of high-grade shoots spaced 70 m apart (Figures 2 and 3).

Depth of the intense high-grade in RK-25-254, at just 454.4 m depth, ranks among the shallowest intersections of massive uranium ever drilled by NexGen. Mineralization is open 300 m up-dip and completely contained in the competent basement rock, consistent with Arrow. Strong continuity of grade across the mineralized footprint is consistent with Arrow’s basement-hosted uranium veins.

Drilling is also extending deeper where strongly developed alteration and structural disruption persist as key indicators of additional mineralization. Further significant expansion potential at PCE remains with mineralization open in most directions.

A total to 21,968.9 m of the planned 43,000m program has been drilled in 2025. Since discovery (see March 11, 2024, news release), 79 drillholes totalling 53,088.9 m have been completed (Figure 4). High-grade growth and overall mineralized extent are the focus with many more targets to be tested across this rapidly developing and growing high-grade system. 48 of the 79 drillholes are mineralized, including 34 intersecting high-grade (>10,000 cps) and 14 intersecting off-scale (>61,000 cps).

Leigh Curyer, Chief Executive Officer, commented: “This program is delivering exactly what we look for in a generational uranium discovery, basement-hosted significant mineralized system, continuity of high-grade mineralization, and growth potential. PCE is evolving in real time into a world-class system in its own right. NexGen’s highly prospective land package continues to demonstrate exciting results and unmatched opportunity for Canada to take its place as the number one source of uranium in the world.”

Jason Craven, Vice President, Exploration, commented: “NexGen’s summer drill program is off to a fantastic start. PCE continues to deliver intense high-grade uranium at shallower depths than the world class Arrow deposit only 3.5km away. Early summer drilling results are building on emerging interpretations that include systematic repetition of high-grade shoots within the overall mineralized footprint, indicating potential for significant expansion at PCE.”

Figure 1: RK-25-254 and RK-25-256 core photos of focused vein intercepts 170 m apart from one another, each having 2 m of massive replacement style uranium mineralization, with elevated radioactivity above and below what is shown; yellow outlines >1,000 cps, red outlines >10,000 cps, >61,000 cps outlined in purple.

 Figure 2: Close-up of long section view of PCE high-grade subdomain around RK-25-232 (15.0 m at 15.9% U₃O₈)

 Figure 3: Interpreted model of mineralization at PCE (as of this release) with newly interpreted high-grade shoots shown; view is a long section that looks perpendicular to the primary mineralized plane; total mineralized footprint in orange and the high-grade subdomains in red

 Figure 4: Interpreted 3D model of PCE shown looking northwest (across strike) and northeast (along strike)

Table 1: 2025 Spectrometer results from summer drilling

• All depths and intervals are meters downhole, true thicknesses are yet to be determined.
• “Off-scale” refers to >61,000 cps (counts per second) readings by gamma spectrometer type RS-125.
• “Anomalous” means >500 cps readings by gamma spectrometer type RS-120.
• Where “CPS Range” is <500 cps, this refers to local low radioactivity within the overall interval.
• Unconformity of ‘N/A’ denotes a lack of visible contact between Athabasca sandstone and basement rock.
• Maximum internal dilution 2.0 m downhole.
• All depths and intervals are meters downhole, true thicknesses are yet to be determined. Resource modelling in conjunction with an updated mineral resource estimate is required before true thicknesses can be determined.

About NexGen

NexGen Energy is a Canadian company focused on delivering clean energy fuel for the future. The Company’s flagship Rook I Project is being optimally developed into the largest low-cost producing uranium mine globally, incorporating the most elite environmental and social governance standards. The Rook I Project is supported by an N.I. 43-101 compliant Feasibility Study, which outlines the elite environmental performance and industry-leading economics. NexGen is led by a team of experienced uranium and mining industry professionals with expertise across the entire mining life cycle, including exploration, financing, project engineering and construction, operations and closure. NexGen is leveraging its proven experience to deliver a Project that leads the entire mining industry socially, technically and environmentally. The Project and prospective portfolio in northern Saskatchewan will provide generational, long-term economic, environmental, and social benefits for Saskatchewan, Canada, and the world.