NexGen Announces 64% Increase in Average Annual After-tax Cash Flow in Pre-Feasibility Study, After Tax NPV of $3.7BN, 43% Increase in Indicated Resources, and Initiates the Largest Drill Campaign in Company’s History to Expedite Arrow to Feasibility

NexGen Announces 64% Increase in Average Annual After-tax Cash

Flow in Pre-Feasibility Study, After Tax NPV of $3.7BN, 43% Increase

in Indicated Resources, and Initiates the Largest Drill Campaign in

Company’s History to Expedite Arrow to Feasibility

VANCOUVER, November 5 , 201 8 - NexGen Energy Ltd. ("NexGen" or the "Company") (TSX:NXE,

NYSE:NXE) is pleased to announce the results of an independent Pre-Feasibility Study ("PFS” or the

“Study") and Mineral Resource update of the basement-hosted Arrow Deposit, located on the Company's

100% owned Rook I project (“Arrow” or the “Project”) in the Athabasca Basin in Saskatchewan, Canada.

The PFS was completed jointly by Wood Group, and Roscoe Postle Associates Inc. ("RPA"), with other

technical inputs completed by sub-consultants.

Pre-Feasibility Study Highlights

Table 1 – Summary of Arrow Deposit Pre-Feasibility Study (based on US $50/lb U3O8)

PEA (July 31, 2017) PFS Variance

After-Tax Net Present Value (8% discount) CAD $3.49 Billion CAD $3.7 Billion +6%

After-Tax Internal Rate of Return (IRR) 56.7% 56.8% -

After-Tax Payback 1.1 Years 1.2 Years +9%

Initial Capital Costs (“CAPEX”) CAD $1.19 Billion CAD $1.25 Billion +5%

Average Annual Production (Life of Mine) 18.5 M lbs U3O8 25.4 M lbs U3O8 +37%

Average Annual Production (Years 1-5) 27.6 M lbs U3O8 29.0 M lbs U3O8 +5%

Average Daily Throughput 1,448 tonnes per day 1,039 tonnes per day -28%

Average Annual Grade 1.73% U3O8 3.09% U3O8 +79%

Mine Life 15 Years 9 Years -6 years

Average Annual After -Tax Net Cash Flow

(Life of Mine) CAD $553 Million CAD $909 Million +64%

Average Annual Operating Cost (“OPEX”,

Life of Mine)

CAD $8.37

(US $6.70)/lb U3O8

CAD $ 5.81

(US $4.36)/lb U3O8 -31%

Operating Margins (Life of Mine) 85.5% 90.6% +6%

Note: PEA based on CAD $1.00 = US $0.80, PFS based on CAD $1.00 = US $0.75

1) CAPEX – Increased due to the introduction of Provincial Sales Tax (PST) applicable to capital

projects. Excluding PST, initial capital costs reduce d by approximately CAD $64 Million to CAD

$1.18 Billion (0.5% lower than PEA). Additionally, due to the reallocation of tailings management

to operating costs, the sustaining capital component of capital expenditures has been significantly

reduced.

2) Mine Life - PFS is based on Indicated Resources only and does not include the current additional

Inferred Resources 91.70 M lbs of U3O8 contained in 4.84 M tonnes grading 0.86% U3O8 or

further potential increases in the resource base at Arrow that remains open in many directions

(Figure 1).

Leigh Curyer, Chief Executive Officer, commented: "An assessment across all of the PFS metrics, results in

a substantial improvement to the PEA with a 64% increase in average annual after tax net cash flow.

Incorporating only the Indicated Mineral Resource, the life of mine drops from 15 to 9 years, yet the

increase in average annual grade - whilst maintaining a consistent capex and lower opex - results in an

after tax NPV of $3.7BN. In addition, the 43% increase in Indicated Mineral Resource growth during 2017

demonstrates with closer spaced drilling, Arrow improves and optimizes mine production plans.

With these strong PFS results, the Company is expediting Arrow to Feasibility by initiating a 2 stage

125,000m (10 rig) high density drilling program. This will be the largest drilling , geotechnical and

hydrogeological focused program in the history of NexGen. Preparations are well underway with the

program brought forward and scheduled to commence in early December 2018.

I would like to take t he opportunity to congratulate the entire NexGen team, key consultants, local

communities and Government departments for their outstanding commitment and execution of Arrow’s

development.”

Conference Call

NexGen will host a conference call today, Monday November 5, 2018 at 11.00 AM Eastern Standard

Time.

To join the call please dial (+1) 416 764 8688 (local/international) or (+1) 888 390 0546 (North America

toll free) with passcode 49399985 and an operator will assist.

A recorded version of the proceedings will be available on NexGen’s website ( www.nexgenenergy.ca)

shortly after the conference. The playback numbers are (+1) 416 764 8677 (local/international) and (+1)

888 390 0541 (North America toll free) and the playback passcode is 399985 #. The playback will be

available until Tuesday, February 05, 2019.

Figure 1 – Arrow Mine Plan in relation to Inferred Resources (Long Section)

Note: Red Arrows reference Inferred Resources not included in the PFS mine plan.

Table 2 – PFS Sensitivity to Uranium Price

Uranium Price ($ USD/lb U3O8) After-Tax NPV8 After-Tax IRR After-Tax Cash Pay Back

$80/lb U3O8 CAD $6.62 Billion 80.4% 0.8 Years

$60/lb U3O8 CAD $4.65 Billion 65.5% 1.0 Years

$50/lb U3O8 CAD $3.66 Billion 56.8% 1.2 Years

$40/lb U3O8 CAD $2.67 Billion 46.9% 1.5 Years

$30/lb U3O8 CAD $1.69 Billion 35.6% 1.9 Years

$25/lb U3O8 CAD $1.19 Billion 28.9% 2.3 Years

Figure 2 – Arrow Undiscounted Cumulative After-Tax Cash Flow

Key Updates of the 2018 PFS from the 2017 PEA

• Reduction in CAPEX due to a reduced mine footprint as a result of higher head grades and also

the reallocation of the underground tailings to operating costs. If the recently introduced PST is

ignored for an apples-to-apples comparison on capital cost estimates from the PEA to the PFS, the

PFS capital cost would be even lower.

• 31% reduction in average annual OPEX to CAD $5.81/lb U3O8(from CAD $8.37/lb U3O8) despite

the PFS recategorizing the underground tailings to OPEX instead of sustaining capital as per the

PEA. These costs account for 21% of OPEX.

• 43% increase in Indicated Mineral Resources from 179.5 M lb of U3O8 contained in 1.18 M tonnes

grading 6.88% U3O8 from the March 2017 Mineral Resource estimate to 256.6 M lbs of U3O8

contained in 2.89 M tonnes grading 4.03% U3O8.

• Average Annual Production increase from 18.5 M lbs U308 in the PEA to 25.4M lbs U308 due to

higher head grades increasing from 1.73% U308 in the PEA to 3.09 % U3O8 in the PFS.

• Average mining rate decrease from 1,448 tonnes per day to 1,039 tonnes per day.

• Metallurgical pilot plant and bench scale testing optimized recovery resulting in increased total

processing recovery rate to 97.6% versus 96.0% in the PEA.

• Metallurgical process was updated resulting in ammonia being eliminated entirely from the

process which strengthens the environmental performance of the envisioned Rook I Project.

• Metallurgical paste-fill test work confirmed proof of concept for uranium tailings to be used for

cemented paste backfill underground.

• Lateral development reduced from 78,805 metres to 39,908 meters due to a reduced mine

footprint.

• Vertical development was reduced from 3,832 in the PEA to 3,059 due to the elimination of a

fresh air raise which has been redesigned and combined with the primary production shaft.

Mineral Resources

The Arrow Deposit Mineral Resource estimate was updated, and the Indicated Mineral Resources form

the basis for the PFS. The Indicated portion of the resource has increased by 43% from the previous

resource estimate (see News Release dated: March 6, 2017). The updated estimate comprises an

Indicated Mineral Resource of 256.6 M lbs of U3O8 contained in 2.89 M tonnes grading 4.03% U3O8,

including the A2 High Grade Core of 181.0 M lbs of U3O8 contained in 0.46 M tonnes grading 17.85%

U3O8 and an Inferred Mineral Resource of 91.7 M lbs of U3O8 contained in 4.84 M tonnes grading 0.86%

U3O8.

The tonnes, grades, and classification of the Mineral Reserves defined in the PFS mine design are

summarized below in Table 4.

Table 3 - Arrow Mineral Resource Estimate

March 2017 Arrow Mineral Resource Estimate 2018 Arrow Mineral Resource Estimate Diff. Between Arrow 2018 & 2017

Mineral Resource Estimate

Structure

Tonnage

(Tonnes)

Grade

(U3O8%)

Metal

U3O8

(U3O8 lb)

Tonnage

(Tonnes)

Grade

(U3O8%)

Metal U3O8

(U3O8 lb)

Tonnage

(Tonnes)

Grade

(U3O8%)

Metal

U3O8

(U3O8 lb)

Indicated Mineral Resources

A2

790,000 0.84

14,500,000 1,240,000

0.79 21,700,000

450,000 (0.05)

7,200,000

A2 HG

400,000 18.87

164,900,000 460,000

17.85 181,000,000

60,000 (1.02)

16,100,000

A3 No Indicated in 2017 1,010,000

0.70 15,500,000

1,010,000 0.70

15,500,000

A3 HG No Indicated in 2017 180,000

9.68 38,400,000

180,000 9.68

38,400,000

Total:

1,180,000 6.88

179,500,000 2,890,000

4.03

256,600,000

1,700,000 (2.85)

77,200,000

Inferred Mineral Resources

A1

860,000 0.75

14,300,000 1,510,000

0.72 23,900,000

650,000 (0.04)

9,600,000

A2

1,100,000 0.76

18,500,000 1,290,000

0.70 19,900,000

190,000 (0.06)

1,400,000

A2 HG

30,000 13.00

8,600,000 5,000

12.70 1,400,000

(25,000) (0.30)

(7,200,000)

A3

1,460,000 1.16

37,300,000 1,230,000

1.11 30,000,000

(230,000) (0.05)

(7,300,000)

A3 HG

150,000 8.53

28,200,000 1,000

9.07

200,000

(149,000) 0.54

(28,000,000)

A4

550,000 1.06

12,900,000 800,000

0.92 16,300,000

250,000 (0.14)

3,400,000

180

110,000 0.95

2,300,000 Combined into A3 & A4

(110,000) (0.95)

(2,300,000)

Total:

4,260,000 1.30

122,100,000 4,840,000

0.86 91,700,000

580,000 (0.44)

(30,400,000)

Notes:

1. CIM Definition Standards were followed for Mineral Resources, Mineral Resources are reported inclusive of Mineral Reserves.

2. Mineral Resources are reported at a cut-off grade of 0.25% U3O8 based on a long-term price of US$50 per lb U3O8 and estimated costs.

3. A minimum mining width of 1.0 m was used, with a Mineral Resource effective date of May 25th, 2018.

4. Numbers may not add due to rounding.

5. Mineral Resources that are not Mineral Reserves do not have demonstrated economics.

Mineral Reserves

The PFS defines Probable Mineral Reserves of 234.1 M lbs of U3O8 contained in 3.43 M tonnes grading

3.09% U3O8 from the Indicated Mineral Resources. The Probable Mineral Reserves include diluting

materials and allowances for losses which may occur when material is mined.

Table 4 - Arrow Probable Mineral Reserves

Probable Mineral Reserves

Structure Tonnage (Tonnes) Grade (U3O8%) Metal U3O8 (U3O8 lb)

A2 2,057,600 4.13% 187,400,000

A3 1,375,500 1.54% 46,700,000

Total 3,433,100 3.09% 234,100,000

Notes:

1. CIM definitions were followed for Mineral Reserves.

2. Mineral Reserves are reported with an effective date of May 25, 2018.

3. Mineral Reserves include transverse and longitudinal stopes, ore development, and incremental ore.

4. Stopes and ore development were estimated at a cut-off grade of 0.25% U3O8.

5. Incremental ore is material between 0.03% U3O8 and 0.25% U3O8 that must be extracted to access mining areas. 0.03% U3O8 is

the limit for what is considered benign waste and material that must be treated and stockpiled in an engineered facility.

6. No by-product credits have been included in the Mineral Reserve statement.

7. Mineral Reserves are estimated using a long-term metal price of US$45 per pound U3O8, and a 0.75 US$/C$ exchange rate (C$1.00 =

US$0.75).

8. A minimum mining width of 3.0 m was applied for all longhole stopes.

9. The density varies according to the U3O8 grade in the block model. Waste density is 2.464 t/m3.

10. Numbers may not add due to rounding.

RPA is not aware of any environmental, permitting, legal, title, taxation, socio -economic, marketing,

political, or other relevant factors that could materially affect the Mineral Resource or Mineral Reserve

estimates.

Mine Plan and Production Profile

A d etailed mine plan based on conventional long -hole stope mining was engineered using Indicated

Mineral Resources only. Geotechnical studies during Pre-Feasibility supported the conventional longhole

stoping mining method including the use of longitudinal and transverse stopes, 30 m level spacing, and

the nominal stope strike length of 15 m etres to 30 metres. This represents an excellent stope stability

range for underground mining in highly competent conditions. The geometry of the Arrow Deposit

enables de coupled production areas in both the A2 and A3, allowing flexibility of mine sequencing. The

PFS production profile is underpinned by longhole stopes in the transverse orientation through A2 High

Grade mineralization. Arcadis was engaged in the modeling and assessment of radiological effects of

underground uranium mining, and they fully endorsed the proposed mining methods and overall plans.

The ability to mine transverse longhole stopes through the A2 High Grade will support significant

scheduling flexibility enabling NexGen to correlate supply quickly and inexpensively to market conditions.

Furthermore, given the competency and conditions of the underground environment, all waste streams

from the process plant are planned to be stored underground.

The PFS mine plan, using a 0.25% U3O8 cut-off grade, includes Probable Mineral Reserves consisting of

234.1 M lbs of U3O8 contained in 3.43 M tonnes grading 3.09% U3O8 that will be extracted by

underground mining in an initial nine (9) year mine life. The mine production schedule envisions a life of

mine rate of 1,039 tonnes per day. The underground workings will be accessed by two shafts, the first

supporting personnel movement s, materials, ore, waste and fresh air. The production sh aft will have

divided compartments, ensuring that fresh air, and personnel entering the mine, remain isolated from ore

being skipped to surface. The second shaft will be used for exhaust air and secondary egress. Mining

extraction is estimated to be 95% of mineralized tonnes for both ore development and stopes. Planned

dilution was included in the generation of the stope shapes, and additional backfill dilution (at zero grade)

was included where appropriate. Overall rock dilution is estimated to be 31%, wi th additional backfill

dilution applied on secondary stopes only. Figure 3 below presents the annual mining schedule based on

set assumptions.

Figure 3 – Arrow Deposit Production Profile

Figure 4 – Cross Section View of PFS Mine Design

Processing and Underground Tailings Management Facility (“UGTMF”)

The PFS confirmed processing and production of Yellowcake from the Arrow Deposit with conventional

processing technology. The main components of the processing plant are:

• Grinding

• Leaching

• Liquid-Solid Separation via Counter Current Decantation