CAMECO CORP

Sampling analysis and data verification

The sampling, sample preparation, analyses, and geophysical downhole logging during the exploration and delineation programs follow the procedures and manuals which adhere to the requirements set out in the State Reserves Commission (SRC) guidelines. In compliance with the requirements of the SRC, drilling conducted on grids of 400 x 50 metres or greater are cored. A minimum core recovery of 70% is required in at least 70% of the drillholes for further studies, including those used for gamma probing and radioactive disequilibrium correlation purposes.

Sampling and Analysis

Drill core is logged in log journals following the developed manuals and representative core samples are selected for the following analyses and tests: determination of the content of uranium, radium and associated elements; determination of bulk density, moisture content, porosity and acid-base balance of monolith rocks; determination of mineralization and host rock physical composition, grain size and carbonate content; and column leach tests for uranium leachability.

Detailed sampling procedures guide the sampling interval within the mineralization. Where core recoveries are greater than 70% and radioactivity is greater than 40 micro-roentgens per hour, core samples are taken at irregular intervals of 0.2 to 1.2 metres. Sample intervals also are differentiated by barren orlow-permeability material. The average core sample length is 0.4 metre. The sampling is conducted from half the core divided along its axis. Core diameter is 60, 70 or 100 millimetres depending on depth. The required sample weight is determined based on the length of the samples and the diameters of the core sampled.

Sample preparation and assaying are done by Volkovgeology following SRC guidelines. When core samples are being analysed for geochemistry, they are primarily analysed for grain size and assayed for uranium, radium, thorium, potassium and carbonate content. On selected fence lines, a more extensive study of geochemistry is undertaken.

The core samples for uranium and radium determination are taken from representative intervals. Samples are ground down to pass 1.0 millimetre mesh size and are subsequently subdivided until the final representative weight of samples and duplicates is reached (0.2 kilogram) at the final division stage.

The laboratory tests for uranium and radium were performed by the Central Analytical Laboratory (CAL) of JSC Volkovgeology, located in Almaty. The laboratory was certified and licensed by the National Centre for Accreditation of the Republic of Kazakhstan to comply with the STRK ISO/IEC 17025-2007 standard, Certificate number KZ.I.02.1029. Volkovgeology is a subsidiary of KAP, which is part owner of JV Inkai. The uranium content was determined by using X-ray fluorescence spectrum analysis while the radium content was determined through gamma-X-ray spectrum analysis. Assays from core sampling are only used for gamma probing correlation and radioactive disequilibrium determination purposes. Additional duplicate samples are collected by a different sampler from the second half of the core split for quality control purposes.

Sample Security

JV Inkai’s current sampling process follows the strict regulations imposed by the Kazakhstan government, and includes the highest level of security measures, quality assurance and quality control. With respect to historical Kazakhstan exploration on the MA Area, we have been unable to locate the documentation on sample security. However, based on the rigorous quality assurance and quality control used in other areas of sampling, the regulations imposed by the Kazakhstan government and comparisons against current data, we believe that the security measures taken to store and ship samples were of the highest quality.

Quality Control

In order to ensure the assay accuracy and reliability for the purposes of correlation with gamma probing and disequilibrium determination for resource estimation, the following quality controls were carried out:

Data Verification

Sampling and analysis procedures used for the MPP Area resource estimate were examined by both our geoscientists and an independent consultant and found to be detailed and thorough. The relationship between radioactive readings and calculated radium grades obtained from the use of the method was studied in detail at that time, showing a good relationship between radioactivity and radium grade in most locations.

All of the drillhole information in use at Inkai is provided to us upon request. The current database has been validated a number of times by geoscientists with JV Inkai, JSC Volkovgeology, the SRC, Two Key LLP, and our geoscientists. Correlation on grade-thickness from radioactivity and from radium grade (and its subsequent conversion to uranium grade based on radium-uranium equilibrium) has been reviewed by our geoscientists and found to be accurate and reliable. Our geoscientists have witnessed or reviewed drilling, core handling, radiometric probing, logging, sampling processes and facilities used at the Inkai mine and consider the methodologies to be satisfactory and the results representative and reliable.

Mineral Processing and Metallurgical Testing

The ISR mining method at Inkai uses a sulphuric acid-based lixiviant. The resulting UBS is processed at the MPP, Sat1 and Sat2 to obtain eluate which is further processed at the MPP to currently produce uranium peroxide yellowcake.

Exploration at Inkai started in the late 1970’s involving sampling, assaying and mineralogical studies at Blocks 1, 2 and 3. Standardized column leach tests on composite samples were performed to measure average uranium UBS grades and levels of acid consumption. Uranium recoveries approaching 85% or greater were achieved with all samples.

A pilot test, using the ISR mining method, was performed in the northeast area of Block 1 starting in December 1988. The pilot leach test in Block 2 started in 2002 and was completed in 2006 while the pilot leach test in Block 3 was initiated in 2015 and completed in 2017.

Commercial production at MPP, Sat1 and Sat2 started in 2009, 2010 and 2018 respectively.

There are three processing facilities on the MA Area: the MPP, Sat1 and Sat2. Since the MPP, Sat1 and Sat2 processing plants have been in commercial production for a significant period, validating the test work results, we have determined that the metallurgical test results for these three operating process circuits are no longer significant or relevant in regard to forming the basis of future recovery assumptions and estimates.

Please see pages 97 and 98 for our mineral reserve and resource estimates for Inkai.