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Measured and Indicated As of December 31, 2025(100% basis)(tonnes in thousands; pounds in millions; totals may not add up due to rounding) MeasuredIndicatedTotal Measured and IndicatedPropertyTonnesGrade%U3O8Content(lbs U3O8)TonnesGrade%U3O8Content(lbs U3O8)Content(lbs U3O8)Cameco’s Share(lbs U3O8)Cigar Lake82.35.09.1153.85.0717.226.314.3Kintyre   3,897.70.6253.553.553.5McArthur River72.02.283.662.62.223.16.74.7Millennium   1,442.62.3975.975.953.0Rabbit Lake   1,836.50.9538.638.638.6Tamarack   183.84.4217.917.910.3Yeelirrie27,172.90.1695.912,178.30.1232.2128.1128.1Crow Butte1,558.10.196.6939.30.357.213.813.8Gas Hills-Peach687.20.111.73,626.10.1511.613.313.3Inkai75,923.10.0358.263,488.40.0234.592.737.1North Butte-Brown Ranch604.20.081.11,438.40.092.83.93.9Ruby Ranch   2,215.30.084.14.14.1Shirley Basin89.20.160.31,638.20.114.14.44.4Smith Ranch-Highland3,703.50.107.914,372.30.0517.024.924.9Total109,892.5-184.4107,462.3-319.7504.0404.0Note that mineral resources:do not include amounts that have been identified as mineral reservesdo not have a demonstrated economic viabilitytotals may not add due to roundingMineral Reserves and ResourcesOur mineral reserves and resources are the foundation of our company and fundamental to our success.We have interests in a number of uranium properties. The tables in this section show the estimates of the proven and probable mineral reserves, and measured, indicated, and inferred mineral resources at those properties. However, only three of the properties listed in those tables are material uranium properties for us: McArthur River/Key Lake, Cigar Lake and Inkai. Mineral reserves and resources are all reported as of December 31, 2025.We estimate and disclose mineral reserves and resources in five categories, using the definition standards adopted by the Canadian Institute of Mining, Metallurgy and Petroleum Council, and in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects (NI 43-101), developed by the Canadian Securities Administrators.  About mineral resourcesMineral resources do not have to demonstrate economic viability but have reasonable prospects for eventual economic extraction. They fall into three categories: measured, indicated and inferred. Our reported mineral resources are exclusive of mineral reserves.measured and indicated mineral resources can be estimated with sufficient confidence to allow the appropriate application of technical, economic, marketing, legal, and sustainability factors to support evaluation of the economic viability of the depositmeasured resources: we can confirm both geological and grade continuity to support detailed mine planningindicated resources: we can reasonably assume geological and grade continuity to support mine planninginferred mineral resources are estimated using limited geological evidence and sampling information. We do not have enough confidence to evaluate their economic viability in a meaningful way. You should not assume that all or any part of an inferred mineral resource will be upgraded to an indicated or measured mineral resource, but it is reasonably expected that the majority of inferred mineral resources could be upgraded to indicated mineral resources with continued exploration.Our share of uranium in the following mineral resource tables is based on our respective ownership interests. Reported mineral resources have not demonstrated economic viability.About mineral reservesMineral reserves are the economically mineable part of measured and/or indicated mineral resources demonstrated by at least a preliminary feasibility study. The reference point at which mineral reserves are defined is the point where the ore is delivered to the processing plant, except for ISR operations where the reference point is where the mineralization occurs under the existing or planned wellfield patterns. Mineral reserves fall into two categories:proven reserves: the economically mineable part of a measured resource for which at least a preliminary feasibility study demonstrates that, at the time of reporting, economic extraction could be reasonably justified with a high degree of confidenceprobable reserves: the economically mineable part of a measured and/or indicated resource for which at least a preliminary feasibility study demonstrates that, at the time of reporting, economic extraction could be reasonably justified with a degree of confidence lower than that applying to proven reserves For properties where we are the operator, we use current geological models, an average uranium price of $63 (US) per pound U3O8, and current or projected operating costs and mine plans to report our mineral reserves, allowing for dilution and mining losses. We apply our standard data verification process for every estimate. For properties in which we have an interest but are not the operator, we will take reasonable steps to ensure that the reserve and resource estimates that we report are reliable.Our share of uranium in the mineral reserves table below is based on our respective ownership interests.Changes this year Our share of proven and probable mineral reserves decreased from 457 million pounds U3O8 at the end of 2024 to 433 million pounds at the end of 2025. The change was primarily the result of production at Cigar Lake, Inkai and McArthur River, which removed 25 million pounds of proven and probable reserves from our mineral inventory slightly offset by other adjustments based on the mineral reserve estimate updates at Cigar Lake, McArthur River and Inkai.Our share of measured and indicated mineral resources decreased from 408 million pounds U3O8 at the end of 2024 to 404 million pounds at the end of 2025. Our share of inferred mineral resources decreased from 153 million pounds U3O8 to 152 million pounds U3O8. Qualified personsThe technical and scientific information discussed on this page for our material properties (McArthur River/Key Lake, Cigar Lake and Inkai) was approved by the following individuals who are qualified persons for the purposes of NI 43-101:McArthur River/Key LakeGreg Murdock, general manager, McArthur River, CamecoDaley McIntyre, general manager, Key Lake, CamecoAlain D. Renaud, principal resource geologist, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoCigar LakeKirk Lamont, general manager, /Cigar Lake, CamecoScott Bishop, director, technical services, CamecoAlain D. Renaud, principal resource geologist, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoInkaiAlain D. Renaud, principal resource geologist, technical services, CamecoScott Bishop, director, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoSergey Ivanov, deputy director general, technical services, Cameco Kazakhstan LLPImportant information about mineral reserve and resource estimatesAlthough we have carefully prepared and verified the mineral reserve and resource figures in this document, the figures are estimates, based in part on forward-looking information.Estimates are based on knowledge, mining experience, analysis of drilling results, the quality of available data and management’s best judgment. They are, however, imprecise by nature, may change over time, and include many variables and assumptions, including:geological interpretationextraction planscommodity prices and currency exchange ratesrecovery ratesoperating and capital costsThere is no assurance that the indicated levels of uranium will be produced, and we may have to re-estimate our mineral reserves based on actual production experience. Changes in the price of uranium, production costs or recovery rates could make it unprofitable for us to operate or develop a particular site or sites for a period of time. See page 2 of our 2025 Q4 MD&A for information about forward-looking information.Please see our mineral reserves and resources section of our most recent annual information form for the specific assumptions, parameters and methods used for McArthur River, Inkai and Cigar Lake mineral reserve and resource estimates. Important information for US investorsWe present information about mineralization, mineral reserves and resources as required by National Instrument 43-101 – Standards of Disclosure for Mineral Projects of the Canadian Securities Administrators (NI 43-101), in accordance with applicable Canadian securities laws. As a foreign private issuer filing reports with the US Securities and Exchange Commission (SEC) under the Multijurisdictional Disclosure System, we are not required to comply with the SEC’s disclosure requirements relating to mining properties. Investors in the United States should be aware that the disclosure requirements of NI 43-101 are different from those under applicable SEC rules, and the information that we present concerning mineralization, mineral reserves and resources may not be comparable to information made public by companies that comply with the SEC’s reporting and disclosure requirements for mining companies.

Cameco is one of the largest global providers of the uranium fuel needed to power a safe, secure energy future.Our competitive position is based on our controlling ownership of the world’s largest high-grade reserves and low-cost operations, as well as significant investments across the nuclear fuel cycle, including ownership interests in Westinghouse Electric Company and Global Laser Enrichment. Utilities around the world rely on Cameco to provide global nuclear fuel solutions for the generation of safe, reliable, carbon-free nuclear power.We are proud to be one of Canada’s largest employers of Indigenous people, and our land holdings, including exploration, span about 1.8 million acres, the majority near our existing operations in northern Saskatchewan. Our head office is in Saskatoon, Saskatchewan, Canada.

Measured and Indicated As of December 31, 2025(100% basis)(tonnes in thousands; pounds in millions; totals may not add up due to rounding) MeasuredIndicatedTotal Measured and IndicatedPropertyTonnesGrade%U3O8Content(lbs U3O8)TonnesGrade%U3O8Content(lbs U3O8)Content(lbs U3O8)Cameco’s Share(lbs U3O8)Cigar Lake82.35.09.1153.85.0717.226.314.3Kintyre   3,897.70.6253.553.553.5McArthur River72.02.283.662.62.223.16.74.7Millennium   1,442.62.3975.975.953.0Rabbit Lake   1,836.50.9538.638.638.6Tamarack   183.84.4217.917.910.3Yeelirrie27,172.90.1695.912,178.30.1232.2128.1128.1Crow Butte1,558.10.196.6939.30.357.213.813.8Gas Hills-Peach687.20.111.73,626.10.1511.613.313.3Inkai75,923.10.0358.263,488.40.0234.592.737.1North Butte-Brown Ranch604.20.081.11,438.40.092.83.93.9Ruby Ranch   2,215.30.084.14.14.1Shirley Basin89.20.160.31,638.20.114.14.44.4Smith Ranch-Highland3,703.50.107.914,372.30.0517.024.924.9Total109,892.5-184.4107,462.3-319.7504.0404.0Note that mineral resources:do not include amounts that have been identified as mineral reservesdo not have a demonstrated economic viabilitytotals may not add due to roundingInferredAs of December 31, 2025(100% basis)(tonnes in thousands; pounds in millions; totals may not add up due to rounding)PropertyTonnesGrade%U3O8Content(lbs U3O8)Cameco’s Share(lbs U3O8)Cigar Lake163.45.5520.010.9Fox Lake386.77.9968.153.3Kintyre517.10.536.06.0McArthur River36.40.532.41.7Millennium412.43.1929.020.2Rabbit Lake2,460.90.6233.733.7Tamarack45.61.021.00.6Crow Butte531.40.161.81.8Gas Hills-Peach3,307.50.086.06.0Inkai33,742.20.0323.38.9North Butte-Brown Ranch294.50.070.40.4Ruby Ranch56.20.140.20.2Shirley Basin508.00.101.11.1Smith Ranch-Highland6,861.00.057.77.7Total49,323.5-201.3153.2Note that mineral resources:do not include amounts that have been identified as mineral reservesdo not have a demonstrated economic viabilitytotals may not add due to roundingMineral Reserves and ResourcesOur mineral reserves and resources are the foundation of our company and fundamental to our success.We have interests in a number of uranium properties. The tables in this section show the estimates of the proven and probable mineral reserves, and measured, indicated, and inferred mineral resources at those properties. However, only three of the properties listed in those tables are material uranium properties for us: McArthur River/Key Lake, Cigar Lake and Inkai. Mineral reserves and resources are all reported as of December 31, 2025.We estimate and disclose mineral reserves and resources in five categories, using the definition standards adopted by the Canadian Institute of Mining, Metallurgy and Petroleum Council, and in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects (NI 43-101), developed by the Canadian Securities Administrators.  About mineral resourcesMineral resources do not have to demonstrate economic viability but have reasonable prospects for eventual economic extraction. They fall into three categories: measured, indicated and inferred. Our reported mineral resources are exclusive of mineral reserves.measured and indicated mineral resources can be estimated with sufficient confidence to allow the appropriate application of technical, economic, marketing, legal, and sustainability factors to support evaluation of the economic viability of the depositmeasured resources: we can confirm both geological and grade continuity to support detailed mine planningindicated resources: we can reasonably assume geological and grade continuity to support mine planninginferred mineral resources are estimated using limited geological evidence and sampling information. We do not have enough confidence to evaluate their economic viability in a meaningful way. You should not assume that all or any part of an inferred mineral resource will be upgraded to an indicated or measured mineral resource, but it is reasonably expected that the majority of inferred mineral resources could be upgraded to indicated mineral resources with continued exploration.Our share of uranium in the following mineral resource tables is based on our respective ownership interests. Reported mineral resources have not demonstrated economic viability.About mineral reservesMineral reserves are the economically mineable part of measured and/or indicated mineral resources demonstrated by at least a preliminary feasibility study. The reference point at which mineral reserves are defined is the point where the ore is delivered to the processing plant, except for ISR operations where the reference point is where the mineralization occurs under the existing or planned wellfield patterns. Mineral reserves fall into two categories:proven reserves: the economically mineable part of a measured resource for which at least a preliminary feasibility study demonstrates that, at the time of reporting, economic extraction could be reasonably justified with a high degree of confidenceprobable reserves: the economically mineable part of a measured and/or indicated resource for which at least a preliminary feasibility study demonstrates that, at the time of reporting, economic extraction could be reasonably justified with a degree of confidence lower than that applying to proven reserves For properties where we are the operator, we use current geological models, an average uranium price of $63 (US) per pound U3O8, and current or projected operating costs and mine plans to report our mineral reserves, allowing for dilution and mining losses. We apply our standard data verification process for every estimate. For properties in which we have an interest but are not the operator, we will take reasonable steps to ensure that the reserve and resource estimates that we report are reliable.Our share of uranium in the mineral reserves table below is based on our respective ownership interests.Changes this year Our share of proven and probable mineral reserves decreased from 457 million pounds U3O8 at the end of 2024 to 433 million pounds at the end of 2025. The change was primarily the result of production at Cigar Lake, Inkai and McArthur River, which removed 25 million pounds of proven and probable reserves from our mineral inventory slightly offset by other adjustments based on the mineral reserve estimate updates at Cigar Lake, McArthur River and Inkai.Our share of measured and indicated mineral resources decreased from 408 million pounds U3O8 at the end of 2024 to 404 million pounds at the end of 2025. Our share of inferred mineral resources decreased from 153 million pounds U3O8 to 152 million pounds U3O8. Qualified personsThe technical and scientific information discussed on this page for our material properties (McArthur River/Key Lake, Cigar Lake and Inkai) was approved by the following individuals who are qualified persons for the purposes of NI 43-101:McArthur River/Key LakeGreg Murdock, general manager, McArthur River, CamecoDaley McIntyre, general manager, Key Lake, CamecoAlain D. Renaud, principal resource geologist, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoCigar LakeKirk Lamont, general manager, /Cigar Lake, CamecoScott Bishop, director, technical services, CamecoAlain D. Renaud, principal resource geologist, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoInkaiAlain D. Renaud, principal resource geologist, technical services, CamecoScott Bishop, director, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoSergey Ivanov, deputy director general, technical services, Cameco Kazakhstan LLPImportant information about mineral reserve and resource estimatesAlthough we have carefully prepared and verified the mineral reserve and resource figures in this document, the figures are estimates, based in part on forward-looking information.Estimates are based on knowledge, mining experience, analysis of drilling results, the quality of available data and management’s best judgment. They are, however, imprecise by nature, may change over time, and include many variables and assumptions, including:geological interpretationextraction planscommodity prices and currency exchange ratesrecovery ratesoperating and capital costsThere is no assurance that the indicated levels of uranium will be produced, and we may have to re-estimate our mineral reserves based on actual production experience. Changes in the price of uranium, production costs or recovery rates could make it unprofitable for us to operate or develop a particular site or sites for a period of time. See page 2 of our 2025 Q4 MD&A for information about forward-looking information.Please see our mineral reserves and resources section of our most recent annual information form for the specific assumptions, parameters and methods used for McArthur River, Inkai and Cigar Lake mineral reserve and resource estimates. Important information for US investorsWe present information about mineralization, mineral reserves and resources as required by National Instrument 43-101 – Standards of Disclosure for Mineral Projects of the Canadian Securities Administrators (NI 43-101), in accordance with applicable Canadian securities laws. As a foreign private issuer filing reports with the US Securities and Exchange Commission (SEC) under the Multijurisdictional Disclosure System, we are not required to comply with the SEC’s disclosure requirements relating to mining properties. Investors in the United States should be aware that the disclosure requirements of NI 43-101 are different from those under applicable SEC rules, and the information that we present concerning mineralization, mineral reserves and resources may not be comparable to information made public by companies that comply with the SEC’s reporting and disclosure requirements for mining companies.

Measured and Indicated As of December 31, 2025(100% basis)(tonnes in thousands; pounds in millions; totals may not add up due to rounding) MeasuredIndicatedTotal Measured and IndicatedPropertyTonnesGrade%U3O8Content(lbs U3O8)TonnesGrade%U3O8Content(lbs U3O8)Content(lbs U3O8)Cameco’s Share(lbs U3O8)Cigar Lake82.35.09.1153.85.0717.226.314.3Kintyre   3,897.70.6253.553.553.5McArthur River72.02.283.662.62.223.16.74.7Millennium   1,442.62.3975.975.953.0Rabbit Lake   1,836.50.9538.638.638.6Tamarack   183.84.4217.917.910.3Yeelirrie27,172.90.1695.912,178.30.1232.2128.1128.1Crow Butte1,558.10.196.6939.30.357.213.813.8Gas Hills-Peach687.20.111.73,626.10.1511.613.313.3Inkai75,923.10.0358.263,488.40.0234.592.737.1North Butte-Brown Ranch604.20.081.11,438.40.092.83.93.9Ruby Ranch   2,215.30.084.14.14.1Shirley Basin89.20.160.31,638.20.114.14.44.4Smith Ranch-Highland3,703.50.107.914,372.30.0517.024.924.9Total109,892.5-184.4107,462.3-319.7504.0404.0Note that mineral resources:do not include amounts that have been identified as mineral reservesdo not have a demonstrated economic viabilitytotals may not add due to roundingInferredAs of December 31, 2025(100% basis)(tonnes in thousands; pounds in millions; totals may not add up due to rounding)PropertyTonnesGrade%U3O8Content(lbs U3O8)Cameco’s Share(lbs U3O8)Cigar Lake163.45.5520.010.9Fox Lake386.77.9968.153.3Kintyre517.10.536.06.0McArthur River36.40.532.41.7Millennium412.43.1929.020.2Rabbit Lake2,460.90.6233.733.7Tamarack45.61.021.00.6Crow Butte531.40.161.81.8Gas Hills-Peach3,307.50.086.06.0Inkai33,742.20.0323.38.9North Butte-Brown Ranch294.50.070.40.4Ruby Ranch56.20.140.20.2Shirley Basin508.00.101.11.1Smith Ranch-Highland6,861.00.057.77.7Total49,323.5-201.3153.2Note that mineral resources:do not include amounts that have been identified as mineral reservesdo not have a demonstrated economic viabilitytotals may not add due to roundingMineral Reserves and ResourcesOur mineral reserves and resources are the foundation of our company and fundamental to our success.We have interests in a number of uranium properties. The tables in this section show the estimates of the proven and probable mineral reserves, and measured, indicated, and inferred mineral resources at those properties. However, only three of the properties listed in those tables are material uranium properties for us: McArthur River/Key Lake, Cigar Lake and Inkai. Mineral reserves and resources are all reported as of December 31, 2025.We estimate and disclose mineral reserves and resources in five categories, using the definition standards adopted by the Canadian Institute of Mining, Metallurgy and Petroleum Council, and in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects (NI 43-101), developed by the Canadian Securities Administrators.  About mineral resourcesMineral resources do not have to demonstrate economic viability but have reasonable prospects for eventual economic extraction. They fall into three categories: measured, indicated and inferred. Our reported mineral resources are exclusive of mineral reserves.measured and indicated mineral resources can be estimated with sufficient confidence to allow the appropriate application of technical, economic, marketing, legal, and sustainability factors to support evaluation of the economic viability of the depositmeasured resources: we can confirm both geological and grade continuity to support detailed mine planningindicated resources: we can reasonably assume geological and grade continuity to support mine planninginferred mineral resources are estimated using limited geological evidence and sampling information. We do not have enough confidence to evaluate their economic viability in a meaningful way. You should not assume that all or any part of an inferred mineral resource will be upgraded to an indicated or measured mineral resource, but it is reasonably expected that the majority of inferred mineral resources could be upgraded to indicated mineral resources with continued exploration.Our share of uranium in the following mineral resource tables is based on our respective ownership interests. Reported mineral resources have not demonstrated economic viability.About mineral reservesMineral reserves are the economically mineable part of measured and/or indicated mineral resources demonstrated by at least a preliminary feasibility study. The reference point at which mineral reserves are defined is the point where the ore is delivered to the processing plant, except for ISR operations where the reference point is where the mineralization occurs under the existing or planned wellfield patterns. Mineral reserves fall into two categories:proven reserves: the economically mineable part of a measured resource for which at least a preliminary feasibility study demonstrates that, at the time of reporting, economic extraction could be reasonably justified with a high degree of confidenceprobable reserves: the economically mineable part of a measured and/or indicated resource for which at least a preliminary feasibility study demonstrates that, at the time of reporting, economic extraction could be reasonably justified with a degree of confidence lower than that applying to proven reserves For properties where we are the operator, we use current geological models, an average uranium price of $63 (US) per pound U3O8, and current or projected operating costs and mine plans to report our mineral reserves, allowing for dilution and mining losses. We apply our standard data verification process for every estimate. For properties in which we have an interest but are not the operator, we will take reasonable steps to ensure that the reserve and resource estimates that we report are reliable.Our share of uranium in the mineral reserves table below is based on our respective ownership interests.Changes this year Our share of proven and probable mineral reserves decreased from 457 million pounds U3O8 at the end of 2024 to 433 million pounds at the end of 2025. The change was primarily the result of production at Cigar Lake, Inkai and McArthur River, which removed 25 million pounds of proven and probable reserves from our mineral inventory slightly offset by other adjustments based on the mineral reserve estimate updates at Cigar Lake, McArthur River and Inkai.Our share of measured and indicated mineral resources decreased from 408 million pounds U3O8 at the end of 2024 to 404 million pounds at the end of 2025. Our share of inferred mineral resources decreased from 153 million pounds U3O8 to 152 million pounds U3O8. Qualified personsThe technical and scientific information discussed on this page for our material properties (McArthur River/Key Lake, Cigar Lake and Inkai) was approved by the following individuals who are qualified persons for the purposes of NI 43-101:McArthur River/Key LakeGreg Murdock, general manager, McArthur River, CamecoDaley McIntyre, general manager, Key Lake, CamecoAlain D. Renaud, principal resource geologist, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoCigar LakeKirk Lamont, general manager, /Cigar Lake, CamecoScott Bishop, director, technical services, CamecoAlain D. Renaud, principal resource geologist, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoInkaiAlain D. Renaud, principal resource geologist, technical services, CamecoScott Bishop, director, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoSergey Ivanov, deputy director general, technical services, Cameco Kazakhstan LLPImportant information about mineral reserve and resource estimatesAlthough we have carefully prepared and verified the mineral reserve and resource figures in this document, the figures are estimates, based in part on forward-looking information.Estimates are based on knowledge, mining experience, analysis of drilling results, the quality of available data and management’s best judgment. They are, however, imprecise by nature, may change over time, and include many variables and assumptions, including:geological interpretationextraction planscommodity prices and currency exchange ratesrecovery ratesoperating and capital costsThere is no assurance that the indicated levels of uranium will be produced, and we may have to re-estimate our mineral reserves based on actual production experience. Changes in the price of uranium, production costs or recovery rates could make it unprofitable for us to operate or develop a particular site or sites for a period of time. See page 2 of our 2025 Q4 MD&A for information about forward-looking information.Please see our mineral reserves and resources section of our most recent annual information form for the specific assumptions, parameters and methods used for McArthur River, Inkai and Cigar Lake mineral reserve and resource estimates. Important information for US investorsWe present information about mineralization, mineral reserves and resources as required by National Instrument 43-101 – Standards of Disclosure for Mineral Projects of the Canadian Securities Administrators (NI 43-101), in accordance with applicable Canadian securities laws. As a foreign private issuer filing reports with the US Securities and Exchange Commission (SEC) under the Multijurisdictional Disclosure System, we are not required to comply with the SEC’s disclosure requirements relating to mining properties. Investors in the United States should be aware that the disclosure requirements of NI 43-101 are different from those under applicable SEC rules, and the information that we present concerning mineralization, mineral reserves and resources may not be comparable to information made public by companies that comply with the SEC’s reporting and disclosure requirements for mining companies.

Measured and Indicated As of December 31, 2025(100% basis)(tonnes in thousands; pounds in millions; totals may not add up due to rounding) MeasuredIndicatedTotal Measured and IndicatedPropertyTonnesGrade%U3O8Content(lbs U3O8)TonnesGrade%U3O8Content(lbs U3O8)Content(lbs U3O8)Cameco’s Share(lbs U3O8)Cigar Lake82.35.09.1153.85.0717.226.314.3Kintyre   3,897.70.6253.553.553.5McArthur River72.02.283.662.62.223.16.74.7Millennium   1,442.62.3975.975.953.0Rabbit Lake   1,836.50.9538.638.638.6Tamarack   183.84.4217.917.910.3Yeelirrie27,172.90.1695.912,178.30.1232.2128.1128.1Crow Butte1,558.10.196.6939.30.357.213.813.8Gas Hills-Peach687.20.111.73,626.10.1511.613.313.3Inkai75,923.10.0358.263,488.40.0234.592.737.1North Butte-Brown Ranch604.20.081.11,438.40.092.83.93.9Ruby Ranch   2,215.30.084.14.14.1Shirley Basin89.20.160.31,638.20.114.14.44.4Smith Ranch-Highland3,703.50.107.914,372.30.0517.024.924.9Total109,892.5-184.4107,462.3-319.7504.0404.0Note that mineral resources:do not include amounts that have been identified as mineral reservesdo not have a demonstrated economic viabilitytotals may not add due to roundingInferredAs of December 31, 2025(100% basis)(tonnes in thousands; pounds in millions; totals may not add up due to rounding)PropertyTonnesGrade%U3O8Content(lbs U3O8)Cameco’s Share(lbs U3O8)Cigar Lake163.45.5520.010.9Fox Lake386.77.9968.153.3Kintyre517.10.536.06.0McArthur River36.40.532.41.7Millennium412.43.1929.020.2Rabbit Lake2,460.90.6233.733.7Tamarack45.61.021.00.6Crow Butte531.40.161.81.8Gas Hills-Peach3,307.50.086.06.0Inkai33,742.20.0323.38.9North Butte-Brown Ranch294.50.070.40.4Ruby Ranch56.20.140.20.2Shirley Basin508.00.101.11.1Smith Ranch-Highland6,861.00.057.77.7Total49,323.5-201.3153.2Note that mineral resources:do not include amounts that have been identified as mineral reservesdo not have a demonstrated economic viabilitytotals may not add due to roundingMineral Reserves and ResourcesOur mineral reserves and resources are the foundation of our company and fundamental to our success.We have interests in a number of uranium properties. The tables in this section show the estimates of the proven and probable mineral reserves, and measured, indicated, and inferred mineral resources at those properties. However, only three of the properties listed in those tables are material uranium properties for us: McArthur River/Key Lake, Cigar Lake and Inkai. Mineral reserves and resources are all reported as of December 31, 2025.We estimate and disclose mineral reserves and resources in five categories, using the definition standards adopted by the Canadian Institute of Mining, Metallurgy and Petroleum Council, and in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects (NI 43-101), developed by the Canadian Securities Administrators.  About mineral resourcesMineral resources do not have to demonstrate economic viability but have reasonable prospects for eventual economic extraction. They fall into three categories: measured, indicated and inferred. Our reported mineral resources are exclusive of mineral reserves.measured and indicated mineral resources can be estimated with sufficient confidence to allow the appropriate application of technical, economic, marketing, legal, and sustainability factors to support evaluation of the economic viability of the depositmeasured resources: we can confirm both geological and grade continuity to support detailed mine planningindicated resources: we can reasonably assume geological and grade continuity to support mine planninginferred mineral resources are estimated using limited geological evidence and sampling information. We do not have enough confidence to evaluate their economic viability in a meaningful way. You should not assume that all or any part of an inferred mineral resource will be upgraded to an indicated or measured mineral resource, but it is reasonably expected that the majority of inferred mineral resources could be upgraded to indicated mineral resources with continued exploration.Our share of uranium in the following mineral resource tables is based on our respective ownership interests. Reported mineral resources have not demonstrated economic viability.About mineral reservesMineral reserves are the economically mineable part of measured and/or indicated mineral resources demonstrated by at least a preliminary feasibility study. The reference point at which mineral reserves are defined is the point where the ore is delivered to the processing plant, except for ISR operations where the reference point is where the mineralization occurs under the existing or planned wellfield patterns. Mineral reserves fall into two categories:proven reserves: the economically mineable part of a measured resource for which at least a preliminary feasibility study demonstrates that, at the time of reporting, economic extraction could be reasonably justified with a high degree of confidenceprobable reserves: the economically mineable part of a measured and/or indicated resource for which at least a preliminary feasibility study demonstrates that, at the time of reporting, economic extraction could be reasonably justified with a degree of confidence lower than that applying to proven reserves For properties where we are the operator, we use current geological models, an average uranium price of $63 (US) per pound U3O8, and current or projected operating costs and mine plans to report our mineral reserves, allowing for dilution and mining losses. We apply our standard data verification process for every estimate. For properties in which we have an interest but are not the operator, we will take reasonable steps to ensure that the reserve and resource estimates that we report are reliable.Our share of uranium in the mineral reserves table below is based on our respective ownership interests.Changes this year Our share of proven and probable mineral reserves decreased from 457 million pounds U3O8 at the end of 2024 to 433 million pounds at the end of 2025. The change was primarily the result of production at Cigar Lake, Inkai and McArthur River, which removed 25 million pounds of proven and probable reserves from our mineral inventory slightly offset by other adjustments based on the mineral reserve estimate updates at Cigar Lake, McArthur River and Inkai.Our share of measured and indicated mineral resources decreased from 408 million pounds U3O8 at the end of 2024 to 404 million pounds at the end of 2025. Our share of inferred mineral resources decreased from 153 million pounds U3O8 to 152 million pounds U3O8. Qualified personsThe technical and scientific information discussed on this page for our material properties (McArthur River/Key Lake, Cigar Lake and Inkai) was approved by the following individuals who are qualified persons for the purposes of NI 43-101:McArthur River/Key LakeGreg Murdock, general manager, McArthur River, CamecoDaley McIntyre, general manager, Key Lake, CamecoAlain D. Renaud, principal resource geologist, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoCigar LakeKirk Lamont, general manager, /Cigar Lake, CamecoScott Bishop, director, technical services, CamecoAlain D. Renaud, principal resource geologist, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoInkaiAlain D. Renaud, principal resource geologist, technical services, CamecoScott Bishop, director, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoSergey Ivanov, deputy director general, technical services, Cameco Kazakhstan LLPImportant information about mineral reserve and resource estimatesAlthough we have carefully prepared and verified the mineral reserve and resource figures in this document, the figures are estimates, based in part on forward-looking information.Estimates are based on knowledge, mining experience, analysis of drilling results, the quality of available data and management’s best judgment. They are, however, imprecise by nature, may change over time, and include many variables and assumptions, including:geological interpretationextraction planscommodity prices and currency exchange ratesrecovery ratesoperating and capital costsThere is no assurance that the indicated levels of uranium will be produced, and we may have to re-estimate our mineral reserves based on actual production experience. Changes in the price of uranium, production costs or recovery rates could make it unprofitable for us to operate or develop a particular site or sites for a period of time. See page 2 of our 2025 Q4 MD&A for information about forward-looking information.Please see our mineral reserves and resources section of our most recent annual information form for the specific assumptions, parameters and methods used for McArthur River, Inkai and Cigar Lake mineral reserve and resource estimates. Important information for US investorsWe present information about mineralization, mineral reserves and resources as required by National Instrument 43-101 – Standards of Disclosure for Mineral Projects of the Canadian Securities Administrators (NI 43-101), in accordance with applicable Canadian securities laws. As a foreign private issuer filing reports with the US Securities and Exchange Commission (SEC) under the Multijurisdictional Disclosure System, we are not required to comply with the SEC’s disclosure requirements relating to mining properties. Investors in the United States should be aware that the disclosure requirements of NI 43-101 are different from those under applicable SEC rules, and the information that we present concerning mineralization, mineral reserves and resources may not be comparable to information made public by companies that comply with the SEC’s reporting and disclosure requirements for mining companies.

Measured and Indicated As of December 31, 2025(100% basis)(tonnes in thousands; pounds in millions; totals may not add up due to rounding) MeasuredIndicatedTotal Measured and IndicatedPropertyTonnesGrade%U3O8Content(lbs U3O8)TonnesGrade%U3O8Content(lbs U3O8)Content(lbs U3O8)Cameco’s Share(lbs U3O8)Cigar Lake82.35.09.1153.85.0717.226.314.3Kintyre   3,897.70.6253.553.553.5McArthur River72.02.283.662.62.223.16.74.7Millennium   1,442.62.3975.975.953.0Rabbit Lake   1,836.50.9538.638.638.6Tamarack   183.84.4217.917.910.3Yeelirrie27,172.90.1695.912,178.30.1232.2128.1128.1Crow Butte1,558.10.196.6939.30.357.213.813.8Gas Hills-Peach687.20.111.73,626.10.1511.613.313.3Inkai75,923.10.0358.263,488.40.0234.592.737.1North Butte-Brown Ranch604.20.081.11,438.40.092.83.93.9Ruby Ranch   2,215.30.084.14.14.1Shirley Basin89.20.160.31,638.20.114.14.44.4Smith Ranch-Highland3,703.50.107.914,372.30.0517.024.924.9Total109,892.5-184.4107,462.3-319.7504.0404.0Note that mineral resources:do not include amounts that have been identified as mineral reservesdo not have a demonstrated economic viabilitytotals may not add due to roundingInferredAs of December 31, 2025(100% basis)(tonnes in thousands; pounds in millions; totals may not add up due to rounding)PropertyTonnesGrade%U3O8Content(lbs U3O8)Cameco’s Share(lbs U3O8)Cigar Lake163.45.5520.010.9Fox Lake386.77.9968.153.3Kintyre517.10.536.06.0McArthur River36.40.532.41.7Millennium412.43.1929.020.2Rabbit Lake2,460.90.6233.733.7Tamarack45.61.021.00.6Crow Butte531.40.161.81.8Gas Hills-Peach3,307.50.086.06.0Inkai33,742.20.0323.38.9North Butte-Brown Ranch294.50.070.40.4Ruby Ranch56.20.140.20.2Shirley Basin508.00.101.11.1Smith Ranch-Highland6,861.00.057.77.7Total49,323.5-201.3153.2Note that mineral resources:do not include amounts that have been identified as mineral reservesdo not have a demonstrated economic viabilitytotals may not add due to roundingMineral Reserves and ResourcesOur mineral reserves and resources are the foundation of our company and fundamental to our success.We have interests in a number of uranium properties. The tables in this section show the estimates of the proven and probable mineral reserves, and measured, indicated, and inferred mineral resources at those properties. However, only three of the properties listed in those tables are material uranium properties for us: McArthur River/Key Lake, Cigar Lake and Inkai. Mineral reserves and resources are all reported as of December 31, 2025.We estimate and disclose mineral reserves and resources in five categories, using the definition standards adopted by the Canadian Institute of Mining, Metallurgy and Petroleum Council, and in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects (NI 43-101), developed by the Canadian Securities Administrators.  About mineral resourcesMineral resources do not have to demonstrate economic viability but have reasonable prospects for eventual economic extraction. They fall into three categories: measured, indicated and inferred. Our reported mineral resources are exclusive of mineral reserves.measured and indicated mineral resources can be estimated with sufficient confidence to allow the appropriate application of technical, economic, marketing, legal, and sustainability factors to support evaluation of the economic viability of the depositmeasured resources: we can confirm both geological and grade continuity to support detailed mine planningindicated resources: we can reasonably assume geological and grade continuity to support mine planninginferred mineral resources are estimated using limited geological evidence and sampling information. We do not have enough confidence to evaluate their economic viability in a meaningful way. You should not assume that all or any part of an inferred mineral resource will be upgraded to an indicated or measured mineral resource, but it is reasonably expected that the majority of inferred mineral resources could be upgraded to indicated mineral resources with continued exploration.Our share of uranium in the following mineral resource tables is based on our respective ownership interests. Reported mineral resources have not demonstrated economic viability.About mineral reservesMineral reserves are the economically mineable part of measured and/or indicated mineral resources demonstrated by at least a preliminary feasibility study. The reference point at which mineral reserves are defined is the point where the ore is delivered to the processing plant, except for ISR operations where the reference point is where the mineralization occurs under the existing or planned wellfield patterns. Mineral reserves fall into two categories:proven reserves: the economically mineable part of a measured resource for which at least a preliminary feasibility study demonstrates that, at the time of reporting, economic extraction could be reasonably justified with a high degree of confidenceprobable reserves: the economically mineable part of a measured and/or indicated resource for which at least a preliminary feasibility study demonstrates that, at the time of reporting, economic extraction could be reasonably justified with a degree of confidence lower than that applying to proven reserves For properties where we are the operator, we use current geological models, an average uranium price of $63 (US) per pound U3O8, and current or projected operating costs and mine plans to report our mineral reserves, allowing for dilution and mining losses. We apply our standard data verification process for every estimate. For properties in which we have an interest but are not the operator, we will take reasonable steps to ensure that the reserve and resource estimates that we report are reliable.Our share of uranium in the mineral reserves table below is based on our respective ownership interests.Changes this year Our share of proven and probable mineral reserves decreased from 457 million pounds U3O8 at the end of 2024 to 433 million pounds at the end of 2025. The change was primarily the result of production at Cigar Lake, Inkai and McArthur River, which removed 25 million pounds of proven and probable reserves from our mineral inventory slightly offset by other adjustments based on the mineral reserve estimate updates at Cigar Lake, McArthur River and Inkai.Our share of measured and indicated mineral resources decreased from 408 million pounds U3O8 at the end of 2024 to 404 million pounds at the end of 2025. Our share of inferred mineral resources decreased from 153 million pounds U3O8 to 152 million pounds U3O8. Qualified personsThe technical and scientific information discussed on this page for our material properties (McArthur River/Key Lake, Cigar Lake and Inkai) was approved by the following individuals who are qualified persons for the purposes of NI 43-101:McArthur River/Key LakeGreg Murdock, general manager, McArthur River, CamecoDaley McIntyre, general manager, Key Lake, CamecoAlain D. Renaud, principal resource geologist, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoCigar LakeKirk Lamont, general manager, /Cigar Lake, CamecoScott Bishop, director, technical services, CamecoAlain D. Renaud, principal resource geologist, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoInkaiAlain D. Renaud, principal resource geologist, technical services, CamecoScott Bishop, director, technical services, CamecoBiman Bharadwaj, principal metallurgist, technical services, CamecoSergey Ivanov, deputy director general, technical services, Cameco Kazakhstan LLPImportant information about mineral reserve and resource estimatesAlthough we have carefully prepared and verified the mineral reserve and resource figures in this document, the figures are estimates, based in part on forward-looking information.Estimates are based on knowledge, mining experience, analysis of drilling results, the quality of available data and management’s best judgment. They are, however, imprecise by nature, may change over time, and include many variables and assumptions, including:geological interpretationextraction planscommodity prices and currency exchange ratesrecovery ratesoperating and capital costsThere is no assurance that the indicated levels of uranium will be produced, and we may have to re-estimate our mineral reserves based on actual production experience. Changes in the price of uranium, production costs or recovery rates could make it unprofitable for us to operate or develop a particular site or sites for a period of time. See page 2 of our 2025 Q4 MD&A for information about forward-looking information.Please see our mineral reserves and resources section of our most recent annual information form for the specific assumptions, parameters and methods used for McArthur River, Inkai and Cigar Lake mineral reserve and resource estimates. Important information for US investorsWe present information about mineralization, mineral reserves and resources as required by National Instrument 43-101 – Standards of Disclosure for Mineral Projects of the Canadian Securities Administrators (NI 43-101), in accordance with applicable Canadian securities laws. As a foreign private issuer filing reports with the US Securities and Exchange Commission (SEC) under the Multijurisdictional Disclosure System, we are not required to comply with the SEC’s disclosure requirements relating to mining properties. Investors in the United States should be aware that the disclosure requirements of NI 43-101 are different from those under applicable SEC rules, and the information that we present concerning mineralization, mineral reserves and resources may not be comparable to information made public by companies that comply with the SEC’s reporting and disclosure requirements for mining companies.

We recognize and embrace our responsibility to minimize our impacts on air, land, and water and to safeguard the biodiversity of surrounding ecosystems.The following are highlights of selected priority environmental topics. Please see our 2024 Sustainability Report for more information or Our Performance for all indicator results. WaterResponsible water management is critical to our business. We recognize the importance of preserving this resource for the Indigenous Peoples and local communities we share it with today. We work continuously with regulators, governments, researchers, and communities to understand possible impacts, develop best practices, and make changes that mitigate potential impacts on the environment. At our sites and facilities, we have robust water management and monitoring programs that apply to all withdrawals and discharges, and we tailor our water management practices to local uses and conditions.Water sources and usesThe vast majority of water (groundwater, surface water, or precipitation) managed by our Saskatchewan facilities is not intentionally withdrawn for mining use but instead intercepted as part of our mining operations through mine dewatering or from the operation of our tailings management facilities. Where possible, we use this intercepted water to support our operational water requirements.Water discharges At Cameco, we carefully manage our treated water discharges to keep potential risks to human health and the environment as low as reasonably achievable and to comply with applicable legal and regulatory requirements. To protect people and the environment, we have implemented management tools consistent with our overall management approach, which include:inflow reductionwater segregationwater treatmentDischarge monitoringWe have monitoring programs to verify that human health and the environment remain protected in the vicinity of our operations. We adhere to regulatory requirements from the Canadian Nuclear Safety Commission, the Saskatchewan Ministry of Environment, and Environment and Climate Change Canada.Watershed stewardshipAs part of our environmental monitoring programs, we take more than 22,000 samples related to water quality each year. We collect water samples at or immediately downstream of our operations (near-field), in close proximities to our operations (mid-field), and at locations at a further distance (five to ten kilometres) from our operations (far-field). These samples are sent for testing for different chemicals and other indicators of quality to both internal laboratories and an accredited third-party facility. Learn more about our watershed stewardshipTailings ManagementTailings and waste rock are an inevitable byproduct of most mining activities. Responsible and safe management of mining waste streams is critical to protecting the environment as well as the safety of our workers, operations and communities.  To strengthen our tailings management approach, we seek to apply lessons learned from industry incidents and are committed to continuous improvement. Milling of uranium ore produces tailings, which are primarily composed of the residual rock left after the uranium is recovered, mineral precipitates, and minor amounts of processing chemicals. These tailings are safely stored on-site within engineered tailings management facilities. The annual tonnage of tailings produced varies and is dependent on the ore grade and the production rate. The high uranium grade of our mines in northern Saskatchewan means we obtain more uranium per tonne of rock processed than low grade facilities, resulting in lower amounts of tailings per unit of uranium produced.Tailings management is relevant only to our Canadian operations because the in situ recovery method used in our US operations does not produce tailings or waste rock. We have four tailings facilities in Saskatchewan, two at our Key Lake site and two at our Rabbit Lake site. Both Key Lake and Rabbit Lake have one active in-pit tailings facility (in-pit facility) and one above-ground tailings management facility (above-ground tailings facility).We employ broad, risk-based practices to effectively manage our tailings and mine waste storage facilities. We have accountability at the highest level of the organization, and systems and procedures that follow best practices contained in industry recognized standards. Learn more about our tailings management practicesGHG EmissionsAt Cameco, we recognize the critical nature of the fight against climate change and that there are risks and opportunities associated with climate change and the energy transition as we seek to achieve our strategic plan.  We are committed to addressing these risks and taking advantage of the opportunities in a manner that we expect to add long-term value for our stakeholders.Our GHG emissions are directly related to the type and amount of energy we consume. Cameco quantifies emissions following the globally recognized GHG Protocol Corporate Standard.Scope 1~131,381 tCO2eOur Scope 1 emissions are primarily associated with the consumption of propane and natural gas for heating. We also use diesel and gasoline to operate heavy-duty and light vehicles across our operations, and relatively small quantities of diesel for back-up power generation. We release small quantities of GHG emissions from chemical processes during milling and from Cameco operated landfills.Scope 2~178,306 tCO2eAll Scope 2 emissions arise from electricity consumption and correlate to the emissions intensity of grid-supplied electricity in the regions we operate. Our main source of power for our northern Saskatchewan operations is hydroelectric. However, our location-based Scope 2 emissions use a single emissions factor that reflects the energy mix from the entire provincial grid in Saskatchewan and Ontario (data in the performance table).Scope 3~620,000 tCO2eScope 3 emissions are not covered in Scope 1 or 2 and result from activities that occur in our value chain. Building on our work from last year, where we reported our total Scope 3 emissions in our 2023 Sustainability Report, we are now reporting our Scope 3 emissions broken down by category as noted below. Scope 3 Emissions by Category   Our GHG reduction targetOur 30 by 30 reduction target means that we will work to permanently reduce our Scope 1 and Scope 2 GHG emissions by 155,000 tCO₂e across our operated facilities by 2030. Under this target, we will also strive to achieve a minimum reduction of 30,000 tCO₂e from Scope 1 emissions specifically. This sub-target demonstrates our commitment to reducing the direct carbon footprint of Cameco facilities and maintain alignment with facility-based emissions reductions required by regulators. Learn more about our GHG emissions and energy useDecommissioningOur commitment to protecting the environment and the needs of the communities around our operations extends to the full life-cycle of our mines and facilities. This includes planning for decommissioning and preparing our sites for permanent closure. Conceptual plans for each site describes activities required to reclaim the site to defined final end-state objectives, after the operating life of a facility. The plan includes a preliminary cost estimate for labour, materials, equipment, waste management, regulatory approvals, monitoring, and administration to carry out the plan.At the end of 2024, our estimated future decommissioning and reclamation costs (total and undiscounted) for our assets were approximately $1.38 billion, with some revised estimates still subject to regulatory approval. We have recorded accounting provisions for the discounted value of these estimates, and every quarter, we update these estimates based on new cash flow estimates, discount, and inflation rates. To verify we can pay for these future obligations, we have financial assurances of $1.13 billion (in the form of letters of credit or surety bonds to satisfy current regulatory requirements), which is based on previously approved preliminary decommissioning estimates and will increase once the regulator approves all revised estimates and confirms the value of financial assurances required. The expected timing for these costs is based on each mine or fuel services facility’s expected operating life. Our required costs for decommissioning and reclamation in each of the next five years are not expected to be material. Proactive reclamationIf part of an active site is ready for reclamation before the full site reaches the end of its life, we can proceed proactively with reclamation work on that area. Some of the projects we have undertaken in the last few years include:Water restoration in the U.S.In 2024, one mine unit had a final restoration report and decommissioning plan submitted. Five mine units are undergoing reverse osmosis treatment, six mine units are currently in stability, and two mine units are preparing to enter the stability stage.Waste rock pile revegetation at Key LakeThe Key Lake operation continues to undergo progressive reclamation. At one of Key Lake’s waste rock piles, we have been successful at revegetating a portion of a covered pile through the application of local lake bottom organic sediments as a nutrient source and seed bank to establish shrubs, bushes, and trees. Learn more2024 Sustainability Report - EnvironmentOur Performance for all indicator results.Environment and safety at our uranium operationsEnvironment and safety at our fuel services businessCigar LakeMcArthur River/Key LakeRabbit LakeBlind River RefineryPort Hope Conversion FacilityCameco Fuel Manufacturing

We are a pure-play investment in the growing demand for nuclear energy, focused on taking advantage of the near-, medium-, and long-term growth occurring in our industry. We provide nuclear fuel and nuclear power products, services, and technologies across the fuel cycle, complemented by our investment in Westinghouse, that support the generation of secure, carbon-free, reliable, and affordable energy. Our strategy is set within the context of what we believe is a transitioning market environment. Increasing populations, a growing focus on electrification and decarbonization, and concerns about energy security and affordability are driving a global focus on tripling nuclear power capacity by 2050, which is expected to durably strengthen the long-term fundamentals for our industry. Nuclear energy must be a central part of the solution to the world’s shift to a low-carbon, secure energy economy. It is an option that can provide the power needed, not only reliably, but also safely and affordably, and in a way that will help achieve climate, energy and national security objectives.Our strategy is to capture full-cycle value by:remaining disciplined in our contracting activity, building a balanced portfolio in accordance with our contracting frameworkprofitably producing from our tier-one assets and aligning our production decisions in all segments of the fuel cycle with contracted demand and customer needsbeing financially disciplined to allow us to:execute our strategyinvest in new opportunities that are expected to add long-term valueself-manage riskexploring other emerging opportunities within the nuclear power value chain, which align with our commitment to manage our business responsibly and sustainably, contribute to decarbonization, and help to provide secure and affordable energyWe expect our strategy will allow us to increase long-term value, and we will execute it with an emphasis on safety, people and the environment.UraniumUranium production is central to our strategy, as it is the biggest value driver of the nuclear fuel cycle and our business. We have tier-one assets that are licensed, permitted, long-lived, and are proven reliable with capacity to expand. These tier-one assets are backed up by idle tier-two assets and what we think is the best exploration portfolio of mineral reserves and resources that in some cases can leverage our existing infrastructure. Currently, we believe that we have ample productive capacity with the ability to expand as the demand for nuclear energy and nuclear fuel grows.We are focused on protecting and extending the value of our contract portfolio, on aligning our production decisions with our contract portfolio and market opportunities thereby optimizing the value of our lowest cost assets. We also prioritize maintaining a strong balance sheet, and on efficiently managing the company. We have undertaken a number of deliberate and disciplined actions, including a focus on operational effectiveness to allow us to operate our assets more efficiently and with more flexibility. Learn moreFuel servicesOur fuel services segment supports our strategy to capture full-cycle value by providing our customers with access to refining and conversion services for both heavy-water and light-water reactors, and CANDU fuel and reactor component manufacturing for heavy-water reactors.As in our uranium segment, we are focused on securing new long-term contracts and on aligning our production decisions with our contract portfolio that will allow us to continue to profitably produce and consistently support the long-term needs of our customers.In addition, we are pursuing non-traditional markets for our UO2 and fuel fabrication business and have been actively securing new contracts for reactor components to support refurbishment of Canadian reactors.Learn moreWestinghouseIn 2023, we completed the acquisition of Westinghouse, a global provider of mission‐critical and specialized technologies, products and services for light-water reactors across most phases of the nuclear power sector, in a strategic partnership with Brookfield. We own a 49% interest in Westinghouse.We are enhancing our ability to compete for more business by investing in additional nuclear fuel cycle assets that we expect will augment the core of our business and offer more solutions to our customers across the nuclear fuel cycle. Like Cameco, Westinghouse has nuclear assets that are strategic, proven, licensed and permitted, and that are in geopolitically attractive jurisdictions. We expect these assets, like ours, will participate in the growing demand profile for nuclear energy.In 2025, our strategic positioning was further reinforced through a binding term sheet with the US Department of Commerce, to establish a long-term partnership aimed at accelerating the deployment of Westinghouse nuclear reactor technologies across the US. This partnership is expected to support the construction of at least US$80 billion in new Westinghouse reactors. Learn moreGlobal Laser EnrichmentWe are interested in the second largest value driver of the fuel cycle, enrichment, and have a 49% interest in Global Laser Enrichment LLC (GLE). GLE is the exclusive licensee of the proprietary SILEX laser enrichment technology, a third-generation uranium enrichment technology. We are the commercial lead for the GLE project with a 49% interest and starting in 2023, an option to attain a majority interest of up to 75% ownership.Learn more

Since 1990, Blind River has received Cameco's top award for safety performance, the Mary-Jean Mitchell Green Award, more times than any other Cameco facility.SafetyWe manage the safety of our workers through programs, systems, and standards, with our Safety, Health, Environment and Quality (SHEQ) Policy providing overarching guidance. There are many aspects of the management system that contribute to a safe work environment, a few examples include:Risk assessments help identify issues and determine the appropriate controls; the corrective action process verifies that incidents and near misses are reported, tracked, investigated and shared with colleagues; and emergency preparedness and planning prepare us to respond to serious incidents.We have developed 12 corporate safety standards to help protect our workers from our most common hazards. Some standards guide our general safety practices, such as our job hazard analysis and our job task observation, and other standards deal with specific hazardous situations (similar to other companies’ life saving rules): such as fall protection, confined space entry, rigging and hoisting, and control of hazardous energy (also referred to as lockout/tagout).Routine audits are conducted to monitor compliance with regulations and our own requirements. These and other aspects of the management system are routinely examined to verify that they continue to be effective at keeping our workers safe.Radiation ProtectionRadiation risks are effectively managed at Blind River through a formal radiation protection program and dedicated personnel who ensure that workers are safe. The program ensures that radiation protection is considered in the physical design of all facilities and operating procedures. It also provides for systematic monitoring of radiation in work areas and tracking the exposures of individual workers using a combination of monitoring devices and health testing. Radiation exposures at Blind River are far below regulatory limits.Environmental ProtectionAt Cameco, protection of the environment is one of our highest corporate priorities during all stages of our activities, from exploration through development, operations, decommissioning, and reclamation.We monitor our performance by tracking corporate and site-specific key performance indicators, conducting environmental monitoring programs, and regularly auditing our adherence to the requirements of these programs We use the information from all of our programs to help us to identify opportunities to improve.Environmental management systemWe have a ISO 14001-certified environmental management system used across our operating sites, which is supported by a corporate Environmental Management Program that outlines the operating requirements sites must meet. Our environmental management system encourages and promotes continuous adaptation of our practices based on new information and technologies.Environmental risk assessmentsWe complete environmental risk assessments to systematically identify, quantify, and to characterize the potential risks to the environment, workers, and the public. We use our environmental risk assessments to inform our decisions and actions. Additionally, we complete an iterative process, where required, to verify that our proposed measures to protect the environment and the public are effective. We review or update the assessments every five years, incorporating results from our environmental monitoring programs and other scientific advances.Corrective action processWe have a corrective action process in place to systematically investigate and address the causes of non-conformance to regulatory requirements or internal standards. The process includes classifying the non-conformance, assigning the appropriate level of investigation (dependent on incident significance), and tracking the recommended corrective actions to prevent and mitigate similar occurrences.AuditsTo support our culture of continuous improvement, our processes and operations undergo regular audits, including:Our environmental management system is audited by a third-party every three years as a requirement to maintain our ISO 14001 certification.Our SHEQ team conducts an internal audit of our SHEQ programs on a three-year cycle. The total audit scope is split in half and executed on a rotating basis. This means that all our sites undergo at least two audits to cover all aspects of our SHEQ programs within every three-year period. The audit follows the ISO 19001 process and encompasses our environmental and safety programs.We also maintain and implement an internal audit program at our corporate office. Results and recommendations from this systematic and documented process are presented to senior management, who are responsible for implementing them and correcting any deficiencies. The internal audit group reports to the audit and finance committee of the board.Environmental Incidents and Other Events​Environmental incidents and other events are reported to regulatory agencies as required by federal and provincial regulations. This includes releases to the environment reportable to Ontario Ministry of Environment's Spills Action Centre.If you have questions about any of the items posted here, please contact us.Latest incident or event:Posting DateApril 14, 2026Incident DateApril 13, 2026IncidentNon-Reportable SpillDetailsDuring the spring thaw, ground movement caused several drums containing uranium ore concentrates to topple. This resulted in a small release of uranium ore concentrate onto the paved surface.There was no risk of uranium escaping the facility boundary, and no risk to the health or safety of the public. The volume of material released was well below the reportable threshold of 200 kg.Corrective ActionDamaged drums and pallets were contained, and residual material was recovered. The area was radiation monitored until cleanup was completed. Cameco informed the Canadian Nuclear Safety Commission.Cameco Environmental Effect Ratingno measurable impact to the environment1Past reportingPosting DateApril 14, 2026Incident DateApril 13, 2026IncidentNon-Reportable SpillDetailsDuring the spring thaw, ground movement caused several drums containing uranium ore concentrates to topple. This resulted in a small release of uranium ore concentrate onto the paved surface.There was no risk of uranium escaping the facility boundary, and no risk to the health or safety of the public. The volume of material released was well below the reportable threshold of 200 kg.Corrective ActionDamaged drums and pallets were contained, and residual material was recovered. The area was radiation monitored until cleanup was completed. Cameco informed the Canadian Nuclear Safety Commission.Cameco Environmental Effect Ratingno measurable impact to the environment1Posting DateFebruary 18, 2026  Incident DateFebruary 9, 2026IncidentTransportation IncidentDetailsUpon opening a sea container at the Blind River Refinery, an employee identified a small amount of contamination on a drum and a very small amount of loose uranium on the plastic liner. There was no health or safety risk posed to the public or the environment.  Corrective ActionThe contaminated drum was cleaned, and the contaminated liner was disposed of in accordance with applicable regulatory requirements. The sea container was monitored for contamination and met release criteria in accordance with applicable regulatory requirements. Cameco notified the consignor and the Canadian Nuclear Safety Commission. Cameco Environmental Effect Ratingno measurable impact to the environment1Posting DateJanuary 12, 2026Incident DateDecember 15, 2025IncidentNon-Reportable SpillDetailsA lift truck carrying eight drums of uranium ore concentrate was involved in a single vehicle incident in the yard of the Blind River Refinery. The lift truck contacted an unmarked curb, covered by snow causing the truck to shift. Six of the eight drums were affected resulting in the release of approximately 150 kilograms of uranium ore concentrate onto the paved surface. There was no health or safety risk posed to the driver, public or the environment.Corrective ActionDamaged drums and pallets were contained, and residual material was recovered. The area was radiation monitored until cleanup was completed. Cameco notified the Canadian Nuclear Safety Commission.Cameco Environmental Effect Ratingnegligible impact 2Posting DateOctober. 21, 2025Incident DateSeptember 18, 2025IncidentERT ActivationDetailsA pull station was activated at the Blind River Refinery when a small fire was observed on a piece of equipment in the plant. The fire was extinguished using a nearby extinguisher. The emergency response team was activated. There was no health or safety risk posed to the workers or environment.Corrective ActionThe small fire was extinguished and cleaned up. The Canadian Nuclear Safety Commission was notified.Cameco Environmental Effect Ratingno measurable impact to the environment1Posting DateMarch 10, 2025Incident DateMarch 6, 2025IncidentTransportation Incident DetailsA tractor trailer carrying three full UO3 tote bins was involved in a minor vehicle incident while travelling south on Highway 12. A passenger vehicle pulled out in front of the tractor trailer causing the driver to swerve into the far lane attempting to avoid a collision but in doing so struck another vehicle with its trailer.There was no damage to the tractor trailer, nor the tote bins so the vehicle continued onto its intended destination.There was no health or safety risk posed to the public or the environment.Corrective ActionThe police were called and attended the scene. As there was no damage to the tractor trailer it continued to its intended destination.Cameco notified the Canadian Nuclear Safety Commission transport section.Cameco Environmental Effect Ratingno measurable impact to the environment1Posting DateFebruary 28, 2025 Incident DateFebruary 27, 2025 IncidentTransportation Incident DetailsA tractor trailer carrying three full UO3 tote bins was involved in a minor incident when stopped at a red traffic light in Blind River eastbound on Highway 17. A passenger vehicle, unable to stop due to slippery road conditions, rear-ended the tractor trailer. There was no damage to the tractor trailer or the tote bins, so the vehicle was able to safely continue onto its intended destination. There was no health or safety risk posed to the public or the environment. Corrective ActionThe police were called and representatives from Cameco and the trucking company attended the scene. As there was no damage to the tractor trailer continued to its intended destination. Cameco notified the Canadian Nuclear Safety Commission transport section. Cameco Environmental Effect Ratingno measurable impact to the environment1Posting DateJanuary 28, 2025Incident DateJanuary 23, 2025IncidentTransport Occurrence (Minor Vehicle Incident)DetailsA tractor trailer carrying a sea container of uranium ore concentrate was involved in a minor incident on Highway 401 east bound near Brockville, Ontario. A passenger vehicle was merging onto Highway 401 when its driver lost control, crossing all lanes and ending up in front of the truck.There was no damage to the trailer nor the sea container, and only minor damage to the front of the truck. The truck was still roadworthy and continued to its intended destination, Cameco’s Blind River Refinery.                             There was no health or safety risk posed to the public or the environment.Corrective ActionThe passenger vehicle was towed from the scene. There was no damage to the trailer or sea container, and only minor damage to the front of the truck. The truck continued to its intended destination. Cameco notified the Canadian Nuclear Safety Commission transport section.Cameco Environmental Effect Ratingno measurable impact to the environment1Posting DateNovember 29, 2024Incident DateNovember 28, 2024IncidentERT ActivationDetailsOn November 28, a pull station was activated at the Blind River Refinery when a small fire was observed inside of a 5-gallon plastic pail in the plant. The fire was extinguished using a nearby fire extinguisher.Due to the speedy response and action of the emergency response team there was no health or safety risk posed to the workers or the environment.Corrective ActionThe fire was extinguished and cleaned up. The Canadian Nuclear Safety Commission was notified.Cameco Environmental Effect Ratingno measurable impact to the environment1Posting DateJuly 30, 2024Incident DateJuly 1, 2024IncidentReportable Leak & DischargeDetailsOn June 26, 2024, when the glycol heating systems were drained for maintenance, a mechanical failure occurred. It was observed that the drain valve on number three coil was leaking glycol. A pipe cap was immediately installed to stop the leak. It was assumed the leak had been minimal and there was minimal glycol in the system since the coil had been isolated and drained in 2023 when it had failed.During a maintenance inspection, it was determined that glycol had passed through the sewage plant and was released to Lake Huron on July 1, 2024. A lab investigation estimates 70L of glycol had spilled.  There was no health or safety risk posed to the public, workers, or the environment by this release.Corrective ActionAn investigation is currently underway by Cameco to prevent future occurrences.The Canadian Nuclear Safety Commission, Town of Blind River and the Ministry of Environment, and Conservation and Parks have been notified.Cameco Environmental Effect Ratingno measurable impact to the environment1Posting DateMay 3, 2024Incident DateMay 2, 2024IncidentReportable SpillDetailsOn April 18, a sink hole was observed near two groundwater supply wells for the Blind River Refinery, close to the Mississaugi River. This sinkhole was located adjacent to the golf course, situated west of the parking lot, which is part of the Town property leased from Cameco. As a precautionary measure, we promptly cordoned off the affected area and initiated the process of determining next steps to have the underground well water supply line repaired. Cameco has been closely monitoring the sinkhole and noted no significant changes. On May 2, it was observed that there is now additional groundwater flow from the well line, carrying sediment and overflowing into the river.There was no health or safety risk posed to the public, workers, or the environment by the release of groundwater that had not been used by the refinery.Corrective ActionCameco is working to rectify the situation and has contacted a contractor to install a silt curtain and are in the process of securing hydrovac services. Additionally, Cameco is actively pursuing a separate contractor to repair the well supply line.The Canadian Nuclear Safety Commission, Town of Blind River and the Ministry of Environment, Conservation and Parks have been notified.Cameco Environmental Effect Ratingno measurable impact to the environment1Cameco Environmental Effect RatingLevel 1 - no measurable impact to the environmentLevel 2 - negligible impactLevel 3 - short-term, seasonal impactLevel 4 - mortality of some species, but not affecting ecosystem functionLevel 5 - impairment of ecosystem functionN/A - not applicableNotes1 Includes all releases to the environment reportable to Ontario Ministry of Environment's Spills Action Centre and other significant events.Waste ManagementSolid wastes contaminated by uranium are reprocessed, recycled and re-used to the extent possible. Waste materials that cannot be reprocessed, recycled or re-used are safely stored on site until appropriate disposal options are available.DecommissioningDetailed plans and financial guarantees are in place to restore the Blind River site to public use once the facility reaches the end of its productive life.Environmental AssessmentAll new significant changes to existing operations are subject to environmental assessments to identify potential effects on the environment.Regulatory OversightThe Blind River refinment facility is licensed and regulated by the Canadian Nuclear Safety Commission (CNSC). The operation is also subject to other federal and provincial regulations for the protection of people and the environment, including by Environment Canada and Ontario’s Ministry of the Environment. Federal and provincial regulators conduct regular site inspections and audits to verify that people and the environment are protected. Sustainability at CamecoWhen measuring the sustainability and ethical impact of a company, environmental, social and governance (ESG) are key factors considered by the public and investors. Sustainability and ESG matters have been an important focus at Cameco for many years and we have a strong performance record.Learn More

On January 18, 2023, the Canadian Nuclear Safety Commission (CNSC) announced that Cameco Fuel Manufacturing (CFM) has been granted a 20-year renewal of its Fuel Facility Operating Licence.The renewed licence allows CFM to operate until February 28, 2043, at which time CFM can request to renew the licence for another period. As part of this licence, CFM will participate in a comprehensive mid-point (10-year) review of its operational performance. This requirement is in addition to the regulatory oversight report meeting and compliance verification activities carried out annually.Safety is at the core of Cameco’s operations and activities, and throughout this renewed licence period we remain committed to the protection of people and the environment.For more information please contact:Sara ForseyManager, Public & Government Affairssara_forsey@cameco.com289.771.1007Why Request a 20-year Term?Over the last 15-20 years, the CNSC strengthened its regulatory framework, with clarity provided in CNSC regulatory documents (REGDOCs) and Canadian Standards Association (CSA) nuclear standards. As well, the CNSC has introduced annual oversight reviews for all of the facilities regulated by the CNSC. These enhancements along with strong performance, have led to increased licence terms of 10 or more years because there are mechanisms in place to ensure that facility operations remain safe and that there are opportunities for the Commission to review performance in a public proceeding.CFM has consistently received satisfactory rankings from the CNSC while meeting all CNSC and other regulatory obligations. CFM’s consistent performance during the current licence period demonstrates our commitment to safety and the protection of people and the environment.What is the Production Limit Change?Currently, CFM’s licence has a monthly production limit which is 125 megagrams (1 megagram = 1 tonne) uranium dioxide (UO2) as pellets during any calendar month. We are requesting a slightly revised licence limit of an annual amount of 1,650 tonnes of uranium as UO2.In order to establish a consistent unit of measure for our production limits at all of our Ontario facilities, we are requesting an annual production limit in tonnes of uranium as UO2 instead of in megagrams. Accounting for the change in unit of measurement, the requested production limit represents an increase of approximately 24%.We are requesting this increase so that our licence limit mirrors the actual production capacity of our facility and the change from the monthly limit to an annual limit ensures that we can flex our operations as needed to meet business demands. What this translates to is a greater security of supply by ensuring we can increase production should there be a disruption in operations for any reason at any time. It will also ensure that we are able to take on new business opportunities when they arise.Application:Cameco Fuel Manufacturing - Licence Renewal - Letter (PDF 2MB) 

The underlying message is clear to us: the fundamentals that have been steadily improving over the past several years gained further traction in 2025, and we expect these trends to continue through 2026 and beyond.- Tim Gitzel, Chief Executive Officer

2026 Q1 UpdateProductionMcArthur River ProductionCameco's Share (million lb)Three months ended March 31  20262025Change2026 Plan3.53.29%10.0 to 11.5In the first quarter of 2026, total packaged production from McArthur River and Key Lake was 5.0 million pounds (3.5 million pounds our share) compared to 4.6 million pounds (3.2 million pounds our share) in the first quarter of 2025.We continue to expect production of 14.0 to 16.5 million pounds (10.0 to 11.5 million pounds our share) in 2026.Maintenance ShutdownsAt the Key Lake mill, the annual maintenance shutdown will begin in the third quarter, which will include the installation of new infrastructure and repairs to major existing infrastructure. As a result of this work, the shutdown is expected to be longer than in previous years. There is no planned shutdown of the McArthur River mine in 2026. Labour RelationsA new collective agreement with the United Steelworkers Local 8914 was reached in April 2026, for a 3-year term, expiring in December 2028.See full Quarterly ReportEnvironment & SafetyWorker safety, environmental monitoring and proper decommissioning, after mining is completed, are of the utmost importance to Cameco.See moreReserves & ResourcesOur mineral reserves and resources are the foundation of our company and fundamental to our success.See more