EXHIBIT 99.13

CONSENT OF EXPERT

Reference is made to the Annual Report on Form 40-F
(the Form 40-F) of Cameco Corporation (the Corporation) to be filed with the United States Securities and Exchange Commission pursuant to the United States Securities Exchange Act of 1934, as amended.

I hereby consent to reference to my name and my involvement in the preparation of, or supervision of the preparation of, scientific and
technical information in the following instances:



| | (a) | under the headings Operations and Development Projects  Uranium Operating Properties  McArthur River/Key Lake, Operations and Development
Projects  Uranium Operating Properties  Inkai, Operations and Development Projects  Uranium Development Project  Cigar Lake, Mineral Reserves and Resources and Governance  Interest of
Experts in the Corporations Annual Information Form for the year ended December 31, 2012 dated February 22, 2013 for the McArthur River/Key Lake, Inkai and Cigar Lake properties; and
| | --- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------



| | (b) | under the headings Our Operations and Development Projects  Uranium Operating Properties  McArthur River/Key Lake, Our Operations and
Development Projects  Uranium Operating Properties  Inkai, Our Operations and Development Projects  Uranium Development Project  Cigar Lake and Mineral Reserves and Resources in Managements
Discussion and Analysis of Financial Condition and Results of Operation for the year ended December 31, 2012 dated February 11, 2013 for the McArthur River/Key Lake, Cigar Lake and Inkai properties,
| | --- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

(collectively the Technical Information) in the Form 40-F, and to the inclusion and incorporation by reference of information derived from
the Technical Information in the Form 40-F.

I also hereby consent to the incorporation by reference of such Technical
Information in the registration statements (Nos. 333-11736, 333-6180 and 333-139165) on Form S-8 for the Cameco Corporation Stock Option Plan, registration statement (No. 333-139324) on Form S-8 for the Cameco Corporation Employee Share Ownership
Plan and registration statement (No.333-181577) on Form F-10.

Sincerely,



|                       |  |                                                           
|---------------------- |  | ----------------------------------------------------------
|/s/ Alain G. Mainville
|Name:                  |  | Alain G. Mainville, P. Geo.                               
|Title:                 |  | Director, Mineral Resources Management, Cameco Corporation
|                       | 
|Date:                  |  | February 22, 2013