Abstract: CANDU deuterium uranium reactor can be used to produce ⁶⁰Co radioactive sources, which has such advantages: high radioactivity, high production and low cost. 21 stainless steel adjuster rod assemblies used in CANDU were replaced by 21 cobalt adjuster rod assemblies at the same position, meeting the same functional requirements and producing ⁶⁰Co radioactive sources. Design requirements and structural design interfaces of cobalt adjuster rod assemblies were mainly discussed in the paper. Through structural integrity analysis, rod lifting and inserting time analysis and drop analysis, the safety of cobalt adjuster rod assemblies used in CANDU reactor is guaranteed. The safety and reliability of cobalt adjuster rod assembly structural design are proved by successful in-core operation experience.