Projects on steel‐making plant follow the stages of steel‐making plant system life cycle. In each life cycle stage, there are exit criteria to be fulfilled before a project can continue to the next stage. Among the exit criteria, we focus on one of the technical exit criteria, that is, the technology maturity. Technology maturity is measured using technical readiness level (TRL) and TRL concept has been largely adopted by numerous organizations and industry. However, the assignment of a certain TRL as one of the exit criteria of life cycle stages are not well adapted. In other words, TRL is not considered as a critical exit criteria of a system life cycle stages. In this paper, we would like to propose that the TRL should be one of the exit criteria of each life cycle stage. In this research, we propose a steel‐making plant system life cycle, define the technical readiness level for a steel‐making plant, and assign a target TRL for each life cycle stage as an exit criteria of that stage. The benefits of target TRL assignment to the life cycle stages are as follows: (1) the technical risk of developing/inserting a technology can be controlled on each life cycle stage, (2) the cost incurred if the technology to be developed/inserted is failed can be analyzed in each life cycle stage, and (3) as a standardization effort of technology readiness at each industrial plant life cycle stage. By directly assigning target TRL for each life cycle stages, we look forward to a more coordinated (in terms of exit criteria) and highly effective (in terms of technical risks identification and eventually project failure prevention) technology development and assessment processes.