The organization of the Generation IV Technology Roadmap is shown in the figure at the right. The Roadmap Integration Team (RIT) was the executive group. Groups of international experts were organized to undertake identification and evaluation of candidate systems, and to define R&D to support them.

In a first step, an Evaluation Methodology Group was formed to develop a process to systematically evaluate the potential of proposed Generation IV nuclear energy systems to meet the Generation IV goals. At the same time, a solicitation was issued worldwide, requesting that concept proponents submit information on nuclear energy systems that they believe could meet some or all of the Generation IV goals. Nearly 100 concepts and ideas were received from researchers in a dozen countries. Technical Working Groups (TWGs) were formed covering nuclear energy systems employing water-cooled, gas-cooled, liquid-metal-cooled, and non-classical reactor concepts to review the proposed systems and evaluate their potential using the tools developed by the Evaluation Methodology Group. Because of the large number of system concepts submitted, the TWGs collected their concepts into sets of concepts with similar attributes. The TWGs conducted an initial screening, termed screening for potential, to eliminate those concepts or concept sets that did not have reasonable potential for advancing the goals, or were too distant or technically infeasible. Following the screening for potential, the TWGs conducted a final screening to assess more quantitatively the potential of each concept or concept set to meet the Generation IV goals.

A Fuel Cycle Crosscut Group (FCCG) was also formed at a very early stage to explore the impact of the choice of fuel cycle on major elements of sustainability especially waste management and fuel utilization. Their members were equally drawn from the working groups, allowing them to compare their insights and findings directly. Later, other Crosscut Groups were formed covering economics, risk and safety, fuels and materials, and energy products. The Crosscut Groups reviewed the TWG reports for consistency in the technical evaluations and subject treatment, and continued to make recommendations regarding the scope and priority for crosscutting R&D in their subject areas. Finally, the TWGs and Crosscut Groups worked together to report on the R&D needs and priorities of the most promising concepts.

The international experts that contributed to this roadmap represented all 10 GIF countries, with several experts from the Organization for Economic Cooperation and Development Nuclear Energy Agency, the European Commission, and the International Atomic Energy Agency. The selection of the systems to be developed as Generation IV was accomplished in the following steps:

• Definition and evaluation of candidate systems
• Review of evaluations and discussion of desired missions (national priorities) for the systems
• Final review of evaluations and performance to missions
• Final decision on selections to Generation IV and identification of near-term deployable designs

The use of a common evaluation methodology is a central feature of the road-map project, providing a consistent basis for evaluating the potential of many concepts to meet the Generation IV goals. The Evaluation Methodology Group developed the methodology at an early stage in the project. The basic approach was to formulate a number of factors that indicate performance relative to the goals, called criteria, and then to evaluate concept performance against these criteria using specific measures, called metrics.

Near the end of the first step, the GIF met to conduct the second step of the selection process in February 2002. The GIF reviewed the preliminary evaluation results and discussed additional considerations that would be important to their final decision. These included a review of the important conclusions of the fuel cycle studies, which helped to suggest the various missions for Generation IV systems that were of interest: electricity and hydrogen production and actinide management.

A final review of the evaluations and performance to missions by the GIF Experts Group completed the third step in April 2002. The GIF met in May and July 2002 to conduct the fourth step. In brief, the candidate concepts that emerged from the final screening were discussed. Each was introduced with a presentation of the concept in terms of final evaluations, performance of missions, and estimated deployment dates and R&D costs. The Policy members discussed the concepts until a consensus was reached on six systems found to be the most promising and worthy of collaborative development.