The Fusion Nuclear Science Pathways Assessment (FNS-PA) is intended to provide information to the OFES on the research and development required to establish a basis for a demonstration fusion power plant. In the ITER era we are entering, the focus on plasma and nuclear science together is becoming more compelling and necessary. ITER will provide critical information on burning plasma physics, as well as a number of technological issues ranging from superconducting magnets to divertor survivability. The Test Blanket Module effort on ITER will provide experience with candidate blanket technologies, at neutron fluxes integrated over time (ITER's total plant life) of 0.3 MW-years/m². For comparison, a power plant is expected to produce 120-160 MW-year/m² over its lifetime, requiring the first wall and blankets to be replaced several times. There is clearly a need to pursue the nuclear aspects of fusion and integrate it with the plasma in order to close this and many other gaps that exist between ITER and a fusion power plant.

The report on "Priorities, Gaps and Opportunities: Toward a Long Range Strategic Plan for Magnetic Fusion Energy" (Greenwald report) and the "Research Needs for Magnetic Fusion Energy Sciences" (ReNeW report) have identified the many issues and research needs for a wide range of topics in fusion science. The present exercise is to dig deeper into the specification of research and development to a level allowing OFES to solicit proposals from the community. In the process this will also provide information to accurately motivate the whats, whys, hows, and whens of this research. Naturally there is an emphasis on the fusion nuclear science, but this will include research to access the required plasma conditions that support this as well.

The three main thrusts are 1) identify DEMO/power plant characteristics in some detail (parameters, assumptions) and roll these back to identify gaps and identify required R&D, 2) examine a series of FNS facility missions at a systems-analysis level to identify possible steps and the associated R&D, and 3) compile a list of research and development activities required to support both the pathway to DEMO and an FNS facility(s). Various members of the FNS-PA group (see below) are in the process of pulling together the information in a number of topical areas ranging from plasma-material interface test stands to generic R&D elements in fusion nuclear science. As part of our mission analysis, we are reviewing the existing FNS-Facility proposals and their design philosophies, to identify what R&D these infer.

Expert groups will be assembled from the community in a number of areas to work with the FNS-PA group to address detailed questions about the R&D needed, available facilities and their capabilities, leverage of international collaborations, and other aspects. As the assessment process evolves to the point of well-defined issues, time will be made available for overall community input and public discussion.

Members of the FNS-PA group:
M. Abdou, V. Chan, R. Fonck, R. Kurtz, S. Milora, J. Minervini, N. Morley, F. Najmabadi, H. Neilson, R. Nygren, M. Peng, D. Rej, R. Stambaugh, M. Tillack, G. Tynan, J. VanDam, D. Whyte, S. Willms, B. Wirth

DOE FNS-PA group:
S. Eckstrand, C. Kessel, M. Koepke, G. Nardella, E. Oktay, A. Opdenaker, E. Synakowski