"Technology development progress should govern mission selection, with the goals of conducting the overall program at the lowest possible cost and maximizing science return from the individual missions. A set of decision gates will be laid out to indicate when mission targets must be selected and what criteria will be used. Generally the final selection will be made about 3 years prior to launch." [NASA/i]
Although technology development is analyzed by the Subcommittee, non-nuclear power supply is not an issue. Instead, one of the technology criteria are that "all top-priority needs can be met by existing programs" [NASA/i].
Other technology issues are lightweight, low-cost, high-performance chemical propulsion, sensor/detector and instrument development, and avionics development.