Research Needs for Magnetic Fusion Energy Sciences - US Burning ...

ex-vessel Considerations — tritium extraction from the in-vessel breeding zones, tritium processing
of the plasma exhaust, and elements of power extraction associated with transporting
hot coolant to the power conversion systems occur away from the plasma chamber. The primary
ex-vessel constraints are: 1) radioactive hazards from tritium and other transmutation products
hazards must be mitigated (e.g., exposure limits remain the same, while hazardous amount increases),
2) tritium inventory must be minimized, efficiently processed, and strictly accounted for,
and 3) heat carried by gas or liquid metal coolants must be efficiently utilized for electricity production
or process heat.
Guiding Principles — at each of the stages of development toward a demonstration of fusion energy
( demo) there is a critical set of capabilities in Fnst that needs to be in place to proceed further.
Fusion development in general, including all aspects of plasma physics research, requires authoritative
information on technology to evaluate technological readiness and identify paths toward
a successful demo. While progress has been steady, new knowledge and increased effort is
needed. Further progress can occur through an integrated program of well-instrumented benchmark
and integrated experiments, first in labs, later in dedicated facilities and supported by validated
computational models. even in the research stage, an emphasis on pathways that improve
the safety and reliability, and not just the performance, must be sought out and emphasized.
Proposed actions
Approach — a host of gaps in sufficient understanding leading up to this Thrust have been identified
and discussed in the harnessing Fusion Power Theme chapter. to optimally fill these gaps
the following progression is proposed. First, fundamental research will be performed. such experiments
might not be prototypic (i.e., a test of “nearly final” component); rather this phase will
focus on experiments designed to elucidate key, individual parameters and behaviors needed before
more complex experiments can be successfully undertaken. This stage will be followed by experiments
to understand multiple effects, e.g., more complex components, environmental conditions
(heating, magnetic field, tritium, etc.) and subsequent synergistic phenomena. Finally, integrated
tests will focus on the performance of a component in a fully representative operating
environment, and/or of an overall facility. The overall progress is shown in Figure 2 and will be
discussed in subsequent sections.
Figure 2. Progression of Thrust 13 activities from fundamental research to integrated tests. Supporting integrated
modeling is discussed in the description of Thrust 15.
335