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

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ex-vessel Considerations — tritium extraction from the in-vessel breeding zones, tritium processing<br />

of the plasma exhaust, and elements of power extraction associated with transporting<br />

hot coolant to the power conversion systems occur away from the plasma chamber. The primary<br />

ex-vessel constraints are: 1) radioactive hazards from tritium and other transmutation products<br />

hazards must be mitigated (e.g., exposure limits remain the same, while hazardous amount increases),<br />

2) tritium inventory must be minimized, efficiently processed, and strictly accounted <strong>for</strong>,<br />

and 3) heat carried by gas or liquid metal coolants must be efficiently utilized <strong>for</strong> electricity production<br />

or process heat.<br />

Guiding Principles — at each of the stages of development toward a demonstration of fusion energy<br />

( demo) there is a critical set of capabilities in Fnst that needs to be in place to proceed further.<br />

<strong>Fusion</strong> development in general, including all aspects of plasma physics research, requires authoritative<br />

in<strong>for</strong>mation on technology to evaluate technological readiness and identify paths toward<br />

a successful demo. While progress has been steady, new knowledge and increased ef<strong>for</strong>t is<br />

needed. Further progress can occur through an integrated program of well-instrumented benchmark<br />

and integrated experiments, first in labs, later in dedicated facilities and supported by validated<br />

computational models. even in the research stage, an emphasis on pathways that improve<br />

the safety and reliability, and not just the per<strong>for</strong>mance, must be sought out and emphasized.<br />

Proposed actions<br />

Approach — a host of gaps in sufficient understanding leading up to this Thrust have been identified<br />

and discussed in the harnessing <strong>Fusion</strong> Power Theme chapter. to optimally fill these gaps<br />

the following progression is proposed. First, fundamental research will be per<strong>for</strong>med. such experiments<br />

might not be prototypic (i.e., a test of “nearly final” component); rather this phase will<br />

focus on experiments designed to elucidate key, individual parameters and behaviors needed be<strong>for</strong>e<br />

more complex experiments can be successfully undertaken. This stage will be followed by experiments<br />

to understand multiple effects, e.g., more complex components, environmental conditions<br />

(heating, magnetic field, tritium, etc.) and subsequent synergistic phenomena. Finally, integrated<br />

tests will focus on the per<strong>for</strong>mance of a component in a fully representative operating<br />

environment, and/or of an overall facility. The overall progress is shown in Figure 2 and will be<br />

discussed in subsequent sections.<br />

Figure 2. Progression of Thrust 13 activities from fundamental research to integrated tests. Supporting integrated<br />

modeling is discussed in the description of Thrust 15.<br />

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