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

demonstrably reliable control in proximity to stability boundaries, including excursions expected
during nominal operation, as well as off-normal or fault-triggered excursions. here we define offnormal
events as those transient phenomena that lie outside the envelope of noise and disturbances
that can be robustly stabilized. such events may be recoverable (but are not robustly controlled),
or may be unrecoverable; they must be responded to in an appropriate way to minimize
machine damage and down time. Their probability of occurrence must be reduced to an acceptable
level for power plant operation, and this must be accomplished through control design. Reliable
operation under nominally disturbed regimes (e.g., intermittent sawteeth, elms, or transient
magnetic island growth) falls under the stability research category. however, novel algorithmic
control and response solutions beyond nominal control are also needed for excursions requiring
transient changes of operating regime (e.g., response to loss of a diagnostic channel or key actuator),
rapid but controlled shutdown (e.g., identification of an impending unrecoverable state), or
emergency uncontrolled shutdown (e.g., identification of immediate unrecoverable state and insufficient
time for controlled shutdown, often envisioned as serving to mitigate potential system
damage).
enabling elements of these solutions include a quantifiably reliable systematic approach and corresponding
integrated system for response to off-normal events and fault-triggered excursions,
real-time predictors for proximity to key operational limits, algorithms and mechanisms for mitigating
damage, and recovery and cleanup strategies to rapidly restore plant availability. This will
require development and validation of theory-based predictors for proximity to stability boundaries,
including assessment of the potential for and development of empirical data-based learning
systems. Provable algorithms for response to various off-normal or fault events must be developed
to deal with degradation or loss of diagnostic data or of actuator performance, impending
or current plasma regime excursion, unexpected disturbances, and impending or current loss
of controllability. control scenarios for controlled (“soft”) shutdown, as well as for preventing or
minimizing device damage during large-scale off-normal events, must be developed.
RELiabiLity anD CERtiFiCatiOn
key solutions are required to quantify performance, risk, and reliability of an operating fusion
power plant. The results of this area of research will enable licensing, certification, and economic
attractiveness of a realizable power plant. Research requirements identified for control reliability
and certification include methods for executing performance assessment (systematically quantifying
performance reliability), and methods for failure modes and effects analysis, a systematic
approach to identifying potential system failure modes, causes, and effects on fusion plant operation.
MODELing anD DESign
most of the requirements for comprehensive high reliability control of fusion power plants rest on
the ability to model and design control solutions with specified and/or quantifiable performance.
This in turn requires computational tools for producing control-level models, integrated and sufficiently
comprehensive simulations, and real-time predictive models for on-line controller adjustment
or operating regime identification. Research requirements identified for control model-
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