Autonomous Control Concepts.pdf

1Richard T. Wood Oak Ridge National Laboratory presented at IWRES 2007 Seoul, Republic of Korea January 24–27, 2007 Autonomous Control Concepts The Oak Ridge National Laboratory (ORNL) is managed for the U.S. Department of Energy by UT-Battelle, LLC, under contract DE-AC-05-00OR22725. This work was performed by ORNL under the sponsorship of the National Aeronautics and Space Administration (NASA) Project Prometheus and was directed by DOE/NNSA Naval Reactors. Opinions and conclusions drawn by the author are not endorsed by DOE/NNSA Naval Reactors. Exploring the water worlds of Jupiter: Callisto, Ganymede, and Europa 2The JIMO Deep-Space Mission Planned to Use a Space Reactor System ? The Jupiter Icy Moons Orbiter, or JIMO, was to orbit three planet-sized moons of Jupiter—Callisto, Ganymede, and Europa— that may harbor vast oceans beneath their icy surfaces ? The JIMO mission would raise NASA’s capability for space exploration to a new level with the use of an electric propulsion system that is powered by a nuclear fission reactor ? This technology not only makes it possible to orbit three of the moons of Jupiter, it also opens the rest of the outer Solar System to detailed exploration in future missions 3The Requirements for a Deep-Space Mission Present Formidable Constraints Challenges for a Space Reactor Control System ? High sustained power ? Mass efficient ? Reliable ? Long-term operation ? Continuous operation ? No maintenance; inaccessible ? Communication time delay ? Severe environment 4Distinct Control Scenarios Must be Accommodated over Mission Lifetime ? Startup (sequence of actions/events) ? Power maneuvering (ascension, load following, and reduction) – Direct reactivity control (move control element) – Indirect inherent feedback control (manage heat removal) ? Response to off-normal events – Reactor protection (diversity and defense-in-depth — limitation, rapid runback) – Autonomous control (fault tolerance — detection, diagnosis,