Evaluation of I and C architecture alternatives required for the jupiter Icy moons orbiter (JIMO) reactor
- Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37831 (United States)
- Athma-Tech., Inc., 306 Treyburn Drive, Knoxville, TN 37934 (United States)
This paper discusses alternative architectural considerations for instrumentation and control (I and C) systems in high-reliability applications to support remote, autonomous, inaccessible nuclear reactors, such as a space nuclear power plant (SNPP) for mission electrical power and space exploration propulsion. This work supported the pre-conceptual design of the reactor control system for the Jupiter Icy Moons Orbiter (JIMO) mission. Long-term continuous operation without intermediate maintenance cycles forces consideration of alternatives to commonly used active, N-multiple redundancy techniques for high-availability systems. Long space missions, where mission duration can exceed the 50% reliability limit of constituent components, can make active, N-multiple redundant systems less reliable than simplex systems. To extend a control system lifetime beyond the 50% reliability limits requires incorporation of passive redundancy of functions. Time-dependent availability requirements must be factored into the use of combinations of active and passive redundancy techniques for different mission phases. Over the course of a 12 to 20-year mission, reactor control, power conversion, and thermal management system components may fail, and the I and C system must react and adjust to accommodate these failures and protect non-failed components to continue the mission. This requires architectural considerations to accommodate partial system failures and to adapt to multiple control schemes according to the state of non-failed components without going through a complete shutdown and restart cycle. Relevant SNPP I and C architecture examples provide insights into real-time fault tolerance and long-term reliability and availability beyond time periods normally associated with terrestrial power reactor I and C systems operating cycles. I and C architectures from aerospace systems provide examples of highly reliable and available control systems associated with short- and long-term space system operations. Reliability concepts are discussed, and differences between various redundancy management schemes are compared. Mission time-dependent availability requirements indicate that a SNPP I and C might employ different types of redundancy at different times in a mission. Conclusions are drawn regarding appropriate architectural features relative to mission duration and control system availability requirements. (authors)
- Research Organization:
- American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
- OSTI ID:
- 22030121
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DESIGN
ENERGY CONVERSION
FAILURES
NESDPS Office of Nuclear Energy Space and Defense Power Systems
NUCLEAR POWER PLANTS
REACTOR CONTROL SYSTEMS
REACTOR INSTRUMENTATION
REACTOR SHUTDOWN
REAL TIME SYSTEMS
REDUNDANCY
RELIABILITY
SPACE PROPULSION REACTORS
TIME DEPENDENCE