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Title: Autonomous Control Capabilities for Space Reactor Power Systems

Abstract

The National Aeronautics and Space Administration's (NASA's) Project Prometheus, the Nuclear Systems Program, is investigating a possible Jupiter Icy Moons Orbiter (JIMO) mission, which would conduct in-depth studies of three of the moons of Jupiter by using a space reactor power system (SRPS) to provide energy for propulsion and spacecraft power for more than a decade. Terrestrial nuclear power plants rely upon varying degrees of direct human control and interaction for operations and maintenance over a forty to sixty year lifetime. In contrast, an SRPS is intended to provide continuous, remote, unattended operation for up to fifteen years with no maintenance. Uncertainties, rare events, degradation, and communications delays with Earth are challenges that SRPS control must accommodate. Autonomous control is needed to address these challenges and optimize the reactor control design. In this paper, we describe an autonomous control concept for generic SRPS designs. The formulation of an autonomous control concept, which includes identification of high-level functional requirements and generation of a research and development plan for enabling technologies, is among the technical activities that are being conducted under the U.S. Department of Energy's Space Reactor Technology Program in support of the NASA's Project Prometheus. The findings from this programmore » are intended to contribute to the successful realization of the JIMO mission.« less

Authors:
; ; ;  [1]
  1. Oak Ridge National Laboratory. P.O. Box 2008, Oak Ridge, TN 37831-6010 (United States)
Publication Date:
OSTI Identifier:
20632871
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 699; Journal Issue: 1; Conference: STAIF 2004: 21. symposium on space nuclear power and propulsion: Human space exploration, space colonization, new frontiers and future concepts, Albuquerque, NM (United States), 8-11 Feb 2004; Other Information: DOI: 10.1063/1.1649625; (c) 2004 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; 22 GENERAL STUDIES OF NUCLEAR REACTORS; CONTROL; CONTROL SYSTEMS; DATA TRANSMISSION; DESIGN; FISSION; LIFETIME; MAINTENANCE; NASA; NUCLEAR POWER PLANTS; OPTIMIZATION; POWER SYSTEMS; REACTOR INSTRUMENTATION; REACTOR OPERATION; REACTOR TECHNOLOGY; SPACE POWER REACTORS; SPACE VEHICLES; NESDPS Office of Nuclear Energy Space and Defense Power Systems

Citation Formats

Wood, Richard T., Neal, John S., Brittain, C. Ray, and Mullens, James A.. Autonomous Control Capabilities for Space Reactor Power Systems. United States: N. p., 2004. Web. doi:10.1063/1.1649625.
Wood, Richard T., Neal, John S., Brittain, C. Ray, & Mullens, James A.. Autonomous Control Capabilities for Space Reactor Power Systems. United States. doi:10.1063/1.1649625.
Wood, Richard T., Neal, John S., Brittain, C. Ray, and Mullens, James A.. Wed . "Autonomous Control Capabilities for Space Reactor Power Systems". United States. doi:10.1063/1.1649625.
@article{osti_20632871,
title = {Autonomous Control Capabilities for Space Reactor Power Systems},
author = {Wood, Richard T. and Neal, John S. and Brittain, C. Ray and Mullens, James A.},
abstractNote = {The National Aeronautics and Space Administration's (NASA's) Project Prometheus, the Nuclear Systems Program, is investigating a possible Jupiter Icy Moons Orbiter (JIMO) mission, which would conduct in-depth studies of three of the moons of Jupiter by using a space reactor power system (SRPS) to provide energy for propulsion and spacecraft power for more than a decade. Terrestrial nuclear power plants rely upon varying degrees of direct human control and interaction for operations and maintenance over a forty to sixty year lifetime. In contrast, an SRPS is intended to provide continuous, remote, unattended operation for up to fifteen years with no maintenance. Uncertainties, rare events, degradation, and communications delays with Earth are challenges that SRPS control must accommodate. Autonomous control is needed to address these challenges and optimize the reactor control design. In this paper, we describe an autonomous control concept for generic SRPS designs. The formulation of an autonomous control concept, which includes identification of high-level functional requirements and generation of a research and development plan for enabling technologies, is among the technical activities that are being conducted under the U.S. Department of Energy's Space Reactor Technology Program in support of the NASA's Project Prometheus. The findings from this program are intended to contribute to the successful realization of the JIMO mission.},
doi = {10.1063/1.1649625},
journal = {AIP Conference Proceedings},
number = 1,
volume = 699,
place = {United States},
year = {Wed Feb 04 00:00:00 EST 2004},
month = {Wed Feb 04 00:00:00 EST 2004}
}
  • No abstract prepared.
  • The application of nuclear reactors for space power and/or propulsion presents some unique challenges regarding the operations and control of the power system. Terrestrial nuclear reactors employ varying degrees of human control and decision-making for operations and benefit from periodic human interaction for maintenance. In contrast, the control system of a space reactor power system (SRPS) employed for deep space missions must be able to accommodate unattended operations due to communications delays and periods of planetary occlusion while adapting to evolving or degraded conditions with no opportunity for repair or refurbishment. Thus, a SRPS control system must provide for operationalmore » autonomy. Oak Ridge National Laboratory (ORNL) has conducted an investigation of the state of the technology for autonomous control to determine the experience base in the nuclear power application domain, both for space and terrestrial use. It was found that control systems with varying levels of autonomy have been employed in robotic, transportation, spacecraft, and manufacturing applications. However, autonomous control has not been implemented for an operating terrestrial nuclear power plant nor has there been any experience beyond automating simple control loops for space reactors. Current automated control technologies for nuclear power plants are reasonably mature, and basic control for a SRPS is clearly feasible under optimum circumstances. However, autonomous control is primarily intended to account for the non optimum circumstances when degradation, failure, and other off-normal events challenge the performance of the reactor and near-term human intervention is not possible. Thus, the development and demonstration of autonomous control capabilities for the specific domain of space nuclear power operations is needed. This paper will discuss the findings of the ORNL study and provide a description of the concept of autonomy, its key characteristics, and a prospective functional architecture that can support SRPS control for an extended deep space mission. The desirable characteristics of autonomous control include intelligence, robustness, optimization, flexibility, and adaptability. The degree of autonomy that is necessary for a given mission will depend on resource constraints, performance goals, operational complexity, technological capabilities, and mission risk considerations. The prospective architectural framework employs a hierarchical structure to integrate needed control, diagnostic, and decision functions and thus enable autonomy. (authors)« less
  • Reliable reactor control is important to reactor safety, both in terrestrial and space systems. For a space system, where the time for communication to Earth is significant, autonomous control is imperative. Based on feedback from reactor diagnostics, a controller must be able to automatically adjust to changes in reactor temperature and power level to maintain nominal operation without user intervention. Model-based predictive control (MBPC) (Clarke 1994; Morari 1994) is investigated as a potential control methodology for reactor start-up and transient operation in the presence of an external source. Bragg-Sitton and Holloway (2004) assessed the applicability of MBPC to reactor start-upmore » from a cold, zero-power condition in the presence of a time-varying external radiation source, where large fluctuations in the external radiation source can significantly impact a reactor during start-up operations. The MBPC algorithm applied the point kinetics model to describe the reactor dynamics, using a single group of delayed neutrons; initial application considered a fast neutron lifetime (10-3 sec) to simplify calculations during initial controller analysis. The present study will more accurately specify the dynamics of a fast reactor, using a more appropriate fast neutron lifetime (10-7 sec) than in the previous work. Controller stability will also be assessed by carefully considering the dependencies of each component in the defined cost (objective) function and its subsequent effect on the selected 'optimal' control maneuvers.« less
  • Distributed digital control system for fossil power plants have been evolving in response to plant needs and technological progress. This paper describes a new monitoring and control system which was developed by building a new system architecture suitable for fossil power plants. The corresponding hardware and software were also developed. The new system covers the plant wide monitoring and control functions including data acquisition, boiler control, burner management, turbine control, auxiliaries control, and protection. The new system meets the need of present-day utilities.
  • This paper describes three key features of the development of an autonomous control strategy for space reactor systems. These include the development of a reactor simulation model for transient analysis, development of model-predictive control as part of the autonomous control strategy, and a fault detection and isolation module. The latter is interfaced with the control supervisor as part of a hierarchical control system. The approach has been applied to the nodal model of the SP-100 reactor with a thermo-electric generator. The results of application demonstrate the effectiveness of the control approach and its ability to reconfigure the control mode undermore » fault conditions. (authors)« less