Probabilistic Risk Management Using Risk-Based Safety Goals for the Design of Spacecraft with Onboard Nuclear Reactor Systems

Abstract

A risk-management framework for space mission launches of nuclear reactors is presented in this paper. The framework is based on a set of risk-based safety goals and relies on decision-theoretic principles that advance system design from concept through operation. Because time-dependent behavior is inherent in space missions, a quasi-dynamic probabilistic risk assessment framework is described. We illustrate a use of the framework with a risk management example.A rationale for, and a trial set of, qualitative safety goals and quantitative design objectives for launching space nuclear power plants are presented. The rationale is based on background risks to the general public, on accident risks to the population in the area of the launch site and on other large-consequence single-event catastrophes. Guidance is also obtained from the safety goals developed by the U.S. Nuclear Regulatory Commission, the U.S. Department of Energy, and the Federal Aviation Administration. The quantitative design objectives developed and presented are also compared to the calculated risks of previous launches with radioisotope thermal-electric generators such as for the Galileo, Ulysses, and Cassini missions.