Long-duration missions with limited solar exposure need a reliable power source to operate. This makes nuclear power sources (NPSs) an attractive alternative to solar energy for such missions. The implementation of the ESA Safety Policy on the Use of Nuclear Power Sources by the European Space Agency’s Independent Safety Office (ISO) provides a framework for ensuring the safe use of NPSs and sets a standard for future ESA missions. This article provides an overview of how the ISO is implementing the policy in the development and operation of the Argonaut mission, which serves as a valuable case study for understanding the practical application of the ESA safety policy and the importance of ensuring the safe use of NPSs in space.

The Nuclear Regulatory Commission has published its annual report to Congress on “abnormal occurrences” for the previous fiscal year, identifying a total of nine incidents in FY 2019.

An abnormal occurrence is defined by the NRC as an unscheduled incident or event that it determines to be significant from a public health or safety standpoint. The NRC uses specific criteria, updated in October 2017, for determining which events qualify.