A national system to discover, warn, and inform on nuclear explosions and other nuclear events - background, needs, and requirements.

This report contains a first reporting of the FOI project "A national measurement, analysis, and reporting system for nuclear events - requirements and design", financed by the Swedish Civil Contingencies Agency (MSB). The goal of the project is to produce a design proposal for an increased and coherent Swedish national capability to detect, warn, and inform about nuclear events, with focus on nuclear explosions on Swedish territory or nearby areas. The system also should have the capability to detect other nuclear events, such as nuclear tests at larger distances, or smaller releases from nuclear facilities. Primarily, we discuss a system consisting of a number of stationary measurement sites equipped with different types of sensors combined with systems for communication, data analysis, and reporting. The report discusses needs and functional requirements based on an inventory of needs and an assessment of technical possibilities and limitations. The report contains a relatively thorough description of the processes in a nuclear explosion, and resulting effects, as well as relevant measurement and analysis techniques. Further, current measurement and analysis capabilities in Sweden are reviewed. These sections can also serve as a knowledge base for actors in the Swedish total defence.