Formal development of an operation monitoring and control system for nuclear reactors using Event-B method

Abstract

Nuclear power plants are complex systems with many regulations, requirements, procedures, and operational constraints. The future autonomous safety monitoring and control system of nuclear plants require a constructive method in integrating and aggregating the accumulated knowledge database normally written in human language. For safety critical systems, formal methods such as model checking and theorem proving are used for verifying its conformance of safety requirements. However, formal specifications and implemented application codes are virtually unreadable for domain experts. To enhance this communication bottleneck and to boost productivity, we use semantic web technology to relate formal specifications with ontologies that are human-readable and have formal semantics. We introduce a nuclear reactor ontology of controlled vocabulary to link elements in a physical system and its Event-B model (a formal method for system-level modeling and analysis). Controlled vocabulary provides several benefits. It is still construction of a spoken language and thus, human readable and transparent. Their formal semantics make it easy to integrate them to the counterparts in their specification. We can generate system logs those are both human and machine friendly. Practitioners can write ad hoc query using SPARQL Protocol and RDF Query Language (SPARQL). As a proof of concept of our methodology, we build a system for safety monitoring and control of a nuclear reactor. We prototype our monitoring system in Event-B model and verify that it satisfies safety requirements and constraints. Then we build an OWL 2 ontology for the semantic web from the Event-B model annotating all metrics and events of the system monitors.