BSafeML: A Model-Based Hazard Management Technique for Safety-Critical Systems Development

Effective management of hazards is at the heart of achieving acceptable safety for any safety-critical system. With the recent advancement in model-based systems engineering, various hazard management techniques have been proposed as a means to transition from a document-based paradigm, such as hazard logs implemented in a relational database to a model-based paradigm with standardized modeling languages. However, a review of the state-of-the-art has shown that the existing methods do not provide sufficient traceability to integrate hazard management with other system lifecycle activities. To address this gap, a new model-based hazard management technique, BSafeML, is developed. BSafeML is a unified modeling language profile, and a procedure extending the existing systems modeling language and SafeML profiles with language for modeling the behavior of hazards and mitigations. BSafeML integrates the structural and behavioral views of hazards, supporting traceability and semantic consistency over them and with the wider system-of-interest. Specific behaviors supported by BSafeML include accident sequences and ordered action of safety functions. BSafeML is evaluated in a case study of a waste package emplacement system in the context of geological disposal of radioactive waste. A hazard log, including a range of hazard types, is converted to model-based format with BSafeML. The evaluation is further supported by a stakeholder survey that revealed mostly positive attitudes toward the safety function modeling by BSafeML.