Harmonization of IEEE 1012 and IEC 60880 standards regarding verification and validation of nuclear power plant safety systems software using model-based methodology

This paper compares two standards, namely IEC 60880 and IEEE 1012, and defines a harmonized core amongst them with regard to their verification and validation processes for the nuclear power plant instrumentation and control safety system software. The problem of harmonizing standards requires a transparent representation of standards in order to make comparison possible. A model-based methodology using SysML is used to establish this transparency. Transformation rules are a crucial part of the methodology. These enable the natural language used in a standard to be translated into structural and behavioural models in SysML. Due to the high level of ambiguity of natural language, certainty definition rules for objects and operations are established as well. The result is a rigorously developed harmonized core that is traceable to the parent standards. The core developed using our methodology supports the argument that there is no one-to-one mapping between major IEEE and IEC standards. Nevertheless, some intersections between them do exist, which support the opinion of other experts. The extent of the harmonization depends on the conformance or traceability. The methodology also offers promise to address the challenge of establishing a harmonized core and the formal transferability between future standards.