The design analysis re-engineering tool - for design basis justification and safety related information management

DART is the acronym for the design analysis re-engineering tool. It embodies a systematic and integrated approach to NPP safety re-assessment and configuration management, that makes use of reverse failure mode and effect analysis in conjunction with a state-of-the-art relational database and a standardized data format, to permit long-term management of plant safety related information. The plant design is reviewed in a step-by-step logical fashion by constructing fault trees that identify the link between undesired consequences and their causes. Each failure cause identified in a fault tree is addressed by defining functional requirements, which are in turn addressed by documenting the specific manner in which the plant complies with the requirement. The database can then be used to generate up-to-date plant safety related documents, including: SAR, systems descriptions, technical specifications and plant procedures. The approach is open-minded by nature and therefore is not regulatory driven; however, the plant licensing basis is also intended to be reviewed and documented within the same database such that a regulatory conformance program may be integrated with the other safety documentation. This methodology can thus reconstitute the plant design bases in a comprehensive and systematic way, while allowing one to uncover weaknesses in design. The original feature of the DART methodology is that it links all the safety related documents together, facilitating the evaluation of the safety impact resulting from any plant modification. Due to its capability to retrieve the basic justifications of the plant design, it is also a useful tool for training the young generation of plant personnel. The DART methodology has been developed for application to units 2, 3 and 4 at Vattenfall's Ringhals site in Sweden. It may be applied to any nuclear power plant or industrial facility where public safety is a concern. (orig.)