no: 1 CEMSIS 1 Potential for influencing standards and broadening collaboration N. Thuy EDF R&D

CEMSIS WP3_edf036_v01_FISA_November 2003 no: 2 Rule-based approaches vs. Claim-based approaches u Rule-based approaches l rules that give (reasonable) assurance for given properties l often: too rigid u Claim-based approaches l may be necessary for specific, unanticipated, or new issues l example: the RID3 project (EPRI)

CEMSIS WP3_edf036_v01_FISA_November 2003 no: 3 RID3 u Risk Informed Defense in Depth and Diversity l for digital I&C upgrades u Evaluation of potential for digital Common Cause Failure u Example: use of the same digital I&C platform in several lines of defence l claim: the operating system software is an unlikely source of digital CCF l claim: the application function library is also an unlikely source

CEMSIS WP3_edf036_v01_FISA_November 2003 no: 4 Revision of IEC u Current standard l lists of (highly) recommended methods / techniques l no clear indication of what is to be achieved u Revised standard l identification of essential properties to be achieved at each stage of the system / software safety lifecycles l gradation of the rigour of evidence according to Safety Integrity Level (SIL) —development process, assessment, independent assessment —technical evidence, + objective acceptance criteria, + rigorous reasoning l recommendation of methods / techniques —that may be used to achieve these properties —that meet the expected level of rigour (SIL)