German - Ukrainian collaboration in the assessment of digital I and C systems for safety applications in NPPs

German - Ukrainian collaboration in safety assessment of digital Instrumentation and Control (IC) systems began to be in progress since 1995 as part of the established collaboration in the field of Ukrainian NPP safety declared by the German Ministry BMU and Ukrainian Ministry of Environmental Protection and Nuclear Safety and aimed at the support of the Ukrainian Regulatory Body in supervision and licensing of NPPs. The collaboration in IC was triggered by the contract between Rovno NPP (Ukraine) and Siemens (Germany) on procurement of digital emergency protection system for Unit 4. The collaboration has been realized between regulatory authorities and supporting organizations of both countries: GRS/ISTec - Germany and Nuclear Regulatory Authority and State Scientific Technical Center of Nuclear and Radiation Safety (SSTC NRS) - Ukraine. From the beginning the collaboration was intended to cover not only the single specific system, but also a great number of tasks concerned with safety assessment of digital IC systems. As a result the existing Ukrainian standards on IC assessment have been re-evaluated and supplemented by requirements concerning software-based digital IC safety systems. (authors)