Comparison between IEC 60880 and IEC 61508 for Certification Purposes in the Nuclear Domain

In the nuclear domain, regulators have strict requirements for safety critical software. In this paper requirements in three documents (two software standards and the Common Position of nuclear domain regulators) were compared. The aim of the work was to find out how these requirements compare to each other in terms of strictness and scope, and to evaluate the usefulness of the documents for certification purposes. Another goal was to determine whether it is possible to choose only one of the standards as the basis of software certification. The nuclear domain software standard IEC 60880 provides requirements for the purpose of achieving highly reliable software. The standard is similar to the part 3 of IEC 61508 standard in the sense that it covers requirements for all software lifecycle activities. The Common Position document ”Licensing of safety critical software for nuclear reactors” states the requirements from the perspective of European nuclear regulators. The comparison was twofold. First, the absolute ‘shall’ requirements of a few key themes were extracted from all three documents. The strictness of these requirements was analyzed against each other. Second, to evaluate the documents’ usefulness for certification, the extent in which these themes were covered by each document was analyzed by expert judgment. The main result was that the use of IEC 60880 alone is not sufficient for software certification.