Comparison of ex-USSR norms and current international practice in design of seismic resistant nuclear power plants

Seismic hazard has been estimated according to ex-USSR norms in the original designs of WWER type Nuclear Power Plants (NPP) in former Soviet Union as well as in all former east European countries. For some steps of the design the national standards has been also taken into account. The original ex-USSR norms and instructions has been several times changed and improved during the time. This contribution is dealing with the development of ex-USSR norms and regulations with the aim to recognise some most important differentiations in comparison with corresponding western or international ones from point of view of civil structures. The understanding of relations of these documents is very important for seismic qualification and upgrading of WWER-type, NPPs. The main Soviet/Russian Standards and Regulations related to the seismic design and qualification of NPP structures as SNiP II-A.12-69, VSN 15-78, SNiP II-7-81, PiNAE G-7-002-86, NTD SEV etc. have been taken into consideration and compared with western or international standards as IAEA 50-SG-S1, IAEA 50-SG-D15, KTA 2201.1-6, ASCE 4-86 etc. The numerical examples of structural seismic qualification has been elaborated according to different standards for better understanding and in order to determine the degree of safety referring to corresponding standards. The authors has tried also to take into account the way of application of ex-USSR norms. The comparison of different norms and regulations has been analysed and corresponding conclusions and recommendations have been derived. These conclusions and recommendations can be helpful by the seismic qualification and upgrading of WWER-type NPPs. (author)